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perlapi(1)             Perl Programmers Reference Guide             perlapi(1)




NAME

       perlapi - autogenerated documentation for the perl public API


DESCRIPTION

       This file contains the documentation of the perl public API generated
       by embed.pl, specifically a listing of functions, macros, flags, and
       variables that may be used by extension writers.  At the end is a list
       of functions which have yet to be documented.  The interfaces of those
       are subject to change without notice.  Anything not listed here is not
       part of the public API, and should not be used by extension writers at
       all.  For these reasons, blindly using functions listed in proto.h is
       to be avoided when writing extensions.

       Note that all Perl API global variables must be referenced with the
       "PL_" prefix.  Again, those not listed here are not to be used by
       extension writers, and can be changed or removed without notice; same
       with macros.  Some macros are provided for compatibility with the
       older, unadorned names, but this support may be disabled in a future
       release.

       Perl was originally written to handle US-ASCII only (that is characters
       whose ordinal numbers are in the range 0 - 127).  And documentation and
       comments may still use the term ASCII, when sometimes in fact the
       entire range from 0 - 255 is meant.

       Note that Perl can be compiled and run under EBCDIC (See perlebcdic) or
       ASCII.  Most of the documentation (and even comments in the code)
       ignore the EBCDIC possibility.  For almost all purposes the differences
       are transparent.  As an example, under EBCDIC, instead of UTF-8, UTF-
       EBCDIC is used to encode Unicode strings, and so whenever this
       documentation refers to "utf8" (and variants of that name, including in
       function names), it also (essentially transparently) means
       "UTF-EBCDIC".  But the ordinals of characters differ between ASCII,
       EBCDIC, and the UTF- encodings, and a string encoded in UTF-EBCDIC may
       occupy more bytes than in UTF-8.

       The listing below is alphabetical, case insensitive.


"Gimme" Values

       GIMME   A backward-compatible version of "GIMME_V" which can only
               return "G_SCALAR" or "G_ARRAY"; in a void context, it returns
               "G_SCALAR".  Deprecated.  Use "GIMME_V" instead.

                       U32     GIMME

       GIMME_V The XSUB-writer's equivalent to Perl's "wantarray".  Returns
               "G_VOID", "G_SCALAR" or "G_ARRAY" for void, scalar or list
               context, respectively.  See perlcall for a usage example.

                       U32     GIMME_V

       G_ARRAY Used to indicate list context.  See "GIMME_V", "GIMME" and
               perlcall.

       G_DISCARD
               Indicates that arguments returned from a callback should be
               discarded.  See perlcall.

       G_EVAL  Used to force a Perl "eval" wrapper around a callback.  See
               perlcall.

       G_NOARGS
               Indicates that no arguments are being sent to a callback.  See
               perlcall.

       G_SCALAR
               Used to indicate scalar context.  See "GIMME_V", "GIMME", and
               perlcall.

       G_VOID  Used to indicate void context.  See "GIMME_V" and perlcall.


Array Manipulation Functions

       AvFILL  Same as "av_top_index()".  Deprecated, use "av_top_index()"
               instead.

                       int     AvFILL(AV* av)

       av_clear
               Clears an array, making it empty.  Does not free the memory the
               av uses to store its list of scalars.  If any destructors are
               triggered as a result, the av itself may be freed when this
               function returns.

               Perl equivalent: "@myarray = ();".

                       void    av_clear(AV *av)

       av_create_and_push
               NOTE: this function is experimental and may change or be
               removed without notice.

               Push an SV onto the end of the array, creating the array if
               necessary.  A small internal helper function to remove a
               commonly duplicated idiom.

                       void    av_create_and_push(AV **const avp,
                                                  SV *const val)

       av_create_and_unshift_one
               NOTE: this function is experimental and may change or be
               removed without notice.

               Unshifts an SV onto the beginning of the array, creating the
               array if necessary.  A small internal helper function to remove
               a commonly duplicated idiom.

                       SV**    av_create_and_unshift_one(AV **const avp,
                                                         SV *const val)

       av_delete
               Deletes the element indexed by "key" from the array, makes the
               element mortal, and returns it.  If "flags" equals "G_DISCARD",
               the element is freed and null is returned.  Perl equivalent:
               "my $elem = delete($myarray[$idx]);" for the non-"G_DISCARD"
               version and a void-context "delete($myarray[$idx]);" for the
               "G_DISCARD" version.

                       SV*     av_delete(AV *av, SSize_t key, I32 flags)

       av_exists
               Returns true if the element indexed by "key" has been
               initialized.

               This relies on the fact that uninitialized array elements are
               set to NULL.

               Perl equivalent: "exists($myarray[$key])".

                       bool    av_exists(AV *av, SSize_t key)

       av_extend
               Pre-extend an array.  The "key" is the index to which the array
               should be extended.

                       void    av_extend(AV *av, SSize_t key)

       av_fetch
               Returns the SV at the specified index in the array.  The "key"
               is the index.  If lval is true, you are guaranteed to get a
               real SV back (in case it wasn't real before), which you can
               then modify.  Check that the return value is non-null before
               dereferencing it to a "SV*".

               See "Understanding the Magic of Tied Hashes and Arrays" in
               perlguts for more information on how to use this function on
               tied arrays.

               The rough perl equivalent is $myarray[$idx].

                       SV**    av_fetch(AV *av, SSize_t key, I32 lval)

       av_fill Set the highest index in the array to the given number,
               equivalent to Perl's "$#array = $fill;".

               The number of elements in the an array will be "fill + 1" after
               av_fill() returns.  If the array was previously shorter, then
               the additional elements appended are set to NULL.  If the array
               was longer, then the excess elements are freed.  "av_fill(av,
               -1)" is the same as "av_clear(av)".

                       void    av_fill(AV *av, SSize_t fill)

       av_len  Same as "av_top_index".  Returns the highest index in the
               array.  Note that the return value is +1 what its name implies
               it returns; and hence differs in meaning from what the
               similarly named "sv_len" returns.

                       SSize_t av_len(AV *av)

       av_make Creates a new AV and populates it with a list of SVs.  The SVs
               are copied into the array, so they may be freed after the call
               to av_make.  The new AV will have a reference count of 1.

               Perl equivalent: "my @new_array = ($scalar1, $scalar2,
               $scalar3...);"

                       AV*     av_make(SSize_t size, SV **strp)

       av_pop  Removes one SV from the end of the array, reducing its size by
               one and returning the SV (transferring control of one reference
               count) to the caller.  Returns &PL_sv_undef if the array is
               empty.

               Perl equivalent: "pop(@myarray);"

                       SV*     av_pop(AV *av)

       av_push Pushes an SV onto the end of the array.  The array will grow
               automatically to accommodate the addition.  This takes
               ownership of one reference count.

               Perl equivalent: "push @myarray, $elem;".

                       void    av_push(AV *av, SV *val)

       av_shift
               Removes one SV from the start of the array, reducing its size
               by one and returning the SV (transferring control of one
               reference count) to the caller.  Returns &PL_sv_undef if the
               array is empty.

               Perl equivalent: "shift(@myarray);"

                       SV*     av_shift(AV *av)

       av_store
               Stores an SV in an array.  The array index is specified as
               "key".  The return value will be NULL if the operation failed
               or if the value did not need to be actually stored within the
               array (as in the case of tied arrays).  Otherwise, it can be
               dereferenced to get the "SV*" that was stored there (= "val")).

               Note that the caller is responsible for suitably incrementing
               the reference count of "val" before the call, and decrementing
               it if the function returned NULL.

               Approximate Perl equivalent: "$myarray[$key] = $val;".

               See "Understanding the Magic of Tied Hashes and Arrays" in
               perlguts for more information on how to use this function on
               tied arrays.

                       SV**    av_store(AV *av, SSize_t key, SV *val)

       av_tindex
               Same as "av_top_index()".

                       int     av_tindex(AV* av)

       av_top_index
               Returns the highest index in the array.  The number of elements
               in the array is "av_top_index(av) + 1".  Returns -1 if the
               array is empty.

               The Perl equivalent for this is $#myarray.

               (A slightly shorter form is "av_tindex".)

                       SSize_t av_top_index(AV *av)

       av_undef
               Undefines the array.  Frees the memory used by the av to store
               its list of scalars.  If any destructors are triggered as a
               result, the av itself may be freed.

                       void    av_undef(AV *av)

       av_unshift
               Unshift the given number of "undef" values onto the beginning
               of the array.  The array will grow automatically to accommodate
               the addition.  You must then use "av_store" to assign values to
               these new elements.

               Perl equivalent: "unshift @myarray, ( (undef) x $n );"

                       void    av_unshift(AV *av, SSize_t num)

       get_av  Returns the AV of the specified Perl global or package array
               with the given name (so it won't work on lexical variables).
               "flags" are passed to "gv_fetchpv".  If "GV_ADD" is set and the
               Perl variable does not exist then it will be created.  If
               "flags" is zero and the variable does not exist then NULL is
               returned.

               Perl equivalent: "@{"$name"}".

               NOTE: the perl_ form of this function is deprecated.

                       AV*     get_av(const char *name, I32 flags)

       newAV   Creates a new AV.  The reference count is set to 1.

               Perl equivalent: "my @array;".

                       AV*     newAV()

       sortsv  Sort an array.  Here is an example:

                   sortsv(AvARRAY(av), av_top_index(av)+1, Perl_sv_cmp_locale);

               Currently this always uses mergesort.  See sortsv_flags for a
               more flexible routine.

                       void    sortsv(SV** array, size_t num_elts,
                                      SVCOMPARE_t cmp)

       sortsv_flags
               Sort an array, with various options.

                       void    sortsv_flags(SV** array, size_t num_elts,
                                            SVCOMPARE_t cmp, U32 flags)


Callback Functions

       call_argv
               Performs a callback to the specified named and package-scoped
               Perl subroutine with "argv" (a NULL-terminated array of
               strings) as arguments.  See perlcall.

               Approximate Perl equivalent: "&{"$sub_name"}(@$argv)".

               NOTE: the perl_ form of this function is deprecated.

                       I32     call_argv(const char* sub_name, I32 flags,
                                         char** argv)

       call_method
               Performs a callback to the specified Perl method.  The blessed
               object must be on the stack.  See perlcall.

               NOTE: the perl_ form of this function is deprecated.

                       I32     call_method(const char* methname, I32 flags)

       call_pv Performs a callback to the specified Perl sub.  See perlcall.

               NOTE: the perl_ form of this function is deprecated.

                       I32     call_pv(const char* sub_name, I32 flags)

       call_sv Performs a callback to the Perl sub whose name is in the SV.
               See perlcall.

               NOTE: the perl_ form of this function is deprecated.

                       I32     call_sv(SV* sv, VOL I32 flags)

       ENTER   Opening bracket on a callback.  See "LEAVE" and perlcall.

                               ENTER;

       eval_pv Tells Perl to "eval" the given string and return an SV* result.

               NOTE: the perl_ form of this function is deprecated.

                       SV*     eval_pv(const char* p, I32 croak_on_error)

       eval_sv Tells Perl to "eval" the string in the SV.  It supports the
               same flags as "call_sv", with the obvious exception of G_EVAL.
               See perlcall.

               NOTE: the perl_ form of this function is deprecated.

                       I32     eval_sv(SV* sv, I32 flags)

       FREETMPS
               Closing bracket for temporaries on a callback.  See "SAVETMPS"
               and perlcall.

                               FREETMPS;

       LEAVE   Closing bracket on a callback.  See "ENTER" and perlcall.

                               LEAVE;

       SAVETMPS
               Opening bracket for temporaries on a callback.  See "FREETMPS"
               and perlcall.

                               SAVETMPS;


Character case changing

       toFOLD  Converts the specified character to foldcase.  If the input is
               anything but an ASCII uppercase character, that input character
               itself is returned.  Variant "toFOLD_A" is equivalent.  (There
               is no equivalent "to_FOLD_L1" for the full Latin1 range, as the
               full generality of "toFOLD_uni" is needed there.)

                       U8      toFOLD(U8 ch)

       toFOLD_uni
               Converts the Unicode code point "cp" to its foldcase version,
               and stores that in UTF-8 in "s", and its length in bytes in
               "lenp".  Note that the buffer pointed to by "s" needs to be at
               least "UTF8_MAXBYTES_CASE+1" bytes since the foldcase version
               may be longer than the original character.

               The first code point of the foldcased version is returned (but
               note, as explained just above, that there may be more.)

                       UV      toFOLD_uni(UV cp, U8* s, STRLEN* lenp)

       toFOLD_utf8
               Converts the UTF-8 encoded character at "p" to its foldcase
               version, and stores that in UTF-8 in "s", and its length in
               bytes in "lenp".  Note that the buffer pointed to by "s" needs
               to be at least "UTF8_MAXBYTES_CASE+1" bytes since the foldcase
               version may be longer than the original character.

               The first code point of the foldcased version is returned (but
               note, as explained just above, that there may be more.)

               The input character at "p" is assumed to be well-formed.

                       UV      toFOLD_utf8(U8* p, U8* s, STRLEN* lenp)

       toLOWER Converts the specified character to lowercase.  If the input is
               anything but an ASCII uppercase character, that input character
               itself is returned.  Variant "toLOWER_A" is equivalent.

                       U8      toLOWER(U8 ch)

       toLOWER_L1
               Converts the specified Latin1 character to lowercase.  The
               results are undefined if the input doesn't fit in a byte.

                       U8      toLOWER_L1(U8 ch)

       toLOWER_LC
               Converts the specified character to lowercase using the current
               locale's rules, if possible; otherwise returns the input
               character itself.

                       U8      toLOWER_LC(U8 ch)

       toLOWER_uni
               Converts the Unicode code point "cp" to its lowercase version,
               and stores that in UTF-8 in "s", and its length in bytes in
               "lenp".  Note that the buffer pointed to by "s" needs to be at
               least "UTF8_MAXBYTES_CASE+1" bytes since the lowercase version
               may be longer than the original character.

               The first code point of the lowercased version is returned (but
               note, as explained just above, that there may be more.)

                       UV      toLOWER_uni(UV cp, U8* s, STRLEN* lenp)

       toLOWER_utf8
               Converts the UTF-8 encoded character at "p" to its lowercase
               version, and stores that in UTF-8 in "s", and its length in
               bytes in "lenp".  Note that the buffer pointed to by "s" needs
               to be at least "UTF8_MAXBYTES_CASE+1" bytes since the lowercase
               version may be longer than the original character.

               The first code point of the lowercased version is returned (but
               note, as explained just above, that there may be more.)

               The input character at "p" is assumed to be well-formed.

                       UV      toLOWER_utf8(U8* p, U8* s, STRLEN* lenp)

       toTITLE Converts the specified character to titlecase.  If the input is
               anything but an ASCII lowercase character, that input character
               itself is returned.  Variant "toTITLE_A" is equivalent.  (There
               is no "toTITLE_L1" for the full Latin1 range, as the full
               generality of "toTITLE_uni" is needed there.  Titlecase is not
               a concept used in locale handling, so there is no functionality
               for that.)

                       U8      toTITLE(U8 ch)

       toTITLE_uni
               Converts the Unicode code point "cp" to its titlecase version,
               and stores that in UTF-8 in "s", and its length in bytes in
               "lenp".  Note that the buffer pointed to by "s" needs to be at
               least "UTF8_MAXBYTES_CASE+1" bytes since the titlecase version
               may be longer than the original character.

               The first code point of the titlecased version is returned (but
               note, as explained just above, that there may be more.)

                       UV      toTITLE_uni(UV cp, U8* s, STRLEN* lenp)

       toTITLE_utf8
               Converts the UTF-8 encoded character at "p" to its titlecase
               version, and stores that in UTF-8 in "s", and its length in
               bytes in "lenp".  Note that the buffer pointed to by "s" needs
               to be at least "UTF8_MAXBYTES_CASE+1" bytes since the titlecase
               version may be longer than the original character.

               The first code point of the titlecased version is returned (but
               note, as explained just above, that there may be more.)

               The input character at "p" is assumed to be well-formed.

                       UV      toTITLE_utf8(U8* p, U8* s, STRLEN* lenp)

       toUPPER Converts the specified character to uppercase.  If the input is
               anything but an ASCII lowercase character, that input character
               itself is returned.  Variant "toUPPER_A" is equivalent.

                       U8      toUPPER(U8 ch)

       toUPPER_uni
               Converts the Unicode code point "cp" to its uppercase version,
               and stores that in UTF-8 in "s", and its length in bytes in
               "lenp".  Note that the buffer pointed to by "s" needs to be at
               least "UTF8_MAXBYTES_CASE+1" bytes since the uppercase version
               may be longer than the original character.

               The first code point of the uppercased version is returned (but
               note, as explained just above, that there may be more.)

                       UV      toUPPER_uni(UV cp, U8* s, STRLEN* lenp)

       toUPPER_utf8
               Converts the UTF-8 encoded character at "p" to its uppercase
               version, and stores that in UTF-8 in "s", and its length in
               bytes in "lenp".  Note that the buffer pointed to by "s" needs
               to be at least "UTF8_MAXBYTES_CASE+1" bytes since the uppercase
               version may be longer than the original character.

               The first code point of the uppercased version is returned (but
               note, as explained just above, that there may be more.)

               The input character at "p" is assumed to be well-formed.

                       UV      toUPPER_utf8(U8* p, U8* s, STRLEN* lenp)


Character classes

       This section is about functions (really macros) that classify
       characters into types, such as punctuation versus alphabetic, etc.
       Most of these are analogous to regular expression character classes.
       (See "POSIX Character Classes" in perlrecharclass.)  There are several
       variants for each class.  (Not all macros have all variants; each item
       below lists the ones valid for it.)  None are affected by "use bytes",
       and only the ones with "LC" in the name are affected by the current
       locale.

       The base function, e.g., "isALPHA()", takes an octet (either a "char"
       or a "U8") as input and returns a boolean as to whether or not the
       character represented by that octet is (or on non-ASCII platforms,
       corresponds to) an ASCII character in the named class based on
       platform, Unicode, and Perl rules.  If the input is a number that
       doesn't fit in an octet, FALSE is returned.

       Variant "isFOO_A" (e.g., "isALPHA_A()") is identical to the base
       function with no suffix "_A".

       Variant "isFOO_L1" imposes the Latin-1 (or EBCDIC equivlalent)
       character set onto the platform.  That is, the code points that are
       ASCII are unaffected, since ASCII is a subset of Latin-1.  But the non-
       ASCII code points are treated as if they are Latin-1 characters.  For
       example, "isWORDCHAR_L1()" will return true when called with the code
       point 0xDF, which is a word character in both ASCII and EBCDIC (though
       it represents different characters in each).

       Variant "isFOO_uni" is like the "isFOO_L1" variant, but accepts any UV
       code point as input.  If the code point is larger than 255, Unicode
       rules are used to determine if it is in the character class.  For
       example, "isWORDCHAR_uni(0x100)" returns TRUE, since 0x100 is LATIN
       CAPITAL LETTER A WITH MACRON in Unicode, and is a word character.

       Variant "isFOO_utf8" is like "isFOO_uni", but the input is a pointer to
       a (known to be well-formed) UTF-8 encoded string ("U8*" or "char*").
       The classification of just the first (possibly multi-byte) character in
       the string is tested.

       Variant "isFOO_LC" is like the "isFOO_A" and "isFOO_L1" variants, but
       the result is based on the current locale, which is what "LC" in the
       name stands for.  If Perl can determine that the current locale is a
       UTF-8 locale, it uses the published Unicode rules; otherwise, it uses
       the C library function that gives the named classification.  For
       example, "isDIGIT_LC()" when not in a UTF-8 locale returns the result
       of calling "isdigit()".  FALSE is always returned if the input won't
       fit into an octet.

       Variant "isFOO_LC_uvchr" is like "isFOO_LC", but is defined on any UV.
       It returns the same as "isFOO_LC" for input code points less than 256,
       and returns the hard-coded, not-affected-by-locale, Unicode results for
       larger ones.

       Variant "isFOO_LC_utf8" is like "isFOO_LC_uvchr", but the input is a
       pointer to a (known to be well-formed) UTF-8 encoded string ("U8*" or
       "char*").  The classification of just the first (possibly multi-byte)
       character in the string is tested.

       isALPHA Returns a boolean indicating whether the specified character is
               an alphabetic character, analogous to "m/[[:alpha:]]/".  See
               the top of this section for an explanation of variants
               "isALPHA_A", "isALPHA_L1", "isALPHA_uni", "isALPHA_utf8",
               "isALPHA_LC", "isALPHA_LC_uvchr", and "isALPHA_LC_utf8".

                       bool    isALPHA(char ch)

       isALPHANUMERIC
               Returns a boolean indicating whether the specified character is
               a either an alphabetic character or decimal digit, analogous to
               "m/[[:alnum:]]/".  See the top of this section for an
               explanation of variants "isALPHANUMERIC_A",
               "isALPHANUMERIC_L1", "isALPHANUMERIC_uni",
               "isALPHANUMERIC_utf8", "isALPHANUMERIC_LC",
               "isALPHANUMERIC_LC_uvchr", and "isALPHANUMERIC_LC_utf8".

                       bool    isALPHANUMERIC(char ch)

       isASCII Returns a boolean indicating whether the specified character is
               one of the 128 characters in the ASCII character set, analogous
               to "m/[[:ascii:]]/".  On non-ASCII platforms, it returns TRUE
               iff this character corresponds to an ASCII character.  Variants
               "isASCII_A()" and "isASCII_L1()" are identical to "isASCII()".
               See the top of this section for an explanation of variants
               "isASCII_uni", "isASCII_utf8", "isASCII_LC",
               "isASCII_LC_uvchr", and "isASCII_LC_utf8".  Note, however, that
               some platforms do not have the C library routine "isascii()".
               In these cases, the variants whose names contain "LC" are the
               same as the corresponding ones without.

               Also note, that because all ASCII characters are UTF-8
               invariant (meaning they have the exact same representation
               (always a single byte) whether encoded in UTF-8 or not),
               "isASCII" will give the correct results when called with any
               byte in any string encoded or not in UTF-8.  And similarly
               "isASCII_utf8" will work properly on any string encoded or not
               in UTF-8.

                       bool    isASCII(char ch)

       isBLANK Returns a boolean indicating whether the specified character is
               a character considered to be a blank, analogous to
               "m/[[:blank:]]/".  See the top of this section for an
               explanation of variants "isBLANK_A", "isBLANK_L1",
               "isBLANK_uni", "isBLANK_utf8", "isBLANK_LC",
               "isBLANK_LC_uvchr", and "isBLANK_LC_utf8".  Note, however, that
               some platforms do not have the C library routine "isblank()".
               In these cases, the variants whose names contain "LC" are the
               same as the corresponding ones without.

                       bool    isBLANK(char ch)

       isCNTRL Returns a boolean indicating whether the specified character is
               a control character, analogous to "m/[[:cntrl:]]/".  See the
               top of this section for an explanation of variants "isCNTRL_A",
               "isCNTRL_L1", "isCNTRL_uni", "isCNTRL_utf8", "isCNTRL_LC",
               "isCNTRL_LC_uvchr", and "isCNTRL_LC_utf8" On EBCDIC platforms,
               you almost always want to use the "isCNTRL_L1" variant.

                       bool    isCNTRL(char ch)

       isDIGIT Returns a boolean indicating whether the specified character is
               a digit, analogous to "m/[[:digit:]]/".  Variants "isDIGIT_A"
               and "isDIGIT_L1" are identical to "isDIGIT".  See the top of
               this section for an explanation of variants "isDIGIT_uni",
               "isDIGIT_utf8", "isDIGIT_LC", "isDIGIT_LC_uvchr", and
               "isDIGIT_LC_utf8".

                       bool    isDIGIT(char ch)

       isGRAPH Returns a boolean indicating whether the specified character is
               a graphic character, analogous to "m/[[:graph:]]/".  See the
               top of this section for an explanation of variants "isGRAPH_A",
               "isGRAPH_L1", "isGRAPH_uni", "isGRAPH_utf8", "isGRAPH_LC",
               "isGRAPH_LC_uvchr", and "isGRAPH_LC_utf8".

                       bool    isGRAPH(char ch)

       isIDCONT
               Returns a boolean indicating whether the specified character
               can be the second or succeeding character of an identifier.
               This is very close to, but not quite the same as the official
               Unicode property "XID_Continue".  The difference is that this
               returns true only if the input character also matches
               "isWORDCHAR".  See the top of this section for an explanation
               of variants "isIDCONT_A", "isIDCONT_L1", "isIDCONT_uni",
               "isIDCONT_utf8", "isIDCONT_LC", "isIDCONT_LC_uvchr", and
               "isIDCONT_LC_utf8".

                       bool    isIDCONT(char ch)

       isIDFIRST
               Returns a boolean indicating whether the specified character
               can be the first character of an identifier.  This is very
               close to, but not quite the same as the official Unicode
               property "XID_Start".  The difference is that this returns true
               only if the input character also matches "isWORDCHAR".  See the
               top of this section for an explanation of variants
               "isIDFIRST_A", "isIDFIRST_L1", "isIDFIRST_uni",
               "isIDFIRST_utf8", "isIDFIRST_LC", "isIDFIRST_LC_uvchr", and
               "isIDFIRST_LC_utf8".

                       bool    isIDFIRST(char ch)

       isLOWER Returns a boolean indicating whether the specified character is
               a lowercase character, analogous to "m/[[:lower:]]/".  See the
               top of this section for an explanation of variants "isLOWER_A",
               "isLOWER_L1", "isLOWER_uni", "isLOWER_utf8", "isLOWER_LC",
               "isLOWER_LC_uvchr", and "isLOWER_LC_utf8".

                       bool    isLOWER(char ch)

       isOCTAL Returns a boolean indicating whether the specified character is
               an octal digit, [0-7].  The only two variants are "isOCTAL_A"
               and "isOCTAL_L1"; each is identical to "isOCTAL".

                       bool    isOCTAL(char ch)

       isPRINT Returns a boolean indicating whether the specified character is
               a printable character, analogous to "m/[[:print:]]/".  See the
               top of this section for an explanation of variants "isPRINT_A",
               "isPRINT_L1", "isPRINT_uni", "isPRINT_utf8", "isPRINT_LC",
               "isPRINT_LC_uvchr", and "isPRINT_LC_utf8".

                       bool    isPRINT(char ch)

       isPSXSPC
               (short for Posix Space) Starting in 5.18, this is identical
               (experimentally) in all its forms to the corresponding
               "isSPACE()" macros.  ("Experimentally" means that this change
               may be backed out in 5.22 if field experience indicates that it
               was unwise.)  The locale forms of this macro are identical to
               their corresponding "isSPACE()" forms in all Perl releases.  In
               releases prior to 5.18, the non-locale forms differ from their
               "isSPACE()" forms only in that the "isSPACE()" forms don't
               match a Vertical Tab, and the "isPSXSPC()" forms do.  Otherwise
               they are identical.  Thus this macro is analogous to what
               "m/[[:space:]]/" matches in a regular expression.  See the top
               of this section for an explanation of variants "isPSXSPC_A",
               "isPSXSPC_L1", "isPSXSPC_uni", "isPSXSPC_utf8", "isPSXSPC_LC",
               "isPSXSPC_LC_uvchr", and "isPSXSPC_LC_utf8".

                       bool    isPSXSPC(char ch)

       isPUNCT Returns a boolean indicating whether the specified character is
               a punctuation character, analogous to "m/[[:punct:]]/".  Note
               that the definition of what is punctuation isn't as
               straightforward as one might desire.  See "POSIX Character
               Classes" in perlrecharclass for details.  See the top of this
               section for an explanation of variants "isPUNCT_A",
               "isPUNCT_L1", "isPUNCT_uni", "isPUNCT_utf8", "isPUNCT_LC",
               "isPUNCT_LC_uvchr", and "isPUNCT_LC_utf8".

                       bool    isPUNCT(char ch)

       isSPACE Returns a boolean indicating whether the specified character is
               a whitespace character.  This is analogous to what "m/\s/"
               matches in a regular expression.  Starting in Perl 5.18
               (experimentally), this also matches what "m/[[:space:]]/" does.
               ("Experimentally" means that this change may be backed out in
               5.22 if field experience indicates that it was unwise.)  Prior
               to 5.18, only the locale forms of this macro (the ones with
               "LC" in their names) matched precisely what "m/[[:space:]]/"
               does.  In those releases, the only difference, in the non-
               locale variants, was that "isSPACE()" did not match a vertical
               tab.  (See "isPSXSPC" for a macro that matches a vertical tab
               in all releases.)  See the top of this section for an
               explanation of variants "isSPACE_A", "isSPACE_L1",
               "isSPACE_uni", "isSPACE_utf8", "isSPACE_LC",
               "isSPACE_LC_uvchr", and "isSPACE_LC_utf8".

                       bool    isSPACE(char ch)

       isUPPER Returns a boolean indicating whether the specified character is
               an uppercase character, analogous to "m/[[:upper:]]/".  See the
               top of this section for an explanation of variants "isUPPER_A",
               "isUPPER_L1", "isUPPER_uni", "isUPPER_utf8", "isUPPER_LC",
               "isUPPER_LC_uvchr", and "isUPPER_LC_utf8".

                       bool    isUPPER(char ch)

       isWORDCHAR
               Returns a boolean indicating whether the specified character is
               a character that is a word character, analogous to what "m/\w/"
               and "m/[[:word:]]/" match in a regular expression.  A word
               character is an alphabetic character, a decimal digit, a
               connecting punctuation character (such as an underscore), or a
               "mark" character that attaches to one of those (like some sort
               of accent).  "isALNUM()" is a synonym provided for backward
               compatibility, even though a word character includes more than
               the standard C language meaning of alphanumeric.  See the top
               of this section for an explanation of variants "isWORDCHAR_A",
               "isWORDCHAR_L1", "isWORDCHAR_uni", "isWORDCHAR_utf8",
               "isWORDCHAR_LC", "isWORDCHAR_LC_uvchr", and
               "isWORDCHAR_LC_utf8".

                       bool    isWORDCHAR(char ch)

       isXDIGIT
               Returns a boolean indicating whether the specified character is
               a hexadecimal digit.  In the ASCII range these are
               "[0-9A-Fa-f]".  Variants "isXDIGIT_A()" and "isXDIGIT_L1()" are
               identical to "isXDIGIT()".  See the top of this section for an
               explanation of variants "isXDIGIT_uni", "isXDIGIT_utf8",
               "isXDIGIT_LC", "isXDIGIT_LC_uvchr", and "isXDIGIT_LC_utf8".

                       bool    isXDIGIT(char ch)


Cloning an interpreter

       perl_clone
               Create and return a new interpreter by cloning the current one.

               perl_clone takes these flags as parameters:

               CLONEf_COPY_STACKS - is used to, well, copy the stacks also,
               without it we only clone the data and zero the stacks, with it
               we copy the stacks and the new perl interpreter is ready to run
               at the exact same point as the previous one.  The pseudo-fork
               code uses COPY_STACKS while the threads->create doesn't.

               CLONEf_KEEP_PTR_TABLE - perl_clone keeps a ptr_table with the
               pointer of the old variable as a key and the new variable as a
               value, this allows it to check if something has been cloned and
               not clone it again but rather just use the value and increase
               the refcount.  If KEEP_PTR_TABLE is not set then perl_clone
               will kill the ptr_table using the function
               "ptr_table_free(PL_ptr_table); PL_ptr_table = NULL;", reason to
               keep it around is if you want to dup some of your own variable
               who are outside the graph perl scans, example of this code is
               in threads.xs create.

               CLONEf_CLONE_HOST - This is a win32 thing, it is ignored on
               unix, it tells perls win32host code (which is c++) to clone
               itself, this is needed on win32 if you want to run two threads
               at the same time, if you just want to do some stuff in a
               separate perl interpreter and then throw it away and return to
               the original one, you don't need to do anything.

                       PerlInterpreter* perl_clone(
                                            PerlInterpreter *proto_perl,
                                            UV flags
                                        )


Compile-time scope hooks

       BhkDISABLE
               NOTE: this function is experimental and may change or be
               removed without notice.

               Temporarily disable an entry in this BHK structure, by clearing
               the appropriate flag.  which is a preprocessor token indicating
               which entry to disable.

                       void    BhkDISABLE(BHK *hk, which)

       BhkENABLE
               NOTE: this function is experimental and may change or be
               removed without notice.

               Re-enable an entry in this BHK structure, by setting the
               appropriate flag.  which is a preprocessor token indicating
               which entry to enable.  This will assert (under -DDEBUGGING) if
               the entry doesn't contain a valid pointer.

                       void    BhkENABLE(BHK *hk, which)

       BhkENTRY_set
               NOTE: this function is experimental and may change or be
               removed without notice.

               Set an entry in the BHK structure, and set the flags to
               indicate it is valid.  which is a preprocessing token
               indicating which entry to set.  The type of ptr depends on the
               entry.

                       void    BhkENTRY_set(BHK *hk, which, void *ptr)

       blockhook_register
               NOTE: this function is experimental and may change or be
               removed without notice.

               Register a set of hooks to be called when the Perl lexical
               scope changes at compile time.  See "Compile-time scope hooks"
               in perlguts.

               NOTE: this function must be explicitly called as
               Perl_blockhook_register with an aTHX_ parameter.

                       void    Perl_blockhook_register(pTHX_ BHK *hk)


COP Hint Hashes

       cophh_2hv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Generates and returns a standard Perl hash representing the
               full set of key/value pairs in the cop hints hash cophh.  flags
               is currently unused and must be zero.

                       HV *    cophh_2hv(const COPHH *cophh, U32 flags)

       cophh_copy
               NOTE: this function is experimental and may change or be
               removed without notice.

               Make and return a complete copy of the cop hints hash cophh.

                       COPHH * cophh_copy(COPHH *cophh)

       cophh_delete_pv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_delete_pvn", but takes a nul-terminated string
               instead of a string/length pair.

                       COPHH * cophh_delete_pv(const COPHH *cophh,
                                               const char *key, U32 hash,
                                               U32 flags)

       cophh_delete_pvn
               NOTE: this function is experimental and may change or be
               removed without notice.

               Delete a key and its associated value from the cop hints hash
               cophh, and returns the modified hash.  The returned hash
               pointer is in general not the same as the hash pointer that was
               passed in.  The input hash is consumed by the function, and the
               pointer to it must not be subsequently used.  Use "cophh_copy"
               if you need both hashes.

               The key is specified by keypv and keylen.  If flags has the
               "COPHH_KEY_UTF8" bit set, the key octets are interpreted as
               UTF-8, otherwise they are interpreted as Latin-1.  hash is a
               precomputed hash of the key string, or zero if it has not been
               precomputed.

                       COPHH * cophh_delete_pvn(COPHH *cophh,
                                                const char *keypv,
                                                STRLEN keylen, U32 hash,
                                                U32 flags)

       cophh_delete_pvs
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_delete_pvn", but takes a literal string instead of
               a string/length pair, and no precomputed hash.

                       COPHH * cophh_delete_pvs(const COPHH *cophh,
                                                const char *key, U32 flags)

       cophh_delete_sv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_delete_pvn", but takes a Perl scalar instead of a
               string/length pair.

                       COPHH * cophh_delete_sv(const COPHH *cophh, SV *key,
                                               U32 hash, U32 flags)

       cophh_fetch_pv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_fetch_pvn", but takes a nul-terminated string
               instead of a string/length pair.

                       SV *    cophh_fetch_pv(const COPHH *cophh,
                                              const char *key, U32 hash,
                                              U32 flags)

       cophh_fetch_pvn
               NOTE: this function is experimental and may change or be
               removed without notice.

               Look up the entry in the cop hints hash cophh with the key
               specified by keypv and keylen.  If flags has the
               "COPHH_KEY_UTF8" bit set, the key octets are interpreted as
               UTF-8, otherwise they are interpreted as Latin-1.  hash is a
               precomputed hash of the key string, or zero if it has not been
               precomputed.  Returns a mortal scalar copy of the value
               associated with the key, or &PL_sv_placeholder if there is no
               value associated with the key.

                       SV *    cophh_fetch_pvn(const COPHH *cophh,
                                               const char *keypv,
                                               STRLEN keylen, U32 hash,
                                               U32 flags)

       cophh_fetch_pvs
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_fetch_pvn", but takes a literal string instead of a
               string/length pair, and no precomputed hash.

                       SV *    cophh_fetch_pvs(const COPHH *cophh,
                                               const char *key, U32 flags)

       cophh_fetch_sv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_fetch_pvn", but takes a Perl scalar instead of a
               string/length pair.

                       SV *    cophh_fetch_sv(const COPHH *cophh, SV *key,
                                              U32 hash, U32 flags)

       cophh_free
               NOTE: this function is experimental and may change or be
               removed without notice.

               Discard the cop hints hash cophh, freeing all resources
               associated with it.

                       void    cophh_free(COPHH *cophh)

       cophh_new_empty
               NOTE: this function is experimental and may change or be
               removed without notice.

               Generate and return a fresh cop hints hash containing no
               entries.

                       COPHH * cophh_new_empty()

       cophh_store_pv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_store_pvn", but takes a nul-terminated string
               instead of a string/length pair.

                       COPHH * cophh_store_pv(const COPHH *cophh,
                                              const char *key, U32 hash,
                                              SV *value, U32 flags)

       cophh_store_pvn
               NOTE: this function is experimental and may change or be
               removed without notice.

               Stores a value, associated with a key, in the cop hints hash
               cophh, and returns the modified hash.  The returned hash
               pointer is in general not the same as the hash pointer that was
               passed in.  The input hash is consumed by the function, and the
               pointer to it must not be subsequently used.  Use "cophh_copy"
               if you need both hashes.

               The key is specified by keypv and keylen.  If flags has the
               "COPHH_KEY_UTF8" bit set, the key octets are interpreted as
               UTF-8, otherwise they are interpreted as Latin-1.  hash is a
               precomputed hash of the key string, or zero if it has not been
               precomputed.

               value is the scalar value to store for this key.  value is
               copied by this function, which thus does not take ownership of
               any reference to it, and later changes to the scalar will not
               be reflected in the value visible in the cop hints hash.
               Complex types of scalar will not be stored with referential
               integrity, but will be coerced to strings.

                       COPHH * cophh_store_pvn(COPHH *cophh, const char *keypv,
                                               STRLEN keylen, U32 hash,
                                               SV *value, U32 flags)

       cophh_store_pvs
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_store_pvn", but takes a literal string instead of a
               string/length pair, and no precomputed hash.

                       COPHH * cophh_store_pvs(const COPHH *cophh,
                                               const char *key, SV *value,
                                               U32 flags)

       cophh_store_sv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "cophh_store_pvn", but takes a Perl scalar instead of a
               string/length pair.

                       COPHH * cophh_store_sv(const COPHH *cophh, SV *key,
                                              U32 hash, SV *value, U32 flags)


COP Hint Reading

       cop_hints_2hv
               Generates and returns a standard Perl hash representing the
               full set of hint entries in the cop cop.  flags is currently
               unused and must be zero.

                       HV *    cop_hints_2hv(const COP *cop, U32 flags)

       cop_hints_fetch_pv
               Like "cop_hints_fetch_pvn", but takes a nul-terminated string
               instead of a string/length pair.

                       SV *    cop_hints_fetch_pv(const COP *cop,
                                                  const char *key, U32 hash,
                                                  U32 flags)

       cop_hints_fetch_pvn
               Look up the hint entry in the cop cop with the key specified by
               keypv and keylen.  If flags has the "COPHH_KEY_UTF8" bit set,
               the key octets are interpreted as UTF-8, otherwise they are
               interpreted as Latin-1.  hash is a precomputed hash of the key
               string, or zero if it has not been precomputed.  Returns a
               mortal scalar copy of the value associated with the key, or
               &PL_sv_placeholder if there is no value associated with the
               key.

                       SV *    cop_hints_fetch_pvn(const COP *cop,
                                                   const char *keypv,
                                                   STRLEN keylen, U32 hash,
                                                   U32 flags)

       cop_hints_fetch_pvs
               Like "cop_hints_fetch_pvn", but takes a literal string instead
               of a string/length pair, and no precomputed hash.

                       SV *    cop_hints_fetch_pvs(const COP *cop,
                                                   const char *key, U32 flags)

       cop_hints_fetch_sv
               Like "cop_hints_fetch_pvn", but takes a Perl scalar instead of
               a string/length pair.

                       SV *    cop_hints_fetch_sv(const COP *cop, SV *key,
                                                  U32 hash, U32 flags)


Custom Operators

       custom_op_register
               Register a custom op.  See "Custom Operators" in perlguts.

               NOTE: this function must be explicitly called as
               Perl_custom_op_register with an aTHX_ parameter.

                       void    Perl_custom_op_register(pTHX_
                                                       Perl_ppaddr_t ppaddr,
                                                       const XOP *xop)

       custom_op_xop
               Return the XOP structure for a given custom op.  This macro
               should be considered internal to OP_NAME and the other access
               macros: use them instead.  This macro does call a function.
               Prior to 5.19.6, this was implemented as a function.

               NOTE: this function must be explicitly called as
               Perl_custom_op_xop with an aTHX_ parameter.

                       const XOP * Perl_custom_op_xop(pTHX_ const OP *o)

       XopDISABLE
               Temporarily disable a member of the XOP, by clearing the
               appropriate flag.

                       void    XopDISABLE(XOP *xop, which)

       XopENABLE
               Reenable a member of the XOP which has been disabled.

                       void    XopENABLE(XOP *xop, which)

       XopENTRY
               Return a member of the XOP structure.  which is a cpp token
               indicating which entry to return.  If the member is not set
               this will return a default value.  The return type depends on
               which.  This macro evaluates its arguments more than once.  If
               you are using "Perl_custom_op_xop" to retreive a "XOP *" from a
               "OP *", use the more efficient "XopENTRYCUSTOM" instead.

                               XopENTRY(XOP *xop, which)

       XopENTRYCUSTOM
               Exactly like "XopENTRY(XopENTRY(Perl_custom_op_xop(aTHX_ o),
               which)" but more efficient.  The which parameter is identical
               to "XopENTRY".

                               XopENTRYCUSTOM(const OP *o, which)

       XopENTRY_set
               Set a member of the XOP structure.  which is a cpp token
               indicating which entry to set.  See "Custom Operators" in
               perlguts for details about the available members and how they
               are used.  This macro evaluates its argument more than once.

                       void    XopENTRY_set(XOP *xop, which, value)

       XopFLAGS
               Return the XOP's flags.

                       U32     XopFLAGS(XOP *xop)


CV Manipulation Functions

       CvSTASH Returns the stash of the CV.  A stash is the symbol table hash,
               containing the package-scoped variables in the package where
               the subroutine was defined.  For more information, see
               perlguts.

               This also has a special use with XS AUTOLOAD subs.  See
               "Autoloading with XSUBs" in perlguts.

                       HV*     CvSTASH(CV* cv)

       get_cv  Uses "strlen" to get the length of "name", then calls
               "get_cvn_flags".

               NOTE: the perl_ form of this function is deprecated.

                       CV*     get_cv(const char* name, I32 flags)

       get_cvn_flags
               Returns the CV of the specified Perl subroutine.  "flags" are
               passed to "gv_fetchpvn_flags".  If "GV_ADD" is set and the Perl
               subroutine does not exist then it will be declared (which has
               the same effect as saying "sub name;").  If "GV_ADD" is not set
               and the subroutine does not exist then NULL is returned.

               NOTE: the perl_ form of this function is deprecated.

                       CV*     get_cvn_flags(const char* name, STRLEN len,
                                             I32 flags)


Debugging Utilities

       dump_all
               Dumps the entire optree of the current program starting at
               "PL_main_root" to "STDERR".  Also dumps the optrees for all
               visible subroutines in "PL_defstash".

                       void    dump_all()

       dump_packsubs
               Dumps the optrees for all visible subroutines in "stash".

                       void    dump_packsubs(const HV* stash)

       op_dump Dumps the optree starting at OP "o" to "STDERR".

                       void    op_dump(const OP *o)

       sv_dump Dumps the contents of an SV to the "STDERR" filehandle.

               For an example of its output, see Devel::Peek.

                       void    sv_dump(SV* sv)


Embedding Functions

       cv_clone
               Clone a CV, making a lexical closure.  proto supplies the
               prototype of the function: its code, pad structure, and other
               attributes.  The prototype is combined with a capture of outer
               lexicals to which the code refers, which are taken from the
               currently-executing instance of the immediately surrounding
               code.

                       CV *    cv_clone(CV *proto)

       cv_undef
               Clear out all the active components of a CV.  This can happen
               either by an explicit "undef &foo", or by the reference count
               going to zero.  In the former case, we keep the CvOUTSIDE
               pointer, so that any anonymous children can still follow the
               full lexical scope chain.

                       void    cv_undef(CV* cv)

       find_rundefsv
               Find and return the variable that is named $_ in the lexical
               scope of the currently-executing function.  This may be a
               lexical $_, or will otherwise be the global one.

                       SV *    find_rundefsv()

       find_rundefsvoffset
               DEPRECATED!  It is planned to remove this function from a
               future release of Perl.  Do not use it for new code; remove it
               from existing code.

               Find the position of the lexical $_ in the pad of the
               currently-executing function.  Returns the offset in the
               current pad, or "NOT_IN_PAD" if there is no lexical $_ in scope
               (in which case the global one should be used instead).
               "find_rundefsv" is likely to be more convenient.

               NOTE: the perl_ form of this function is deprecated.

                       PADOFFSET find_rundefsvoffset()

       load_module
               Loads the module whose name is pointed to by the string part of
               name.  Note that the actual module name, not its filename,
               should be given.  Eg, "Foo::Bar" instead of "Foo/Bar.pm".
               flags can be any of PERL_LOADMOD_DENY, PERL_LOADMOD_NOIMPORT,
               or PERL_LOADMOD_IMPORT_OPS (or 0 for no flags).  ver, if
               specified and not NULL, provides version semantics similar to
               "use Foo::Bar VERSION".  The optional trailing SV* arguments
               can be used to specify arguments to the module's import()
               method, similar to "use Foo::Bar VERSION LIST".  They must be
               terminated with a final NULL pointer.  Note that this list can
               only be omitted when the PERL_LOADMOD_NOIMPORT flag has been
               used.  Otherwise at least a single NULL pointer to designate
               the default import list is required.

               The reference count for each specified "SV*" parameter is
               decremented.

                       void    load_module(U32 flags, SV* name, SV* ver, ...)

       nothreadhook
               Stub that provides thread hook for perl_destruct when there are
               no threads.

                       int     nothreadhook()

       pad_add_anon
               Allocates a place in the currently-compiling pad (via
               "pad_alloc") for an anonymous function that is lexically scoped
               inside the currently-compiling function.  The function func is
               linked into the pad, and its "CvOUTSIDE" link to the outer
               scope is weakened to avoid a reference loop.

               One reference count is stolen, so you may need to do
               "SvREFCNT_inc(func)".

               optype should be an opcode indicating the type of operation
               that the pad entry is to support.  This doesn't affect
               operational semantics, but is used for debugging.

                       PADOFFSET pad_add_anon(CV *func, I32 optype)

       pad_add_name_pv
               Exactly like "pad_add_name_pvn", but takes a nul-terminated
               string instead of a string/length pair.

                       PADOFFSET pad_add_name_pv(const char *name, U32 flags,
                                                 HV *typestash, HV *ourstash)

       pad_add_name_pvn
               Allocates a place in the currently-compiling pad for a named
               lexical variable.  Stores the name and other metadata in the
               name part of the pad, and makes preparations to manage the
               variable's lexical scoping.  Returns the offset of the
               allocated pad slot.

               namepv/namelen specify the variable's name, including leading
               sigil.  If typestash is non-null, the name is for a typed
               lexical, and this identifies the type.  If ourstash is non-
               null, it's a lexical reference to a package variable, and this
               identifies the package.  The following flags can be OR'ed
               together:

                   padadd_OUR          redundantly specifies if it's a package var
                   padadd_STATE        variable will retain value persistently
                   padadd_NO_DUP_CHECK skip check for lexical shadowing

                       PADOFFSET pad_add_name_pvn(const char *namepv,
                                                  STRLEN namelen, U32 flags,
                                                  HV *typestash, HV *ourstash)

       pad_add_name_sv
               Exactly like "pad_add_name_pvn", but takes the name string in
               the form of an SV instead of a string/length pair.

                       PADOFFSET pad_add_name_sv(SV *name, U32 flags,
                                                 HV *typestash, HV *ourstash)

       pad_alloc
               NOTE: this function is experimental and may change or be
               removed without notice.

               Allocates a place in the currently-compiling pad, returning the
               offset of the allocated pad slot.  No name is initially
               attached to the pad slot.  tmptype is a set of flags indicating
               the kind of pad entry required, which will be set in the value
               SV for the allocated pad entry:

                   SVs_PADMY    named lexical variable ("my", "our", "state")
                   SVs_PADTMP   unnamed temporary store
                   SVf_READONLY constant shared between recursion levels

               "SVf_READONLY" has been supported here only since perl 5.20.
               To work with earlier versions as well, use
               "SVf_READONLY|SVs_PADTMP".  "SVf_READONLY" does not cause the
               SV in the pad slot to be marked read-only, but simply tells
               "pad_alloc" that it will be made read-only (by the caller), or
               at least should be treated as such.

               optype should be an opcode indicating the type of operation
               that the pad entry is to support.  This doesn't affect
               operational semantics, but is used for debugging.

                       PADOFFSET pad_alloc(I32 optype, U32 tmptype)

       pad_compname_type
               Looks up the type of the lexical variable at position po in the
               currently-compiling pad.  If the variable is typed, the stash
               of the class to which it is typed is returned.  If not, "NULL"
               is returned.

                       HV *    pad_compname_type(PADOFFSET po)

       pad_findmy_pv
               Exactly like "pad_findmy_pvn", but takes a nul-terminated
               string instead of a string/length pair.

                       PADOFFSET pad_findmy_pv(const char *name, U32 flags)

       pad_findmy_pvn
               Given the name of a lexical variable, find its position in the
               currently-compiling pad.  namepv/namelen specify the variable's
               name, including leading sigil.  flags is reserved and must be
               zero.  If it is not in the current pad but appears in the pad
               of any lexically enclosing scope, then a pseudo-entry for it is
               added in the current pad.  Returns the offset in the current
               pad, or "NOT_IN_PAD" if no such lexical is in scope.

                       PADOFFSET pad_findmy_pvn(const char *namepv,
                                                STRLEN namelen, U32 flags)

       pad_findmy_sv
               Exactly like "pad_findmy_pvn", but takes the name string in the
               form of an SV instead of a string/length pair.

                       PADOFFSET pad_findmy_sv(SV *name, U32 flags)

       pad_setsv
               Set the value at offset po in the current (compiling or
               executing) pad.  Use the macro PAD_SETSV() rather than calling
               this function directly.

                       void    pad_setsv(PADOFFSET po, SV *sv)

       pad_sv  Get the value at offset po in the current (compiling or
               executing) pad.  Use macro PAD_SV instead of calling this
               function directly.

                       SV *    pad_sv(PADOFFSET po)

       pad_tidy
               NOTE: this function is experimental and may change or be
               removed without notice.

               Tidy up a pad at the end of compilation of the code to which it
               belongs.  Jobs performed here are: remove most stuff from the
               pads of anonsub prototypes; give it a @_; mark temporaries as
               such.  type indicates the kind of subroutine:

                   padtidy_SUB        ordinary subroutine
                   padtidy_SUBCLONE   prototype for lexical closure
                   padtidy_FORMAT     format

                       void    pad_tidy(padtidy_type type)

       perl_alloc
               Allocates a new Perl interpreter.  See perlembed.

                       PerlInterpreter* perl_alloc()

       perl_construct
               Initializes a new Perl interpreter.  See perlembed.

                       void    perl_construct(PerlInterpreter *my_perl)

       perl_destruct
               Shuts down a Perl interpreter.  See perlembed.

                       int     perl_destruct(PerlInterpreter *my_perl)

       perl_free
               Releases a Perl interpreter.  See perlembed.

                       void    perl_free(PerlInterpreter *my_perl)

       perl_parse
               Tells a Perl interpreter to parse a Perl script.  See
               perlembed.

                       int     perl_parse(PerlInterpreter *my_perl,
                                          XSINIT_t xsinit, int argc,
                                          char** argv, char** env)

       perl_run
               Tells a Perl interpreter to run.  See perlembed.

                       int     perl_run(PerlInterpreter *my_perl)

       require_pv
               Tells Perl to "require" the file named by the string argument.
               It is analogous to the Perl code "eval "require '$file'"".
               It's even implemented that way; consider using load_module
               instead.

               NOTE: the perl_ form of this function is deprecated.

                       void    require_pv(const char* pv)


Functions in file dump.c

       pv_display
               Similar to

                 pv_escape(dsv,pv,cur,pvlim,PERL_PV_ESCAPE_QUOTE);

               except that an additional "\0" will be appended to the string
               when len > cur and pv[cur] is "\0".

               Note that the final string may be up to 7 chars longer than
               pvlim.

                       char*   pv_display(SV *dsv, const char *pv, STRLEN cur,
                                          STRLEN len, STRLEN pvlim)

       pv_escape
               Escapes at most the first "count" chars of pv and puts the
               results into dsv such that the size of the escaped string will
               not exceed "max" chars and will not contain any incomplete
               escape sequences.

               If flags contains PERL_PV_ESCAPE_QUOTE then any double quotes
               in the string will also be escaped.

               Normally the SV will be cleared before the escaped string is
               prepared, but when PERL_PV_ESCAPE_NOCLEAR is set this will not
               occur.

               If PERL_PV_ESCAPE_UNI is set then the input string is treated
               as Unicode, if PERL_PV_ESCAPE_UNI_DETECT is set then the input
               string is scanned using "is_utf8_string()" to determine if it
               is Unicode.

               If PERL_PV_ESCAPE_ALL is set then all input chars will be
               output using "\x01F1" style escapes, otherwise if
               PERL_PV_ESCAPE_NONASCII is set, only non-ASCII chars will be
               escaped using this style; otherwise, only chars above 255 will
               be so escaped; other non printable chars will use octal or
               common escaped patterns like "\n".  Otherwise, if
               PERL_PV_ESCAPE_NOBACKSLASH then all chars below 255 will be
               treated as printable and will be output as literals.

               If PERL_PV_ESCAPE_FIRSTCHAR is set then only the first char of
               the string will be escaped, regardless of max.  If the output
               is to be in hex, then it will be returned as a plain hex
               sequence.  Thus the output will either be a single char, an
               octal escape sequence, a special escape like "\n" or a hex
               value.

               If PERL_PV_ESCAPE_RE is set then the escape char used will be a
               '%' and not a '\\'.  This is because regexes very often contain
               backslashed sequences, whereas '%' is not a particularly common
               character in patterns.

               Returns a pointer to the escaped text as held by dsv.

                       char*   pv_escape(SV *dsv, char const * const str,
                                         const STRLEN count, const STRLEN max,
                                         STRLEN * const escaped,
                                         const U32 flags)

       pv_pretty
               Converts a string into something presentable, handling escaping
               via pv_escape() and supporting quoting and ellipses.

               If the PERL_PV_PRETTY_QUOTE flag is set then the result will be
               double quoted with any double quotes in the string escaped.
               Otherwise if the PERL_PV_PRETTY_LTGT flag is set then the
               result be wrapped in angle brackets.

               If the PERL_PV_PRETTY_ELLIPSES flag is set and not all
               characters in string were output then an ellipsis "..." will be
               appended to the string.  Note that this happens AFTER it has
               been quoted.

               If start_color is non-null then it will be inserted after the
               opening quote (if there is one) but before the escaped text.
               If end_color is non-null then it will be inserted after the
               escaped text but before any quotes or ellipses.

               Returns a pointer to the prettified text as held by dsv.

                       char*   pv_pretty(SV *dsv, char const * const str,
                                         const STRLEN count, const STRLEN max,
                                         char const * const start_color,
                                         char const * const end_color,
                                         const U32 flags)


Functions in file inline.h

       is_safe_syscall
               Test that the given "pv" doesn't contain any internal NUL
               characters.  If it does, set "errno" to ENOENT, optionally
               warn, and return FALSE.

               Return TRUE if the name is safe.

               Used by the IS_SAFE_SYSCALL() macro.

                       bool    is_safe_syscall(const char *pv, STRLEN len,
                                               const char *what,
                                               const char *op_name)


Functions in file mathoms.c

       custom_op_desc
               Return the description of a given custom op.  This was once
               used by the OP_DESC macro, but is no longer: it has only been
               kept for compatibility, and should not be used.

                       const char * custom_op_desc(const OP *o)

       custom_op_name
               Return the name for a given custom op.  This was once used by
               the OP_NAME macro, but is no longer: it has only been kept for
               compatibility, and should not be used.

                       const char * custom_op_name(const OP *o)

       gv_fetchmethod
               See "gv_fetchmethod_autoload".

                       GV*     gv_fetchmethod(HV* stash, const char* name)

       pack_cat
               The engine implementing pack() Perl function.  Note: parameters
               next_in_list and flags are not used.  This call should not be
               used; use packlist instead.

                       void    pack_cat(SV *cat, const char *pat,
                                        const char *patend, SV **beglist,
                                        SV **endlist, SV ***next_in_list,
                                        U32 flags)

       sv_2pvbyte_nolen
               Return a pointer to the byte-encoded representation of the SV.
               May cause the SV to be downgraded from UTF-8 as a side-effect.

               Usually accessed via the "SvPVbyte_nolen" macro.

                       char*   sv_2pvbyte_nolen(SV* sv)

       sv_2pvutf8_nolen
               Return a pointer to the UTF-8-encoded representation of the SV.
               May cause the SV to be upgraded to UTF-8 as a side-effect.

               Usually accessed via the "SvPVutf8_nolen" macro.

                       char*   sv_2pvutf8_nolen(SV* sv)

       sv_2pv_nolen
               Like "sv_2pv()", but doesn't return the length too.  You should
               usually use the macro wrapper "SvPV_nolen(sv)" instead.

                       char*   sv_2pv_nolen(SV* sv)

       sv_catpvn_mg
               Like "sv_catpvn", but also handles 'set' magic.

                       void    sv_catpvn_mg(SV *sv, const char *ptr,
                                            STRLEN len)

       sv_catsv_mg
               Like "sv_catsv", but also handles 'set' magic.

                       void    sv_catsv_mg(SV *dsv, SV *ssv)

       sv_force_normal
               Undo various types of fakery on an SV: if the PV is a shared
               string, make a private copy; if we're a ref, stop refing; if
               we're a glob, downgrade to an xpvmg.  See also
               "sv_force_normal_flags".

                       void    sv_force_normal(SV *sv)

       sv_iv   A private implementation of the "SvIVx" macro for compilers
               which can't cope with complex macro expressions.  Always use
               the macro instead.

                       IV      sv_iv(SV* sv)

       sv_nolocking
               Dummy routine which "locks" an SV when there is no locking
               module present.  Exists to avoid test for a NULL function
               pointer and because it could potentially warn under some level
               of strict-ness.

               "Superseded" by sv_nosharing().

                       void    sv_nolocking(SV *sv)

       sv_nounlocking
               Dummy routine which "unlocks" an SV when there is no locking
               module present.  Exists to avoid test for a NULL function
               pointer and because it could potentially warn under some level
               of strict-ness.

               "Superseded" by sv_nosharing().

                       void    sv_nounlocking(SV *sv)

       sv_nv   A private implementation of the "SvNVx" macro for compilers
               which can't cope with complex macro expressions.  Always use
               the macro instead.

                       NV      sv_nv(SV* sv)

       sv_pv   Use the "SvPV_nolen" macro instead

                       char*   sv_pv(SV *sv)

       sv_pvbyte
               Use "SvPVbyte_nolen" instead.

                       char*   sv_pvbyte(SV *sv)

       sv_pvbyten
               A private implementation of the "SvPVbyte" macro for compilers
               which can't cope with complex macro expressions.  Always use
               the macro instead.

                       char*   sv_pvbyten(SV *sv, STRLEN *lp)

       sv_pvn  A private implementation of the "SvPV" macro for compilers
               which can't cope with complex macro expressions.  Always use
               the macro instead.

                       char*   sv_pvn(SV *sv, STRLEN *lp)

       sv_pvutf8
               Use the "SvPVutf8_nolen" macro instead

                       char*   sv_pvutf8(SV *sv)

       sv_pvutf8n
               A private implementation of the "SvPVutf8" macro for compilers
               which can't cope with complex macro expressions.  Always use
               the macro instead.

                       char*   sv_pvutf8n(SV *sv, STRLEN *lp)

       sv_taint
               Taint an SV.  Use "SvTAINTED_on" instead.

                       void    sv_taint(SV* sv)

       sv_unref
               Unsets the RV status of the SV, and decrements the reference
               count of whatever was being referenced by the RV.  This can
               almost be thought of as a reversal of "newSVrv".  This is
               "sv_unref_flags" with the "flag" being zero.  See "SvROK_off".

                       void    sv_unref(SV* sv)

       sv_usepvn
               Tells an SV to use "ptr" to find its string value.  Implemented
               by calling "sv_usepvn_flags" with "flags" of 0, hence does not
               handle 'set' magic.  See "sv_usepvn_flags".

                       void    sv_usepvn(SV* sv, char* ptr, STRLEN len)

       sv_usepvn_mg
               Like "sv_usepvn", but also handles 'set' magic.

                       void    sv_usepvn_mg(SV *sv, char *ptr, STRLEN len)

       sv_uv   A private implementation of the "SvUVx" macro for compilers
               which can't cope with complex macro expressions.  Always use
               the macro instead.

                       UV      sv_uv(SV* sv)

       unpack_str
               The engine implementing unpack() Perl function.  Note:
               parameters strbeg, new_s and ocnt are not used.  This call
               should not be used, use unpackstring instead.

                       I32     unpack_str(const char *pat, const char *patend,
                                          const char *s, const char *strbeg,
                                          const char *strend, char **new_s,
                                          I32 ocnt, U32 flags)


Functions in file op.c

       alloccopstash
               NOTE: this function is experimental and may change or be
               removed without notice.

               Available only under threaded builds, this function allocates
               an entry in "PL_stashpad" for the stash passed to it.

                       PADOFFSET alloccopstash(HV *hv)

       op_contextualize
               Applies a syntactic context to an op tree representing an
               expression.  o is the op tree, and context must be "G_SCALAR",
               "G_ARRAY", or "G_VOID" to specify the context to apply.  The
               modified op tree is returned.

                       OP *    op_contextualize(OP *o, I32 context)

       op_free Free an op.  Only use this when an op is no longer linked to
               from any optree.

                       void    op_free(OP *o)

       op_null Neutralizes an op when it is no longer needed, but is still
               linked to from other ops.

                       void    op_null(OP *o)


Functions in file perl.h

       PERL_SYS_INIT
               Provides system-specific tune up of the C runtime environment
               necessary to run Perl interpreters.  This should be called only
               once, before creating any Perl interpreters.

                       void    PERL_SYS_INIT(int *argc, char*** argv)

       PERL_SYS_INIT3
               Provides system-specific tune up of the C runtime environment
               necessary to run Perl interpreters.  This should be called only
               once, before creating any Perl interpreters.

                       void    PERL_SYS_INIT3(int *argc, char*** argv,
                                              char*** env)

       PERL_SYS_TERM
               Provides system-specific clean up of the C runtime environment
               after running Perl interpreters.  This should be called only
               once, after freeing any remaining Perl interpreters.

                       void    PERL_SYS_TERM()


Functions in file pp_ctl.c

       caller_cx
               The XSUB-writer's equivalent of caller().  The returned
               "PERL_CONTEXT" structure can be interrogated to find all the
               information returned to Perl by "caller".  Note that XSUBs
               don't get a stack frame, so "caller_cx(0, NULL)" will return
               information for the immediately-surrounding Perl code.

               This function skips over the automatic calls to &DB::sub made
               on the behalf of the debugger.  If the stack frame requested
               was a sub called by "DB::sub", the return value will be the
               frame for the call to "DB::sub", since that has the correct
               line number/etc. for the call site.  If dbcxp is non-"NULL", it
               will be set to a pointer to the frame for the sub call itself.

                       const PERL_CONTEXT * caller_cx(
                                                I32 level,
                                                const PERL_CONTEXT **dbcxp
                                            )

       find_runcv
               Locate the CV corresponding to the currently executing sub or
               eval.  If db_seqp is non_null, skip CVs that are in the DB
               package and populate *db_seqp with the cop sequence number at
               the point that the DB:: code was entered.  (This allows
               debuggers to eval in the scope of the breakpoint rather than in
               the scope of the debugger itself.)

                       CV*     find_runcv(U32 *db_seqp)


Functions in file pp_pack.c

       packlist
               The engine implementing pack() Perl function.

                       void    packlist(SV *cat, const char *pat,
                                        const char *patend, SV **beglist,
                                        SV **endlist)

       unpackstring
               The engine implementing the unpack() Perl function.

               Using the template pat..patend, this function unpacks the
               string s..strend into a number of mortal SVs, which it pushes
               onto the perl argument (@_) stack (so you will need to issue a
               "PUTBACK" before and "SPAGAIN" after the call to this
               function).  It returns the number of pushed elements.

               The strend and patend pointers should point to the byte
               following the last character of each string.

               Although this function returns its values on the perl argument
               stack, it doesn't take any parameters from that stack (and thus
               in particular there's no need to do a PUSHMARK before calling
               it, unlike "call_pv" for example).

                       I32     unpackstring(const char *pat,
                                            const char *patend, const char *s,
                                            const char *strend, U32 flags)


Functions in file pp_sys.c

       setdefout
               Sets PL_defoutgv, the default file handle for output, to the
               passed in typeglob.  As PL_defoutgv "owns" a reference on its
               typeglob, the reference count of the passed in typeglob is
               increased by one, and the reference count of the typeglob that
               PL_defoutgv points to is decreased by one.

                       void    setdefout(GV* gv)


Functions in file utf8.h

       ibcmp_utf8
               This is a synonym for (! foldEQ_utf8())

                       I32     ibcmp_utf8(const char *s1, char **pe1, UV l1,
                                          bool u1, const char *s2, char **pe2,
                                          UV l2, bool u2)


Functions in file util.h

       ibcmp   This is a synonym for (! foldEQ())

                       I32     ibcmp(const char* a, const char* b, I32 len)

       ibcmp_locale
               This is a synonym for (! foldEQ_locale())

                       I32     ibcmp_locale(const char* a, const char* b,
                                            I32 len)


Functions in file vutil.c

       new_version
               Returns a new version object based on the passed in SV:

                   SV *sv = new_version(SV *ver);

               Does not alter the passed in ver SV.  See "upg_version" if you
               want to upgrade the SV.

                       SV*     new_version(SV *ver)

       prescan_version
               Validate that a given string can be parsed as a version object,
               but doesn't actually perform the parsing.  Can use either
               strict or lax validation rules.  Can optionally set a number of
               hint variables to save the parsing code some time when
               tokenizing.

                       const char* prescan_version(const char *s, bool strict,
                                                   const char** errstr,
                                                   bool *sqv,
                                                   int *ssaw_decimal,
                                                   int *swidth, bool *salpha)

       scan_version
               Returns a pointer to the next character after the parsed
               version string, as well as upgrading the passed in SV to an RV.

               Function must be called with an already existing SV like

                   sv = newSV(0);
                   s = scan_version(s, SV *sv, bool qv);

               Performs some preprocessing to the string to ensure that it has
               the correct characteristics of a version.  Flags the object if
               it contains an underscore (which denotes this is an alpha
               version).  The boolean qv denotes that the version should be
               interpreted as if it had multiple decimals, even if it doesn't.

                       const char* scan_version(const char *s, SV *rv, bool qv)

       upg_version
               In-place upgrade of the supplied SV to a version object.

                   SV *sv = upg_version(SV *sv, bool qv);

               Returns a pointer to the upgraded SV.  Set the boolean qv if
               you want to force this SV to be interpreted as an "extended"
               version.

                       SV*     upg_version(SV *ver, bool qv)

       vcmp    Version object aware cmp.  Both operands must already have been
               converted into version objects.

                       int     vcmp(SV *lhv, SV *rhv)

       vnormal Accepts a version object and returns the normalized string
               representation.  Call like:

                   sv = vnormal(rv);

               NOTE: you can pass either the object directly or the SV
               contained within the RV.

               The SV returned has a refcount of 1.

                       SV*     vnormal(SV *vs)

       vnumify Accepts a version object and returns the normalized floating
               point representation.  Call like:

                   sv = vnumify(rv);

               NOTE: you can pass either the object directly or the SV
               contained within the RV.

               The SV returned has a refcount of 1.

                       SV*     vnumify(SV *vs)

       vstringify
               In order to maintain maximum compatibility with earlier
               versions of Perl, this function will return either the floating
               point notation or the multiple dotted notation, depending on
               whether the original version contained 1 or more dots,
               respectively.

               The SV returned has a refcount of 1.

                       SV*     vstringify(SV *vs)

       vverify Validates that the SV contains valid internal structure for a
               version object.  It may be passed either the version object
               (RV) or the hash itself (HV).  If the structure is valid, it
               returns the HV.  If the structure is invalid, it returns NULL.

                   SV *hv = vverify(sv);

               Note that it only confirms the bare minimum structure (so as
               not to get confused by derived classes which may contain
               additional hash entries):

                       SV*     vverify(SV *vs)


Global Variables

       PL_check
               Array, indexed by opcode, of functions that will be called for
               the "check" phase of optree building during compilation of Perl
               code.  For most (but not all) types of op, once the op has been
               initially built and populated with child ops it will be
               filtered through the check function referenced by the
               appropriate element of this array.  The new op is passed in as
               the sole argument to the check function, and the check function
               returns the completed op.  The check function may (as the name
               suggests) check the op for validity and signal errors.  It may
               also initialise or modify parts of the ops, or perform more
               radical surgery such as adding or removing child ops, or even
               throw the op away and return a different op in its place.

               This array of function pointers is a convenient place to hook
               into the compilation process.  An XS module can put its own
               custom check function in place of any of the standard ones, to
               influence the compilation of a particular type of op.  However,
               a custom check function must never fully replace a standard
               check function (or even a custom check function from another
               module).  A module modifying checking must instead wrap the
               preexisting check function.  A custom check function must be
               selective about when to apply its custom behaviour.  In the
               usual case where it decides not to do anything special with an
               op, it must chain the preexisting op function.  Check functions
               are thus linked in a chain, with the core's base checker at the
               end.

               For thread safety, modules should not write directly to this
               array.  Instead, use the function "wrap_op_checker".

       PL_keyword_plugin
               NOTE: this function is experimental and may change or be
               removed without notice.

               Function pointer, pointing at a function used to handle
               extended keywords.  The function should be declared as

                       int keyword_plugin_function(pTHX_
                               char *keyword_ptr, STRLEN keyword_len,
                               OP **op_ptr)

               The function is called from the tokeniser, whenever a possible
               keyword is seen.  "keyword_ptr" points at the word in the
               parser's input buffer, and "keyword_len" gives its length; it
               is not null-terminated.  The function is expected to examine
               the word, and possibly other state such as %^H, to decide
               whether it wants to handle it as an extended keyword.  If it
               does not, the function should return "KEYWORD_PLUGIN_DECLINE",
               and the normal parser process will continue.

               If the function wants to handle the keyword, it first must
               parse anything following the keyword that is part of the syntax
               introduced by the keyword.  See "Lexer interface" for details.

               When a keyword is being handled, the plugin function must build
               a tree of "OP" structures, representing the code that was
               parsed.  The root of the tree must be stored in *op_ptr.  The
               function then returns a constant indicating the syntactic role
               of the construct that it has parsed: "KEYWORD_PLUGIN_STMT" if
               it is a complete statement, or "KEYWORD_PLUGIN_EXPR" if it is
               an expression.  Note that a statement construct cannot be used
               inside an expression (except via "do BLOCK" and similar), and
               an expression is not a complete statement (it requires at least
               a terminating semicolon).

               When a keyword is handled, the plugin function may also have
               (compile-time) side effects.  It may modify "%^H", define
               functions, and so on.  Typically, if side effects are the main
               purpose of a handler, it does not wish to generate any ops to
               be included in the normal compilation.  In this case it is
               still required to supply an op tree, but it suffices to
               generate a single null op.

               That's how the *PL_keyword_plugin function needs to behave
               overall.  Conventionally, however, one does not completely
               replace the existing handler function.  Instead, take a copy of
               "PL_keyword_plugin" before assigning your own function pointer
               to it.  Your handler function should look for keywords that it
               is interested in and handle those.  Where it is not interested,
               it should call the saved plugin function, passing on the
               arguments it received.  Thus "PL_keyword_plugin" actually
               points at a chain of handler functions, all of which have an
               opportunity to handle keywords, and only the last function in
               the chain (built into the Perl core) will normally return
               "KEYWORD_PLUGIN_DECLINE".


GV Functions

       GvAV    Return the AV from the GV.

                       AV*     GvAV(GV* gv)

       GvCV    Return the CV from the GV.

                       CV*     GvCV(GV* gv)

       GvHV    Return the HV from the GV.

                       HV*     GvHV(GV* gv)

       GvSV    Return the SV from the GV.

                       SV*     GvSV(GV* gv)

       gv_const_sv
               If "gv" is a typeglob whose subroutine entry is a constant sub
               eligible for inlining, or "gv" is a placeholder reference that
               would be promoted to such a typeglob, then returns the value
               returned by the sub.  Otherwise, returns NULL.

                       SV*     gv_const_sv(GV* gv)

       gv_fetchmeth
               Like "gv_fetchmeth_pvn", but lacks a flags parameter.

                       GV*     gv_fetchmeth(HV* stash, const char* name,
                                            STRLEN len, I32 level)

       gv_fetchmethod_autoload
               Returns the glob which contains the subroutine to call to
               invoke the method on the "stash".  In fact in the presence of
               autoloading this may be the glob for "AUTOLOAD".  In this case
               the corresponding variable $AUTOLOAD is already setup.

               The third parameter of "gv_fetchmethod_autoload" determines
               whether AUTOLOAD lookup is performed if the given method is not
               present: non-zero means yes, look for AUTOLOAD; zero means no,
               don't look for AUTOLOAD.  Calling "gv_fetchmethod" is
               equivalent to calling "gv_fetchmethod_autoload" with a non-zero
               "autoload" parameter.

               These functions grant "SUPER" token as a prefix of the method
               name.  Note that if you want to keep the returned glob for a
               long time, you need to check for it being "AUTOLOAD", since at
               the later time the call may load a different subroutine due to
               $AUTOLOAD changing its value.  Use the glob created as a side
               effect to do this.

               These functions have the same side-effects as "gv_fetchmeth"
               with "level==0".  The warning against passing the GV returned
               by "gv_fetchmeth" to "call_sv" applies equally to these
               functions.

                       GV*     gv_fetchmethod_autoload(HV* stash,
                                                       const char* name,
                                                       I32 autoload)

       gv_fetchmeth_autoload
               This is the old form of "gv_fetchmeth_pvn_autoload", which has
               no flags parameter.

                       GV*     gv_fetchmeth_autoload(HV* stash,
                                                     const char* name,
                                                     STRLEN len, I32 level)

       gv_fetchmeth_pv
               Exactly like "gv_fetchmeth_pvn", but takes a nul-terminated
               string instead of a string/length pair.

                       GV*     gv_fetchmeth_pv(HV* stash, const char* name,
                                               I32 level, U32 flags)

       gv_fetchmeth_pvn
               Returns the glob with the given "name" and a defined subroutine
               or "NULL".  The glob lives in the given "stash", or in the
               stashes accessible via @ISA and UNIVERSAL::.

               The argument "level" should be either 0 or -1.  If "level==0",
               as a side-effect creates a glob with the given "name" in the
               given "stash" which in the case of success contains an alias
               for the subroutine, and sets up caching info for this glob.

               The only significant values for "flags" are GV_SUPER and
               SVf_UTF8.

               GV_SUPER indicates that we want to look up the method in the
               superclasses of the "stash".

               The GV returned from "gv_fetchmeth" may be a method cache
               entry, which is not visible to Perl code.  So when calling
               "call_sv", you should not use the GV directly; instead, you
               should use the method's CV, which can be obtained from the GV
               with the "GvCV" macro.

                       GV*     gv_fetchmeth_pvn(HV* stash, const char* name,
                                                STRLEN len, I32 level,
                                                U32 flags)

       gv_fetchmeth_pvn_autoload
               Same as gv_fetchmeth_pvn(), but looks for autoloaded
               subroutines too.  Returns a glob for the subroutine.

               For an autoloaded subroutine without a GV, will create a GV
               even if "level < 0".  For an autoloaded subroutine without a
               stub, GvCV() of the result may be zero.

               Currently, the only significant value for "flags" is SVf_UTF8.

                       GV*     gv_fetchmeth_pvn_autoload(HV* stash,
                                                         const char* name,
                                                         STRLEN len, I32 level,
                                                         U32 flags)

       gv_fetchmeth_pv_autoload
               Exactly like "gv_fetchmeth_pvn_autoload", but takes a nul-
               terminated string instead of a string/length pair.

                       GV*     gv_fetchmeth_pv_autoload(HV* stash,
                                                        const char* name,
                                                        I32 level, U32 flags)

       gv_fetchmeth_sv
               Exactly like "gv_fetchmeth_pvn", but takes the name string in
               the form of an SV instead of a string/length pair.

                       GV*     gv_fetchmeth_sv(HV* stash, SV* namesv,
                                               I32 level, U32 flags)

       gv_fetchmeth_sv_autoload
               Exactly like "gv_fetchmeth_pvn_autoload", but takes the name
               string in the form of an SV instead of a string/length pair.

                       GV*     gv_fetchmeth_sv_autoload(HV* stash, SV* namesv,
                                                        I32 level, U32 flags)

       gv_init The old form of gv_init_pvn().  It does not work with UTF8
               strings, as it has no flags parameter.  If the "multi"
               parameter is set, the GV_ADDMULTI flag will be passed to
               gv_init_pvn().

                       void    gv_init(GV* gv, HV* stash, const char* name,
                                       STRLEN len, int multi)

       gv_init_pv
               Same as gv_init_pvn(), but takes a nul-terminated string for
               the name instead of separate char * and length parameters.

                       void    gv_init_pv(GV* gv, HV* stash, const char* name,
                                          U32 flags)

       gv_init_pvn
               Converts a scalar into a typeglob.  This is an incoercible
               typeglob; assigning a reference to it will assign to one of its
               slots, instead of overwriting it as happens with typeglobs
               created by SvSetSV.  Converting any scalar that is SvOK() may
               produce unpredictable results and is reserved for perl's
               internal use.

               "gv" is the scalar to be converted.

               "stash" is the parent stash/package, if any.

               "name" and "len" give the name.  The name must be unqualified;
               that is, it must not include the package name.  If "gv" is a
               stash element, it is the caller's responsibility to ensure that
               the name passed to this function matches the name of the
               element.  If it does not match, perl's internal bookkeeping
               will get out of sync.

               "flags" can be set to SVf_UTF8 if "name" is a UTF8 string, or
               the return value of SvUTF8(sv).  It can also take the
               GV_ADDMULTI flag, which means to pretend that the GV has been
               seen before (i.e., suppress "Used once" warnings).

                       void    gv_init_pvn(GV* gv, HV* stash, const char* name,
                                           STRLEN len, U32 flags)

       gv_init_sv
               Same as gv_init_pvn(), but takes an SV * for the name instead
               of separate char * and length parameters.  "flags" is currently
               unused.

                       void    gv_init_sv(GV* gv, HV* stash, SV* namesv,
                                          U32 flags)

       gv_stashpv
               Returns a pointer to the stash for a specified package.  Uses
               "strlen" to determine the length of "name", then calls
               "gv_stashpvn()".

                       HV*     gv_stashpv(const char* name, I32 flags)

       gv_stashpvn
               Returns a pointer to the stash for a specified package.  The
               "namelen" parameter indicates the length of the "name", in
               bytes.  "flags" is passed to "gv_fetchpvn_flags()", so if set
               to "GV_ADD" then the package will be created if it does not
               already exist.  If the package does not exist and "flags" is 0
               (or any other setting that does not create packages) then NULL
               is returned.

               Flags may be one of:

                   GV_ADD
                   SVf_UTF8
                   GV_NOADD_NOINIT
                   GV_NOINIT
                   GV_NOEXPAND
                   GV_ADDMG

               The most important of which are probably GV_ADD and SVf_UTF8.

                       HV*     gv_stashpvn(const char* name, U32 namelen,
                                           I32 flags)

       gv_stashpvs
               Like "gv_stashpvn", but takes a literal string instead of a
               string/length pair.

                       HV*     gv_stashpvs(const char* name, I32 create)

       gv_stashsv
               Returns a pointer to the stash for a specified package.  See
               "gv_stashpvn".

                       HV*     gv_stashsv(SV* sv, I32 flags)


Handy Values

       Nullav  Null AV pointer.

               (deprecated - use "(AV *)NULL" instead)

       Nullch  Null character pointer.  (No longer available when "PERL_CORE"
               is defined.)

       Nullcv  Null CV pointer.

               (deprecated - use "(CV *)NULL" instead)

       Nullhv  Null HV pointer.

               (deprecated - use "(HV *)NULL" instead)

       Nullsv  Null SV pointer.  (No longer available when "PERL_CORE" is
               defined.)


Hash Manipulation Functions

       cop_fetch_label
               NOTE: this function is experimental and may change or be
               removed without notice.

               Returns the label attached to a cop.  The flags pointer may be
               set to "SVf_UTF8" or 0.

                       const char * cop_fetch_label(COP *const cop,
                                                    STRLEN *len, U32 *flags)

       cop_store_label
               NOTE: this function is experimental and may change or be
               removed without notice.

               Save a label into a "cop_hints_hash".  You need to set flags to
               "SVf_UTF8" for a utf-8 label.

                       void    cop_store_label(COP *const cop,
                                               const char *label, STRLEN len,
                                               U32 flags)

       get_hv  Returns the HV of the specified Perl hash.  "flags" are passed
               to "gv_fetchpv".  If "GV_ADD" is set and the Perl variable does
               not exist then it will be created.  If "flags" is zero and the
               variable does not exist then NULL is returned.

               NOTE: the perl_ form of this function is deprecated.

                       HV*     get_hv(const char *name, I32 flags)

       HEf_SVKEY
               This flag, used in the length slot of hash entries and magic
               structures, specifies the structure contains an "SV*" pointer
               where a "char*" pointer is to be expected.  (For information
               only--not to be used).

       HeHASH  Returns the computed hash stored in the hash entry.

                       U32     HeHASH(HE* he)

       HeKEY   Returns the actual pointer stored in the key slot of the hash
               entry.  The pointer may be either "char*" or "SV*", depending
               on the value of "HeKLEN()".  Can be assigned to.  The "HePV()"
               or "HeSVKEY()" macros are usually preferable for finding the
               value of a key.

                       void*   HeKEY(HE* he)

       HeKLEN  If this is negative, and amounts to "HEf_SVKEY", it indicates
               the entry holds an "SV*" key.  Otherwise, holds the actual
               length of the key.  Can be assigned to.  The "HePV()" macro is
               usually preferable for finding key lengths.

                       STRLEN  HeKLEN(HE* he)

       HePV    Returns the key slot of the hash entry as a "char*" value,
               doing any necessary dereferencing of possibly "SV*" keys.  The
               length of the string is placed in "len" (this is a macro, so do
               not use &len).  If you do not care about what the length of the
               key is, you may use the global variable "PL_na", though this is
               rather less efficient than using a local variable.  Remember
               though, that hash keys in perl are free to contain embedded
               nulls, so using "strlen()" or similar is not a good way to find
               the length of hash keys.  This is very similar to the "SvPV()"
               macro described elsewhere in this document.  See also "HeUTF8".

               If you are using "HePV" to get values to pass to "newSVpvn()"
               to create a new SV, you should consider using
               "newSVhek(HeKEY_hek(he))" as it is more efficient.

                       char*   HePV(HE* he, STRLEN len)

       HeSVKEY Returns the key as an "SV*", or "NULL" if the hash entry does
               not contain an "SV*" key.

                       SV*     HeSVKEY(HE* he)

       HeSVKEY_force
               Returns the key as an "SV*".  Will create and return a
               temporary mortal "SV*" if the hash entry contains only a
               "char*" key.

                       SV*     HeSVKEY_force(HE* he)

       HeSVKEY_set
               Sets the key to a given "SV*", taking care to set the
               appropriate flags to indicate the presence of an "SV*" key, and
               returns the same "SV*".

                       SV*     HeSVKEY_set(HE* he, SV* sv)

       HeUTF8  Returns whether the "char *" value returned by "HePV" is
               encoded in UTF-8, doing any necessary dereferencing of possibly
               "SV*" keys.  The value returned will be 0 or non-0, not
               necessarily 1 (or even a value with any low bits set), so do
               not blindly assign this to a "bool" variable, as "bool" may be
               a typedef for "char".

                       U32     HeUTF8(HE* he)

       HeVAL   Returns the value slot (type "SV*") stored in the hash entry.
               Can be assigned to.

                 SV *foo= HeVAL(hv);
                 HeVAL(hv)= sv;


                       SV*     HeVAL(HE* he)

       HvENAME Returns the effective name of a stash, or NULL if there is
               none.  The effective name represents a location in the symbol
               table where this stash resides.  It is updated automatically
               when packages are aliased or deleted.  A stash that is no
               longer in the symbol table has no effective name.  This name is
               preferable to "HvNAME" for use in MRO linearisations and isa
               caches.

                       char*   HvENAME(HV* stash)

       HvENAMELEN
               Returns the length of the stash's effective name.

                       STRLEN  HvENAMELEN(HV *stash)

       HvENAMEUTF8
               Returns true if the effective name is in UTF8 encoding.

                       unsigned char HvENAMEUTF8(HV *stash)

       HvNAME  Returns the package name of a stash, or NULL if "stash" isn't a
               stash.  See "SvSTASH", "CvSTASH".

                       char*   HvNAME(HV* stash)

       HvNAMELEN
               Returns the length of the stash's name.

                       STRLEN  HvNAMELEN(HV *stash)

       HvNAMEUTF8
               Returns true if the name is in UTF8 encoding.

                       unsigned char HvNAMEUTF8(HV *stash)

       hv_assert
               Check that a hash is in an internally consistent state.

                       void    hv_assert(HV *hv)

       hv_clear
               Frees the all the elements of a hash, leaving it empty.  The XS
               equivalent of "%hash = ()".  See also "hv_undef".

               If any destructors are triggered as a result, the hv itself may
               be freed.

                       void    hv_clear(HV *hv)

       hv_clear_placeholders
               Clears any placeholders from a hash.  If a restricted hash has
               any of its keys marked as readonly and the key is subsequently
               deleted, the key is not actually deleted but is marked by
               assigning it a value of &PL_sv_placeholder.  This tags it so it
               will be ignored by future operations such as iterating over the
               hash, but will still allow the hash to have a value reassigned
               to the key at some future point.  This function clears any such
               placeholder keys from the hash.  See Hash::Util::lock_keys()
               for an example of its use.

                       void    hv_clear_placeholders(HV *hv)

       hv_copy_hints_hv
               A specialised version of "newHVhv" for copying "%^H".  ohv must
               be a pointer to a hash (which may have "%^H" magic, but should
               be generally non-magical), or "NULL" (interpreted as an empty
               hash).  The content of ohv is copied to a new hash, which has
               the "%^H"-specific magic added to it.  A pointer to the new
               hash is returned.

                       HV *    hv_copy_hints_hv(HV *ohv)

       hv_delete
               Deletes a key/value pair in the hash.  The value's SV is
               removed from the hash, made mortal, and returned to the caller.
               The absolute value of "klen" is the length of the key.  If
               "klen" is negative the key is assumed to be in UTF-8-encoded
               Unicode.  The "flags" value will normally be zero; if set to
               G_DISCARD then NULL will be returned.  NULL will also be
               returned if the key is not found.

                       SV*     hv_delete(HV *hv, const char *key, I32 klen,
                                         I32 flags)

       hv_delete_ent
               Deletes a key/value pair in the hash.  The value SV is removed
               from the hash, made mortal, and returned to the caller.  The
               "flags" value will normally be zero; if set to G_DISCARD then
               NULL will be returned.  NULL will also be returned if the key
               is not found.  "hash" can be a valid precomputed hash value, or
               0 to ask for it to be computed.

                       SV*     hv_delete_ent(HV *hv, SV *keysv, I32 flags,
                                             U32 hash)

       hv_exists
               Returns a boolean indicating whether the specified hash key
               exists.  The absolute value of "klen" is the length of the key.
               If "klen" is negative the key is assumed to be in UTF-8-encoded
               Unicode.

                       bool    hv_exists(HV *hv, const char *key, I32 klen)

       hv_exists_ent
               Returns a boolean indicating whether the specified hash key
               exists.  "hash" can be a valid precomputed hash value, or 0 to
               ask for it to be computed.

                       bool    hv_exists_ent(HV *hv, SV *keysv, U32 hash)

       hv_fetch
               Returns the SV which corresponds to the specified key in the
               hash.  The absolute value of "klen" is the length of the key.
               If "klen" is negative the key is assumed to be in UTF-8-encoded
               Unicode.  If "lval" is set then the fetch will be part of a
               store.  This means that if there is no value in the hash
               associated with the given key, then one is created and a
               pointer to it is returned.  The "SV*" it points to can be
               assigned to.  But always check that the return value is non-
               null before dereferencing it to an "SV*".

               See "Understanding the Magic of Tied Hashes and Arrays" in
               perlguts for more information on how to use this function on
               tied hashes.

                       SV**    hv_fetch(HV *hv, const char *key, I32 klen,
                                        I32 lval)

       hv_fetchs
               Like "hv_fetch", but takes a literal string instead of a
               string/length pair.

                       SV**    hv_fetchs(HV* tb, const char* key, I32 lval)

       hv_fetch_ent
               Returns the hash entry which corresponds to the specified key
               in the hash.  "hash" must be a valid precomputed hash number
               for the given "key", or 0 if you want the function to compute
               it.  IF "lval" is set then the fetch will be part of a store.
               Make sure the return value is non-null before accessing it.
               The return value when "hv" is a tied hash is a pointer to a
               static location, so be sure to make a copy of the structure if
               you need to store it somewhere.

               See "Understanding the Magic of Tied Hashes and Arrays" in
               perlguts for more information on how to use this function on
               tied hashes.

                       HE*     hv_fetch_ent(HV *hv, SV *keysv, I32 lval,
                                            U32 hash)

       hv_fill Returns the number of hash buckets that happen to be in use.
               This function is wrapped by the macro "HvFILL".

               Previously this value was always stored in the HV structure,
               which created an overhead on every hash (and pretty much every
               object) for something that was rarely used.  Now we calculate
               it on demand the first time that it is needed, and cache it if
               that calculation is going to be costly to repeat.  The cached
               value is updated by insertions and deletions, but (currently)
               discarded if the hash is split.

                       STRLEN  hv_fill(HV *const hv)

       hv_iterinit
               Prepares a starting point to traverse a hash table.  Returns
               the number of keys in the hash (i.e. the same as
               "HvUSEDKEYS(hv)").  The return value is currently only
               meaningful for hashes without tie magic.

               NOTE: Before version 5.004_65, "hv_iterinit" used to return the
               number of hash buckets that happen to be in use.  If you still
               need that esoteric value, you can get it through the macro
               "HvFILL(hv)".

                       I32     hv_iterinit(HV *hv)

       hv_iterkey
               Returns the key from the current position of the hash iterator.
               See "hv_iterinit".

                       char*   hv_iterkey(HE* entry, I32* retlen)

       hv_iterkeysv
               Returns the key as an "SV*" from the current position of the
               hash iterator.  The return value will always be a mortal copy
               of the key.  Also see "hv_iterinit".

                       SV*     hv_iterkeysv(HE* entry)

       hv_iternext
               Returns entries from a hash iterator.  See "hv_iterinit".

               You may call "hv_delete" or "hv_delete_ent" on the hash entry
               that the iterator currently points to, without losing your
               place or invalidating your iterator.  Note that in this case
               the current entry is deleted from the hash with your iterator
               holding the last reference to it.  Your iterator is flagged to
               free the entry on the next call to "hv_iternext", so you must
               not discard your iterator immediately else the entry will leak
               - call "hv_iternext" to trigger the resource deallocation.

                       HE*     hv_iternext(HV *hv)

       hv_iternextsv
               Performs an "hv_iternext", "hv_iterkey", and "hv_iterval" in
               one operation.

                       SV*     hv_iternextsv(HV *hv, char **key, I32 *retlen)

       hv_iternext_flags
               NOTE: this function is experimental and may change or be
               removed without notice.

               Returns entries from a hash iterator.  See "hv_iterinit" and
               "hv_iternext".  The "flags" value will normally be zero; if
               HV_ITERNEXT_WANTPLACEHOLDERS is set the placeholders keys (for
               restricted hashes) will be returned in addition to normal keys.
               By default placeholders are automatically skipped over.
               Currently a placeholder is implemented with a value that is
               &PL_sv_placeholder.  Note that the implementation of
               placeholders and restricted hashes may change, and the
               implementation currently is insufficiently abstracted for any
               change to be tidy.

                       HE*     hv_iternext_flags(HV *hv, I32 flags)

       hv_iterval
               Returns the value from the current position of the hash
               iterator.  See "hv_iterkey".

                       SV*     hv_iterval(HV *hv, HE *entry)

       hv_magic
               Adds magic to a hash.  See "sv_magic".

                       void    hv_magic(HV *hv, GV *gv, int how)

       hv_scalar
               Evaluates the hash in scalar context and returns the result.
               Handles magic when the hash is tied.

                       SV*     hv_scalar(HV *hv)

       hv_store
               Stores an SV in a hash.  The hash key is specified as "key" and
               the absolute value of "klen" is the length of the key.  If
               "klen" is negative the key is assumed to be in UTF-8-encoded
               Unicode.  The "hash" parameter is the precomputed hash value;
               if it is zero then Perl will compute it.

               The return value will be NULL if the operation failed or if the
               value did not need to be actually stored within the hash (as in
               the case of tied hashes).  Otherwise it can be dereferenced to
               get the original "SV*".  Note that the caller is responsible
               for suitably incrementing the reference count of "val" before
               the call, and decrementing it if the function returned NULL.
               Effectively a successful hv_store takes ownership of one
               reference to "val".  This is usually what you want; a newly
               created SV has a reference count of one, so if all your code
               does is create SVs then store them in a hash, hv_store will own
               the only reference to the new SV, and your code doesn't need to
               do anything further to tidy up.  hv_store is not implemented as
               a call to hv_store_ent, and does not create a temporary SV for
               the key, so if your key data is not already in SV form then use
               hv_store in preference to hv_store_ent.

               See "Understanding the Magic of Tied Hashes and Arrays" in
               perlguts for more information on how to use this function on
               tied hashes.

                       SV**    hv_store(HV *hv, const char *key, I32 klen,
                                        SV *val, U32 hash)

       hv_stores
               Like "hv_store", but takes a literal string instead of a
               string/length pair and omits the hash parameter.

                       SV**    hv_stores(HV* tb, const char* key,
                                         NULLOK SV* val)

       hv_store_ent
               Stores "val" in a hash.  The hash key is specified as "key".
               The "hash" parameter is the precomputed hash value; if it is
               zero then Perl will compute it.  The return value is the new
               hash entry so created.  It will be NULL if the operation failed
               or if the value did not need to be actually stored within the
               hash (as in the case of tied hashes).  Otherwise the contents
               of the return value can be accessed using the "He?" macros
               described here.  Note that the caller is responsible for
               suitably incrementing the reference count of "val" before the
               call, and decrementing it if the function returned NULL.
               Effectively a successful hv_store_ent takes ownership of one
               reference to "val".  This is usually what you want; a newly
               created SV has a reference count of one, so if all your code
               does is create SVs then store them in a hash, hv_store will own
               the only reference to the new SV, and your code doesn't need to
               do anything further to tidy up.  Note that hv_store_ent only
               reads the "key"; unlike "val" it does not take ownership of it,
               so maintaining the correct reference count on "key" is entirely
               the caller's responsibility.  hv_store is not implemented as a
               call to hv_store_ent, and does not create a temporary SV for
               the key, so if your key data is not already in SV form then use
               hv_store in preference to hv_store_ent.

               See "Understanding the Magic of Tied Hashes and Arrays" in
               perlguts for more information on how to use this function on
               tied hashes.

                       HE*     hv_store_ent(HV *hv, SV *key, SV *val, U32 hash)

       hv_undef
               Undefines the hash.  The XS equivalent of "undef(%hash)".

               As well as freeing all the elements of the hash (like
               hv_clear()), this also frees any auxiliary data and storage
               associated with the hash.

               If any destructors are triggered as a result, the hv itself may
               be freed.

               See also "hv_clear".

                       void    hv_undef(HV *hv)

       newHV   Creates a new HV.  The reference count is set to 1.

                       HV*     newHV()


Hook manipulation

       wrap_op_checker
               Puts a C function into the chain of check functions for a
               specified op type.  This is the preferred way to manipulate the
               "PL_check" array.  opcode specifies which type of op is to be
               affected.  new_checker is a pointer to the C function that is
               to be added to that opcode's check chain, and old_checker_p
               points to the storage location where a pointer to the next
               function in the chain will be stored.  The value of new_pointer
               is written into the "PL_check" array, while the value
               previously stored there is written to *old_checker_p.

               The function should be defined like this:

                   static OP *new_checker(pTHX_ OP *op) { ... }

               It is intended to be called in this manner:

                   new_checker(aTHX_ op)

               old_checker_p should be defined like this:

                   static Perl_check_t old_checker_p;

               "PL_check" is global to an entire process, and a module wishing
               to hook op checking may find itself invoked more than once per
               process, typically in different threads.  To handle that
               situation, this function is idempotent.  The location
               *old_checker_p must initially (once per process) contain a null
               pointer.  A C variable of static duration (declared at file
               scope, typically also marked "static" to give it internal
               linkage) will be implicitly initialised appropriately, if it
               does not have an explicit initialiser.  This function will only
               actually modify the check chain if it finds *old_checker_p to
               be null.  This function is also thread safe on the small scale.
               It uses appropriate locking to avoid race conditions in
               accessing "PL_check".

               When this function is called, the function referenced by
               new_checker must be ready to be called, except for
               *old_checker_p being unfilled.  In a threading situation,
               new_checker may be called immediately, even before this
               function has returned.  *old_checker_p will always be
               appropriately set before new_checker is called.  If new_checker
               decides not to do anything special with an op that it is given
               (which is the usual case for most uses of op check hooking), it
               must chain the check function referenced by *old_checker_p.

               If you want to influence compilation of calls to a specific
               subroutine, then use "cv_set_call_checker" rather than hooking
               checking of all "entersub" ops.

                       void    wrap_op_checker(Optype opcode,
                                               Perl_check_t new_checker,
                                               Perl_check_t *old_checker_p)


Lexer interface

       lex_bufutf8
               NOTE: this function is experimental and may change or be
               removed without notice.

               Indicates whether the octets in the lexer buffer
               ("PL_parser->linestr") should be interpreted as the UTF-8
               encoding of Unicode characters.  If not, they should be
               interpreted as Latin-1 characters.  This is analogous to the
               "SvUTF8" flag for scalars.

               In UTF-8 mode, it is not guaranteed that the lexer buffer
               actually contains valid UTF-8.  Lexing code must be robust in
               the face of invalid encoding.

               The actual "SvUTF8" flag of the "PL_parser->linestr" scalar is
               significant, but not the whole story regarding the input
               character encoding.  Normally, when a file is being read, the
               scalar contains octets and its "SvUTF8" flag is off, but the
               octets should be interpreted as UTF-8 if the "use utf8" pragma
               is in effect.  During a string eval, however, the scalar may
               have the "SvUTF8" flag on, and in this case its octets should
               be interpreted as UTF-8 unless the "use bytes" pragma is in
               effect.  This logic may change in the future; use this function
               instead of implementing the logic yourself.

                       bool    lex_bufutf8()

       lex_discard_to
               NOTE: this function is experimental and may change or be
               removed without notice.

               Discards the first part of the "PL_parser->linestr" buffer, up
               to ptr.  The remaining content of the buffer will be moved, and
               all pointers into the buffer updated appropriately.  ptr must
               not be later in the buffer than the position of
               "PL_parser->bufptr": it is not permitted to discard text that
               has yet to be lexed.

               Normally it is not necessarily to do this directly, because it
               suffices to use the implicit discarding behaviour of
               "lex_next_chunk" and things based on it.  However, if a token
               stretches across multiple lines, and the lexing code has kept
               multiple lines of text in the buffer for that purpose, then
               after completion of the token it would be wise to explicitly
               discard the now-unneeded earlier lines, to avoid future multi-
               line tokens growing the buffer without bound.

                       void    lex_discard_to(char *ptr)

       lex_grow_linestr
               NOTE: this function is experimental and may change or be
               removed without notice.

               Reallocates the lexer buffer ("PL_parser->linestr") to
               accommodate at least len octets (including terminating NUL).
               Returns a pointer to the reallocated buffer.  This is necessary
               before making any direct modification of the buffer that would
               increase its length.  "lex_stuff_pvn" provides a more
               convenient way to insert text into the buffer.

               Do not use "SvGROW" or "sv_grow" directly on
               "PL_parser->linestr"; this function updates all of the lexer's
               variables that point directly into the buffer.

                       char *  lex_grow_linestr(STRLEN len)

       lex_next_chunk
               NOTE: this function is experimental and may change or be
               removed without notice.

               Reads in the next chunk of text to be lexed, appending it to
               "PL_parser->linestr".  This should be called when lexing code
               has looked to the end of the current chunk and wants to know
               more.  It is usual, but not necessary, for lexing to have
               consumed the entirety of the current chunk at this time.

               If "PL_parser->bufptr" is pointing to the very end of the
               current chunk (i.e., the current chunk has been entirely
               consumed), normally the current chunk will be discarded at the
               same time that the new chunk is read in.  If flags includes
               "LEX_KEEP_PREVIOUS", the current chunk will not be discarded.
               If the current chunk has not been entirely consumed, then it
               will not be discarded regardless of the flag.

               Returns true if some new text was added to the buffer, or false
               if the buffer has reached the end of the input text.

                       bool    lex_next_chunk(U32 flags)

       lex_peek_unichar
               NOTE: this function is experimental and may change or be
               removed without notice.

               Looks ahead one (Unicode) character in the text currently being
               lexed.  Returns the codepoint (unsigned integer value) of the
               next character, or -1 if lexing has reached the end of the
               input text.  To consume the peeked character, use
               "lex_read_unichar".

               If the next character is in (or extends into) the next chunk of
               input text, the next chunk will be read in.  Normally the
               current chunk will be discarded at the same time, but if flags
               includes "LEX_KEEP_PREVIOUS" then the current chunk will not be
               discarded.

               If the input is being interpreted as UTF-8 and a UTF-8 encoding
               error is encountered, an exception is generated.

                       I32     lex_peek_unichar(U32 flags)

       lex_read_space
               NOTE: this function is experimental and may change or be
               removed without notice.

               Reads optional spaces, in Perl style, in the text currently
               being lexed.  The spaces may include ordinary whitespace
               characters and Perl-style comments.  "#line" directives are
               processed if encountered.  "PL_parser->bufptr" is moved past
               the spaces, so that it points at a non-space character (or the
               end of the input text).

               If spaces extend into the next chunk of input text, the next
               chunk will be read in.  Normally the current chunk will be
               discarded at the same time, but if flags includes
               "LEX_KEEP_PREVIOUS" then the current chunk will not be
               discarded.

                       void    lex_read_space(U32 flags)

       lex_read_to
               NOTE: this function is experimental and may change or be
               removed without notice.

               Consume text in the lexer buffer, from "PL_parser->bufptr" up
               to ptr.  This advances "PL_parser->bufptr" to match ptr,
               performing the correct bookkeeping whenever a newline character
               is passed.  This is the normal way to consume lexed text.

               Interpretation of the buffer's octets can be abstracted out by
               using the slightly higher-level functions "lex_peek_unichar"
               and "lex_read_unichar".

                       void    lex_read_to(char *ptr)

       lex_read_unichar
               NOTE: this function is experimental and may change or be
               removed without notice.

               Reads the next (Unicode) character in the text currently being
               lexed.  Returns the codepoint (unsigned integer value) of the
               character read, and moves "PL_parser->bufptr" past the
               character, or returns -1 if lexing has reached the end of the
               input text.  To non-destructively examine the next character,
               use "lex_peek_unichar" instead.

               If the next character is in (or extends into) the next chunk of
               input text, the next chunk will be read in.  Normally the
               current chunk will be discarded at the same time, but if flags
               includes "LEX_KEEP_PREVIOUS" then the current chunk will not be
               discarded.

               If the input is being interpreted as UTF-8 and a UTF-8 encoding
               error is encountered, an exception is generated.

                       I32     lex_read_unichar(U32 flags)

       lex_start
               NOTE: this function is experimental and may change or be
               removed without notice.

               Creates and initialises a new lexer/parser state object,
               supplying a context in which to lex and parse from a new source
               of Perl code.  A pointer to the new state object is placed in
               "PL_parser".  An entry is made on the save stack so that upon
               unwinding the new state object will be destroyed and the former
               value of "PL_parser" will be restored.  Nothing else need be
               done to clean up the parsing context.

               The code to be parsed comes from line and rsfp.  line, if non-
               null, provides a string (in SV form) containing code to be
               parsed.  A copy of the string is made, so subsequent
               modification of line does not affect parsing.  rsfp, if non-
               null, provides an input stream from which code will be read to
               be parsed.  If both are non-null, the code in line comes first
               and must consist of complete lines of input, and rsfp supplies
               the remainder of the source.

               The flags parameter is reserved for future use.  Currently it
               is only used by perl internally, so extensions should always
               pass zero.

                       void    lex_start(SV *line, PerlIO *rsfp, U32 flags)

       lex_stuff_pv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Insert characters into the lexer buffer ("PL_parser->linestr"),
               immediately after the current lexing point
               ("PL_parser->bufptr"), reallocating the buffer if necessary.
               This means that lexing code that runs later will see the
               characters as if they had appeared in the input.  It is not
               recommended to do this as part of normal parsing, and most uses
               of this facility run the risk of the inserted characters being
               interpreted in an unintended manner.

               The string to be inserted is represented by octets starting at
               pv and continuing to the first nul.  These octets are
               interpreted as either UTF-8 or Latin-1, according to whether
               the "LEX_STUFF_UTF8" flag is set in flags.  The characters are
               recoded for the lexer buffer, according to how the buffer is
               currently being interpreted ("lex_bufutf8").  If it is not
               convenient to nul-terminate a string to be inserted, the
               "lex_stuff_pvn" function is more appropriate.

                       void    lex_stuff_pv(const char *pv, U32 flags)

       lex_stuff_pvn
               NOTE: this function is experimental and may change or be
               removed without notice.

               Insert characters into the lexer buffer ("PL_parser->linestr"),
               immediately after the current lexing point
               ("PL_parser->bufptr"), reallocating the buffer if necessary.
               This means that lexing code that runs later will see the
               characters as if they had appeared in the input.  It is not
               recommended to do this as part of normal parsing, and most uses
               of this facility run the risk of the inserted characters being
               interpreted in an unintended manner.

               The string to be inserted is represented by len octets starting
               at pv.  These octets are interpreted as either UTF-8 or
               Latin-1, according to whether the "LEX_STUFF_UTF8" flag is set
               in flags.  The characters are recoded for the lexer buffer,
               according to how the buffer is currently being interpreted
               ("lex_bufutf8").  If a string to be inserted is available as a
               Perl scalar, the "lex_stuff_sv" function is more convenient.

                       void    lex_stuff_pvn(const char *pv, STRLEN len,
                                             U32 flags)

       lex_stuff_pvs
               NOTE: this function is experimental and may change or be
               removed without notice.

               Like "lex_stuff_pvn", but takes a literal string instead of a
               string/length pair.

                       void    lex_stuff_pvs(const char *pv, U32 flags)

       lex_stuff_sv
               NOTE: this function is experimental and may change or be
               removed without notice.

               Insert characters into the lexer buffer ("PL_parser->linestr"),
               immediately after the current lexing point
               ("PL_parser->bufptr"), reallocating the buffer if necessary.
               This means that lexing code that runs later will see the
               characters as if they had appeared in the input.  It is not
               recommended to do this as part of normal parsing, and most uses
               of this facility run the risk of the inserted characters being
               interpreted in an unintended manner.

               The string to be inserted is the string value of sv.  The
               characters are recoded for the lexer buffer, according to how
               the buffer is currently being interpreted ("lex_bufutf8").  If
               a string to be inserted is not already a Perl scalar, the
               "lex_stuff_pvn" function avoids the need to construct a scalar.

                       void    lex_stuff_sv(SV *sv, U32 flags)

       lex_unstuff
               NOTE: this function is experimental and may change or be
               removed without notice.

               Discards text about to be lexed, from "PL_parser->bufptr" up to
               ptr.  Text following ptr will be moved, and the buffer
               shortened.  This hides the discarded text from any lexing code
               that runs later, as if the text had never appeared.

               This is not the normal way to consume lexed text.  For that,
               use "lex_read_to".

                       void    lex_unstuff(char *ptr)

       parse_arithexpr
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a Perl arithmetic expression.  This may contain operators
               of precedence down to the bit shift operators.  The expression
               must be followed (and thus terminated) either by a comparison
               or lower-precedence operator or by something that would
               normally terminate an expression such as semicolon.  If flags
               includes "PARSE_OPTIONAL" then the expression is optional,
               otherwise it is mandatory.  It is up to the caller to ensure
               that the dynamic parser state ("PL_parser" et al) is correctly
               set to reflect the source of the code to be parsed and the
               lexical context for the expression.

               The op tree representing the expression is returned.  If an
               optional expression is absent, a null pointer is returned,
               otherwise the pointer will be non-null.

               If an error occurs in parsing or compilation, in most cases a
               valid op tree is returned anyway.  The error is reflected in
               the parser state, normally resulting in a single exception at
               the top level of parsing which covers all the compilation
               errors that occurred.  Some compilation errors, however, will
               throw an exception immediately.

                       OP *    parse_arithexpr(U32 flags)

       parse_barestmt
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a single unadorned Perl statement.  This may be a normal
               imperative statement or a declaration that has compile-time
               effect.  It does not include any label or other affixture.  It
               is up to the caller to ensure that the dynamic parser state
               ("PL_parser" et al) is correctly set to reflect the source of
               the code to be parsed and the lexical context for the
               statement.

               The op tree representing the statement is returned.  This may
               be a null pointer if the statement is null, for example if it
               was actually a subroutine definition (which has compile-time
               side effects).  If not null, it will be ops directly
               implementing the statement, suitable to pass to "newSTATEOP".
               It will not normally include a "nextstate" or equivalent op
               (except for those embedded in a scope contained entirely within
               the statement).

               If an error occurs in parsing or compilation, in most cases a
               valid op tree (most likely null) is returned anyway.  The error
               is reflected in the parser state, normally resulting in a
               single exception at the top level of parsing which covers all
               the compilation errors that occurred.  Some compilation errors,
               however, will throw an exception immediately.

               The flags parameter is reserved for future use, and must always
               be zero.

                       OP *    parse_barestmt(U32 flags)

       parse_block
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a single complete Perl code block.  This consists of an
               opening brace, a sequence of statements, and a closing brace.
               The block constitutes a lexical scope, so "my" variables and
               various compile-time effects can be contained within it.  It is
               up to the caller to ensure that the dynamic parser state
               ("PL_parser" et al) is correctly set to reflect the source of
               the code to be parsed and the lexical context for the
               statement.

               The op tree representing the code block is returned.  This is
               always a real op, never a null pointer.  It will normally be a
               "lineseq" list, including "nextstate" or equivalent ops.  No
               ops to construct any kind of runtime scope are included by
               virtue of it being a block.

               If an error occurs in parsing or compilation, in most cases a
               valid op tree (most likely null) is returned anyway.  The error
               is reflected in the parser state, normally resulting in a
               single exception at the top level of parsing which covers all
               the compilation errors that occurred.  Some compilation errors,
               however, will throw an exception immediately.

               The flags parameter is reserved for future use, and must always
               be zero.

                       OP *    parse_block(U32 flags)

       parse_fullexpr
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a single complete Perl expression.  This allows the full
               expression grammar, including the lowest-precedence operators
               such as "or".  The expression must be followed (and thus
               terminated) by a token that an expression would normally be
               terminated by: end-of-file, closing bracketing punctuation,
               semicolon, or one of the keywords that signals a postfix
               expression-statement modifier.  If flags includes
               "PARSE_OPTIONAL" then the expression is optional, otherwise it
               is mandatory.  It is up to the caller to ensure that the
               dynamic parser state ("PL_parser" et al) is correctly set to
               reflect the source of the code to be parsed and the lexical
               context for the expression.

               The op tree representing the expression is returned.  If an
               optional expression is absent, a null pointer is returned,
               otherwise the pointer will be non-null.

               If an error occurs in parsing or compilation, in most cases a
               valid op tree is returned anyway.  The error is reflected in
               the parser state, normally resulting in a single exception at
               the top level of parsing which covers all the compilation
               errors that occurred.  Some compilation errors, however, will
               throw an exception immediately.

                       OP *    parse_fullexpr(U32 flags)

       parse_fullstmt
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a single complete Perl statement.  This may be a normal
               imperative statement or a declaration that has compile-time
               effect, and may include optional labels.  It is up to the
               caller to ensure that the dynamic parser state ("PL_parser" et
               al) is correctly set to reflect the source of the code to be
               parsed and the lexical context for the statement.

               The op tree representing the statement is returned.  This may
               be a null pointer if the statement is null, for example if it
               was actually a subroutine definition (which has compile-time
               side effects).  If not null, it will be the result of a
               "newSTATEOP" call, normally including a "nextstate" or
               equivalent op.

               If an error occurs in parsing or compilation, in most cases a
               valid op tree (most likely null) is returned anyway.  The error
               is reflected in the parser state, normally resulting in a
               single exception at the top level of parsing which covers all
               the compilation errors that occurred.  Some compilation errors,
               however, will throw an exception immediately.

               The flags parameter is reserved for future use, and must always
               be zero.

                       OP *    parse_fullstmt(U32 flags)

       parse_label
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a single label, possibly optional, of the type that may
               prefix a Perl statement.  It is up to the caller to ensure that
               the dynamic parser state ("PL_parser" et al) is correctly set
               to reflect the source of the code to be parsed.  If flags
               includes "PARSE_OPTIONAL" then the label is optional, otherwise
               it is mandatory.

               The name of the label is returned in the form of a fresh
               scalar.  If an optional label is absent, a null pointer is
               returned.

               If an error occurs in parsing, which can only occur if the
               label is mandatory, a valid label is returned anyway.  The
               error is reflected in the parser state, normally resulting in a
               single exception at the top level of parsing which covers all
               the compilation errors that occurred.

                       SV *    parse_label(U32 flags)

       parse_listexpr
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a Perl list expression.  This may contain operators of
               precedence down to the comma operator.  The expression must be
               followed (and thus terminated) either by a low-precedence logic
               operator such as "or" or by something that would normally
               terminate an expression such as semicolon.  If flags includes
               "PARSE_OPTIONAL" then the expression is optional, otherwise it
               is mandatory.  It is up to the caller to ensure that the
               dynamic parser state ("PL_parser" et al) is correctly set to
               reflect the source of the code to be parsed and the lexical
               context for the expression.

               The op tree representing the expression is returned.  If an
               optional expression is absent, a null pointer is returned,
               otherwise the pointer will be non-null.

               If an error occurs in parsing or compilation, in most cases a
               valid op tree is returned anyway.  The error is reflected in
               the parser state, normally resulting in a single exception at
               the top level of parsing which covers all the compilation
               errors that occurred.  Some compilation errors, however, will
               throw an exception immediately.

                       OP *    parse_listexpr(U32 flags)

       parse_stmtseq
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a sequence of zero or more Perl statements.  These may be
               normal imperative statements, including optional labels, or
               declarations that have compile-time effect, or any mixture
               thereof.  The statement sequence ends when a closing brace or
               end-of-file is encountered in a place where a new statement
               could have validly started.  It is up to the caller to ensure
               that the dynamic parser state ("PL_parser" et al) is correctly
               set to reflect the source of the code to be parsed and the
               lexical context for the statements.

               The op tree representing the statement sequence is returned.
               This may be a null pointer if the statements were all null, for
               example if there were no statements or if there were only
               subroutine definitions (which have compile-time side effects).
               If not null, it will be a "lineseq" list, normally including
               "nextstate" or equivalent ops.

               If an error occurs in parsing or compilation, in most cases a
               valid op tree is returned anyway.  The error is reflected in
               the parser state, normally resulting in a single exception at
               the top level of parsing which covers all the compilation
               errors that occurred.  Some compilation errors, however, will
               throw an exception immediately.

               The flags parameter is reserved for future use, and must always
               be zero.

                       OP *    parse_stmtseq(U32 flags)

       parse_termexpr
               NOTE: this function is experimental and may change or be
               removed without notice.

               Parse a Perl term expression.  This may contain operators of
               precedence down to the assignment operators.  The expression
               must be followed (and thus terminated) either by a comma or
               lower-precedence operator or by something that would normally
               terminate an expression such as semicolon.  If flags includes
               "PARSE_OPTIONAL" then the expression is optional, otherwise it
               is mandatory.  It is up to the caller to ensure that the
               dynamic parser state ("PL_parser" et al) is correctly set to
               reflect the source of the code to be parsed and the lexical
               context for the expression.

               The op tree representing the expression is returned.  If an
               optional expression is absent, a null pointer is returned,
               otherwise the pointer will be non-null.

               If an error occurs in parsing or compilation, in most cases a
               valid op tree is returned anyway.  The error is reflected in
               the parser state, normally resulting in a single exception at
               the top level of parsing which covers all the compilation
               errors that occurred.  Some compilation errors, however, will
               throw an exception immediately.

                       OP *    parse_termexpr(U32 flags)

       PL_parser
               Pointer to a structure encapsulating the state of the parsing
               operation currently in progress.  The pointer can be locally
               changed to perform a nested parse without interfering with the
               state of an outer parse.  Individual members of "PL_parser"
               have their own documentation.

       PL_parser->bufend
               NOTE: this function is experimental and may change or be
               removed without notice.

               Direct pointer to the end of the chunk of text currently being
               lexed, the end of the lexer buffer.  This is equal to
               "SvPVX(PL_parser->linestr) + SvCUR(PL_parser->linestr)".  A NUL
               character (zero octet) is always located at the end of the
               buffer, and does not count as part of the buffer's contents.

       PL_parser->bufptr
               NOTE: this function is experimental and may change or be
               removed without notice.

               Points to the current position of lexing inside the lexer
               buffer.  Characters around this point may be freely examined,
               within the range delimited by "SvPVX("PL_parser->linestr")" and
               "PL_parser->bufend".  The octets of the buffer may be intended
               to be interpreted as either UTF-8 or Latin-1, as indicated by
               "lex_bufutf8".

               Lexing code (whether in the Perl core or not) moves this
               pointer past the characters that it consumes.  It is also
               expected to perform some bookkeeping whenever a newline
               character is consumed.  This movement can be more conveniently
               performed by the function "lex_read_to", which handles newlines
               appropriately.

               Interpretation of the buffer's octets can be abstracted out by
               using the slightly higher-level functions "lex_peek_unichar"
               and "lex_read_unichar".

       PL_parser->linestart
               NOTE: this function is experimental and may change or be
               removed without notice.

               Points to the start of the current line inside the lexer
               buffer.  This is useful for indicating at which column an error
               occurred, and not much else.  This must be updated by any
               lexing code that consumes a newline; the function "lex_read_to"
               handles this detail.

       PL_parser->linestr
               NOTE: this function is experimental and may change or be
               removed without notice.

               Buffer scalar containing the chunk currently under
               consideration of the text currently being lexed.  This is
               always a plain string scalar (for which "SvPOK" is true).  It
               is not intended to be used as a scalar by normal scalar means;
               instead refer to the buffer directly by the pointer variables
               described below.

               The lexer maintains various "char*" pointers to things in the
               "PL_parser->linestr" buffer.  If "PL_parser->linestr" is ever
               reallocated, all of these pointers must be updated.  Don't
               attempt to do this manually, but rather use "lex_grow_linestr"
               if you need to reallocate the buffer.

               The content of the text chunk in the buffer is commonly exactly
               one complete line of input, up to and including a newline
               terminator, but there are situations where it is otherwise.
               The octets of the buffer may be intended to be interpreted as
               either UTF-8 or Latin-1.  The function "lex_bufutf8" tells you
               which.  Do not use the "SvUTF8" flag on this scalar, which may
               disagree with it.

               For direct examination of the buffer, the variable
               "PL_parser->bufend" points to the end of the buffer.  The
               current lexing position is pointed to by "PL_parser->bufptr".
               Direct use of these pointers is usually preferable to
               examination of the scalar through normal scalar means.


Magical Functions

       mg_clear
               Clear something magical that the SV represents.  See
               "sv_magic".

                       int     mg_clear(SV* sv)

       mg_copy Copies the magic from one SV to another.  See "sv_magic".

                       int     mg_copy(SV *sv, SV *nsv, const char *key,
                                       I32 klen)

       mg_find Finds the magic pointer for type matching the SV.  See
               "sv_magic".

                       MAGIC*  mg_find(const SV* sv, int type)

       mg_findext
               Finds the magic pointer of "type" with the given "vtbl" for the
               "SV".  See "sv_magicext".

                       MAGIC*  mg_findext(const SV* sv, int type,
                                          const MGVTBL *vtbl)

       mg_free Free any magic storage used by the SV.  See "sv_magic".

                       int     mg_free(SV* sv)

       mg_free_type
               Remove any magic of type how from the SV sv.  See "sv_magic".

                       void    mg_free_type(SV *sv, int how)

       mg_get  Do magic before a value is retrieved from the SV.  The type of
               SV must be >= SVt_PVMG.  See "sv_magic".

                       int     mg_get(SV* sv)

       mg_length
               DEPRECATED!  It is planned to remove this function from a
               future release of Perl.  Do not use it for new code; remove it
               from existing code.

               Reports on the SV's length in bytes, calling length magic if
               available, but does not set the UTF8 flag on the sv.  It will
               fall back to 'get' magic if there is no 'length' magic, but
               with no indication as to whether it called 'get' magic.  It
               assumes the sv is a PVMG or higher.  Use sv_len() instead.

                       U32     mg_length(SV* sv)

       mg_magical
               Turns on the magical status of an SV.  See "sv_magic".

                       void    mg_magical(SV* sv)

       mg_set  Do magic after a value is assigned to the SV.  See "sv_magic".

                       int     mg_set(SV* sv)

       SvGETMAGIC
               Invokes "mg_get" on an SV if it has 'get' magic.  For example,
               this will call "FETCH" on a tied variable.  This macro
               evaluates its argument more than once.

                       void    SvGETMAGIC(SV* sv)

       SvLOCK  Arranges for a mutual exclusion lock to be obtained on sv if a
               suitable module has been loaded.

                       void    SvLOCK(SV* sv)

       SvSETMAGIC
               Invokes "mg_set" on an SV if it has 'set' magic.  This is
               necessary after modifying a scalar, in case it is a magical
               variable like $| or a tied variable (it calls "STORE").  This
               macro evaluates its argument more than once.

                       void    SvSETMAGIC(SV* sv)

       SvSetMagicSV
               Like "SvSetSV", but does any set magic required afterwards.

                       void    SvSetMagicSV(SV* dsv, SV* ssv)

       SvSetMagicSV_nosteal
               Like "SvSetSV_nosteal", but does any set magic required
               afterwards.

                       void    SvSetMagicSV_nosteal(SV* dsv, SV* ssv)

       SvSetSV Calls "sv_setsv" if dsv is not the same as ssv.  May evaluate
               arguments more than once.

                       void    SvSetSV(SV* dsv, SV* ssv)

       SvSetSV_nosteal
               Calls a non-destructive version of "sv_setsv" if dsv is not the
               same as ssv.  May evaluate arguments more than once.

                       void    SvSetSV_nosteal(SV* dsv, SV* ssv)

       SvSHARE Arranges for sv to be shared between threads if a suitable
               module has been loaded.

                       void    SvSHARE(SV* sv)

       SvUNLOCK
               Releases a mutual exclusion lock on sv if a suitable module has
               been loaded.

                       void    SvUNLOCK(SV* sv)


Memory Management

       Copy    The XSUB-writer's interface to the C "memcpy" function.  The
               "src" is the source, "dest" is the destination, "nitems" is the
               number of items, and "type" is the type.  May fail on
               overlapping copies.  See also "Move".

                       void    Copy(void* src, void* dest, int nitems, type)

       CopyD   Like "Copy" but returns dest.  Useful for encouraging compilers
               to tail-call optimise.

                       void *  CopyD(void* src, void* dest, int nitems, type)

       Move    The XSUB-writer's interface to the C "memmove" function.  The
               "src" is the source, "dest" is the destination, "nitems" is the
               number of items, and "type" is the type.  Can do overlapping
               moves.  See also "Copy".

                       void    Move(void* src, void* dest, int nitems, type)

       MoveD   Like "Move" but returns dest.  Useful for encouraging compilers
               to tail-call optimise.

                       void *  MoveD(void* src, void* dest, int nitems, type)

       Newx    The XSUB-writer's interface to the C "malloc" function.

               Memory obtained by this should ONLY be freed with "Safefree".

               In 5.9.3, Newx() and friends replace the older New() API, and
               drops the first parameter, x, a debug aid which allowed callers
               to identify themselves.  This aid has been superseded by a new
               build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in
               perlhacktips).  The older API is still there for use in XS
               modules supporting older perls.

                       void    Newx(void* ptr, int nitems, type)

       Newxc   The XSUB-writer's interface to the C "malloc" function, with
               cast.  See also "Newx".

               Memory obtained by this should ONLY be freed with "Safefree".

                       void    Newxc(void* ptr, int nitems, type, cast)

       Newxz   The XSUB-writer's interface to the C "malloc" function.  The
               allocated memory is zeroed with "memzero".  See also "Newx".

               Memory obtained by this should ONLY be freed with "Safefree".

                       void    Newxz(void* ptr, int nitems, type)

       Poison  PoisonWith(0xEF) for catching access to freed memory.

                       void    Poison(void* dest, int nitems, type)

       PoisonFree
               PoisonWith(0xEF) for catching access to freed memory.

                       void    PoisonFree(void* dest, int nitems, type)

       PoisonNew
               PoisonWith(0xAB) for catching access to allocated but
               uninitialized memory.

                       void    PoisonNew(void* dest, int nitems, type)

       PoisonWith
               Fill up memory with a byte pattern (a byte repeated over and
               over again) that hopefully catches attempts to access
               uninitialized memory.

                       void    PoisonWith(void* dest, int nitems, type,
                                          U8 byte)

       Renew   The XSUB-writer's interface to the C "realloc" function.

               Memory obtained by this should ONLY be freed with "Safefree".

                       void    Renew(void* ptr, int nitems, type)

       Renewc  The XSUB-writer's interface to the C "realloc" function, with
               cast.

               Memory obtained by this should ONLY be freed with "Safefree".

                       void    Renewc(void* ptr, int nitems, type, cast)

       Safefree
               The XSUB-writer's interface to the C "free" function.

               This should ONLY be used on memory obtained using "Newx" and
               friends.

                       void    Safefree(void* ptr)

       savepv  Perl's version of "strdup()".  Returns a pointer to a newly
               allocated string which is a duplicate of "pv".  The size of the
               string is determined by "strlen()".  The memory allocated for
               the new string can be freed with the "Safefree()" function.

               On some platforms, Windows for example, all allocated memory
               owned by a thread is deallocated when that thread ends.  So if
               you need that not to happen, you need to use the shared memory
               functions, such as "savesharedpv".

                       char*   savepv(const char* pv)

       savepvn Perl's version of what "strndup()" would be if it existed.
               Returns a pointer to a newly allocated string which is a
               duplicate of the first "len" bytes from "pv", plus a trailing
               NUL byte.  The memory allocated for the new string can be freed
               with the "Safefree()" function.

               On some platforms, Windows for example, all allocated memory
               owned by a thread is deallocated when that thread ends.  So if
               you need that not to happen, you need to use the shared memory
               functions, such as "savesharedpvn".

                       char*   savepvn(const char* pv, I32 len)

       savepvs Like "savepvn", but takes a literal string instead of a
               string/length pair.

                       char*   savepvs(const char* s)

       savesharedpv
               A version of "savepv()" which allocates the duplicate string in
               memory which is shared between threads.

                       char*   savesharedpv(const char* pv)

       savesharedpvn
               A version of "savepvn()" which allocates the duplicate string
               in memory which is shared between threads.  (With the specific
               difference that a NULL pointer is not acceptable)

                       char*   savesharedpvn(const char *const pv,
                                             const STRLEN len)

       savesharedpvs
               A version of "savepvs()" which allocates the duplicate string
               in memory which is shared between threads.

                       char*   savesharedpvs(const char* s)

       savesharedsvpv
               A version of "savesharedpv()" which allocates the duplicate
               string in memory which is shared between threads.

                       char*   savesharedsvpv(SV *sv)

       savesvpv
               A version of "savepv()"/"savepvn()" which gets the string to
               duplicate from the passed in SV using "SvPV()"

               On some platforms, Windows for example, all allocated memory
               owned by a thread is deallocated when that thread ends.  So if
               you need that not to happen, you need to use the shared memory
               functions, such as "savesharedsvpv".

                       char*   savesvpv(SV* sv)

       StructCopy
               This is an architecture-independent macro to copy one structure
               to another.

                       void    StructCopy(type *src, type *dest, type)

       Zero    The XSUB-writer's interface to the C "memzero" function.  The
               "dest" is the destination, "nitems" is the number of items, and
               "type" is the type.

                       void    Zero(void* dest, int nitems, type)

       ZeroD   Like "Zero" but returns dest.  Useful for encouraging compilers
               to tail-call optimise.

                       void *  ZeroD(void* dest, int nitems, type)


Miscellaneous Functions

       fbm_compile
               Analyses the string in order to make fast searches on it using
               fbm_instr() -- the Boyer-Moore algorithm.

                       void    fbm_compile(SV* sv, U32 flags)

       fbm_instr
               Returns the location of the SV in the string delimited by "big"
               and "bigend".  It returns "NULL" if the string can't be found.
               The "sv" does not have to be fbm_compiled, but the search will
               not be as fast then.

                       char*   fbm_instr(unsigned char* big,
                                         unsigned char* bigend, SV* littlestr,
                                         U32 flags)

       foldEQ  Returns true if the leading len bytes of the strings s1 and s2
               are the same case-insensitively; false otherwise.  Uppercase
               and lowercase ASCII range bytes match themselves and their
               opposite case counterparts.  Non-cased and non-ASCII range
               bytes match only themselves.

                       I32     foldEQ(const char* a, const char* b, I32 len)

       foldEQ_locale
               Returns true if the leading len bytes of the strings s1 and s2
               are the same case-insensitively in the current locale; false
               otherwise.

                       I32     foldEQ_locale(const char* a, const char* b,
                                             I32 len)

       form    Takes a sprintf-style format pattern and conventional (non-SV)
               arguments and returns the formatted string.

                   (char *) Perl_form(pTHX_ const char* pat, ...)

               can be used any place a string (char *) is required:

                   char * s = Perl_form("%d.%d",major,minor);

               Uses a single private buffer so if you want to format several
               strings you must explicitly copy the earlier strings away (and
               free the copies when you are done).

                       char*   form(const char* pat, ...)

       getcwd_sv
               Fill the sv with current working directory

                       int     getcwd_sv(SV* sv)

       mess    Take a sprintf-style format pattern and argument list.  These
               are used to generate a string message.  If the message does not
               end with a newline, then it will be extended with some
               indication of the current location in the code, as described
               for "mess_sv".

               Normally, the resulting message is returned in a new mortal SV.
               During global destruction a single SV may be shared between
               uses of this function.

                       SV *    mess(const char *pat, ...)

       mess_sv Expands a message, intended for the user, to include an
               indication of the current location in the code, if the message
               does not already appear to be complete.

               "basemsg" is the initial message or object.  If it is a
               reference, it will be used as-is and will be the result of this
               function.  Otherwise it is used as a string, and if it already
               ends with a newline, it is taken to be complete, and the result
               of this function will be the same string.  If the message does
               not end with a newline, then a segment such as "at foo.pl line
               37" will be appended, and possibly other clauses indicating the
               current state of execution.  The resulting message will end
               with a dot and a newline.

               Normally, the resulting message is returned in a new mortal SV.
               During global destruction a single SV may be shared between
               uses of this function.  If "consume" is true, then the function
               is permitted (but not required) to modify and return "basemsg"
               instead of allocating a new SV.

                       SV *    mess_sv(SV *basemsg, bool consume)

       my_snprintf
               The C library "snprintf" functionality, if available and
               standards-compliant (uses "vsnprintf", actually).  However, if
               the "vsnprintf" is not available, will unfortunately use the
               unsafe "vsprintf" which can overrun the buffer (there is an
               overrun check, but that may be too late).  Consider using
               "sv_vcatpvf" instead, or getting "vsnprintf".

                       int     my_snprintf(char *buffer, const Size_t len,
                                           const char *format, ...)

       my_sprintf
               The C library "sprintf", wrapped if necessary, to ensure that
               it will return the length of the string written to the buffer.
               Only rare pre-ANSI systems need the wrapper function - usually
               this is a direct call to "sprintf".

                       int     my_sprintf(char *buffer, const char *pat, ...)

       my_strlcat
               The C library "strlcat" if available, or a Perl implementation
               of it.  This operates on C NUL-terminated strings.

               "my_strlcat()" appends string "src" to the end of "dst".  It
               will append at most "size - strlen(dst) - 1" characters.  It
               will then NUL-terminate, unless "size" is 0 or the original
               "dst" string was longer than "size" (in practice this should
               not happen as it means that either "size" is incorrect or that
               "dst" is not a proper NUL-terminated string).

               Note that "size" is the full size of the destination buffer and
               the result is guaranteed to be NUL-terminated if there is room.
               Note that room for the NUL should be included in "size".

                       Size_t  my_strlcat(char *dst, const char *src,
                                          Size_t size)

       my_strlcpy
               The C library "strlcpy" if available, or a Perl implementation
               of it.  This operates on C NUL-terminated strings.

               "my_strlcpy()" copies up to "size - 1" characters from the
               string "src" to "dst", NUL-terminating the result if "size" is
               not 0.

                       Size_t  my_strlcpy(char *dst, const char *src,
                                          Size_t size)

       my_vsnprintf
               The C library "vsnprintf" if available and standards-compliant.
               However, if if the "vsnprintf" is not available, will
               unfortunately use the unsafe "vsprintf" which can overrun the
               buffer (there is an overrun check, but that may be too late).
               Consider using "sv_vcatpvf" instead, or getting "vsnprintf".

                       int     my_vsnprintf(char *buffer, const Size_t len,
                                            const char *format, va_list ap)

       READ_XDIGIT
               Returns the value of an ASCII-range hex digit and advances the
               string pointer.  Behaviour is only well defined when
               isXDIGIT(*str) is true.

                       U8      READ_XDIGIT(char str*)

       strEQ   Test two strings to see if they are equal.  Returns true or
               false.

                       bool    strEQ(char* s1, char* s2)

       strGE   Test two strings to see if the first, "s1", is greater than or
               equal to the second, "s2".  Returns true or false.

                       bool    strGE(char* s1, char* s2)

       strGT   Test two strings to see if the first, "s1", is greater than the
               second, "s2".  Returns true or false.

                       bool    strGT(char* s1, char* s2)

       strLE   Test two strings to see if the first, "s1", is less than or
               equal to the second, "s2".  Returns true or false.

                       bool    strLE(char* s1, char* s2)

       strLT   Test two strings to see if the first, "s1", is less than the
               second, "s2".  Returns true or false.

                       bool    strLT(char* s1, char* s2)

       strNE   Test two strings to see if they are different.  Returns true or
               false.

                       bool    strNE(char* s1, char* s2)

       strnEQ  Test two strings to see if they are equal.  The "len" parameter
               indicates the number of bytes to compare.  Returns true or
               false.  (A wrapper for "strncmp").

                       bool    strnEQ(char* s1, char* s2, STRLEN len)

       strnNE  Test two strings to see if they are different.  The "len"
               parameter indicates the number of bytes to compare.  Returns
               true or false.  (A wrapper for "strncmp").

                       bool    strnNE(char* s1, char* s2, STRLEN len)

       sv_destroyable
               Dummy routine which reports that object can be destroyed when
               there is no sharing module present.  It ignores its single SV
               argument, and returns 'true'.  Exists to avoid test for a NULL
               function pointer and because it could potentially warn under
               some level of strict-ness.

                       bool    sv_destroyable(SV *sv)

       sv_nosharing
               Dummy routine which "shares" an SV when there is no sharing
               module present.  Or "locks" it.  Or "unlocks" it.  In other
               words, ignores its single SV argument.  Exists to avoid test
               for a NULL function pointer and because it could potentially
               warn under some level of strict-ness.

                       void    sv_nosharing(SV *sv)

       vmess   "pat" and "args" are a sprintf-style format pattern and
               encapsulated argument list.  These are used to generate a
               string message.  If the message does not end with a newline,
               then it will be extended with some indication of the current
               location in the code, as described for "mess_sv".

               Normally, the resulting message is returned in a new mortal SV.
               During global destruction a single SV may be shared between
               uses of this function.

                       SV *    vmess(const char *pat, va_list *args)


MRO Functions

       mro_get_linear_isa
               Returns the mro linearisation for the given stash.  By default,
               this will be whatever "mro_get_linear_isa_dfs" returns unless
               some other MRO is in effect for the stash.  The return value is
               a read-only AV*.

               You are responsible for "SvREFCNT_inc()" on the return value if
               you plan to store it anywhere semi-permanently (otherwise it
               might be deleted out from under you the next time the cache is
               invalidated).

                       AV*     mro_get_linear_isa(HV* stash)

       mro_method_changed_in
               Invalidates method caching on any child classes of the given
               stash, so that they might notice the changes in this one.

               Ideally, all instances of "PL_sub_generation++" in perl source
               outside of mro.c should be replaced by calls to this.

               Perl automatically handles most of the common ways a method
               might be redefined.  However, there are a few ways you could
               change a method in a stash without the cache code noticing, in
               which case you need to call this method afterwards:

               1) Directly manipulating the stash HV entries from XS code.

               2) Assigning a reference to a readonly scalar constant into a
               stash entry in order to create a constant subroutine (like
               constant.pm does).

               This same method is available from pure perl via,
               "mro::method_changed_in(classname)".

                       void    mro_method_changed_in(HV* stash)

       mro_register
               Registers a custom mro plugin.  See perlmroapi for details.

                       void    mro_register(const struct mro_alg *mro)


Multicall Functions

       dMULTICALL
               Declare local variables for a multicall.  See "LIGHTWEIGHT
               CALLBACKS" in perlcall.

                               dMULTICALL;

       MULTICALL
               Make a lightweight callback.  See "LIGHTWEIGHT CALLBACKS" in
               perlcall.

                               MULTICALL;

       POP_MULTICALL
               Closing bracket for a lightweight callback.  See "LIGHTWEIGHT
               CALLBACKS" in perlcall.

                               POP_MULTICALL;

       PUSH_MULTICALL
               Opening bracket for a lightweight callback.  See "LIGHTWEIGHT
               CALLBACKS" in perlcall.

                               PUSH_MULTICALL;


Numeric functions

       grok_bin
               converts a string representing a binary number to numeric form.

               On entry start and *len give the string to scan, *flags gives
               conversion flags, and result should be NULL or a pointer to an
               NV.  The scan stops at the end of the string, or the first
               invalid character.  Unless "PERL_SCAN_SILENT_ILLDIGIT" is set
               in *flags, encountering an invalid character will also trigger
               a warning.  On return *len is set to the length of the scanned
               string, and *flags gives output flags.

               If the value is <= "UV_MAX" it is returned as a UV, the output
               flags are clear, and nothing is written to *result.  If the
               value is > UV_MAX "grok_bin" returns UV_MAX, sets
               "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes
               the value to *result (or the value is discarded if result is
               NULL).

               The binary number may optionally be prefixed with "0b" or "b"
               unless "PERL_SCAN_DISALLOW_PREFIX" is set in *flags on entry.
               If "PERL_SCAN_ALLOW_UNDERSCORES" is set in *flags then the
               binary number may use '_' characters to separate digits.

                       UV      grok_bin(const char* start, STRLEN* len_p,
                                        I32* flags, NV *result)

       grok_hex
               converts a string representing a hex number to numeric form.

               On entry start and *len_p give the string to scan, *flags gives
               conversion flags, and result should be NULL or a pointer to an
               NV.  The scan stops at the end of the string, or the first
               invalid character.  Unless "PERL_SCAN_SILENT_ILLDIGIT" is set
               in *flags, encountering an invalid character will also trigger
               a warning.  On return *len is set to the length of the scanned
               string, and *flags gives output flags.

               If the value is <= UV_MAX it is returned as a UV, the output
               flags are clear, and nothing is written to *result.  If the
               value is > UV_MAX "grok_hex" returns UV_MAX, sets
               "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes
               the value to *result (or the value is discarded if result is
               NULL).

               The hex number may optionally be prefixed with "0x" or "x"
               unless "PERL_SCAN_DISALLOW_PREFIX" is set in *flags on entry.
               If "PERL_SCAN_ALLOW_UNDERSCORES" is set in *flags then the hex
               number may use '_' characters to separate digits.

                       UV      grok_hex(const char* start, STRLEN* len_p,
                                        I32* flags, NV *result)

       grok_number
               Recognise (or not) a number.  The type of the number is
               returned (0 if unrecognised), otherwise it is a bit-ORed
               combination of IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX,
               IS_NUMBER_NOT_INT, IS_NUMBER_NEG, IS_NUMBER_INFINITY,
               IS_NUMBER_NAN (defined in perl.h).

               If the value of the number can fit in a UV, it is returned in
               the *valuep IS_NUMBER_IN_UV will be set to indicate that
               *valuep is valid, IS_NUMBER_IN_UV will never be set unless
               *valuep is valid, but *valuep may have been assigned to during
               processing even though IS_NUMBER_IN_UV is not set on return.
               If valuep is NULL, IS_NUMBER_IN_UV will be set for the same
               cases as when valuep is non-NULL, but no actual assignment (or
               SEGV) will occur.

               IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing
               decimals were seen (in which case *valuep gives the true value
               truncated to an integer), and IS_NUMBER_NEG if the number is
               negative (in which case *valuep holds the absolute value).
               IS_NUMBER_IN_UV is not set if e notation was used or the number
               is larger than a UV.

                       int     grok_number(const char *pv, STRLEN len,
                                           UV *valuep)

       grok_numeric_radix
               Scan and skip for a numeric decimal separator (radix).

                       bool    grok_numeric_radix(const char **sp,
                                                  const char *send)

       grok_oct
               converts a string representing an octal number to numeric form.

               On entry start and *len give the string to scan, *flags gives
               conversion flags, and result should be NULL or a pointer to an
               NV.  The scan stops at the end of the string, or the first
               invalid character.  Unless "PERL_SCAN_SILENT_ILLDIGIT" is set
               in *flags, encountering an 8 or 9 will also trigger a warning.
               On return *len is set to the length of the scanned string, and
               *flags gives output flags.

               If the value is <= UV_MAX it is returned as a UV, the output
               flags are clear, and nothing is written to *result.  If the
               value is > UV_MAX "grok_oct" returns UV_MAX, sets
               "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes
               the value to *result (or the value is discarded if result is
               NULL).

               If "PERL_SCAN_ALLOW_UNDERSCORES" is set in *flags then the
               octal number may use '_' characters to separate digits.

                       UV      grok_oct(const char* start, STRLEN* len_p,
                                        I32* flags, NV *result)

       Perl_signbit
               NOTE: this function is experimental and may change or be
               removed without notice.

               Return a non-zero integer if the sign bit on an NV is set, and
               0 if it is not.

               If Configure detects this system has a signbit() that will work
               with our NVs, then we just use it via the #define in perl.h.
               Otherwise, fall back on this implementation.  As a first pass,
               this gets everything right except -0.0.  Alas, catching -0.0 is
               the main use for this function, so this is not too helpful yet.
               Still, at least we have the scaffolding in place to support
               other systems, should that prove useful.

               Configure notes:  This function is called 'Perl_signbit'
               instead of a plain 'signbit' because it is easy to imagine a
               system having a signbit() function or macro that doesn't happen
               to work with our particular choice of NVs.  We shouldn't just
               re-#define signbit as Perl_signbit and expect the standard
               system headers to be happy.  Also, this is a no-context
               function (no pTHX_) because Perl_signbit() is usually
               re-#defined in perl.h as a simple macro call to the system's
               signbit().  Users should just always call Perl_signbit().

                       int     Perl_signbit(NV f)

       scan_bin
               For backwards compatibility.  Use "grok_bin" instead.

                       NV      scan_bin(const char* start, STRLEN len,
                                        STRLEN* retlen)

       scan_hex
               For backwards compatibility.  Use "grok_hex" instead.

                       NV      scan_hex(const char* start, STRLEN len,
                                        STRLEN* retlen)

       scan_oct
               For backwards compatibility.  Use "grok_oct" instead.

                       NV      scan_oct(const char* start, STRLEN len,
                                        STRLEN* retlen)


Optree construction

       newASSIGNOP
               Constructs, checks, and returns an assignment op.  left and
               right supply the parameters of the assignment; they are
               consumed by this function and become part of the constructed op
               tree.

               If optype is "OP_ANDASSIGN", "OP_ORASSIGN", or "OP_DORASSIGN",
               then a suitable conditional optree is constructed.  If optype
               is the opcode of a binary operator, such as "OP_BIT_OR", then
               an op is constructed that performs the binary operation and
               assigns the result to the left argument.  Either way, if optype
               is non-zero then flags has no effect.

               If optype is zero, then a plain scalar or list assignment is
               constructed.  Which type of assignment it is is automatically
               determined.  flags gives the eight bits of "op_flags", except
               that "OPf_KIDS" will be set automatically, and, shifted up
               eight bits, the eight bits of "op_private", except that the bit
               with value 1 or 2 is automatically set as required.

                       OP *    newASSIGNOP(I32 flags, OP *left, I32 optype,
                                           OP *right)

       newBINOP
               Constructs, checks, and returns an op of any binary type.  type
               is the opcode.  flags gives the eight bits of "op_flags",
               except that "OPf_KIDS" will be set automatically, and, shifted
               up eight bits, the eight bits of "op_private", except that the
               bit with value 1 or 2 is automatically set as required.  first
               and last supply up to two ops to be the direct children of the
               binary op; they are consumed by this function and become part
               of the constructed op tree.

                       OP *    newBINOP(I32 type, I32 flags, OP *first,
                                        OP *last)

       newCONDOP
               Constructs, checks, and returns a conditional-expression
               ("cond_expr") op.  flags gives the eight bits of "op_flags",
               except that "OPf_KIDS" will be set automatically, and, shifted
               up eight bits, the eight bits of "op_private", except that the
               bit with value 1 is automatically set.  first supplies the
               expression selecting between the two branches, and trueop and
               falseop supply the branches; they are consumed by this function
               and become part of the constructed op tree.

                       OP *    newCONDOP(I32 flags, OP *first, OP *trueop,
                                         OP *falseop)

       newFOROP
               Constructs, checks, and returns an op tree expressing a
               "foreach" loop (iteration through a list of values).  This is a
               heavyweight loop, with structure that allows exiting the loop
               by "last" and suchlike.

               sv optionally supplies the variable that will be aliased to
               each item in turn; if null, it defaults to $_ (either lexical
               or global).  expr supplies the list of values to iterate over.
               block supplies the main body of the loop, and cont optionally
               supplies a "continue" block that operates as a second half of
               the body.  All of these optree inputs are consumed by this
               function and become part of the constructed op tree.

               flags gives the eight bits of "op_flags" for the "leaveloop" op
               and, shifted up eight bits, the eight bits of "op_private" for
               the "leaveloop" op, except that (in both cases) some bits will
               be set automatically.

                       OP *    newFOROP(I32 flags, OP *sv, OP *expr, OP *block,
                                        OP *cont)

       newGIVENOP
               Constructs, checks, and returns an op tree expressing a "given"
               block.  cond supplies the expression that will be locally
               assigned to a lexical variable, and block supplies the body of
               the "given" construct; they are consumed by this function and
               become part of the constructed op tree.  defsv_off is the pad
               offset of the scalar lexical variable that will be affected.
               If it is 0, the global $_ will be used.

                       OP *    newGIVENOP(OP *cond, OP *block,
                                          PADOFFSET defsv_off)

       newGVOP Constructs, checks, and returns an op of any type that involves
               an embedded reference to a GV.  type is the opcode.  flags
               gives the eight bits of "op_flags".  gv identifies the GV that
               the op should reference; calling this function does not
               transfer ownership of any reference to it.

                       OP *    newGVOP(I32 type, I32 flags, GV *gv)

       newLISTOP
               Constructs, checks, and returns an op of any list type.  type
               is the opcode.  flags gives the eight bits of "op_flags",
               except that "OPf_KIDS" will be set automatically if required.
               first and last supply up to two ops to be direct children of
               the list op; they are consumed by this function and become part
               of the constructed op tree.

                       OP *    newLISTOP(I32 type, I32 flags, OP *first,
                                         OP *last)

       newLOGOP
               Constructs, checks, and returns a logical (flow control) op.
               type is the opcode.  flags gives the eight bits of "op_flags",
               except that "OPf_KIDS" will be set automatically, and, shifted
               up eight bits, the eight bits of "op_private", except that the
               bit with value 1 is automatically set.  first supplies the
               expression controlling the flow, and other supplies the side
               (alternate) chain of ops; they are consumed by this function
               and become part of the constructed op tree.

                       OP *    newLOGOP(I32 type, I32 flags, OP *first,
                                        OP *other)

       newLOOPEX
               Constructs, checks, and returns a loop-exiting op (such as
               "goto" or "last").  type is the opcode.  label supplies the
               parameter determining the target of the op; it is consumed by
               this function and becomes part of the constructed op tree.

                       OP *    newLOOPEX(I32 type, OP *label)

       newLOOPOP
               Constructs, checks, and returns an op tree expressing a loop.
               This is only a loop in the control flow through the op tree; it
               does not have the heavyweight loop structure that allows
               exiting the loop by "last" and suchlike.  flags gives the eight
               bits of "op_flags" for the top-level op, except that some bits
               will be set automatically as required.  expr supplies the
               expression controlling loop iteration, and block supplies the
               body of the loop; they are consumed by this function and become
               part of the constructed op tree.  debuggable is currently
               unused and should always be 1.

                       OP *    newLOOPOP(I32 flags, I32 debuggable, OP *expr,
                                         OP *block)

       newNULLLIST
               Constructs, checks, and returns a new "stub" op, which
               represents an empty list expression.

                       OP *    newNULLLIST()

       newOP   Constructs, checks, and returns an op of any base type (any
               type that has no extra fields).  type is the opcode.  flags
               gives the eight bits of "op_flags", and, shifted up eight bits,
               the eight bits of "op_private".

                       OP *    newOP(I32 type, I32 flags)

       newPADOP
               Constructs, checks, and returns an op of any type that involves
               a reference to a pad element.  type is the opcode.  flags gives
               the eight bits of "op_flags".  A pad slot is automatically
               allocated, and is populated with sv; this function takes
               ownership of one reference to it.

               This function only exists if Perl has been compiled to use
               ithreads.

                       OP *    newPADOP(I32 type, I32 flags, SV *sv)

       newPMOP Constructs, checks, and returns an op of any pattern matching
               type.  type is the opcode.  flags gives the eight bits of
               "op_flags" and, shifted up eight bits, the eight bits of
               "op_private".

                       OP *    newPMOP(I32 type, I32 flags)

       newPVOP Constructs, checks, and returns an op of any type that involves
               an embedded C-level pointer (PV).  type is the opcode.  flags
               gives the eight bits of "op_flags".  pv supplies the C-level
               pointer, which must have been allocated using
               "PerlMemShared_malloc"; the memory will be freed when the op is
               destroyed.

                       OP *    newPVOP(I32 type, I32 flags, char *pv)

       newRANGE
               Constructs and returns a "range" op, with subordinate "flip"
               and "flop" ops.  flags gives the eight bits of "op_flags" for
               the "flip" op and, shifted up eight bits, the eight bits of
               "op_private" for both the "flip" and "range" ops, except that
               the bit with value 1 is automatically set.  left and right
               supply the expressions controlling the endpoints of the range;
               they are consumed by this function and become part of the
               constructed op tree.

                       OP *    newRANGE(I32 flags, OP *left, OP *right)

       newSLICEOP
               Constructs, checks, and returns an "lslice" (list slice) op.
               flags gives the eight bits of "op_flags", except that
               "OPf_KIDS" will be set automatically, and, shifted up eight
               bits, the eight bits of "op_private", except that the bit with
               value 1 or 2 is automatically set as required.  listval and
               subscript supply the parameters of the slice; they are consumed
               by this function and become part of the constructed op tree.

                       OP *    newSLICEOP(I32 flags, OP *subscript,
                                          OP *listval)

       newSTATEOP
               Constructs a state op (COP).  The state op is normally a
               "nextstate" op, but will be a "dbstate" op if debugging is
               enabled for currently-compiled code.  The state op is populated
               from "PL_curcop" (or "PL_compiling").  If label is non-null, it
               supplies the name of a label to attach to the state op; this
               function takes ownership of the memory pointed at by label, and
               will free it.  flags gives the eight bits of "op_flags" for the
               state op.

               If o is null, the state op is returned.  Otherwise the state op
               is combined with o into a "lineseq" list op, which is returned.
               o is consumed by this function and becomes part of the returned
               op tree.

                       OP *    newSTATEOP(I32 flags, char *label, OP *o)

       newSVOP Constructs, checks, and returns an op of any type that involves
               an embedded SV.  type is the opcode.  flags gives the eight
               bits of "op_flags".  sv gives the SV to embed in the op; this
               function takes ownership of one reference to it.

                       OP *    newSVOP(I32 type, I32 flags, SV *sv)

       newUNOP Constructs, checks, and returns an op of any unary type.  type
               is the opcode.  flags gives the eight bits of "op_flags",
               except that "OPf_KIDS" will be set automatically if required,
               and, shifted up eight bits, the eight bits of "op_private",
               except that the bit with value 1 is automatically set.  first
               supplies an optional op to be the direct child of the unary op;
               it is consumed by this function and become part of the
               constructed op tree.

                       OP *    newUNOP(I32 type, I32 flags, OP *first)

       newWHENOP
               Constructs, checks, and returns an op tree expressing a "when"
               block.  cond supplies the test expression, and block supplies
               the block that will be executed if the test evaluates to true;
               they are consumed by this function and become part of the
               constructed op tree.  cond will be interpreted DWIMically,
               often as a comparison against $_, and may be null to generate a
               "default" block.

                       OP *    newWHENOP(OP *cond, OP *block)

       newWHILEOP
               Constructs, checks, and returns an op tree expressing a "while"
               loop.  This is a heavyweight loop, with structure that allows
               exiting the loop by "last" and suchlike.

               loop is an optional preconstructed "enterloop" op to use in the
               loop; if it is null then a suitable op will be constructed
               automatically.  expr supplies the loop's controlling
               expression.  block supplies the main body of the loop, and cont
               optionally supplies a "continue" block that operates as a
               second half of the body.  All of these optree inputs are
               consumed by this function and become part of the constructed op
               tree.

               flags gives the eight bits of "op_flags" for the "leaveloop" op
               and, shifted up eight bits, the eight bits of "op_private" for
               the "leaveloop" op, except that (in both cases) some bits will
               be set automatically.  debuggable is currently unused and
               should always be 1.  has_my can be supplied as true to force
               the loop body to be enclosed in its own scope.

                       OP *    newWHILEOP(I32 flags, I32 debuggable,
                                          LOOP *loop, OP *expr, OP *block,
                                          OP *cont, I32 has_my)


Optree Manipulation Functions

       ck_entersub_args_list
               Performs the default fixup of the arguments part of an
               "entersub" op tree.  This consists of applying list context to
               each of the argument ops.  This is the standard treatment used
               on a call marked with "&", or a method call, or a call through
               a subroutine reference, or any other call where the callee
               can't be identified at compile time, or a call where the callee
               has no prototype.

                       OP *    ck_entersub_args_list(OP *entersubop)

       ck_entersub_args_proto
               Performs the fixup of the arguments part of an "entersub" op
               tree based on a subroutine prototype.  This makes various
               modifications to the argument ops, from applying context up to
               inserting "refgen" ops, and checking the number and syntactic
               types of arguments, as directed by the prototype.  This is the
               standard treatment used on a subroutine call, not marked with
               "&", where the callee can be identified at compile time and has
               a prototype.

               protosv supplies the subroutine prototype to be applied to the
               call.  It may be a normal defined scalar, of which the string
               value will be used.  Alternatively, for convenience, it may be
               a subroutine object (a "CV*" that has been cast to "SV*") which
               has a prototype.  The prototype supplied, in whichever form,
               does not need to match the actual callee referenced by the op
               tree.

               If the argument ops disagree with the prototype, for example by
               having an unacceptable number of arguments, a valid op tree is
               returned anyway.  The error is reflected in the parser state,
               normally resulting in a single exception at the top level of
               parsing which covers all the compilation errors that occurred.
               In the error message, the callee is referred to by the name
               defined by the namegv parameter.

                       OP *    ck_entersub_args_proto(OP *entersubop,
                                                      GV *namegv, SV *protosv)

       ck_entersub_args_proto_or_list
               Performs the fixup of the arguments part of an "entersub" op
               tree either based on a subroutine prototype or using default
               list-context processing.  This is the standard treatment used
               on a subroutine call, not marked with "&", where the callee can
               be identified at compile time.

               protosv supplies the subroutine prototype to be applied to the
               call, or indicates that there is no prototype.  It may be a
               normal scalar, in which case if it is defined then the string
               value will be used as a prototype, and if it is undefined then
               there is no prototype.  Alternatively, for convenience, it may
               be a subroutine object (a "CV*" that has been cast to "SV*"),
               of which the prototype will be used if it has one.  The
               prototype (or lack thereof) supplied, in whichever form, does
               not need to match the actual callee referenced by the op tree.

               If the argument ops disagree with the prototype, for example by
               having an unacceptable number of arguments, a valid op tree is
               returned anyway.  The error is reflected in the parser state,
               normally resulting in a single exception at the top level of
               parsing which covers all the compilation errors that occurred.
               In the error message, the callee is referred to by the name
               defined by the namegv parameter.

                       OP *    ck_entersub_args_proto_or_list(OP *entersubop,
                                                              GV *namegv,
                                                              SV *protosv)

       cv_const_sv
               If "cv" is a constant sub eligible for inlining, returns the
               constant value returned by the sub.  Otherwise, returns NULL.

               Constant subs can be created with "newCONSTSUB" or as described
               in "Constant Functions" in perlsub.

                       SV*     cv_const_sv(const CV *const cv)

       cv_get_call_checker
               Retrieves the function that will be used to fix up a call to
               cv.  Specifically, the function is applied to an "entersub" op
               tree for a subroutine call, not marked with "&", where the
               callee can be identified at compile time as cv.

               The C-level function pointer is returned in *ckfun_p, and an SV
               argument for it is returned in *ckobj_p.  The function is
               intended to be called in this manner:

                   entersubop = (*ckfun_p)(aTHX_ entersubop, namegv, (*ckobj_p));

               In this call, entersubop is a pointer to the "entersub" op,
               which may be replaced by the check function, and namegv is a GV
               supplying the name that should be used by the check function to
               refer to the callee of the "entersub" op if it needs to emit
               any diagnostics.  It is permitted to apply the check function
               in non-standard situations, such as to a call to a different
               subroutine or to a method call.

               By default, the function is
               Perl_ck_entersub_args_proto_or_list, and the SV parameter is cv
               itself.  This implements standard prototype processing.  It can
               be changed, for a particular subroutine, by
               "cv_set_call_checker".

                       void    cv_get_call_checker(CV *cv,
                                                   Perl_call_checker *ckfun_p,
                                                   SV **ckobj_p)

       cv_set_call_checker
               Sets the function that will be used to fix up a call to cv.
               Specifically, the function is applied to an "entersub" op tree
               for a subroutine call, not marked with "&", where the callee
               can be identified at compile time as cv.

               The C-level function pointer is supplied in ckfun, and an SV
               argument for it is supplied in ckobj.  The function should be
               defined like this:

                   STATIC OP * ckfun(pTHX_ OP *op, GV *namegv, SV *ckobj)

               It is intended to be called in this manner:

                   entersubop = ckfun(aTHX_ entersubop, namegv, ckobj);

               In this call, entersubop is a pointer to the "entersub" op,
               which may be replaced by the check function, and namegv is a GV
               supplying the name that should be used by the check function to
               refer to the callee of the "entersub" op if it needs to emit
               any diagnostics.  It is permitted to apply the check function
               in non-standard situations, such as to a call to a different
               subroutine or to a method call.

               The current setting for a particular CV can be retrieved by
               "cv_get_call_checker".

                       void    cv_set_call_checker(CV *cv,
                                                   Perl_call_checker ckfun,
                                                   SV *ckobj)

       LINKLIST
               Given the root of an optree, link the tree in execution order
               using the "op_next" pointers and return the first op executed.
               If this has already been done, it will not be redone, and
               "o->op_next" will be returned.  If "o->op_next" is not already
               set, o should be at least an "UNOP".

                       OP*     LINKLIST(OP *o)

       newCONSTSUB
               See "newCONSTSUB_flags".

                       CV*     newCONSTSUB(HV* stash, const char* name, SV* sv)

       newCONSTSUB_flags
               Creates a constant sub equivalent to Perl "sub FOO () { 123 }"
               which is eligible for inlining at compile-time.

               Currently, the only useful value for "flags" is SVf_UTF8.

               The newly created subroutine takes ownership of a reference to
               the passed in SV.

               Passing NULL for SV creates a constant sub equivalent to "sub
               BAR () {}", which won't be called if used as a destructor, but
               will suppress the overhead of a call to "AUTOLOAD".  (This
               form, however, isn't eligible for inlining at compile time.)

                       CV*     newCONSTSUB_flags(HV* stash, const char* name,
                                                 STRLEN len, U32 flags, SV* sv)

       newXS   Used by "xsubpp" to hook up XSUBs as Perl subs.  filename needs
               to be static storage, as it is used directly as CvFILE(),
               without a copy being made.

       op_append_elem
               Append an item to the list of ops contained directly within a
               list-type op, returning the lengthened list.  first is the
               list-type op, and last is the op to append to the list.  optype
               specifies the intended opcode for the list.  If first is not
               already a list of the right type, it will be upgraded into one.
               If either first or last is null, the other is returned
               unchanged.

                       OP *    op_append_elem(I32 optype, OP *first, OP *last)

       op_append_list
               Concatenate the lists of ops contained directly within two
               list-type ops, returning the combined list.  first and last are
               the list-type ops to concatenate.  optype specifies the
               intended opcode for the list.  If either first or last is not
               already a list of the right type, it will be upgraded into one.
               If either first or last is null, the other is returned
               unchanged.

                       OP *    op_append_list(I32 optype, OP *first, OP *last)

       OP_CLASS
               Return the class of the provided OP: that is, which of the *OP
               structures it uses.  For core ops this currently gets the
               information out of PL_opargs, which does not always accurately
               reflect the type used.  For custom ops the type is returned
               from the registration, and it is up to the registree to ensure
               it is accurate.  The value returned will be one of the OA_*
               constants from op.h.

                       U32     OP_CLASS(OP *o)

       OP_DESC Return a short description of the provided OP.

                       const char * OP_DESC(OP *o)

       op_linklist
               This function is the implementation of the "LINKLIST" macro.
               It should not be called directly.

                       OP*     op_linklist(OP *o)

       op_lvalue
               NOTE: this function is experimental and may change or be
               removed without notice.

               Propagate lvalue ("modifiable") context to an op and its
               children.  type represents the context type, roughly based on
               the type of op that would do the modifying, although "local()"
               is represented by OP_NULL, because it has no op type of its own
               (it is signalled by a flag on the lvalue op).

               This function detects things that can't be modified, such as
               "$x+1", and generates errors for them.  For example, "$x+1 = 2"
               would cause it to be called with an op of type OP_ADD and a
               "type" argument of OP_SASSIGN.

               It also flags things that need to behave specially in an lvalue
               context, such as "$$x = 5" which might have to vivify a
               reference in $x.

                       OP *    op_lvalue(OP *o, I32 type)

       OP_NAME Return the name of the provided OP.  For core ops this looks up
               the name from the op_type; for custom ops from the op_ppaddr.

                       const char * OP_NAME(OP *o)

       op_prepend_elem
               Prepend an item to the list of ops contained directly within a
               list-type op, returning the lengthened list.  first is the op
               to prepend to the list, and last is the list-type op.  optype
               specifies the intended opcode for the list.  If last is not
               already a list of the right type, it will be upgraded into one.
               If either first or last is null, the other is returned
               unchanged.

                       OP *    op_prepend_elem(I32 optype, OP *first, OP *last)

       op_scope
               NOTE: this function is experimental and may change or be
               removed without notice.

               Wraps up an op tree with some additional ops so that at runtime
               a dynamic scope will be created.  The original ops run in the
               new dynamic scope, and then, provided that they exit normally,
               the scope will be unwound.  The additional ops used to create
               and unwind the dynamic scope will normally be an
               "enter"/"leave" pair, but a "scope" op may be used instead if
               the ops are simple enough to not need the full dynamic scope
               structure.

                       OP *    op_scope(OP *o)

       OP_TYPE_IS
               Returns true if the given OP is not a NULL pointer and if it is
               of the given type.

               The negation of this macro, "OP_TYPE_ISNT" is also available as
               well as "OP_TYPE_IS_NN" and "OP_TYPE_ISNT_NN" which elide the
               NULL pointer check.

                       bool    OP_TYPE_IS(OP *o, Optype type)

       OP_TYPE_IS_OR_WAS
               Returns true if the given OP is not a NULL pointer and if it is
               of the given type or used to be before being replaced by an OP
               of type OP_NULL.

               The negation of this macro, "OP_TYPE_ISNT_AND_WASNT" is also
               available as well as "OP_TYPE_IS_OR_WAS_NN" and
               "OP_TYPE_ISNT_AND_WASNT_NN" which elide the NULL pointer check.

                       bool    OP_TYPE_IS_OR_WAS(OP *o, Optype type)

       rv2cv_op_cv
               Examines an op, which is expected to identify a subroutine at
               runtime, and attempts to determine at compile time which
               subroutine it identifies.  This is normally used during Perl
               compilation to determine whether a prototype can be applied to
               a function call.  cvop is the op being considered, normally an
               "rv2cv" op.  A pointer to the identified subroutine is
               returned, if it could be determined statically, and a null
               pointer is returned if it was not possible to determine
               statically.

               Currently, the subroutine can be identified statically if the
               RV that the "rv2cv" is to operate on is provided by a suitable
               "gv" or "const" op.  A "gv" op is suitable if the GV's CV slot
               is populated.  A "const" op is suitable if the constant value
               must be an RV pointing to a CV.  Details of this process may
               change in future versions of Perl.  If the "rv2cv" op has the
               "OPpENTERSUB_AMPER" flag set then no attempt is made to
               identify the subroutine statically: this flag is used to
               suppress compile-time magic on a subroutine call, forcing it to
               use default runtime behaviour.

               If flags has the bit "RV2CVOPCV_MARK_EARLY" set, then the
               handling of a GV reference is modified.  If a GV was examined
               and its CV slot was found to be empty, then the "gv" op has the
               "OPpEARLY_CV" flag set.  If the op is not optimised away, and
               the CV slot is later populated with a subroutine having a
               prototype, that flag eventually triggers the warning "called
               too early to check prototype".

               If flags has the bit "RV2CVOPCV_RETURN_NAME_GV" set, then
               instead of returning a pointer to the subroutine it returns a
               pointer to the GV giving the most appropriate name for the
               subroutine in this context.  Normally this is just the "CvGV"
               of the subroutine, but for an anonymous ("CvANON") subroutine
               that is referenced through a GV it will be the referencing GV.
               The resulting "GV*" is cast to "CV*" to be returned.  A null
               pointer is returned as usual if there is no statically-
               determinable subroutine.

                       CV *    rv2cv_op_cv(OP *cvop, U32 flags)


Pad Data Structures

       CvPADLIST
               NOTE: this function is experimental and may change or be
               removed without notice.

               CV's can have CvPADLIST(cv) set to point to a PADLIST.  This is
               the CV's scratchpad, which stores lexical variables and opcode
               temporary and per-thread values.

               For these purposes "formats" are a kind-of CV; eval""s are too
               (except they're not callable at will and are always thrown away
               after the eval"" is done executing).  Require'd files are
               simply evals without any outer lexical scope.

               XSUBs don't have CvPADLIST set - dXSTARG fetches values from
               PL_curpad, but that is really the callers pad (a slot of which
               is allocated by every entersub).

               The PADLIST has a C array where pads are stored.

               The 0th entry of the PADLIST is a PADNAMELIST (which is
               actually just an AV, but that may change) which represents the
               "names" or rather the "static type information" for lexicals.
               The individual elements of a PADNAMELIST are PADNAMEs (just
               SVs; but, again, that may change).  Future refactorings might
               stop the PADNAMELIST from being stored in the PADLIST's array,
               so don't rely on it.  See "PadlistNAMES".

               The CvDEPTH'th entry of a PADLIST is a PAD (an AV) which is the
               stack frame at that depth of recursion into the CV.  The 0th
               slot of a frame AV is an AV which is @_.  Other entries are
               storage for variables and op targets.

               Iterating over the PADNAMELIST iterates over all possible pad
               items.  Pad slots for targets (SVs_PADTMP) and GVs end up
               having &PL_sv_no "names", while slots for constants have
               &PL_sv_no "names" (see pad_alloc()).  That &PL_sv_no is used is
               an implementation detail subject to change.  To test for it,
               use "PadnamePV(name) && !PadnameLEN(name)".

               Only my/our variable (SvPADMY/PADNAME_isOUR) slots get valid
               names.  The rest are op targets/GVs/constants which are
               statically allocated or resolved at compile time.  These don't
               have names by which they can be looked up from Perl code at run
               time through eval"" the way my/our variables can be.  Since
               they can't be looked up by "name" but only by their index
               allocated at compile time (which is usually in PL_op->op_targ),
               wasting a name SV for them doesn't make sense.

               The SVs in the names AV have their PV being the name of the
               variable.  xlow+1..xhigh inclusive in the NV union is a range
               of cop_seq numbers for which the name is valid (accessed
               through the macros COP_SEQ_RANGE_LOW and _HIGH).  During
               compilation, these fields may hold the special value
               PERL_PADSEQ_INTRO to indicate various stages:

                  COP_SEQ_RANGE_LOW        _HIGH
                  -----------------        -----
                  PERL_PADSEQ_INTRO            0   variable not yet introduced:   { my ($x
                  valid-seq#   PERL_PADSEQ_INTRO   variable in scope:             { my ($x)
                  valid-seq#          valid-seq#   compilation of scope complete: { my ($x) }

               For typed lexicals name SV is SVt_PVMG and SvSTASH points at
               the type.  For "our" lexicals, the type is also SVt_PVMG, with
               the SvOURSTASH slot pointing at the stash of the associated
               global (so that duplicate "our" declarations in the same
               package can be detected).  SvUVX is sometimes hijacked to store
               the generation number during compilation.

               If PADNAME_OUTER (SvFAKE) is set on the name SV, then that slot
               in the frame AV is a REFCNT'ed reference to a lexical from
               "outside".  In this case, the name SV does not use xlow and
               xhigh to store a cop_seq range, since it is in scope
               throughout.  Instead xhigh stores some flags containing info
               about the real lexical (is it declared in an anon, and is it
               capable of being instantiated multiple times?), and for fake
               ANONs, xlow contains the index within the parent's pad where
               the lexical's value is stored, to make cloning quicker.

               If the 'name' is '&' the corresponding entry in the PAD is a CV
               representing a possible closure.  (PADNAME_OUTER and name of
               '&' is not a meaningful combination currently but could become
               so if "my sub foo {}" is implemented.)

               Note that formats are treated as anon subs, and are cloned each
               time write is called (if necessary).

               The flag SVs_PADSTALE is cleared on lexicals each time the my()
               is executed, and set on scope exit.  This allows the 'Variable
               $x is not available' warning to be generated in evals, such as

                   { my $x = 1; sub f { eval '$x'} } f();

               For state vars, SVs_PADSTALE is overloaded to mean 'not yet
               initialised'.

                       PADLIST * CvPADLIST(CV *cv)

       PadARRAY
               NOTE: this function is experimental and may change or be
               removed without notice.

               The C array of pad entries.

                       SV **   PadARRAY(PAD pad)

       PadlistARRAY
               NOTE: this function is experimental and may change or be
               removed without notice.

               The C array of a padlist, containing the pads.  Only subscript
               it with numbers >= 1, as the 0th entry is not guaranteed to
               remain usable.

                       PAD **  PadlistARRAY(PADLIST padlist)

       PadlistMAX
               NOTE: this function is experimental and may change or be
               removed without notice.

               The index of the last allocated space in the padlist.  Note
               that the last pad may be in an earlier slot.  Any entries
               following it will be NULL in that case.

                       SSize_t PadlistMAX(PADLIST padlist)

       PadlistNAMES
               NOTE: this function is experimental and may change or be
               removed without notice.

               The names associated with pad entries.

                       PADNAMELIST * PadlistNAMES(PADLIST padlist)

       PadlistNAMESARRAY
               NOTE: this function is experimental and may change or be
               removed without notice.

               The C array of pad names.

                       PADNAME ** PadlistNAMESARRAY(PADLIST padlist)

       PadlistNAMESMAX
               NOTE: this function is experimental and may change or be
               removed without notice.

               The index of the last pad name.

                       SSize_t PadlistNAMESMAX(PADLIST padlist)

       PadlistREFCNT
               NOTE: this function is experimental and may change or be
               removed without notice.

               The reference count of the padlist.  Currently this is always
               1.

                       U32     PadlistREFCNT(PADLIST padlist)

       PadMAX  NOTE: this function is experimental and may change or be
               removed without notice.

               The index of the last pad entry.

                       SSize_t PadMAX(PAD pad)

       PadnameLEN
               NOTE: this function is experimental and may change or be
               removed without notice.

               The length of the name.

                       STRLEN  PadnameLEN(PADNAME pn)

       PadnamelistARRAY
               NOTE: this function is experimental and may change or be
               removed without notice.

               The C array of pad names.

                       PADNAME ** PadnamelistARRAY(PADNAMELIST pnl)

       PadnamelistMAX
               NOTE: this function is experimental and may change or be
               removed without notice.

               The index of the last pad name.

                       SSize_t PadnamelistMAX(PADNAMELIST pnl)

       PadnamePV
               NOTE: this function is experimental and may change or be
               removed without notice.

               The name stored in the pad name struct.  This returns NULL for
               a target or GV slot.

                       char *  PadnamePV(PADNAME pn)

       PadnameSV
               NOTE: this function is experimental and may change or be
               removed without notice.

               Returns the pad name as an SV.  This is currently just "pn".
               It will begin returning a new mortal SV if pad names ever stop
               being SVs.

                       SV *    PadnameSV(PADNAME pn)

       PadnameUTF8
               NOTE: this function is experimental and may change or be
               removed without notice.

               Whether PadnamePV is in UTF8.

                       bool    PadnameUTF8(PADNAME pn)

       pad_add_name_pvs
               Exactly like "pad_add_name_pvn", but takes a literal string
               instead of a string/length pair.

                       PADOFFSET pad_add_name_pvs(const char *name, U32 flags,
                                                  HV *typestash, HV *ourstash)

       pad_findmy_pvs
               Exactly like "pad_findmy_pvn", but takes a literal string
               instead of a string/length pair.

                       PADOFFSET pad_findmy_pvs(const char *name, U32 flags)

       pad_new Create a new padlist, updating the global variables for the
               currently-compiling padlist to point to the new padlist.  The
               following flags can be OR'ed together:

                   padnew_CLONE        this pad is for a cloned CV
                   padnew_SAVE         save old globals on the save stack
                   padnew_SAVESUB      also save extra stuff for start of sub

                       PADLIST * pad_new(int flags)

       PL_comppad
               NOTE: this function is experimental and may change or be
               removed without notice.

               During compilation, this points to the array containing the
               values part of the pad for the currently-compiling code.  (At
               runtime a CV may have many such value arrays; at compile time
               just one is constructed.)  At runtime, this points to the array
               containing the currently-relevant values for the pad for the
               currently-executing code.

       PL_comppad_name
               NOTE: this function is experimental and may change or be
               removed without notice.

               During compilation, this points to the array containing the
               names part of the pad for the currently-compiling code.

       PL_curpad
               NOTE: this function is experimental and may change or be
               removed without notice.

               Points directly to the body of the "PL_comppad" array.  (I.e.,
               this is "PAD_ARRAY(PL_comppad)".)


Per-Interpreter Variables

       PL_modglobal
               "PL_modglobal" is a general purpose, interpreter global HV for
               use by extensions that need to keep information on a per-
               interpreter basis.  In a pinch, it can also be used as a symbol
               table for extensions to share data among each other.  It is a
               good idea to use keys prefixed by the package name of the
               extension that owns the data.

                       HV*     PL_modglobal

       PL_na   A convenience variable which is typically used with "SvPV" when
               one doesn't care about the length of the string.  It is usually
               more efficient to either declare a local variable and use that
               instead or to use the "SvPV_nolen" macro.

                       STRLEN  PL_na

       PL_opfreehook
               When non-"NULL", the function pointed by this variable will be
               called each time an OP is freed with the corresponding OP as
               the argument.  This allows extensions to free any extra
               attribute they have locally attached to an OP.  It is also
               assured to first fire for the parent OP and then for its kids.

               When you replace this variable, it is considered a good
               practice to store the possibly previously installed hook and
               that you recall it inside your own.

                       Perl_ophook_t   PL_opfreehook

       PL_peepp
               Pointer to the per-subroutine peephole optimiser.  This is a
               function that gets called at the end of compilation of a Perl
               subroutine (or equivalently independent piece of Perl code) to
               perform fixups of some ops and to perform small-scale
               optimisations.  The function is called once for each subroutine
               that is compiled, and is passed, as sole parameter, a pointer
               to the op that is the entry point to the subroutine.  It
               modifies the op tree in place.

               The peephole optimiser should never be completely replaced.
               Rather, add code to it by wrapping the existing optimiser.  The
               basic way to do this can be seen in "Compile pass 3: peephole
               optimization" in perlguts.  If the new code wishes to operate
               on ops throughout the subroutine's structure, rather than just
               at the top level, it is likely to be more convenient to wrap
               the "PL_rpeepp" hook.

                       peep_t  PL_peepp

       PL_rpeepp
               Pointer to the recursive peephole optimiser.  This is a
               function that gets called at the end of compilation of a Perl
               subroutine (or equivalently independent piece of Perl code) to
               perform fixups of some ops and to perform small-scale
               optimisations.  The function is called once for each chain of
               ops linked through their "op_next" fields; it is recursively
               called to handle each side chain.  It is passed, as sole
               parameter, a pointer to the op that is at the head of the
               chain.  It modifies the op tree in place.

               The peephole optimiser should never be completely replaced.
               Rather, add code to it by wrapping the existing optimiser.  The
               basic way to do this can be seen in "Compile pass 3: peephole
               optimization" in perlguts.  If the new code wishes to operate
               only on ops at a subroutine's top level, rather than throughout
               the structure, it is likely to be more convenient to wrap the
               "PL_peepp" hook.

                       peep_t  PL_rpeepp

       PL_sv_no
               This is the "false" SV.  See "PL_sv_yes".  Always refer to this
               as &PL_sv_no.

                       SV      PL_sv_no

       PL_sv_undef
               This is the "undef" SV.  Always refer to this as &PL_sv_undef.

                       SV      PL_sv_undef

       PL_sv_yes
               This is the "true" SV.  See "PL_sv_no".  Always refer to this
               as &PL_sv_yes.

                       SV      PL_sv_yes


REGEXP Functions

       SvRX    Convenience macro to get the REGEXP from a SV.  This is
               approximately equivalent to the following snippet:

                   if (SvMAGICAL(sv))
                       mg_get(sv);
                   if (SvROK(sv))
                       sv = MUTABLE_SV(SvRV(sv));
                   if (SvTYPE(sv) == SVt_REGEXP)
                       return (REGEXP*) sv;

               NULL will be returned if a REGEXP* is not found.

                       REGEXP * SvRX(SV *sv)

       SvRXOK  Returns a boolean indicating whether the SV (or the one it
               references) is a REGEXP.

               If you want to do something with the REGEXP* later use SvRX
               instead and check for NULL.

                       bool    SvRXOK(SV* sv)


Simple Exception Handling Macros

       dXCPT   Set up necessary local variables for exception handling.  See
               "Exception Handling" in perlguts.

                               dXCPT;

       XCPT_CATCH
               Introduces a catch block.  See "Exception Handling" in
               perlguts.

       XCPT_RETHROW
               Rethrows a previously caught exception.  See "Exception
               Handling" in perlguts.

                               XCPT_RETHROW;

       XCPT_TRY_END
               Ends a try block.  See "Exception Handling" in perlguts.

       XCPT_TRY_START
               Starts a try block.  See "Exception Handling" in perlguts.


Stack Manipulation Macros

       dMARK   Declare a stack marker variable, "mark", for the XSUB.  See
               "MARK" and "dORIGMARK".

                               dMARK;

       dORIGMARK
               Saves the original stack mark for the XSUB.  See "ORIGMARK".

                               dORIGMARK;

       dSP     Declares a local copy of perl's stack pointer for the XSUB,
               available via the "SP" macro.  See "SP".

                               dSP;

       EXTEND  Used to extend the argument stack for an XSUB's return values.
               Once used, guarantees that there is room for at least "nitems"
               to be pushed onto the stack.

                       void    EXTEND(SP, SSize_t nitems)

       MARK    Stack marker variable for the XSUB.  See "dMARK".

       mPUSHi  Push an integer onto the stack.  The stack must have room for
               this element.  Does not use "TARG".  See also "PUSHi",
               "mXPUSHi" and "XPUSHi".

                       void    mPUSHi(IV iv)

       mPUSHn  Push a double onto the stack.  The stack must have room for
               this element.  Does not use "TARG".  See also "PUSHn",
               "mXPUSHn" and "XPUSHn".

                       void    mPUSHn(NV nv)

       mPUSHp  Push a string onto the stack.  The stack must have room for
               this element.  The "len" indicates the length of the string.
               Does not use "TARG".  See also "PUSHp", "mXPUSHp" and "XPUSHp".

                       void    mPUSHp(char* str, STRLEN len)

       mPUSHs  Push an SV onto the stack and mortalizes the SV.  The stack
               must have room for this element.  Does not use "TARG".  See
               also "PUSHs" and "mXPUSHs".

                       void    mPUSHs(SV* sv)

       mPUSHu  Push an unsigned integer onto the stack.  The stack must have
               room for this element.  Does not use "TARG".  See also "PUSHu",
               "mXPUSHu" and "XPUSHu".

                       void    mPUSHu(UV uv)

       mXPUSHi Push an integer onto the stack, extending the stack if
               necessary.  Does not use "TARG".  See also "XPUSHi", "mPUSHi"
               and "PUSHi".

                       void    mXPUSHi(IV iv)

       mXPUSHn Push a double onto the stack, extending the stack if necessary.
               Does not use "TARG".  See also "XPUSHn", "mPUSHn" and "PUSHn".

                       void    mXPUSHn(NV nv)

       mXPUSHp Push a string onto the stack, extending the stack if necessary.
               The "len" indicates the length of the string.  Does not use
               "TARG".  See also "XPUSHp", "mPUSHp" and "PUSHp".

                       void    mXPUSHp(char* str, STRLEN len)

       mXPUSHs Push an SV onto the stack, extending the stack if necessary and
               mortalizes the SV.  Does not use "TARG".  See also "XPUSHs" and
               "mPUSHs".

                       void    mXPUSHs(SV* sv)

       mXPUSHu Push an unsigned integer onto the stack, extending the stack if
               necessary.  Does not use "TARG".  See also "XPUSHu", "mPUSHu"
               and "PUSHu".

                       void    mXPUSHu(UV uv)

       ORIGMARK
               The original stack mark for the XSUB.  See "dORIGMARK".

       POPi    Pops an integer off the stack.

                       IV      POPi

       POPl    Pops a long off the stack.

                       long    POPl

       POPn    Pops a double off the stack.

                       NV      POPn

       POPp    Pops a string off the stack.

                       char*   POPp

       POPpbytex
               Pops a string off the stack which must consist of bytes i.e.
               characters < 256.

                       char*   POPpbytex

       POPpx   Pops a string off the stack.  Identical to POPp.  There are two
               names for historical reasons.

                       char*   POPpx

       POPs    Pops an SV off the stack.

                       SV*     POPs

       PUSHi   Push an integer onto the stack.  The stack must have room for
               this element.  Handles 'set' magic.  Uses "TARG", so "dTARGET"
               or "dXSTARG" should be called to declare it.  Do not call
               multiple "TARG"-oriented macros to return lists from XSUB's -
               see "mPUSHi" instead.  See also "XPUSHi" and "mXPUSHi".

                       void    PUSHi(IV iv)

       PUSHMARK
               Opening bracket for arguments on a callback.  See "PUTBACK" and
               perlcall.

                       void    PUSHMARK(SP)

       PUSHmortal
               Push a new mortal SV onto the stack.  The stack must have room
               for this element.  Does not use "TARG".  See also "PUSHs",
               "XPUSHmortal" and "XPUSHs".

                       void    PUSHmortal()

       PUSHn   Push a double onto the stack.  The stack must have room for
               this element.  Handles 'set' magic.  Uses "TARG", so "dTARGET"
               or "dXSTARG" should be called to declare it.  Do not call
               multiple "TARG"-oriented macros to return lists from XSUB's -
               see "mPUSHn" instead.  See also "XPUSHn" and "mXPUSHn".

                       void    PUSHn(NV nv)

       PUSHp   Push a string onto the stack.  The stack must have room for
               this element.  The "len" indicates the length of the string.
               Handles 'set' magic.  Uses "TARG", so "dTARGET" or "dXSTARG"
               should be called to declare it.  Do not call multiple
               "TARG"-oriented macros to return lists from XSUB's - see
               "mPUSHp" instead.  See also "XPUSHp" and "mXPUSHp".

                       void    PUSHp(char* str, STRLEN len)

       PUSHs   Push an SV onto the stack.  The stack must have room for this
               element.  Does not handle 'set' magic.  Does not use "TARG".
               See also "PUSHmortal", "XPUSHs" and "XPUSHmortal".

                       void    PUSHs(SV* sv)

       PUSHu   Push an unsigned integer onto the stack.  The stack must have
               room for this element.  Handles 'set' magic.  Uses "TARG", so
               "dTARGET" or "dXSTARG" should be called to declare it.  Do not
               call multiple "TARG"-oriented macros to return lists from
               XSUB's - see "mPUSHu" instead.  See also "XPUSHu" and
               "mXPUSHu".

                       void    PUSHu(UV uv)

       PUTBACK Closing bracket for XSUB arguments.  This is usually handled by
               "xsubpp".  See "PUSHMARK" and perlcall for other uses.

                               PUTBACK;

       SP      Stack pointer.  This is usually handled by "xsubpp".  See "dSP"
               and "SPAGAIN".

       SPAGAIN Refetch the stack pointer.  Used after a callback.  See
               perlcall.

                               SPAGAIN;

       XPUSHi  Push an integer onto the stack, extending the stack if
               necessary.  Handles 'set' magic.  Uses "TARG", so "dTARGET" or
               "dXSTARG" should be called to declare it.  Do not call multiple
               "TARG"-oriented macros to return lists from XSUB's - see
               "mXPUSHi" instead.  See also "PUSHi" and "mPUSHi".

                       void    XPUSHi(IV iv)

       XPUSHmortal
               Push a new mortal SV onto the stack, extending the stack if
               necessary.  Does not use "TARG".  See also "XPUSHs",
               "PUSHmortal" and "PUSHs".

                       void    XPUSHmortal()

       XPUSHn  Push a double onto the stack, extending the stack if necessary.
               Handles 'set' magic.  Uses "TARG", so "dTARGET" or "dXSTARG"
               should be called to declare it.  Do not call multiple
               "TARG"-oriented macros to return lists from XSUB's - see
               "mXPUSHn" instead.  See also "PUSHn" and "mPUSHn".

                       void    XPUSHn(NV nv)

       XPUSHp  Push a string onto the stack, extending the stack if necessary.
               The "len" indicates the length of the string.  Handles 'set'
               magic.  Uses "TARG", so "dTARGET" or "dXSTARG" should be called
               to declare it.  Do not call multiple "TARG"-oriented macros to
               return lists from XSUB's - see "mXPUSHp" instead.  See also
               "PUSHp" and "mPUSHp".

                       void    XPUSHp(char* str, STRLEN len)

       XPUSHs  Push an SV onto the stack, extending the stack if necessary.
               Does not handle 'set' magic.  Does not use "TARG".  See also
               "XPUSHmortal", "PUSHs" and "PUSHmortal".

                       void    XPUSHs(SV* sv)

       XPUSHu  Push an unsigned integer onto the stack, extending the stack if
               necessary.  Handles 'set' magic.  Uses "TARG", so "dTARGET" or
               "dXSTARG" should be called to declare it.  Do not call multiple
               "TARG"-oriented macros to return lists from XSUB's - see
               "mXPUSHu" instead.  See also "PUSHu" and "mPUSHu".

                       void    XPUSHu(UV uv)

       XSRETURN
               Return from XSUB, indicating number of items on the stack.
               This is usually handled by "xsubpp".

                       void    XSRETURN(int nitems)

       XSRETURN_EMPTY
               Return an empty list from an XSUB immediately.

                               XSRETURN_EMPTY;

       XSRETURN_IV
               Return an integer from an XSUB immediately.  Uses "XST_mIV".

                       void    XSRETURN_IV(IV iv)

       XSRETURN_NO
               Return &PL_sv_no from an XSUB immediately.  Uses "XST_mNO".

                               XSRETURN_NO;

       XSRETURN_NV
               Return a double from an XSUB immediately.  Uses "XST_mNV".

                       void    XSRETURN_NV(NV nv)

       XSRETURN_PV
               Return a copy of a string from an XSUB immediately.  Uses
               "XST_mPV".

                       void    XSRETURN_PV(char* str)

       XSRETURN_UNDEF
               Return &PL_sv_undef from an XSUB immediately.  Uses
               "XST_mUNDEF".

                               XSRETURN_UNDEF;

       XSRETURN_UV
               Return an integer from an XSUB immediately.  Uses "XST_mUV".

                       void    XSRETURN_UV(IV uv)

       XSRETURN_YES
               Return &PL_sv_yes from an XSUB immediately.  Uses "XST_mYES".

                               XSRETURN_YES;

       XST_mIV Place an integer into the specified position "pos" on the
               stack.  The value is stored in a new mortal SV.

                       void    XST_mIV(int pos, IV iv)

       XST_mNO Place &PL_sv_no into the specified position "pos" on the stack.

                       void    XST_mNO(int pos)

       XST_mNV Place a double into the specified position "pos" on the stack.
               The value is stored in a new mortal SV.

                       void    XST_mNV(int pos, NV nv)

       XST_mPV Place a copy of a string into the specified position "pos" on
               the stack.  The value is stored in a new mortal SV.

                       void    XST_mPV(int pos, char* str)

       XST_mUNDEF
               Place &PL_sv_undef into the specified position "pos" on the
               stack.

                       void    XST_mUNDEF(int pos)

       XST_mYES
               Place &PL_sv_yes into the specified position "pos" on the
               stack.

                       void    XST_mYES(int pos)


SV Flags

       svtype  An enum of flags for Perl types.  These are found in the file
               sv.h in the "svtype" enum.  Test these flags with the "SvTYPE"
               macro.

               The types are:

                   SVt_NULL
                   SVt_IV
                   SVt_NV
                   SVt_RV
                   SVt_PV
                   SVt_PVIV
                   SVt_PVNV
                   SVt_PVMG
                   SVt_INVLIST
                   SVt_REGEXP
                   SVt_PVGV
                   SVt_PVLV
                   SVt_PVAV
                   SVt_PVHV
                   SVt_PVCV
                   SVt_PVFM
                   SVt_PVIO

               These are most easily explained from the bottom up.

               SVt_PVIO is for I/O objects, SVt_PVFM for formats, SVt_PVCV for
               subroutines, SVt_PVHV for hashes and SVt_PVAV for arrays.

               All the others are scalar types, that is, things that can be
               bound to a "$" variable.  For these, the internal types are
               mostly orthogonal to types in the Perl language.

               Hence, checking "SvTYPE(sv) < SVt_PVAV" is the best way to see
               whether something is a scalar.

               SVt_PVGV represents a typeglob.  If !SvFAKE(sv), then it is a
               real, incoercible typeglob.  If SvFAKE(sv), then it is a scalar
               to which a typeglob has been assigned.  Assigning to it again
               will stop it from being a typeglob.  SVt_PVLV represents a
               scalar that delegates to another scalar behind the scenes.  It
               is used, e.g., for the return value of "substr" and for tied
               hash and array elements.  It can hold any scalar value,
               including a typeglob.  SVt_REGEXP is for regular expressions.
               SVt_INVLIST is for Perl core internal use only.

               SVt_PVMG represents a "normal" scalar (not a typeglob, regular
               expression, or delegate).  Since most scalars do not need all
               the internal fields of a PVMG, we save memory by allocating
               smaller structs when possible.  All the other types are just
               simpler forms of SVt_PVMG, with fewer internal fields.
                SVt_NULL can only hold undef.  SVt_IV can hold undef, an
               integer, or a reference.  (SVt_RV is an alias for SVt_IV, which
               exists for backward compatibility.)  SVt_NV can hold any of
               those or a double.  SVt_PV can only hold undef or a string.
               SVt_PVIV is a superset of SVt_PV and SVt_IV.  SVt_PVNV is
               similar.  SVt_PVMG can hold anything SVt_PVNV can hold, but it
               can, but does not have to, be blessed or magical.

       SVt_INVLIST
               Type flag for scalars.  See "svtype".

       SVt_IV  Type flag for scalars.  See "svtype".

       SVt_NULL
               Type flag for scalars.  See "svtype".

       SVt_NV  Type flag for scalars.  See "svtype".

       SVt_PV  Type flag for scalars.  See "svtype".

       SVt_PVAV
               Type flag for arrays.  See "svtype".

       SVt_PVCV
               Type flag for subroutines.  See "svtype".

       SVt_PVFM
               Type flag for formats.  See "svtype".

       SVt_PVGV
               Type flag for typeglobs.  See "svtype".

       SVt_PVHV
               Type flag for hashes.  See "svtype".

       SVt_PVIO
               Type flag for I/O objects.  See "svtype".

       SVt_PVIV
               Type flag for scalars.  See "svtype".

       SVt_PVLV
               Type flag for scalars.  See "svtype".

       SVt_PVMG
               Type flag for scalars.  See "svtype".

       SVt_PVNV
               Type flag for scalars.  See "svtype".

       SVt_REGEXP
               Type flag for regular expressions.  See "svtype".


SV Manipulation Functions

       boolSV  Returns a true SV if "b" is a true value, or a false SV if "b"
               is 0.

               See also "PL_sv_yes" and "PL_sv_no".

                       SV *    boolSV(bool b)

       croak_xs_usage
               A specialised variant of "croak()" for emitting the usage
               message for xsubs

                   croak_xs_usage(cv, "eee_yow");

               works out the package name and subroutine name from "cv", and
               then calls "croak()".  Hence if "cv" is &ouch::awk, it would
               call "croak" as:

                   Perl_croak(aTHX_ "Usage: %"SVf"::%"SVf"(%s)", "ouch" "awk", "eee_yow");

                       void    croak_xs_usage(const CV *const cv,
                                              const char *const params)

       get_sv  Returns the SV of the specified Perl scalar.  "flags" are
               passed to "gv_fetchpv".  If "GV_ADD" is set and the Perl
               variable does not exist then it will be created.  If "flags" is
               zero and the variable does not exist then NULL is returned.

               NOTE: the perl_ form of this function is deprecated.

                       SV*     get_sv(const char *name, I32 flags)

       newRV_inc
               Creates an RV wrapper for an SV.  The reference count for the
               original SV is incremented.

                       SV*     newRV_inc(SV* sv)

       newSVpadname
               NOTE: this function is experimental and may change or be
               removed without notice.

               Creates a new SV containing the pad name.  This is currently
               identical to "newSVsv", but pad names may cease being SVs at
               some point, so "newSVpadname" is preferable.

                       SV*     newSVpadname(PADNAME *pn)

       newSVpvn_utf8
               Creates a new SV and copies a string into it.  If utf8 is true,
               calls "SvUTF8_on" on the new SV.  Implemented as a wrapper
               around "newSVpvn_flags".

                       SV*     newSVpvn_utf8(NULLOK const char* s, STRLEN len,
                                             U32 utf8)

       SvCUR   Returns the length of the string which is in the SV.  See
               "SvLEN".

                       STRLEN  SvCUR(SV* sv)

       SvCUR_set
               Set the current length of the string which is in the SV.  See
               "SvCUR" and "SvIV_set".

                       void    SvCUR_set(SV* sv, STRLEN len)

       SvEND   Returns a pointer to the spot just after the last character in
               the string which is in the SV, where there is usually a
               trailing null (even though Perl scalars do not strictly require
               it).  See "SvCUR".  Access the character as *(SvEND(sv)).

               Warning: If "SvCUR" is equal to "SvLEN", then "SvEND" points to
               unallocated memory.

                       char*   SvEND(SV* sv)

       SvGAMAGIC
               Returns true if the SV has get magic or overloading.  If either
               is true then the scalar is active data, and has the potential
               to return a new value every time it is accessed.  Hence you
               must be careful to only read it once per user logical operation
               and work with that returned value.  If neither is true then the
               scalar's value cannot change unless written to.

                       U32     SvGAMAGIC(SV* sv)

       SvGROW  Expands the character buffer in the SV so that it has room for
               the indicated number of bytes (remember to reserve space for an
               extra trailing NUL character).  Calls "sv_grow" to perform the
               expansion if necessary.  Returns a pointer to the character
               buffer.  SV must be of type >= SVt_PV.  One alternative is to
               call "sv_grow" if you are not sure of the type of SV.

                       char *  SvGROW(SV* sv, STRLEN len)

       SvIOK   Returns a U32 value indicating whether the SV contains an
               integer.

                       U32     SvIOK(SV* sv)

       SvIOKp  Returns a U32 value indicating whether the SV contains an
               integer.  Checks the private setting.  Use "SvIOK" instead.

                       U32     SvIOKp(SV* sv)

       SvIOK_notUV
               Returns a boolean indicating whether the SV contains a signed
               integer.

                       bool    SvIOK_notUV(SV* sv)

       SvIOK_off
               Unsets the IV status of an SV.

                       void    SvIOK_off(SV* sv)

       SvIOK_on
               Tells an SV that it is an integer.

                       void    SvIOK_on(SV* sv)

       SvIOK_only
               Tells an SV that it is an integer and disables all other OK
               bits.

                       void    SvIOK_only(SV* sv)

       SvIOK_only_UV
               Tells an SV that it is an unsigned integer and disables all
               other OK bits.

                       void    SvIOK_only_UV(SV* sv)

       SvIOK_UV
               Returns a boolean indicating whether the SV contains an integer
               that must be interpreted as unsigned.  A non-negative integer
               whose value is within the range of both an IV and a UV may be
               be flagged as either SvUOK or SVIOK.

                       bool    SvIOK_UV(SV* sv)

       SvIsCOW Returns a U32 value indicating whether the SV is Copy-On-Write
               (either shared hash key scalars, or full Copy On Write scalars
               if 5.9.0 is configured for COW).

                       U32     SvIsCOW(SV* sv)

       SvIsCOW_shared_hash
               Returns a boolean indicating whether the SV is Copy-On-Write
               shared hash key scalar.

                       bool    SvIsCOW_shared_hash(SV* sv)

       SvIV    Coerces the given SV to an integer and returns it.  See "SvIVx"
               for a version which guarantees to evaluate sv only once.

                       IV      SvIV(SV* sv)

       SvIVX   Returns the raw value in the SV's IV slot, without checks or
               conversions.  Only use when you are sure SvIOK is true.  See
               also "SvIV()".

                       IV      SvIVX(SV* sv)

       SvIVx   Coerces the given SV to an integer and returns it.  Guarantees
               to evaluate "sv" only once.  Only use this if "sv" is an
               expression with side effects, otherwise use the more efficient
               "SvIV".

                       IV      SvIVx(SV* sv)

       SvIV_nomg
               Like "SvIV" but doesn't process magic.

                       IV      SvIV_nomg(SV* sv)

       SvIV_set
               Set the value of the IV pointer in sv to val.  It is possible
               to perform the same function of this macro with an lvalue
               assignment to "SvIVX".  With future Perls, however, it will be
               more efficient to use "SvIV_set" instead of the lvalue
               assignment to "SvIVX".

                       void    SvIV_set(SV* sv, IV val)

       SvLEN   Returns the size of the string buffer in the SV, not including
               any part attributable to "SvOOK".  See "SvCUR".

                       STRLEN  SvLEN(SV* sv)

       SvLEN_set
               Set the actual length of the string which is in the SV.  See
               "SvIV_set".

                       void    SvLEN_set(SV* sv, STRLEN len)

       SvMAGIC_set
               Set the value of the MAGIC pointer in sv to val.  See
               "SvIV_set".

                       void    SvMAGIC_set(SV* sv, MAGIC* val)

       SvNIOK  Returns a U32 value indicating whether the SV contains a
               number, integer or double.

                       U32     SvNIOK(SV* sv)

       SvNIOKp Returns a U32 value indicating whether the SV contains a
               number, integer or double.  Checks the private setting.  Use
               "SvNIOK" instead.

                       U32     SvNIOKp(SV* sv)

       SvNIOK_off
               Unsets the NV/IV status of an SV.

                       void    SvNIOK_off(SV* sv)

       SvNOK   Returns a U32 value indicating whether the SV contains a
               double.

                       U32     SvNOK(SV* sv)

       SvNOKp  Returns a U32 value indicating whether the SV contains a
               double.  Checks the private setting.  Use "SvNOK" instead.

                       U32     SvNOKp(SV* sv)

       SvNOK_off
               Unsets the NV status of an SV.

                       void    SvNOK_off(SV* sv)

       SvNOK_on
               Tells an SV that it is a double.

                       void    SvNOK_on(SV* sv)

       SvNOK_only
               Tells an SV that it is a double and disables all other OK bits.

                       void    SvNOK_only(SV* sv)

       SvNV    Coerce the given SV to a double and return it.  See "SvNVx" for
               a version which guarantees to evaluate sv only once.

                       NV      SvNV(SV* sv)

       SvNVX   Returns the raw value in the SV's NV slot, without checks or
               conversions.  Only use when you are sure SvNOK is true.  See
               also "SvNV()".

                       NV      SvNVX(SV* sv)

       SvNVx   Coerces the given SV to a double and returns it.  Guarantees to
               evaluate "sv" only once.  Only use this if "sv" is an
               expression with side effects, otherwise use the more efficient
               "SvNV".

                       NV      SvNVx(SV* sv)

       SvNV_nomg
               Like "SvNV" but doesn't process magic.

                       NV      SvNV_nomg(SV* sv)

       SvNV_set
               Set the value of the NV pointer in sv to val.  See "SvIV_set".

                       void    SvNV_set(SV* sv, NV val)

       SvOK    Returns a U32 value indicating whether the value is defined.
               This is only meaningful for scalars.

                       U32     SvOK(SV* sv)

       SvOOK   Returns a U32 indicating whether the pointer to the string
               buffer is offset.  This hack is used internally to speed up
               removal of characters from the beginning of a SvPV.  When SvOOK
               is true, then the start of the allocated string buffer is
               actually "SvOOK_offset()" bytes before SvPVX.  This offset used
               to be stored in SvIVX, but is now stored within the spare part
               of the buffer.

                       U32     SvOOK(SV* sv)

       SvOOK_offset
               Reads into len the offset from SvPVX back to the true start of
               the allocated buffer, which will be non-zero if "sv_chop" has
               been used to efficiently remove characters from start of the
               buffer.  Implemented as a macro, which takes the address of
               len, which must be of type "STRLEN".  Evaluates sv more than
               once.  Sets len to 0 if "SvOOK(sv)" is false.

                       void    SvOOK_offset(NN SV*sv, STRLEN len)

       SvPOK   Returns a U32 value indicating whether the SV contains a
               character string.

                       U32     SvPOK(SV* sv)

       SvPOKp  Returns a U32 value indicating whether the SV contains a
               character string.  Checks the private setting.  Use "SvPOK"
               instead.

                       U32     SvPOKp(SV* sv)

       SvPOK_off
               Unsets the PV status of an SV.

                       void    SvPOK_off(SV* sv)

       SvPOK_on
               Tells an SV that it is a string.

                       void    SvPOK_on(SV* sv)

       SvPOK_only
               Tells an SV that it is a string and disables all other OK bits.
               Will also turn off the UTF-8 status.

                       void    SvPOK_only(SV* sv)

       SvPOK_only_UTF8
               Tells an SV that it is a string and disables all other OK bits,
               and leaves the UTF-8 status as it was.

                       void    SvPOK_only_UTF8(SV* sv)

       SvPV    Returns a pointer to the string in the SV, or a stringified
               form of the SV if the SV does not contain a string.  The SV may
               cache the stringified version becoming "SvPOK".  Handles 'get'
               magic.  The "len" variable will be set to the length of the
               string (this is a macro, so don't use &len). See also "SvPVx"
               for a version which guarantees to evaluate sv only once.

               Note that there is no guarantee that the return value of
               "SvPV()" is equal to "SvPVX(sv)", or that "SvPVX(sv)" contains
               valid data, or that successive calls to "SvPV(sv)" will return
               the same pointer value each time.  This is due to the way that
               things like overloading and Copy-On-Write are handled.  In
               these cases, the return value may point to a temporary buffer
               or similar.  If you absolutely need the SvPVX field to be valid
               (for example, if you intend to write to it), then see
               "SvPV_force".

                       char*   SvPV(SV* sv, STRLEN len)

       SvPVbyte
               Like "SvPV", but converts sv to byte representation first if
               necessary.

                       char*   SvPVbyte(SV* sv, STRLEN len)

       SvPVbytex
               Like "SvPV", but converts sv to byte representation first if
               necessary.  Guarantees to evaluate sv only once; use the more
               efficient "SvPVbyte" otherwise.

                       char*   SvPVbytex(SV* sv, STRLEN len)

       SvPVbytex_force
               Like "SvPV_force", but converts sv to byte representation first
               if necessary.  Guarantees to evaluate sv only once; use the
               more efficient "SvPVbyte_force" otherwise.

                       char*   SvPVbytex_force(SV* sv, STRLEN len)

       SvPVbyte_force
               Like "SvPV_force", but converts sv to byte representation first
               if necessary.

                       char*   SvPVbyte_force(SV* sv, STRLEN len)

       SvPVbyte_nolen
               Like "SvPV_nolen", but converts sv to byte representation first
               if necessary.

                       char*   SvPVbyte_nolen(SV* sv)

       SvPVutf8
               Like "SvPV", but converts sv to utf8 first if necessary.

                       char*   SvPVutf8(SV* sv, STRLEN len)

       SvPVutf8x
               Like "SvPV", but converts sv to utf8 first if necessary.
               Guarantees to evaluate sv only once; use the more efficient
               "SvPVutf8" otherwise.

                       char*   SvPVutf8x(SV* sv, STRLEN len)

       SvPVutf8x_force
               Like "SvPV_force", but converts sv to utf8 first if necessary.
               Guarantees to evaluate sv only once; use the more efficient
               "SvPVutf8_force" otherwise.

                       char*   SvPVutf8x_force(SV* sv, STRLEN len)

       SvPVutf8_force
               Like "SvPV_force", but converts sv to utf8 first if necessary.

                       char*   SvPVutf8_force(SV* sv, STRLEN len)

       SvPVutf8_nolen
               Like "SvPV_nolen", but converts sv to utf8 first if necessary.

                       char*   SvPVutf8_nolen(SV* sv)

       SvPVX   Returns a pointer to the physical string in the SV.  The SV
               must contain a string.  Prior to 5.9.3 it is not safe to
               execute this macro unless the SV's type >= SVt_PV.

               This is also used to store the name of an autoloaded subroutine
               in an XS AUTOLOAD routine.  See "Autoloading with XSUBs" in
               perlguts.

                       char*   SvPVX(SV* sv)

       SvPVx   A version of "SvPV" which guarantees to evaluate "sv" only
               once.  Only use this if "sv" is an expression with side
               effects, otherwise use the more efficient "SvPV".

                       char*   SvPVx(SV* sv, STRLEN len)

       SvPV_force
               Like "SvPV" but will force the SV into containing a string
               ("SvPOK"), and only a string ("SvPOK_only"), by hook or by
               crook.  You need force if you are going to update the "SvPVX"
               directly.  Processes get magic.

               Note that coercing an arbitrary scalar into a plain PV will
               potentially strip useful data from it.  For example if the SV
               was "SvROK", then the referent will have its reference count
               decremented, and the SV itself may be converted to an "SvPOK"
               scalar with a string buffer containing a value such as
               "ARRAY(0x1234)".

                       char*   SvPV_force(SV* sv, STRLEN len)

       SvPV_force_nomg
               Like "SvPV_force", but doesn't process get magic.

                       char*   SvPV_force_nomg(SV* sv, STRLEN len)

       SvPV_nolen
               Like "SvPV" but doesn't set a length variable.

                       char*   SvPV_nolen(SV* sv)

       SvPV_nomg
               Like "SvPV" but doesn't process magic.

                       char*   SvPV_nomg(SV* sv, STRLEN len)

       SvPV_nomg_nolen
               Like "SvPV_nolen" but doesn't process magic.

                       char*   SvPV_nomg_nolen(SV* sv)

       SvPV_set
               Set the value of the PV pointer in sv to val.  See also
               "SvIV_set".

               Beware that the existing pointer may be involved in copy-on-
               write or other mischief, so do "SvOOK_off(sv)" and use
               "sv_force_normal" or "SvPV_force" (or check the SvIsCOW flag)
               first to make sure this modification is safe.

                       void    SvPV_set(SV* sv, char* val)

       SvREFCNT
               Returns the value of the object's reference count.

                       U32     SvREFCNT(SV* sv)

       SvREFCNT_dec
               Decrements the reference count of the given SV.  sv may be
               NULL.

                       void    SvREFCNT_dec(SV* sv)

       SvREFCNT_dec_NN
               Same as SvREFCNT_dec, but can only be used if you know sv is
               not NULL.  Since we don't have to check the NULLness, it's
               faster and smaller.

                       void    SvREFCNT_dec_NN(SV* sv)

       SvREFCNT_inc
               Increments the reference count of the given SV, returning the
               SV.

               All of the following SvREFCNT_inc* macros are optimized
               versions of SvREFCNT_inc, and can be replaced with
               SvREFCNT_inc.

                       SV*     SvREFCNT_inc(SV* sv)

       SvREFCNT_inc_NN
               Same as SvREFCNT_inc, but can only be used if you know sv is
               not NULL.  Since we don't have to check the NULLness, it's
               faster and smaller.

                       SV*     SvREFCNT_inc_NN(SV* sv)

       SvREFCNT_inc_simple
               Same as SvREFCNT_inc, but can only be used with expressions
               without side effects.  Since we don't have to store a temporary
               value, it's faster.

                       SV*     SvREFCNT_inc_simple(SV* sv)

       SvREFCNT_inc_simple_NN
               Same as SvREFCNT_inc_simple, but can only be used if you know
               sv is not NULL.  Since we don't have to check the NULLness,
               it's faster and smaller.

                       SV*     SvREFCNT_inc_simple_NN(SV* sv)

       SvREFCNT_inc_simple_void
               Same as SvREFCNT_inc_simple, but can only be used if you don't
               need the return value.  The macro doesn't need to return a
               meaningful value.

                       void    SvREFCNT_inc_simple_void(SV* sv)

       SvREFCNT_inc_simple_void_NN
               Same as SvREFCNT_inc, but can only be used if you don't need
               the return value, and you know that sv is not NULL.  The macro
               doesn't need to return a meaningful value, or check for
               NULLness, so it's smaller and faster.

                       void    SvREFCNT_inc_simple_void_NN(SV* sv)

       SvREFCNT_inc_void
               Same as SvREFCNT_inc, but can only be used if you don't need
               the return value.  The macro doesn't need to return a
               meaningful value.

                       void    SvREFCNT_inc_void(SV* sv)

       SvREFCNT_inc_void_NN
               Same as SvREFCNT_inc, but can only be used if you don't need
               the return value, and you know that sv is not NULL.  The macro
               doesn't need to return a meaningful value, or check for
               NULLness, so it's smaller and faster.

                       void    SvREFCNT_inc_void_NN(SV* sv)

       SvROK   Tests if the SV is an RV.

                       U32     SvROK(SV* sv)

       SvROK_off
               Unsets the RV status of an SV.

                       void    SvROK_off(SV* sv)

       SvROK_on
               Tells an SV that it is an RV.

                       void    SvROK_on(SV* sv)

       SvRV    Dereferences an RV to return the SV.

                       SV*     SvRV(SV* sv)

       SvRV_set
               Set the value of the RV pointer in sv to val.  See "SvIV_set".

                       void    SvRV_set(SV* sv, SV* val)

       SvSTASH Returns the stash of the SV.

                       HV*     SvSTASH(SV* sv)

       SvSTASH_set
               Set the value of the STASH pointer in sv to val.  See
               "SvIV_set".

                       void    SvSTASH_set(SV* sv, HV* val)

       SvTAINT Taints an SV if tainting is enabled, and if some input to the
               current expression is tainted--usually a variable, but possibly
               also implicit inputs such as locale settings.  "SvTAINT"
               propagates that taintedness to the outputs of an expression in
               a pessimistic fashion; i.e., without paying attention to
               precisely which outputs are influenced by which inputs.

                       void    SvTAINT(SV* sv)

       SvTAINTED
               Checks to see if an SV is tainted.  Returns TRUE if it is,
               FALSE if not.

                       bool    SvTAINTED(SV* sv)

       SvTAINTED_off
               Untaints an SV.  Be very careful with this routine, as it
               short-circuits some of Perl's fundamental security features.
               XS module authors should not use this function unless they
               fully understand all the implications of unconditionally
               untainting the value.  Untainting should be done in the
               standard perl fashion, via a carefully crafted regexp, rather
               than directly untainting variables.

                       void    SvTAINTED_off(SV* sv)

       SvTAINTED_on
               Marks an SV as tainted if tainting is enabled.

                       void    SvTAINTED_on(SV* sv)

       SvTRUE  Returns a boolean indicating whether Perl would evaluate the SV
               as true or false.  See SvOK() for a defined/undefined test.
               Handles 'get' magic unless the scalar is already SvPOK, SvIOK
               or SvNOK (the public, not the private flags).

                       bool    SvTRUE(SV* sv)

       SvTRUE_nomg
               Returns a boolean indicating whether Perl would evaluate the SV
               as true or false.  See SvOK() for a defined/undefined test.
               Does not handle 'get' magic.

                       bool    SvTRUE_nomg(SV* sv)

       SvTYPE  Returns the type of the SV.  See "svtype".

                       svtype  SvTYPE(SV* sv)

       SvUOK   Returns a boolean indicating whether the SV contains an integer
               that must be interpreted as unsigned.  A non-negative integer
               whose value is within the range of both an IV and a UV may be
               be flagged as either SvUOK or SVIOK.

                       bool    SvUOK(SV* sv)

       SvUPGRADE
               Used to upgrade an SV to a more complex form.  Uses
               "sv_upgrade" to perform the upgrade if necessary.  See
               "svtype".

                       void    SvUPGRADE(SV* sv, svtype type)

       SvUTF8  Returns a U32 value indicating the UTF-8 status of an SV.  If
               things are set-up properly, this indicates whether or not the
               SV contains UTF-8 encoded data.  You should use this after a
               call to SvPV() or one of its variants, in case any call to
               string overloading updates the internal flag.

                       U32     SvUTF8(SV* sv)

       SvUTF8_off
               Unsets the UTF-8 status of an SV (the data is not changed, just
               the flag).  Do not use frivolously.

                       void    SvUTF8_off(SV *sv)

       SvUTF8_on
               Turn on the UTF-8 status of an SV (the data is not changed,
               just the flag).  Do not use frivolously.

                       void    SvUTF8_on(SV *sv)

       SvUV    Coerces the given SV to an unsigned integer and returns it.
               See "SvUVx" for a version which guarantees to evaluate sv only
               once.

                       UV      SvUV(SV* sv)

       SvUVX   Returns the raw value in the SV's UV slot, without checks or
               conversions.  Only use when you are sure SvIOK is true.  See
               also "SvUV()".

                       UV      SvUVX(SV* sv)

       SvUVx   Coerces the given SV to an unsigned integer and returns it.
               Guarantees to evaluate "sv" only once.  Only use this if "sv"
               is an expression with side effects, otherwise use the more
               efficient "SvUV".

                       UV      SvUVx(SV* sv)

       SvUV_nomg
               Like "SvUV" but doesn't process magic.

                       UV      SvUV_nomg(SV* sv)

       SvUV_set
               Set the value of the UV pointer in sv to val.  See "SvIV_set".

                       void    SvUV_set(SV* sv, UV val)

       SvVOK   Returns a boolean indicating whether the SV contains a
               v-string.

                       bool    SvVOK(SV* sv)

       sv_catpvn_nomg
               Like "sv_catpvn" but doesn't process magic.

                       void    sv_catpvn_nomg(SV* sv, const char* ptr,
                                              STRLEN len)

       sv_catpv_nomg
               Like "sv_catpv" but doesn't process magic.

                       void    sv_catpv_nomg(SV* sv, const char* ptr)

       sv_catsv_nomg
               Like "sv_catsv" but doesn't process magic.

                       void    sv_catsv_nomg(SV* dsv, SV* ssv)

       sv_derived_from
               Exactly like "sv_derived_from_pv", but doesn't take a "flags"
               parameter.

                       bool    sv_derived_from(SV* sv, const char *const name)

       sv_derived_from_pv
               Exactly like "sv_derived_from_pvn", but takes a nul-terminated
               string instead of a string/length pair.

                       bool    sv_derived_from_pv(SV* sv,
                                                  const char *const name,
                                                  U32 flags)

       sv_derived_from_pvn
               Returns a boolean indicating whether the SV is derived from the
               specified class at the C level.  To check derivation at the
               Perl level, call "isa()" as a normal Perl method.

               Currently, the only significant value for "flags" is SVf_UTF8.

                       bool    sv_derived_from_pvn(SV* sv,
                                                   const char *const name,
                                                   const STRLEN len, U32 flags)

       sv_derived_from_sv
               Exactly like "sv_derived_from_pvn", but takes the name string
               in the form of an SV instead of a string/length pair.

                       bool    sv_derived_from_sv(SV* sv, SV *namesv,
                                                  U32 flags)

       sv_does Like "sv_does_pv", but doesn't take a "flags" parameter.

                       bool    sv_does(SV* sv, const char *const name)

       sv_does_pv
               Like "sv_does_sv", but takes a nul-terminated string instead of
               an SV.

                       bool    sv_does_pv(SV* sv, const char *const name,
                                          U32 flags)

       sv_does_pvn
               Like "sv_does_sv", but takes a string/length pair instead of an
               SV.

                       bool    sv_does_pvn(SV* sv, const char *const name,
                                           const STRLEN len, U32 flags)

       sv_does_sv
               Returns a boolean indicating whether the SV performs a
               specific, named role.  The SV can be a Perl object or the name
               of a Perl class.

                       bool    sv_does_sv(SV* sv, SV* namesv, U32 flags)

       sv_report_used
               Dump the contents of all SVs not yet freed (debugging aid).

                       void    sv_report_used()

       sv_setsv_nomg
               Like "sv_setsv" but doesn't process magic.

                       void    sv_setsv_nomg(SV* dsv, SV* ssv)

       sv_utf8_upgrade_nomg
               Like sv_utf8_upgrade, but doesn't do magic on "sv".

                       STRLEN  sv_utf8_upgrade_nomg(NN SV *sv)


SV-Body Allocation

       looks_like_number
               Test if the content of an SV looks like a number (or is a
               number).  "Inf" and "Infinity" are treated as numbers (so will
               not issue a non-numeric warning), even if your atof() doesn't
               grok them.  Get-magic is ignored.

                       I32     looks_like_number(SV *const sv)

       newRV_noinc
               Creates an RV wrapper for an SV.  The reference count for the
               original SV is not incremented.

                       SV*     newRV_noinc(SV *const sv)

       newSV   Creates a new SV.  A non-zero "len" parameter indicates the
               number of bytes of preallocated string space the SV should
               have.  An extra byte for a trailing NUL is also reserved.
               (SvPOK is not set for the SV even if string space is
               allocated.)  The reference count for the new SV is set to 1.

               In 5.9.3, newSV() replaces the older NEWSV() API, and drops the
               first parameter, x, a debug aid which allowed callers to
               identify themselves.  This aid has been superseded by a new
               build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in
               perlhacktips).  The older API is still there for use in XS
               modules supporting older perls.

                       SV*     newSV(const STRLEN len)

       newSVhek
               Creates a new SV from the hash key structure.  It will generate
               scalars that point to the shared string table where possible.
               Returns a new (undefined) SV if the hek is NULL.

                       SV*     newSVhek(const HEK *const hek)

       newSViv Creates a new SV and copies an integer into it.  The reference
               count for the SV is set to 1.

                       SV*     newSViv(const IV i)

       newSVnv Creates a new SV and copies a floating point value into it.
               The reference count for the SV is set to 1.

                       SV*     newSVnv(const NV n)

       newSVpv Creates a new SV and copies a string into it.  The reference
               count for the SV is set to 1.  If "len" is zero, Perl will
               compute the length using strlen().  For efficiency, consider
               using "newSVpvn" instead.

                       SV*     newSVpv(const char *const s, const STRLEN len)

       newSVpvf
               Creates a new SV and initializes it with the string formatted
               like "sprintf".

                       SV*     newSVpvf(const char *const pat, ...)

       newSVpvn
               Creates a new SV and copies a buffer into it, which may contain
               NUL characters ("\0") and other binary data.  The reference
               count for the SV is set to 1.  Note that if "len" is zero, Perl
               will create a zero length (Perl) string.  You are responsible
               for ensuring that the source buffer is at least "len" bytes
               long.  If the "buffer" argument is NULL the new SV will be
               undefined.

                       SV*     newSVpvn(const char *const s, const STRLEN len)

       newSVpvn_flags
               Creates a new SV and copies a string into it.  The reference
               count for the SV is set to 1.  Note that if "len" is zero, Perl
               will create a zero length string.  You are responsible for
               ensuring that the source string is at least "len" bytes long.
               If the "s" argument is NULL the new SV will be undefined.
               Currently the only flag bits accepted are "SVf_UTF8" and
               "SVs_TEMP".  If "SVs_TEMP" is set, then "sv_2mortal()" is
               called on the result before returning.  If "SVf_UTF8" is set,
               "s" is considered to be in UTF-8 and the "SVf_UTF8" flag will
               be set on the new SV.  "newSVpvn_utf8()" is a convenience
               wrapper for this function, defined as

                   #define newSVpvn_utf8(s, len, u)                    \
                       newSVpvn_flags((s), (len), (u) ? SVf_UTF8 : 0)

                       SV*     newSVpvn_flags(const char *const s,
                                              const STRLEN len,
                                              const U32 flags)

       newSVpvn_share
               Creates a new SV with its SvPVX_const pointing to a shared
               string in the string table.  If the string does not already
               exist in the table, it is created first.  Turns on the SvIsCOW
               flag (or READONLY and FAKE in 5.16 and earlier).  If the "hash"
               parameter is non-zero, that value is used; otherwise the hash
               is computed.  The string's hash can later be retrieved from the
               SV with the "SvSHARED_HASH()" macro.  The idea here is that as
               the string table is used for shared hash keys these strings
               will have SvPVX_const == HeKEY and hash lookup will avoid
               string compare.

                       SV*     newSVpvn_share(const char* s, I32 len, U32 hash)

       newSVpvs
               Like "newSVpvn", but takes a literal string instead of a
               string/length pair.

                       SV*     newSVpvs(const char* s)

       newSVpvs_flags
               Like "newSVpvn_flags", but takes a literal string instead of a
               string/length pair.

                       SV*     newSVpvs_flags(const char* s, U32 flags)

       newSVpvs_share
               Like "newSVpvn_share", but takes a literal string instead of a
               string/length pair and omits the hash parameter.

                       SV*     newSVpvs_share(const char* s)

       newSVpv_share
               Like "newSVpvn_share", but takes a nul-terminated string
               instead of a string/length pair.

                       SV*     newSVpv_share(const char* s, U32 hash)

       newSVrv Creates a new SV for the existing RV, "rv", to point to.  If
               "rv" is not an RV then it will be upgraded to one.  If
               "classname" is non-null then the new SV will be blessed in the
               specified package.  The new SV is returned and its reference
               count is 1.  The reference count 1 is owned by "rv".

                       SV*     newSVrv(SV *const rv,
                                       const char *const classname)

       newSVsv Creates a new SV which is an exact duplicate of the original
               SV.  (Uses "sv_setsv".)

                       SV*     newSVsv(SV *const old)

       newSVuv Creates a new SV and copies an unsigned integer into it.  The
               reference count for the SV is set to 1.

                       SV*     newSVuv(const UV u)

       newSV_type
               Creates a new SV, of the type specified.  The reference count
               for the new SV is set to 1.

                       SV*     newSV_type(const svtype type)

       sv_2bool
               This macro is only used by sv_true() or its macro equivalent,
               and only if the latter's argument is neither SvPOK, SvIOK nor
               SvNOK.  It calls sv_2bool_flags with the SV_GMAGIC flag.

                       bool    sv_2bool(SV *const sv)

       sv_2bool_flags
               This function is only used by sv_true() and friends,  and only
               if the latter's argument is neither SvPOK, SvIOK nor SvNOK.  If
               the flags contain SV_GMAGIC, then it does an mg_get() first.

                       bool    sv_2bool_flags(SV *sv, I32 flags)

       sv_2cv  Using various gambits, try to get a CV from an SV; in addition,
               try if possible to set *st and *gvp to the stash and GV
               associated with it.  The flags in "lref" are passed to
               gv_fetchsv.

                       CV*     sv_2cv(SV* sv, HV **const st, GV **const gvp,
                                      const I32 lref)

       sv_2io  Using various gambits, try to get an IO from an SV: the IO slot
               if its a GV; or the recursive result if we're an RV; or the IO
               slot of the symbol named after the PV if we're a string.

               'Get' magic is ignored on the sv passed in, but will be called
               on "SvRV(sv)" if sv is an RV.

                       IO*     sv_2io(SV *const sv)

       sv_2iv_flags
               Return the integer value of an SV, doing any necessary string
               conversion.  If flags includes SV_GMAGIC, does an mg_get()
               first.  Normally used via the "SvIV(sv)" and "SvIVx(sv)"
               macros.

                       IV      sv_2iv_flags(SV *const sv, const I32 flags)

       sv_2mortal
               Marks an existing SV as mortal.  The SV will be destroyed
               "soon", either by an explicit call to FREETMPS, or by an
               implicit call at places such as statement boundaries.  SvTEMP()
               is turned on which means that the SV's string buffer can be
               "stolen" if this SV is copied.  See also "sv_newmortal" and
               "sv_mortalcopy".

                       SV*     sv_2mortal(SV *const sv)

       sv_2nv_flags
               Return the num value of an SV, doing any necessary string or
               integer conversion.  If flags includes SV_GMAGIC, does an
               mg_get() first.  Normally used via the "SvNV(sv)" and
               "SvNVx(sv)" macros.

                       NV      sv_2nv_flags(SV *const sv, const I32 flags)

       sv_2pvbyte
               Return a pointer to the byte-encoded representation of the SV,
               and set *lp to its length.  May cause the SV to be downgraded
               from UTF-8 as a side-effect.

               Usually accessed via the "SvPVbyte" macro.

                       char*   sv_2pvbyte(SV *sv, STRLEN *const lp)

       sv_2pvutf8
               Return a pointer to the UTF-8-encoded representation of the SV,
               and set *lp to its length.  May cause the SV to be upgraded to
               UTF-8 as a side-effect.

               Usually accessed via the "SvPVutf8" macro.

                       char*   sv_2pvutf8(SV *sv, STRLEN *const lp)

       sv_2pv_flags
               Returns a pointer to the string value of an SV, and sets *lp to
               its length.  If flags includes SV_GMAGIC, does an mg_get()
               first.  Coerces sv to a string if necessary.  Normally invoked
               via the "SvPV_flags" macro.  "sv_2pv()" and "sv_2pv_nomg"
               usually end up here too.

                       char*   sv_2pv_flags(SV *const sv, STRLEN *const lp,
                                            const I32 flags)

       sv_2uv_flags
               Return the unsigned integer value of an SV, doing any necessary
               string conversion.  If flags includes SV_GMAGIC, does an
               mg_get() first.  Normally used via the "SvUV(sv)" and
               "SvUVx(sv)" macros.

                       UV      sv_2uv_flags(SV *const sv, const I32 flags)

       sv_backoff
               Remove any string offset.  You should normally use the
               "SvOOK_off" macro wrapper instead.

                       int     sv_backoff(SV *const sv)

       sv_bless
               Blesses an SV into a specified package.  The SV must be an RV.
               The package must be designated by its stash (see
               "gv_stashpv()").  The reference count of the SV is unaffected.

                       SV*     sv_bless(SV *const sv, HV *const stash)

       sv_catpv
               Concatenates the string onto the end of the string which is in
               the SV.  If the SV has the UTF-8 status set, then the bytes
               appended should be valid UTF-8.  Handles 'get' magic, but not
               'set' magic.  See "sv_catpv_mg".

                       void    sv_catpv(SV *const sv, const char* ptr)

       sv_catpvf
               Processes its arguments like "sprintf" and appends the
               formatted output to an SV.  If the appended data contains
               "wide" characters (including, but not limited to, SVs with a
               UTF-8 PV formatted with %s, and characters >255 formatted with
               %c), the original SV might get upgraded to UTF-8.  Handles
               'get' magic, but not 'set' magic.  See "sv_catpvf_mg".  If the
               original SV was UTF-8, the pattern should be valid UTF-8; if
               the original SV was bytes, the pattern should be too.

                       void    sv_catpvf(SV *const sv, const char *const pat,
                                         ...)

       sv_catpvf_mg
               Like "sv_catpvf", but also handles 'set' magic.

                       void    sv_catpvf_mg(SV *const sv,
                                            const char *const pat, ...)

       sv_catpvn
               Concatenates the string onto the end of the string which is in
               the SV.  The "len" indicates number of bytes to copy.  If the
               SV has the UTF-8 status set, then the bytes appended should be
               valid UTF-8.  Handles 'get' magic, but not 'set' magic.  See
               "sv_catpvn_mg".

                       void    sv_catpvn(SV *dsv, const char *sstr, STRLEN len)

       sv_catpvn_flags
               Concatenates the string onto the end of the string which is in
               the SV.  The "len" indicates number of bytes to copy.  If the
               SV has the UTF-8 status set, then the bytes appended should be
               valid UTF-8.  If "flags" has the "SV_SMAGIC" bit set, will
               "mg_set" on "dsv" afterwards if appropriate.  "sv_catpvn" and
               "sv_catpvn_nomg" are implemented in terms of this function.

                       void    sv_catpvn_flags(SV *const dstr,
                                               const char *sstr,
                                               const STRLEN len,
                                               const I32 flags)

       sv_catpvs
               Like "sv_catpvn", but takes a literal string instead of a
               string/length pair.

                       void    sv_catpvs(SV* sv, const char* s)

       sv_catpvs_flags
               Like "sv_catpvn_flags", but takes a literal string instead of a
               string/length pair.

                       void    sv_catpvs_flags(SV* sv, const char* s,
                                               I32 flags)

       sv_catpvs_mg
               Like "sv_catpvn_mg", but takes a literal string instead of a
               string/length pair.

                       void    sv_catpvs_mg(SV* sv, const char* s)

       sv_catpvs_nomg
               Like "sv_catpvn_nomg", but takes a literal string instead of a
               string/length pair.

                       void    sv_catpvs_nomg(SV* sv, const char* s)

       sv_catpv_flags
               Concatenates the string onto the end of the string which is in
               the SV.  If the SV has the UTF-8 status set, then the bytes
               appended should be valid UTF-8.  If "flags" has the "SV_SMAGIC"
               bit set, will "mg_set" on the modified SV if appropriate.

                       void    sv_catpv_flags(SV *dstr, const char *sstr,
                                              const I32 flags)

       sv_catpv_mg
               Like "sv_catpv", but also handles 'set' magic.

                       void    sv_catpv_mg(SV *const sv, const char *const ptr)

       sv_catsv
               Concatenates the string from SV "ssv" onto the end of the
               string in SV "dsv".  If "ssv" is null, does nothing; otherwise
               modifies only "dsv".  Handles 'get' magic on both SVs, but no
               'set' magic.  See "sv_catsv_mg" and "sv_catsv_nomg".

                       void    sv_catsv(SV *dstr, SV *sstr)

       sv_catsv_flags
               Concatenates the string from SV "ssv" onto the end of the
               string in SV "dsv".  If "ssv" is null, does nothing; otherwise
               modifies only "dsv".  If "flags" include "SV_GMAGIC" bit set,
               will call "mg_get" on both SVs if appropriate.  If "flags"
               include "SV_SMAGIC", "mg_set" will be called on the modified SV
               afterward, if appropriate.  "sv_catsv", "sv_catsv_nomg", and
               "sv_catsv_mg" are implemented in terms of this function.

                       void    sv_catsv_flags(SV *const dsv, SV *const ssv,
                                              const I32 flags)

       sv_chop Efficient removal of characters from the beginning of the
               string buffer.  SvPOK(sv), or at least SvPOKp(sv), must be true
               and the "ptr" must be a pointer to somewhere inside the string
               buffer.  The "ptr" becomes the first character of the adjusted
               string.  Uses the "OOK hack".  On return, only SvPOK(sv) and
               SvPOKp(sv) among the OK flags will be true.

               Beware: after this function returns, "ptr" and SvPVX_const(sv)
               may no longer refer to the same chunk of data.

               The unfortunate similarity of this function's name to that of
               Perl's "chop" operator is strictly coincidental.  This function
               works from the left; "chop" works from the right.

                       void    sv_chop(SV *const sv, const char *const ptr)

       sv_clear
               Clear an SV: call any destructors, free up any memory used by
               the body, and free the body itself.  The SV's head is not
               freed, although its type is set to all 1's so that it won't
               inadvertently be assumed to be live during global destruction
               etc.  This function should only be called when REFCNT is zero.
               Most of the time you'll want to call "sv_free()" (or its macro
               wrapper "SvREFCNT_dec") instead.

                       void    sv_clear(SV *const orig_sv)

       sv_cmp  Compares the strings in two SVs.  Returns -1, 0, or 1
               indicating whether the string in "sv1" is less than, equal to,
               or greater than the string in "sv2".  Is UTF-8 and 'use bytes'
               aware, handles get magic, and will coerce its args to strings
               if necessary.  See also "sv_cmp_locale".

                       I32     sv_cmp(SV *const sv1, SV *const sv2)

       sv_cmp_flags
               Compares the strings in two SVs.  Returns -1, 0, or 1
               indicating whether the string in "sv1" is less than, equal to,
               or greater than the string in "sv2".  Is UTF-8 and 'use bytes'
               aware and will coerce its args to strings if necessary.  If the
               flags include SV_GMAGIC, it handles get magic.  See also
               "sv_cmp_locale_flags".

                       I32     sv_cmp_flags(SV *const sv1, SV *const sv2,
                                            const U32 flags)

       sv_cmp_locale
               Compares the strings in two SVs in a locale-aware manner.  Is
               UTF-8 and 'use bytes' aware, handles get magic, and will coerce
               its args to strings if necessary.  See also "sv_cmp".

                       I32     sv_cmp_locale(SV *const sv1, SV *const sv2)

       sv_cmp_locale_flags
               Compares the strings in two SVs in a locale-aware manner.  Is
               UTF-8 and 'use bytes' aware and will coerce its args to strings
               if necessary.  If the flags contain SV_GMAGIC, it handles get
               magic.  See also "sv_cmp_flags".

                       I32     sv_cmp_locale_flags(SV *const sv1,
                                                   SV *const sv2,
                                                   const U32 flags)

       sv_collxfrm
               This calls "sv_collxfrm_flags" with the SV_GMAGIC flag.  See
               "sv_collxfrm_flags".

                       char*   sv_collxfrm(SV *const sv, STRLEN *const nxp)

       sv_collxfrm_flags
               Add Collate Transform magic to an SV if it doesn't already have
               it.  If the flags contain SV_GMAGIC, it handles get-magic.

               Any scalar variable may carry PERL_MAGIC_collxfrm magic that
               contains the scalar data of the variable, but transformed to
               such a format that a normal memory comparison can be used to
               compare the data according to the locale settings.

                       char*   sv_collxfrm_flags(SV *const sv,
                                                 STRLEN *const nxp,
                                                 I32 const flags)

       sv_copypv_flags
               Implementation of sv_copypv and sv_copypv_nomg.  Calls get
               magic iff flags include SV_GMAGIC.

                       void    sv_copypv_flags(SV *const dsv, SV *const ssv,
                                               const I32 flags)

       sv_copypv_nomg
               Like sv_copypv, but doesn't invoke get magic first.

                       void    sv_copypv_nomg(SV *const dsv, SV *const ssv)

       sv_dec  Auto-decrement of the value in the SV, doing string to numeric
               conversion if necessary.  Handles 'get' magic and operator
               overloading.

                       void    sv_dec(SV *const sv)

       sv_dec_nomg
               Auto-decrement of the value in the SV, doing string to numeric
               conversion if necessary.  Handles operator overloading.  Skips
               handling 'get' magic.

                       void    sv_dec_nomg(SV *const sv)

       sv_eq   Returns a boolean indicating whether the strings in the two SVs
               are identical.  Is UTF-8 and 'use bytes' aware, handles get
               magic, and will coerce its args to strings if necessary.

                       I32     sv_eq(SV* sv1, SV* sv2)

       sv_eq_flags
               Returns a boolean indicating whether the strings in the two SVs
               are identical.  Is UTF-8 and 'use bytes' aware and coerces its
               args to strings if necessary.  If the flags include SV_GMAGIC,
               it handles get-magic, too.

                       I32     sv_eq_flags(SV* sv1, SV* sv2, const U32 flags)

       sv_force_normal_flags
               Undo various types of fakery on an SV, where fakery means "more
               than" a string: if the PV is a shared string, make a private
               copy; if we're a ref, stop refing; if we're a glob, downgrade
               to an xpvmg; if we're a copy-on-write scalar, this is the on-
               write time when we do the copy, and is also used locally; if
               this is a vstring, drop the vstring magic.  If "SV_COW_DROP_PV"
               is set then a copy-on-write scalar drops its PV buffer (if any)
               and becomes SvPOK_off rather than making a copy.  (Used where
               this scalar is about to be set to some other value.)  In
               addition, the "flags" parameter gets passed to
               "sv_unref_flags()" when unreffing.  "sv_force_normal" calls
               this function with flags set to 0.

               This function is expected to be used to signal to perl that
               this SV is about to be written to, and any extra book-keeping
               needs to be taken care of.  Hence, it croaks on read-only
               values.

                       void    sv_force_normal_flags(SV *const sv,
                                                     const U32 flags)

       sv_free Decrement an SV's reference count, and if it drops to zero,
               call "sv_clear" to invoke destructors and free up any memory
               used by the body; finally, deallocate the SV's head itself.
               Normally called via a wrapper macro "SvREFCNT_dec".

                       void    sv_free(SV *const sv)

       sv_gets Get a line from the filehandle and store it into the SV,
               optionally appending to the currently-stored string.  If
               "append" is not 0, the line is appended to the SV instead of
               overwriting it.  "append" should be set to the byte offset that
               the appended string should start at in the SV (typically,
               "SvCUR(sv)" is a suitable choice).

                       char*   sv_gets(SV *const sv, PerlIO *const fp,
                                       I32 append)

       sv_grow Expands the character buffer in the SV.  If necessary, uses
               "sv_unref" and upgrades the SV to "SVt_PV".  Returns a pointer
               to the character buffer.  Use the "SvGROW" wrapper instead.

                       char*   sv_grow(SV *const sv, STRLEN newlen)

       sv_inc  Auto-increment of the value in the SV, doing string to numeric
               conversion if necessary.  Handles 'get' magic and operator
               overloading.

                       void    sv_inc(SV *const sv)

       sv_inc_nomg
               Auto-increment of the value in the SV, doing string to numeric
               conversion if necessary.  Handles operator overloading.  Skips
               handling 'get' magic.

                       void    sv_inc_nomg(SV *const sv)

       sv_insert
               Inserts a string at the specified offset/length within the SV.
               Similar to the Perl substr() function.  Handles get magic.

                       void    sv_insert(SV *const bigstr, const STRLEN offset,
                                         const STRLEN len,
                                         const char *const little,
                                         const STRLEN littlelen)

       sv_insert_flags
               Same as "sv_insert", but the extra "flags" are passed to the
               "SvPV_force_flags" that applies to "bigstr".

                       void    sv_insert_flags(SV *const bigstr,
                                               const STRLEN offset,
                                               const STRLEN len,
                                               const char *const little,
                                               const STRLEN littlelen,
                                               const U32 flags)

       sv_isa  Returns a boolean indicating whether the SV is blessed into the
               specified class.  This does not check for subtypes; use
               "sv_derived_from" to verify an inheritance relationship.

                       int     sv_isa(SV* sv, const char *const name)

       sv_isobject
               Returns a boolean indicating whether the SV is an RV pointing
               to a blessed object.  If the SV is not an RV, or if the object
               is not blessed, then this will return false.

                       int     sv_isobject(SV* sv)

       sv_len  Returns the length of the string in the SV.  Handles magic and
               type coercion and sets the UTF8 flag appropriately.  See also
               "SvCUR", which gives raw access to the xpv_cur slot.

                       STRLEN  sv_len(SV *const sv)

       sv_len_utf8
               Returns the number of characters in the string in an SV,
               counting wide UTF-8 bytes as a single character.  Handles magic
               and type coercion.

                       STRLEN  sv_len_utf8(SV *const sv)

       sv_magic
               Adds magic to an SV.  First upgrades "sv" to type "SVt_PVMG" if
               necessary, then adds a new magic item of type "how" to the head
               of the magic list.

               See "sv_magicext" (which "sv_magic" now calls) for a
               description of the handling of the "name" and "namlen"
               arguments.

               You need to use "sv_magicext" to add magic to SvREADONLY SVs
               and also to add more than one instance of the same 'how'.

                       void    sv_magic(SV *const sv, SV *const obj,
                                        const int how, const char *const name,
                                        const I32 namlen)

       sv_magicext
               Adds magic to an SV, upgrading it if necessary.  Applies the
               supplied vtable and returns a pointer to the magic added.

               Note that "sv_magicext" will allow things that "sv_magic" will
               not.  In particular, you can add magic to SvREADONLY SVs, and
               add more than one instance of the same 'how'.

               If "namlen" is greater than zero then a "savepvn" copy of
               "name" is stored, if "namlen" is zero then "name" is stored as-
               is and - as another special case - if "(name && namlen ==
               HEf_SVKEY)" then "name" is assumed to contain an "SV*" and is
               stored as-is with its REFCNT incremented.

               (This is now used as a subroutine by "sv_magic".)

                       MAGIC * sv_magicext(SV *const sv, SV *const obj,
                                           const int how,
                                           const MGVTBL *const vtbl,
                                           const char *const name,
                                           const I32 namlen)

       sv_mortalcopy
               Creates a new SV which is a copy of the original SV (using
               "sv_setsv").  The new SV is marked as mortal.  It will be
               destroyed "soon", either by an explicit call to FREETMPS, or by
               an implicit call at places such as statement boundaries.  See
               also "sv_newmortal" and "sv_2mortal".

                       SV*     sv_mortalcopy(SV *const oldsv)

       sv_newmortal
               Creates a new null SV which is mortal.  The reference count of
               the SV is set to 1.  It will be destroyed "soon", either by an
               explicit call to FREETMPS, or by an implicit call at places
               such as statement boundaries.  See also "sv_mortalcopy" and
               "sv_2mortal".

                       SV*     sv_newmortal()

       sv_newref
               Increment an SV's reference count.  Use the "SvREFCNT_inc()"
               wrapper instead.

                       SV*     sv_newref(SV *const sv)

       sv_pos_b2u
               Converts the value pointed to by offsetp from a count of bytes
               from the start of the string, to a count of the equivalent
               number of UTF-8 chars.  Handles magic and type coercion.

               Use "sv_pos_b2u_flags" in preference, which correctly handles
               strings longer than 2Gb.

                       void    sv_pos_b2u(SV *const sv, I32 *const offsetp)

       sv_pos_b2u_flags
               Converts the offset from a count of bytes from the start of the
               string, to a count of the equivalent number of UTF-8 chars.
               Handles type coercion.  flags is passed to "SvPV_flags", and
               usually should be "SV_GMAGIC|SV_CONST_RETURN" to handle magic.

                       STRLEN  sv_pos_b2u_flags(SV *const sv,
                                                STRLEN const offset, U32 flags)

       sv_pos_u2b
               Converts the value pointed to by offsetp from a count of UTF-8
               chars from the start of the string, to a count of the
               equivalent number of bytes; if lenp is non-zero, it does the
               same to lenp, but this time starting from the offset, rather
               than from the start of the string.  Handles magic and type
               coercion.

               Use "sv_pos_u2b_flags" in preference, which correctly handles
               strings longer than 2Gb.

                       void    sv_pos_u2b(SV *const sv, I32 *const offsetp,
                                          I32 *const lenp)

       sv_pos_u2b_flags
               Converts the offset from a count of UTF-8 chars from the start
               of the string, to a count of the equivalent number of bytes; if
               lenp is non-zero, it does the same to lenp, but this time
               starting from the offset, rather than from the start of the
               string.  Handles type coercion.  flags is passed to
               "SvPV_flags", and usually should be "SV_GMAGIC|SV_CONST_RETURN"
               to handle magic.

                       STRLEN  sv_pos_u2b_flags(SV *const sv, STRLEN uoffset,
                                                STRLEN *const lenp, U32 flags)

       sv_pvbyten_force
               The backend for the "SvPVbytex_force" macro.  Always use the
               macro instead.

                       char*   sv_pvbyten_force(SV *const sv, STRLEN *const lp)

       sv_pvn_force
               Get a sensible string out of the SV somehow.  A private
               implementation of the "SvPV_force" macro for compilers which
               can't cope with complex macro expressions.  Always use the
               macro instead.

                       char*   sv_pvn_force(SV* sv, STRLEN* lp)

       sv_pvn_force_flags
               Get a sensible string out of the SV somehow.  If "flags" has
               "SV_GMAGIC" bit set, will "mg_get" on "sv" if appropriate, else
               not.  "sv_pvn_force" and "sv_pvn_force_nomg" are implemented in
               terms of this function.  You normally want to use the various
               wrapper macros instead: see "SvPV_force" and "SvPV_force_nomg"

                       char*   sv_pvn_force_flags(SV *const sv,
                                                  STRLEN *const lp,
                                                  const I32 flags)

       sv_pvutf8n_force
               The backend for the "SvPVutf8x_force" macro.  Always use the
               macro instead.

                       char*   sv_pvutf8n_force(SV *const sv, STRLEN *const lp)

       sv_reftype
               Returns a string describing what the SV is a reference to.

                       const char* sv_reftype(const SV *const sv, const int ob)

       sv_replace
               Make the first argument a copy of the second, then delete the
               original.  The target SV physically takes over ownership of the
               body of the source SV and inherits its flags; however, the
               target keeps any magic it owns, and any magic in the source is
               discarded.  Note that this is a rather specialist SV copying
               operation; most of the time you'll want to use "sv_setsv" or
               one of its many macro front-ends.

                       void    sv_replace(SV *const sv, SV *const nsv)

       sv_reset
               Underlying implementation for the "reset" Perl function.  Note
               that the perl-level function is vaguely deprecated.

                       void    sv_reset(const char* s, HV *const stash)

       sv_rvweaken
               Weaken a reference: set the "SvWEAKREF" flag on this RV; give
               the referred-to SV "PERL_MAGIC_backref" magic if it hasn't
               already; and push a back-reference to this RV onto the array of
               backreferences associated with that magic.  If the RV is
               magical, set magic will be called after the RV is cleared.

                       SV*     sv_rvweaken(SV *const sv)

       sv_setiv
               Copies an integer into the given SV, upgrading first if
               necessary.  Does not handle 'set' magic.  See also
               "sv_setiv_mg".

                       void    sv_setiv(SV *const sv, const IV num)

       sv_setiv_mg
               Like "sv_setiv", but also handles 'set' magic.

                       void    sv_setiv_mg(SV *const sv, const IV i)

       sv_setnv
               Copies a double into the given SV, upgrading first if
               necessary.  Does not handle 'set' magic.  See also
               "sv_setnv_mg".

                       void    sv_setnv(SV *const sv, const NV num)

       sv_setnv_mg
               Like "sv_setnv", but also handles 'set' magic.

                       void    sv_setnv_mg(SV *const sv, const NV num)

       sv_setpv
               Copies a string into an SV.  The string must be null-
               terminated.  Does not handle 'set' magic.  See "sv_setpv_mg".

                       void    sv_setpv(SV *const sv, const char *const ptr)

       sv_setpvf
               Works like "sv_catpvf" but copies the text into the SV instead
               of appending it.  Does not handle 'set' magic.  See
               "sv_setpvf_mg".

                       void    sv_setpvf(SV *const sv, const char *const pat,
                                         ...)

       sv_setpvf_mg
               Like "sv_setpvf", but also handles 'set' magic.

                       void    sv_setpvf_mg(SV *const sv,
                                            const char *const pat, ...)

       sv_setpviv
               Copies an integer into the given SV, also updating its string
               value.  Does not handle 'set' magic.  See "sv_setpviv_mg".

                       void    sv_setpviv(SV *const sv, const IV num)

       sv_setpviv_mg
               Like "sv_setpviv", but also handles 'set' magic.

                       void    sv_setpviv_mg(SV *const sv, const IV iv)

       sv_setpvn
               Copies a string into an SV.  The "len" parameter indicates the
               number of bytes to be copied.  If the "ptr" argument is NULL
               the SV will become undefined.  Does not handle 'set' magic.
               See "sv_setpvn_mg".

                       void    sv_setpvn(SV *const sv, const char *const ptr,
                                         const STRLEN len)

       sv_setpvn_mg
               Like "sv_setpvn", but also handles 'set' magic.

                       void    sv_setpvn_mg(SV *const sv,
                                            const char *const ptr,
                                            const STRLEN len)

       sv_setpvs
               Like "sv_setpvn", but takes a literal string instead of a
               string/length pair.

                       void    sv_setpvs(SV* sv, const char* s)

       sv_setpvs_mg
               Like "sv_setpvn_mg", but takes a literal string instead of a
               string/length pair.

                       void    sv_setpvs_mg(SV* sv, const char* s)

       sv_setpv_mg
               Like "sv_setpv", but also handles 'set' magic.

                       void    sv_setpv_mg(SV *const sv, const char *const ptr)

       sv_setref_iv
               Copies an integer into a new SV, optionally blessing the SV.
               The "rv" argument will be upgraded to an RV.  That RV will be
               modified to point to the new SV.  The "classname" argument
               indicates the package for the blessing.  Set "classname" to
               "NULL" to avoid the blessing.  The new SV will have a reference
               count of 1, and the RV will be returned.

                       SV*     sv_setref_iv(SV *const rv,
                                            const char *const classname,
                                            const IV iv)

       sv_setref_nv
               Copies a double into a new SV, optionally blessing the SV.  The
               "rv" argument will be upgraded to an RV.  That RV will be
               modified to point to the new SV.  The "classname" argument
               indicates the package for the blessing.  Set "classname" to
               "NULL" to avoid the blessing.  The new SV will have a reference
               count of 1, and the RV will be returned.

                       SV*     sv_setref_nv(SV *const rv,
                                            const char *const classname,
                                            const NV nv)

       sv_setref_pv
               Copies a pointer into a new SV, optionally blessing the SV.
               The "rv" argument will be upgraded to an RV.  That RV will be
               modified to point to the new SV.  If the "pv" argument is NULL
               then "PL_sv_undef" will be placed into the SV.  The "classname"
               argument indicates the package for the blessing.  Set
               "classname" to "NULL" to avoid the blessing.  The new SV will
               have a reference count of 1, and the RV will be returned.

               Do not use with other Perl types such as HV, AV, SV, CV,
               because those objects will become corrupted by the pointer copy
               process.

               Note that "sv_setref_pvn" copies the string while this copies
               the pointer.

                       SV*     sv_setref_pv(SV *const rv,
                                            const char *const classname,
                                            void *const pv)

       sv_setref_pvn
               Copies a string into a new SV, optionally blessing the SV.  The
               length of the string must be specified with "n".  The "rv"
               argument will be upgraded to an RV.  That RV will be modified
               to point to the new SV.  The "classname" argument indicates the
               package for the blessing.  Set "classname" to "NULL" to avoid
               the blessing.  The new SV will have a reference count of 1, and
               the RV will be returned.

               Note that "sv_setref_pv" copies the pointer while this copies
               the string.

                       SV*     sv_setref_pvn(SV *const rv,
                                             const char *const classname,
                                             const char *const pv,
                                             const STRLEN n)

       sv_setref_pvs
               Like "sv_setref_pvn", but takes a literal string instead of a
               string/length pair.

                       SV *    sv_setref_pvs(const char* s)

       sv_setref_uv
               Copies an unsigned integer into a new SV, optionally blessing
               the SV.  The "rv" argument will be upgraded to an RV.  That RV
               will be modified to point to the new SV.  The "classname"
               argument indicates the package for the blessing.  Set
               "classname" to "NULL" to avoid the blessing.  The new SV will
               have a reference count of 1, and the RV will be returned.

                       SV*     sv_setref_uv(SV *const rv,
                                            const char *const classname,
                                            const UV uv)

       sv_setsv
               Copies the contents of the source SV "ssv" into the destination
               SV "dsv".  The source SV may be destroyed if it is mortal, so
               don't use this function if the source SV needs to be reused.
               Does not handle 'set' magic on destination SV.  Calls 'get'
               magic on source SV.  Loosely speaking, it performs a copy-by-
               value, obliterating any previous content of the destination.

               You probably want to use one of the assortment of wrappers,
               such as "SvSetSV", "SvSetSV_nosteal", "SvSetMagicSV" and
               "SvSetMagicSV_nosteal".

                       void    sv_setsv(SV *dstr, SV *sstr)

       sv_setsv_flags
               Copies the contents of the source SV "ssv" into the destination
               SV "dsv".  The source SV may be destroyed if it is mortal, so
               don't use this function if the source SV needs to be reused.
               Does not handle 'set' magic.  Loosely speaking, it performs a
               copy-by-value, obliterating any previous content of the
               destination.  If the "flags" parameter has the "SV_GMAGIC" bit
               set, will "mg_get" on "ssv" if appropriate, else not.  If the
               "flags" parameter has the "SV_NOSTEAL" bit set then the buffers
               of temps will not be stolen.  <sv_setsv> and "sv_setsv_nomg"
               are implemented in terms of this function.

               You probably want to use one of the assortment of wrappers,
               such as "SvSetSV", "SvSetSV_nosteal", "SvSetMagicSV" and
               "SvSetMagicSV_nosteal".

               This is the primary function for copying scalars, and most
               other copy-ish functions and macros use this underneath.

                       void    sv_setsv_flags(SV *dstr, SV *sstr,
                                              const I32 flags)

       sv_setsv_mg
               Like "sv_setsv", but also handles 'set' magic.

                       void    sv_setsv_mg(SV *const dstr, SV *const sstr)

       sv_setuv
               Copies an unsigned integer into the given SV, upgrading first
               if necessary.  Does not handle 'set' magic.  See also
               "sv_setuv_mg".

                       void    sv_setuv(SV *const sv, const UV num)

       sv_setuv_mg
               Like "sv_setuv", but also handles 'set' magic.

                       void    sv_setuv_mg(SV *const sv, const UV u)

       sv_tainted
               Test an SV for taintedness.  Use "SvTAINTED" instead.

                       bool    sv_tainted(SV *const sv)

       sv_true Returns true if the SV has a true value by Perl's rules.  Use
               the "SvTRUE" macro instead, which may call "sv_true()" or may
               instead use an in-line version.

                       I32     sv_true(SV *const sv)

       sv_unmagic
               Removes all magic of type "type" from an SV.

                       int     sv_unmagic(SV *const sv, const int type)

       sv_unmagicext
               Removes all magic of type "type" with the specified "vtbl" from
               an SV.

                       int     sv_unmagicext(SV *const sv, const int type,
                                             MGVTBL *vtbl)

       sv_unref_flags
               Unsets the RV status of the SV, and decrements the reference
               count of whatever was being referenced by the RV.  This can
               almost be thought of as a reversal of "newSVrv".  The "cflags"
               argument can contain "SV_IMMEDIATE_UNREF" to force the
               reference count to be decremented (otherwise the decrementing
               is conditional on the reference count being different from one
               or the reference being a readonly SV).  See "SvROK_off".

                       void    sv_unref_flags(SV *const ref, const U32 flags)

       sv_untaint
               Untaint an SV.  Use "SvTAINTED_off" instead.

                       void    sv_untaint(SV *const sv)

       sv_upgrade
               Upgrade an SV to a more complex form.  Generally adds a new
               body type to the SV, then copies across as much information as
               possible from the old body.  It croaks if the SV is already in
               a more complex form than requested.  You generally want to use
               the "SvUPGRADE" macro wrapper, which checks the type before
               calling "sv_upgrade", and hence does not croak.  See also
               "svtype".

                       void    sv_upgrade(SV *const sv, svtype new_type)

       sv_usepvn_flags
               Tells an SV to use "ptr" to find its string value.  Normally
               the string is stored inside the SV but sv_usepvn allows the SV
               to use an outside string.  The "ptr" should point to memory
               that was allocated by "malloc".  It must be the start of a
               mallocked block of memory, and not a pointer to the middle of
               it.  The string length, "len", must be supplied.  By default
               this function will realloc (i.e. move) the memory pointed to by
               "ptr", so that pointer should not be freed or used by the
               programmer after giving it to sv_usepvn, and neither should any
               pointers from "behind" that pointer (e.g. ptr + 1) be used.

               If "flags" & SV_SMAGIC is true, will call SvSETMAGIC.  If
               "flags" & SV_HAS_TRAILING_NUL is true, then "ptr[len]" must be
               NUL, and the realloc will be skipped (i.e. the buffer is
               actually at least 1 byte longer than "len", and already meets
               the requirements for storing in "SvPVX").

                       void    sv_usepvn_flags(SV *const sv, char* ptr,
                                               const STRLEN len,
                                               const U32 flags)

       sv_utf8_decode
               NOTE: this function is experimental and may change or be
               removed without notice.

               If the PV of the SV is an octet sequence in UTF-8 and contains
               a multiple-byte character, the "SvUTF8" flag is turned on so
               that it looks like a character.  If the PV contains only
               single-byte characters, the "SvUTF8" flag stays off.  Scans PV
               for validity and returns false if the PV is invalid UTF-8.

                       bool    sv_utf8_decode(SV *const sv)

       sv_utf8_downgrade
               NOTE: this function is experimental and may change or be
               removed without notice.

               Attempts to convert the PV of an SV from characters to bytes.
               If the PV contains a character that cannot fit in a byte, this
               conversion will fail; in this case, either returns false or, if
               "fail_ok" is not true, croaks.

               This is not a general purpose Unicode to byte encoding
               interface: use the Encode extension for that.

                       bool    sv_utf8_downgrade(SV *const sv,
                                                 const bool fail_ok)

       sv_utf8_encode
               Converts the PV of an SV to UTF-8, but then turns the "SvUTF8"
               flag off so that it looks like octets again.

                       void    sv_utf8_encode(SV *const sv)

       sv_utf8_upgrade
               Converts the PV of an SV to its UTF-8-encoded form.  Forces the
               SV to string form if it is not already.  Will "mg_get" on "sv"
               if appropriate.  Always sets the SvUTF8 flag to avoid future
               validity checks even if the whole string is the same in UTF-8
               as not.  Returns the number of bytes in the converted string

               This is not a general purpose byte encoding to Unicode
               interface: use the Encode extension for that.

                       STRLEN  sv_utf8_upgrade(SV *sv)

       sv_utf8_upgrade_flags
               Converts the PV of an SV to its UTF-8-encoded form.  Forces the
               SV to string form if it is not already.  Always sets the SvUTF8
               flag to avoid future validity checks even if all the bytes are
               invariant in UTF-8.  If "flags" has "SV_GMAGIC" bit set, will
               "mg_get" on "sv" if appropriate, else not.

               If "flags" has SV_FORCE_UTF8_UPGRADE set, this function assumes
               that the PV will expand when converted to UTF-8, and skips the
               extra work of checking for that.  Typically this flag is used
               by a routine that has already parsed the string and found such
               characters, and passes this information on so that the work
               doesn't have to be repeated.

               Returns the number of bytes in the converted string.

               This is not a general purpose byte encoding to Unicode
               interface: use the Encode extension for that.

                       STRLEN  sv_utf8_upgrade_flags(SV *const sv,
                                                     const I32 flags)

       sv_utf8_upgrade_flags_grow
               Like sv_utf8_upgrade_flags, but has an additional parameter
               "extra", which is the number of unused bytes the string of 'sv'
               is guaranteed to have free after it upon return.  This allows
               the caller to reserve extra space that it intends to fill, to
               avoid extra grows.

               "sv_utf8_upgrade", "sv_utf8_upgrade_nomg", and
               "sv_utf8_upgrade_flags" are implemented in terms of this
               function.

               Returns the number of bytes in the converted string (not
               including the spares).

                       STRLEN  sv_utf8_upgrade_flags_grow(SV *const sv,
                                                          const I32 flags,
                                                          STRLEN extra)

       sv_utf8_upgrade_nomg
               Like sv_utf8_upgrade, but doesn't do magic on "sv".

                       STRLEN  sv_utf8_upgrade_nomg(SV *sv)

       sv_vcatpvf
               Processes its arguments like "vsprintf" and appends the
               formatted output to an SV.  Does not handle 'set' magic.  See
               "sv_vcatpvf_mg".

               Usually used via its frontend "sv_catpvf".

                       void    sv_vcatpvf(SV *const sv, const char *const pat,
                                          va_list *const args)

       sv_vcatpvfn
                       void    sv_vcatpvfn(SV *const sv, const char *const pat,
                                           const STRLEN patlen,
                                           va_list *const args,
                                           SV **const svargs, const I32 svmax,
                                           bool *const maybe_tainted)

       sv_vcatpvfn_flags
               Processes its arguments like "vsprintf" and appends the
               formatted output to an SV.  Uses an array of SVs if the C style
               variable argument list is missing (NULL).  When running with
               taint checks enabled, indicates via "maybe_tainted" if results
               are untrustworthy (often due to the use of locales).

               If called as "sv_vcatpvfn" or flags include "SV_GMAGIC", calls
               get magic.

               Usually used via one of its frontends "sv_vcatpvf" and
               "sv_vcatpvf_mg".

                       void    sv_vcatpvfn_flags(SV *const sv,
                                                 const char *const pat,
                                                 const STRLEN patlen,
                                                 va_list *const args,
                                                 SV **const svargs,
                                                 const I32 svmax,
                                                 bool *const maybe_tainted,
                                                 const U32 flags)

       sv_vcatpvf_mg
               Like "sv_vcatpvf", but also handles 'set' magic.

               Usually used via its frontend "sv_catpvf_mg".

                       void    sv_vcatpvf_mg(SV *const sv,
                                             const char *const pat,
                                             va_list *const args)

       sv_vsetpvf
               Works like "sv_vcatpvf" but copies the text into the SV instead
               of appending it.  Does not handle 'set' magic.  See
               "sv_vsetpvf_mg".

               Usually used via its frontend "sv_setpvf".

                       void    sv_vsetpvf(SV *const sv, const char *const pat,
                                          va_list *const args)

       sv_vsetpvfn
               Works like "sv_vcatpvfn" but copies the text into the SV
               instead of appending it.

               Usually used via one of its frontends "sv_vsetpvf" and
               "sv_vsetpvf_mg".

                       void    sv_vsetpvfn(SV *const sv, const char *const pat,
                                           const STRLEN patlen,
                                           va_list *const args,
                                           SV **const svargs, const I32 svmax,
                                           bool *const maybe_tainted)

       sv_vsetpvf_mg
               Like "sv_vsetpvf", but also handles 'set' magic.

               Usually used via its frontend "sv_setpvf_mg".

                       void    sv_vsetpvf_mg(SV *const sv,
                                             const char *const pat,
                                             va_list *const args)


Unicode Support

       bytes_cmp_utf8
               Compares the sequence of characters (stored as octets) in "b",
               "blen" with the sequence of characters (stored as UTF-8) in
               "u", "ulen".  Returns 0 if they are equal, -1 or -2 if the
               first string is less than the second string, +1 or +2 if the
               first string is greater than the second string.

               -1 or +1 is returned if the shorter string was identical to the
               start of the longer string.  -2 or +2 is returned if there was
               a difference between characters within the strings.

                       int     bytes_cmp_utf8(const U8 *b, STRLEN blen,
                                              const U8 *u, STRLEN ulen)

       bytes_from_utf8
               NOTE: this function is experimental and may change or be
               removed without notice.

               Converts a string "s" of length "len" from UTF-8 into native
               byte encoding.  Unlike "utf8_to_bytes" but like
               "bytes_to_utf8", returns a pointer to the newly-created string,
               and updates "len" to contain the new length.  Returns the
               original string if no conversion occurs, "len" is unchanged.
               Do nothing if "is_utf8" points to 0.  Sets "is_utf8" to 0 if
               "s" is converted or consisted entirely of characters that are
               invariant in utf8 (i.e., US-ASCII on non-EBCDIC machines).

                       U8*     bytes_from_utf8(const U8 *s, STRLEN *len,
                                               bool *is_utf8)

       bytes_to_utf8
               NOTE: this function is experimental and may change or be
               removed without notice.

               Converts a string "s" of length "len" bytes from the native
               encoding into UTF-8.  Returns a pointer to the newly-created
               string, and sets "len" to reflect the new length in bytes.

               A "NUL" character will be written after the end of the string.

               If you want to convert to UTF-8 from encodings other than the
               native (Latin1 or EBCDIC), see "sv_recode_to_utf8"().

                       U8*     bytes_to_utf8(const U8 *s, STRLEN *len)

       foldEQ_utf8
               Returns true if the leading portions of the strings "s1" and
               "s2" (either or both of which may be in UTF-8) are the same
               case-insensitively; false otherwise.  How far into the strings
               to compare is determined by other input parameters.

               If "u1" is true, the string "s1" is assumed to be in
               UTF-8-encoded Unicode; otherwise it is assumed to be in native
               8-bit encoding.  Correspondingly for "u2" with respect to "s2".

               If the byte length "l1" is non-zero, it says how far into "s1"
               to check for fold equality.  In other words, "s1"+"l1" will be
               used as a goal to reach.  The scan will not be considered to be
               a match unless the goal is reached, and scanning won't continue
               past that goal.  Correspondingly for "l2" with respect to "s2".

               If "pe1" is non-NULL and the pointer it points to is not NULL,
               that pointer is considered an end pointer to the position 1
               byte past the maximum point in "s1" beyond which scanning will
               not continue under any circumstances.  (This routine assumes
               that UTF-8 encoded input strings are not malformed; malformed
               input can cause it to read past "pe1").  This means that if
               both "l1" and "pe1" are specified, and "pe1" is less than
               "s1"+"l1", the match will never be successful because it can
               never get as far as its goal (and in fact is asserted against).
               Correspondingly for "pe2" with respect to "s2".

               At least one of "s1" and "s2" must have a goal (at least one of
               "l1" and "l2" must be non-zero), and if both do, both have to
               be reached for a successful match.   Also, if the fold of a
               character is multiple characters, all of them must be matched
               (see tr21 reference below for 'folding').

               Upon a successful match, if "pe1" is non-NULL, it will be set
               to point to the beginning of the next character of "s1" beyond
               what was matched.  Correspondingly for "pe2" and "s2".

               For case-insensitiveness, the "casefolding" of Unicode is used
               instead of upper/lowercasing both the characters, see
               <http://www.unicode.org/unicode/reports/tr21/> (Case Mappings).

                       I32     foldEQ_utf8(const char *s1, char **pe1, UV l1,
                                           bool u1, const char *s2, char **pe2,
                                           UV l2, bool u2)

       is_ascii_string
               Returns true if the first "len" bytes of the string "s" are the
               same whether or not the string is encoded in UTF-8 (or UTF-
               EBCDIC on EBCDIC machines).  That is, if they are invariant.
               On ASCII-ish machines, only ASCII characters fit this
               definition, hence the function's name.

               If "len" is 0, it will be calculated using strlen(s), (which
               means if you use this option, that "s" can't have embedded
               "NUL" characters and has to have a terminating "NUL" byte).

               See also "is_utf8_string"(), "is_utf8_string_loclen"(), and
               "is_utf8_string_loc"().

                       bool    is_ascii_string(const U8 *s, STRLEN len)

       is_utf8_char
               DEPRECATED!  It is planned to remove this function from a
               future release of Perl.  Do not use it for new code; remove it
               from existing code.

               Tests if some arbitrary number of bytes begins in a valid UTF-8
               character.  Note that an INVARIANT (i.e. ASCII on non-EBCDIC
               machines) character is a valid UTF-8 character.  The actual
               number of bytes in the UTF-8 character will be returned if it
               is valid, otherwise 0.

               This function is deprecated due to the possibility that
               malformed input could cause reading beyond the end of the input
               buffer.  Use "is_utf8_char_buf" instead.

                       STRLEN  is_utf8_char(const U8 *s)

       is_utf8_char_buf
               Returns the number of bytes that comprise the first UTF-8
               encoded character in buffer "buf".  "buf_end" should point to
               one position beyond the end of the buffer.  0 is returned if
               "buf" does not point to a complete, valid UTF-8 encoded
               character.

               Note that an INVARIANT character (i.e. ASCII on non-EBCDIC
               machines) is a valid UTF-8 character.

                       STRLEN  is_utf8_char_buf(const U8 *buf,
                                                const U8 *buf_end)

       is_utf8_string
               Returns true if the first "len" bytes of string "s" form a
               valid UTF-8 string, false otherwise.  If "len" is 0, it will be
               calculated using strlen(s) (which means if you use this option,
               that "s" can't have embedded "NUL" characters and has to have a
               terminating "NUL" byte).  Note that all characters being ASCII
               constitute 'a valid UTF-8 string'.

               See also "is_ascii_string"(), "is_utf8_string_loclen"(), and
               "is_utf8_string_loc"().

                       bool    is_utf8_string(const U8 *s, STRLEN len)

       is_utf8_string_loc
               Like "is_utf8_string" but stores the location of the failure
               (in the case of "utf8ness failure") or the location "s"+"len"
               (in the case of "utf8ness success") in the "ep".

               See also "is_utf8_string_loclen"() and "is_utf8_string"().

                       bool    is_utf8_string_loc(const U8 *s, STRLEN len,
                                                  const U8 **ep)

       is_utf8_string_loclen
               Like "is_utf8_string"() but stores the location of the failure
               (in the case of "utf8ness failure") or the location "s"+"len"
               (in the case of "utf8ness success") in the "ep", and the number
               of UTF-8 encoded characters in the "el".

               See also "is_utf8_string_loc"() and "is_utf8_string"().

                       bool    is_utf8_string_loclen(const U8 *s, STRLEN len,
                                                     const U8 **ep, STRLEN *el)

       pv_uni_display
               Build to the scalar "dsv" a displayable version of the string
               "spv", length "len", the displayable version being at most
               "pvlim" bytes long (if longer, the rest is truncated and "..."
               will be appended).

               The "flags" argument can have UNI_DISPLAY_ISPRINT set to
               display isPRINT()able characters as themselves,
               UNI_DISPLAY_BACKSLASH to display the \\[nrfta\\] as the
               backslashed versions (like '\n') (UNI_DISPLAY_BACKSLASH is
               preferred over UNI_DISPLAY_ISPRINT for \\).  UNI_DISPLAY_QQ
               (and its alias UNI_DISPLAY_REGEX) have both
               UNI_DISPLAY_BACKSLASH and UNI_DISPLAY_ISPRINT turned on.

               The pointer to the PV of the "dsv" is returned.

                       char*   pv_uni_display(SV *dsv, const U8 *spv,
                                              STRLEN len, STRLEN pvlim,
                                              UV flags)

       sv_cat_decode
               The encoding is assumed to be an Encode object, the PV of the
               ssv is assumed to be octets in that encoding and decoding the
               input starts from the position which (PV + *offset) pointed to.
               The dsv will be concatenated the decoded UTF-8 string from ssv.
               Decoding will terminate when the string tstr appears in
               decoding output or the input ends on the PV of the ssv.  The
               value which the offset points will be modified to the last
               input position on the ssv.

               Returns TRUE if the terminator was found, else returns FALSE.

                       bool    sv_cat_decode(SV* dsv, SV *encoding, SV *ssv,
                                             int *offset, char* tstr, int tlen)

       sv_recode_to_utf8
               The encoding is assumed to be an Encode object, on entry the PV
               of the sv is assumed to be octets in that encoding, and the sv
               will be converted into Unicode (and UTF-8).

               If the sv already is UTF-8 (or if it is not POK), or if the
               encoding is not a reference, nothing is done to the sv.  If the
               encoding is not an "Encode::XS" Encoding object, bad things
               will happen.  (See lib/encoding.pm and Encode.)

               The PV of the sv is returned.

                       char*   sv_recode_to_utf8(SV* sv, SV *encoding)

       sv_uni_display
               Build to the scalar "dsv" a displayable version of the scalar
               "sv", the displayable version being at most "pvlim" bytes long
               (if longer, the rest is truncated and "..." will be appended).

               The "flags" argument is as in "pv_uni_display"().

               The pointer to the PV of the "dsv" is returned.

                       char*   sv_uni_display(SV *dsv, SV *ssv, STRLEN pvlim,
                                              UV flags)

       to_utf8_case
               "p" contains the pointer to the UTF-8 string encoding the
               character that is being converted.  This routine assumes that
               the character at "p" is well-formed.

               "ustrp" is a pointer to the character buffer to put the
               conversion result to.  "lenp" is a pointer to the length of the
               result.

               "swashp" is a pointer to the swash to use.

               Both the special and normal mappings are stored in
               lib/unicore/To/Foo.pl, and loaded by SWASHNEW, using
               lib/utf8_heavy.pl.  "special" (usually, but not always, a
               multicharacter mapping), is tried first.

               "special" is a string, normally "NULL" or "".  "NULL" means to
               not use any special mappings; "" means to use the special
               mappings.  Values other than these two are treated as the name
               of the hash containing the special mappings, like
               "utf8::ToSpecLower".

               "normal" is a string like "ToLower" which means the swash
               %utf8::ToLower.

                       UV      to_utf8_case(const U8 *p, U8* ustrp,
                                            STRLEN *lenp, SV **swashp,
                                            const char *normal,
                                            const char *special)

       to_utf8_fold
               Instead use "toFOLD_utf8".

                       UV      to_utf8_fold(const U8 *p, U8* ustrp,
                                            STRLEN *lenp)

       to_utf8_lower
               Instead use "toLOWER_utf8".

                       UV      to_utf8_lower(const U8 *p, U8* ustrp,
                                             STRLEN *lenp)

       to_utf8_title
               Instead use "toTITLE_utf8".

                       UV      to_utf8_title(const U8 *p, U8* ustrp,
                                             STRLEN *lenp)

       to_utf8_upper
               Instead use "toUPPER_utf8".

                       UV      to_utf8_upper(const U8 *p, U8* ustrp,
                                             STRLEN *lenp)

       utf8n_to_uvchr
               THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED
               CIRCUMSTANCES.  Most code should use "utf8_to_uvchr_buf"()
               rather than call this directly.

               Bottom level UTF-8 decode routine.  Returns the native code
               point value of the first character in the string "s", which is
               assumed to be in UTF-8 (or UTF-EBCDIC) encoding, and no longer
               than "curlen" bytes; *retlen (if "retlen" isn't NULL) will be
               set to the length, in bytes, of that character.

               The value of "flags" determines the behavior when "s" does not
               point to a well-formed UTF-8 character.  If "flags" is 0, when
               a malformation is found, zero is returned and *retlen is set so
               that ("s" + *retlen) is the next possible position in "s" that
               could begin a non-malformed character.  Also, if UTF-8 warnings
               haven't been lexically disabled, a warning is raised.

               Various ALLOW flags can be set in "flags" to allow (and not
               warn on) individual types of malformations, such as the
               sequence being overlong (that is, when there is a shorter
               sequence that can express the same code point; overlong
               sequences are expressly forbidden in the UTF-8 standard due to
               potential security issues).  Another malformation example is
               the first byte of a character not being a legal first byte.
               See utf8.h for the list of such flags.  For allowed 0 length
               strings, this function returns 0; for allowed overlong
               sequences, the computed code point is returned; for all other
               allowed malformations, the Unicode REPLACEMENT CHARACTER is
               returned, as these have no determinable reasonable value.

               The UTF8_CHECK_ONLY flag overrides the behavior when a non-
               allowed (by other flags) malformation is found.  If this flag
               is set, the routine assumes that the caller will raise a
               warning, and this function will silently just set "retlen" to
               "-1" (cast to "STRLEN") and return zero.

               Note that this API requires disambiguation between successful
               decoding a "NUL" character, and an error return (unless the
               UTF8_CHECK_ONLY flag is set), as in both cases, 0 is returned.
               To disambiguate, upon a zero return, see if the first byte of
               "s" is 0 as well.  If so, the input was a "NUL"; if not, the
               input had an error.

               Certain code points are considered problematic.  These are
               Unicode surrogates, Unicode non-characters, and code points
               above the Unicode maximum of 0x10FFFF.  By default these are
               considered regular code points, but certain situations warrant
               special handling for them.  If "flags" contains
               UTF8_DISALLOW_ILLEGAL_INTERCHANGE, all three classes are
               treated as malformations and handled as such.  The flags
               UTF8_DISALLOW_SURROGATE, UTF8_DISALLOW_NONCHAR, and
               UTF8_DISALLOW_SUPER (meaning above the legal Unicode maximum)
               can be set to disallow these categories individually.

               The flags UTF8_WARN_ILLEGAL_INTERCHANGE, UTF8_WARN_SURROGATE,
               UTF8_WARN_NONCHAR, and UTF8_WARN_SUPER will cause warning
               messages to be raised for their respective categories, but
               otherwise the code points are considered valid (not
               malformations).  To get a category to both be treated as a
               malformation and raise a warning, specify both the WARN and
               DISALLOW flags.  (But note that warnings are not raised if
               lexically disabled nor if UTF8_CHECK_ONLY is also specified.)

               Very large code points (above 0x7FFF_FFFF) are considered more
               problematic than the others that are above the Unicode legal
               maximum.  There are several reasons: they requre at least 32
               bits to represent them on ASCII platforms, are not
               representable at all on EBCDIC platforms, and the original
               UTF-8 specification never went above this number (the current
               0x10FFFF limit was imposed later).  (The smaller ones, those
               that fit into 32 bits, are representable by a UV on ASCII
               platforms, but not by an IV, which means that the number of
               operations that can be performed on them is quite restricted.)
               The UTF-8 encoding on ASCII platforms for these large code
               points begins with a byte containing 0xFE or 0xFF.  The
               UTF8_DISALLOW_FE_FF flag will cause them to be treated as
               malformations, while allowing smaller above-Unicode code
               points.  (Of course UTF8_DISALLOW_SUPER will treat all above-
               Unicode code points, including these, as malformations.)
               Similarly, UTF8_WARN_FE_FF acts just like the other WARN flags,
               but applies just to these code points.

               All other code points corresponding to Unicode characters,
               including private use and those yet to be assigned, are never
               considered malformed and never warn.

                       UV      utf8n_to_uvchr(const U8 *s, STRLEN curlen,
                                              STRLEN *retlen, U32 flags)

       utf8n_to_uvuni
               Instead use "utf8_to_uvchr_buf", or rarely, "utf8n_to_uvchr".

               This function was useful for code that wanted to handle both
               EBCDIC and ASCII platforms with Unicode properties, but
               starting in Perl v5.20, the distinctions between the platforms
               have mostly been made invisible to most code, so this function
               is quite unlikely to be what you want.  If you do need this
               precise functionality, use instead
               "NATIVE_TO_UNI(utf8_to_uvchr_buf(...))"  or
               "NATIVE_TO_UNI(utf8n_to_uvchr(...))".

                       UV      utf8n_to_uvuni(const U8 *s, STRLEN curlen,
                                              STRLEN *retlen, U32 flags)

       utf8_distance
               Returns the number of UTF-8 characters between the UTF-8
               pointers "a" and "b".

               WARNING: use only if you *know* that the pointers point inside
               the same UTF-8 buffer.

                       IV      utf8_distance(const U8 *a, const U8 *b)

       utf8_hop
               Return the UTF-8 pointer "s" displaced by "off" characters,
               either forward or backward.

               WARNING: do not use the following unless you *know* "off" is
               within the UTF-8 data pointed to by "s" *and* that on entry "s"
               is aligned on the first byte of character or just after the
               last byte of a character.

                       U8*     utf8_hop(const U8 *s, I32 off)

       utf8_length
               Return the length of the UTF-8 char encoded string "s" in
               characters.  Stops at "e" (inclusive).  If "e < s" or if the
               scan would end up past "e", croaks.

                       STRLEN  utf8_length(const U8* s, const U8 *e)

       utf8_to_bytes
               NOTE: this function is experimental and may change or be
               removed without notice.

               Converts a string "s" of length "len" from UTF-8 into native
               byte encoding.  Unlike "bytes_to_utf8", this over-writes the
               original string, and updates "len" to contain the new length.
               Returns zero on failure, setting "len" to -1.

               If you need a copy of the string, see "bytes_from_utf8".

                       U8*     utf8_to_bytes(U8 *s, STRLEN *len)

       utf8_to_uvchr
               DEPRECATED!  It is planned to remove this function from a
               future release of Perl.  Do not use it for new code; remove it
               from existing code.

               Returns the native code point of the first character in the
               string "s" which is assumed to be in UTF-8 encoding; "retlen"
               will be set to the length, in bytes, of that character.

               Some, but not all, UTF-8 malformations are detected, and in
               fact, some malformed input could cause reading beyond the end
               of the input buffer, which is why this function is deprecated.
               Use "utf8_to_uvchr_buf" instead.

               If "s" points to one of the detected malformations, and UTF8
               warnings are enabled, zero is returned and *retlen is set (if
               "retlen" isn't NULL) to -1.  If those warnings are off, the
               computed value if well-defined (or the Unicode REPLACEMENT
               CHARACTER, if not) is silently returned, and *retlen is set (if
               "retlen" isn't NULL) so that ("s" + *retlen) is the next
               possible position in "s" that could begin a non-malformed
               character.  See "utf8n_to_uvchr" for details on when the
               REPLACEMENT CHARACTER is returned.

                       UV      utf8_to_uvchr(const U8 *s, STRLEN *retlen)

       utf8_to_uvchr_buf
               Returns the native code point of the first character in the
               string "s" which is assumed to be in UTF-8 encoding; "send"
               points to 1 beyond the end of "s".  *retlen will be set to the
               length, in bytes, of that character.

               If "s" does not point to a well-formed UTF-8 character and UTF8
               warnings are enabled, zero is returned and *retlen is set (if
               "retlen" isn't NULL) to -1.  If those warnings are off, the
               computed value, if well-defined (or the Unicode REPLACEMENT
               CHARACTER if not), is silently returned, and *retlen is set (if
               "retlen" isn't NULL) so that ("s" + *retlen) is the next
               possible position in "s" that could begin a non-malformed
               character.  See "utf8n_to_uvchr" for details on when the
               REPLACEMENT CHARACTER is returned.

                       UV      utf8_to_uvchr_buf(const U8 *s, const U8 *send,
                                                 STRLEN *retlen)

       utf8_to_uvuni
               DEPRECATED!  It is planned to remove this function from a
               future release of Perl.  Do not use it for new code; remove it
               from existing code.

               Returns the Unicode code point of the first character in the
               string "s" which is assumed to be in UTF-8 encoding; "retlen"
               will be set to the length, in bytes, of that character.

               Some, but not all, UTF-8 malformations are detected, and in
               fact, some malformed input could cause reading beyond the end
               of the input buffer, which is one reason why this function is
               deprecated.  The other is that only in extremely limited
               circumstances should the Unicode versus native code point be of
               any interest to you.  See "utf8_to_uvuni_buf" for alternatives.

               If "s" points to one of the detected malformations, and UTF8
               warnings are enabled, zero is returned and *retlen is set (if
               "retlen" doesn't point to NULL) to -1.  If those warnings are
               off, the computed value if well-defined (or the Unicode
               REPLACEMENT CHARACTER, if not) is silently returned, and
               *retlen is set (if "retlen" isn't NULL) so that ("s" + *retlen)
               is the next possible position in "s" that could begin a non-
               malformed character.  See "utf8n_to_uvchr" for details on when
               the REPLACEMENT CHARACTER is returned.

                       UV      utf8_to_uvuni(const U8 *s, STRLEN *retlen)

       utf8_to_uvuni_buf
               DEPRECATED!  It is planned to remove this function from a
               future release of Perl.  Do not use it for new code; remove it
               from existing code.

               Only in very rare circumstances should code need to be dealing
               in Unicode (as opposed to native) code points.  In those few
               cases, use "NATIVE_TO_UNI(utf8_to_uvchr_buf(...))" instead.

               Returns the Unicode (not-native) code point of the first
               character in the string "s" which is assumed to be in UTF-8
               encoding; "send" points to 1 beyond the end of "s".  "retlen"
               will be set to the length, in bytes, of that character.

               If "s" does not point to a well-formed UTF-8 character and UTF8
               warnings are enabled, zero is returned and *retlen is set (if
               "retlen" isn't NULL) to -1.  If those warnings are off, the
               computed value if well-defined (or the Unicode REPLACEMENT
               CHARACTER, if not) is silently returned, and *retlen is set (if
               "retlen" isn't NULL) so that ("s" + *retlen) is the next
               possible position in "s" that could begin a non-malformed
               character.  See "utf8n_to_uvchr" for details on when the
               REPLACEMENT CHARACTER is returned.

                       UV      utf8_to_uvuni_buf(const U8 *s, const U8 *send,
                                                 STRLEN *retlen)

       uvchr_to_utf8
               Adds the UTF-8 representation of the native code point "uv" to
               the end of the string "d"; "d" should have at least
               "UNISKIP(uv)+1" (up to "UTF8_MAXBYTES+1") free bytes available.
               The return value is the pointer to the byte after the end of
               the new character.  In other words,

                   d = uvchr_to_utf8(d, uv);

               is the recommended wide native character-aware way of saying

                   *(d++) = uv;

               This function accepts any UV as input.  To forbid or warn on
               non-Unicode code points, or those that may be problematic, see
               "uvchr_to_utf8_flags".

                       U8*     uvchr_to_utf8(U8 *d, UV uv)

       uvchr_to_utf8_flags
               Adds the UTF-8 representation of the native code point "uv" to
               the end of the string "d"; "d" should have at least
               "UNISKIP(uv)+1" (up to "UTF8_MAXBYTES+1") free bytes available.
               The return value is the pointer to the byte after the end of
               the new character.  In other words,

                   d = uvchr_to_utf8_flags(d, uv, flags);

               or, in most cases,

                   d = uvchr_to_utf8_flags(d, uv, 0);

               This is the Unicode-aware way of saying

                   *(d++) = uv;

               This function will convert to UTF-8 (and not warn) even code
               points that aren't legal Unicode or are problematic, unless
               "flags" contains one or more of the following flags:

               If "uv" is a Unicode surrogate code point and
               UNICODE_WARN_SURROGATE is set, the function will raise a
               warning, provided UTF8 warnings are enabled.  If instead
               UNICODE_DISALLOW_SURROGATE is set, the function will fail and
               return NULL.  If both flags are set, the function will both
               warn and return NULL.

               The UNICODE_WARN_NONCHAR and UNICODE_DISALLOW_NONCHAR flags
               affect how the function handles a Unicode non-character.  And
               likewise, the UNICODE_WARN_SUPER and UNICODE_DISALLOW_SUPER
               flags affect the handling of code points that are above the
               Unicode maximum of 0x10FFFF.  Code points above 0x7FFF_FFFF
               (which are even less portable) can be warned and/or disallowed
               even if other above-Unicode code points are accepted, by the
               UNICODE_WARN_FE_FF and UNICODE_DISALLOW_FE_FF flags.

               And finally, the flag UNICODE_WARN_ILLEGAL_INTERCHANGE selects
               all four of the above WARN flags; and
               UNICODE_DISALLOW_ILLEGAL_INTERCHANGE selects all four DISALLOW
               flags.

                       U8*     uvchr_to_utf8_flags(U8 *d, UV uv, UV flags)

       uvoffuni_to_utf8_flags
               THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED
               CIRCUMSTANCES.  Instead, Almost all code should use
               "uvchr_to_utf8" or "uvchr_to_utf8_flags".

               This function is like them, but the input is a strict Unicode
               (as opposed to native) code point.  Only in very rare
               circumstances should code not be using the native code point.

               For details, see the description for "uvchr_to_utf8_flags">.

                       U8*     uvoffuni_to_utf8_flags(U8 *d, UV uv, UV flags)

       uvuni_to_utf8_flags
               Instead you almost certainly want to use "uvchr_to_utf8" or
               "uvchr_to_utf8_flags">.

               This function is a deprecated synonym for
               "uvoffuni_to_utf8_flags", which itself, while not deprecated,
               should be used only in isolated circumstances.  These functions
               were useful for code that wanted to handle both EBCDIC and
               ASCII platforms with Unicode properties, but starting in Perl
               v5.20, the distinctions between the platforms have mostly been
               made invisible to most code, so this function is quite unlikely
               to be what you want.

                       U8*     uvuni_to_utf8_flags(U8 *d, UV uv, UV flags)


Variables created by "xsubpp" and "xsubpp" internal functions

       ax      Variable which is setup by "xsubpp" to indicate the stack base
               offset, used by the "ST", "XSprePUSH" and "XSRETURN" macros.
               The "dMARK" macro must be called prior to setup the "MARK"
               variable.

                       I32     ax

       CLASS   Variable which is setup by "xsubpp" to indicate the class name
               for a C++ XS constructor.  This is always a "char*".  See
               "THIS".

                       char*   CLASS

       dAX     Sets up the "ax" variable.  This is usually handled
               automatically by "xsubpp" by calling "dXSARGS".

                               dAX;

       dAXMARK Sets up the "ax" variable and stack marker variable "mark".
               This is usually handled automatically by "xsubpp" by calling
               "dXSARGS".

                               dAXMARK;

       dITEMS  Sets up the "items" variable.  This is usually handled
               automatically by "xsubpp" by calling "dXSARGS".

                               dITEMS;

       dUNDERBAR
               Sets up any variable needed by the "UNDERBAR" macro.  It used
               to define "padoff_du", but it is currently a noop.  However, it
               is strongly advised to still use it for ensuring past and
               future compatibility.

                               dUNDERBAR;

       dXSARGS Sets up stack and mark pointers for an XSUB, calling dSP and
               dMARK.  Sets up the "ax" and "items" variables by calling "dAX"
               and "dITEMS".  This is usually handled automatically by
               "xsubpp".

                               dXSARGS;

       dXSI32  Sets up the "ix" variable for an XSUB which has aliases.  This
               is usually handled automatically by "xsubpp".

                               dXSI32;

       items   Variable which is setup by "xsubpp" to indicate the number of
               items on the stack.  See "Variable-length Parameter Lists" in
               perlxs.

                       I32     items

       ix      Variable which is setup by "xsubpp" to indicate which of an
               XSUB's aliases was used to invoke it.  See "The ALIAS: Keyword"
               in perlxs.

                       I32     ix

       newXSproto
               Used by "xsubpp" to hook up XSUBs as Perl subs.  Adds Perl
               prototypes to the subs.

       RETVAL  Variable which is setup by "xsubpp" to hold the return value
               for an XSUB.  This is always the proper type for the XSUB.  See
               "The RETVAL Variable" in perlxs.

                       (whatever)      RETVAL

       ST      Used to access elements on the XSUB's stack.

                       SV*     ST(int ix)

       THIS    Variable which is setup by "xsubpp" to designate the object in
               a C++ XSUB.  This is always the proper type for the C++ object.
               See "CLASS" and "Using XS With C++" in perlxs.

                       (whatever)      THIS

       UNDERBAR
               The SV* corresponding to the $_ variable.  Works even if there
               is a lexical $_ in scope.

       XS      Macro to declare an XSUB and its C parameter list.  This is
               handled by "xsubpp".  It is the same as using the more explicit
               XS_EXTERNAL macro.

       XS_APIVERSION_BOOTCHECK
               Macro to verify that the perl api version an XS module has been
               compiled against matches the api version of the perl
               interpreter it's being loaded into.

                               XS_APIVERSION_BOOTCHECK;

       XS_EXTERNAL
               Macro to declare an XSUB and its C parameter list explicitly
               exporting the symbols.

       XS_INTERNAL
               Macro to declare an XSUB and its C parameter list without
               exporting the symbols.  This is handled by "xsubpp" and
               generally preferable over exporting the XSUB symbols
               unnecessarily.

       XS_VERSION
               The version identifier for an XS module.  This is usually
               handled automatically by "ExtUtils::MakeMaker".  See
               "XS_VERSION_BOOTCHECK".

       XS_VERSION_BOOTCHECK
               Macro to verify that a PM module's $VERSION variable matches
               the XS module's "XS_VERSION" variable.  This is usually handled
               automatically by "xsubpp".  See "The VERSIONCHECK: Keyword" in
               perlxs.

                               XS_VERSION_BOOTCHECK;


Warning and Dieing

       croak   This is an XS interface to Perl's "die" function.

               Take a sprintf-style format pattern and argument list.  These
               are used to generate a string message.  If the message does not
               end with a newline, then it will be extended with some
               indication of the current location in the code, as described
               for "mess_sv".

               The error message will be used as an exception, by default
               returning control to the nearest enclosing "eval", but subject
               to modification by a $SIG{__DIE__} handler.  In any case, the
               "croak" function never returns normally.

               For historical reasons, if "pat" is null then the contents of
               "ERRSV" ($@) will be used as an error message or object instead
               of building an error message from arguments.  If you want to
               throw a non-string object, or build an error message in an SV
               yourself, it is preferable to use the "croak_sv" function,
               which does not involve clobbering "ERRSV".

                       void    croak(const char *pat, ...)

       croak_no_modify
               Exactly equivalent to "Perl_croak(aTHX_ "%s", PL_no_modify)",
               but generates terser object code than using "Perl_croak".  Less
               code used on exception code paths reduces CPU cache pressure.

                       void    croak_no_modify()

       croak_sv
               This is an XS interface to Perl's "die" function.

               "baseex" is the error message or object.  If it is a reference,
               it will be used as-is.  Otherwise it is used as a string, and
               if it does not end with a newline then it will be extended with
               some indication of the current location in the code, as
               described for "mess_sv".

               The error message or object will be used as an exception, by
               default returning control to the nearest enclosing "eval", but
               subject to modification by a $SIG{__DIE__} handler.  In any
               case, the "croak_sv" function never returns normally.

               To die with a simple string message, the "croak" function may
               be more convenient.

                       void    croak_sv(SV *baseex)

       die     Behaves the same as "croak", except for the return type.  It
               should be used only where the "OP *" return type is required.
               The function never actually returns.

                       OP *    die(const char *pat, ...)

       die_sv  Behaves the same as "croak_sv", except for the return type.  It
               should be used only where the "OP *" return type is required.
               The function never actually returns.

                       OP *    die_sv(SV *baseex)

       vcroak  This is an XS interface to Perl's "die" function.

               "pat" and "args" are a sprintf-style format pattern and
               encapsulated argument list.  These are used to generate a
               string message.  If the message does not end with a newline,
               then it will be extended with some indication of the current
               location in the code, as described for "mess_sv".

               The error message will be used as an exception, by default
               returning control to the nearest enclosing "eval", but subject
               to modification by a $SIG{__DIE__} handler.  In any case, the
               "croak" function never returns normally.

               For historical reasons, if "pat" is null then the contents of
               "ERRSV" ($@) will be used as an error message or object instead
               of building an error message from arguments.  If you want to
               throw a non-string object, or build an error message in an SV
               yourself, it is preferable to use the "croak_sv" function,
               which does not involve clobbering "ERRSV".

                       void    vcroak(const char *pat, va_list *args)

       vwarn   This is an XS interface to Perl's "warn" function.

               "pat" and "args" are a sprintf-style format pattern and
               encapsulated argument list.  These are used to generate a
               string message.  If the message does not end with a newline,
               then it will be extended with some indication of the current
               location in the code, as described for "mess_sv".

               The error message or object will by default be written to
               standard error, but this is subject to modification by a
               $SIG{__WARN__} handler.

               Unlike with "vcroak", "pat" is not permitted to be null.

                       void    vwarn(const char *pat, va_list *args)

       warn    This is an XS interface to Perl's "warn" function.

               Take a sprintf-style format pattern and argument list.  These
               are used to generate a string message.  If the message does not
               end with a newline, then it will be extended with some
               indication of the current location in the code, as described
               for "mess_sv".

               The error message or object will by default be written to
               standard error, but this is subject to modification by a
               $SIG{__WARN__} handler.

               Unlike with "croak", "pat" is not permitted to be null.

                       void    warn(const char *pat, ...)

       warn_sv This is an XS interface to Perl's "warn" function.

               "baseex" is the error message or object.  If it is a reference,
               it will be used as-is.  Otherwise it is used as a string, and
               if it does not end with a newline then it will be extended with
               some indication of the current location in the code, as
               described for "mess_sv".

               The error message or object will by default be written to
               standard error, but this is subject to modification by a
               $SIG{__WARN__} handler.

               To warn with a simple string message, the "warn" function may
               be more convenient.

                       void    warn_sv(SV *baseex)


Undocumented functions

       The following functions have been flagged as part of the public API,
       but are currently undocumented.  Use them at your own risk, as the
       interfaces are subject to change.  Functions that are not listed in
       this document are not intended for public use, and should NOT be used
       under any circumstances.

       If you use one of the undocumented functions below, you may wish to
       consider creating and submitting documentation for it.  If your patch
       is accepted, this will indicate that the interface is stable (unless it
       is explicitly marked otherwise).

       GetVars
       Gv_AMupdate
       PerlIO_clearerr
       PerlIO_close
       PerlIO_context_layers
       PerlIO_eof
       PerlIO_error
       PerlIO_fileno
       PerlIO_fill
       PerlIO_flush
       PerlIO_get_base
       PerlIO_get_bufsiz
       PerlIO_get_cnt
       PerlIO_get_ptr
       PerlIO_read
       PerlIO_seek
       PerlIO_set_cnt
       PerlIO_set_ptrcnt
       PerlIO_setlinebuf
       PerlIO_stderr
       PerlIO_stdin
       PerlIO_stdout
       PerlIO_tell
       PerlIO_unread
       PerlIO_write
       amagic_call
       amagic_deref_call
       any_dup
       atfork_lock
       atfork_unlock
       av_arylen_p
       av_iter_p
       block_gimme
       call_atexit
       call_list
       calloc
       cast_i32
       cast_iv
       cast_ulong
       cast_uv
       ck_warner
       ck_warner_d
       ckwarn
       ckwarn_d
       clone_params_del
       clone_params_new
       croak_memory_wrap
       croak_nocontext
       csighandler
       cx_dump
       cx_dup
       cxinc
       deb
       deb_nocontext
       debop
       debprofdump
       debstack
       debstackptrs
       delimcpy
       despatch_signals
       die_nocontext
       dirp_dup
       do_aspawn
       do_binmode
       do_close
       do_gv_dump
       do_gvgv_dump
       do_hv_dump
       do_join
       do_magic_dump
       do_op_dump
       do_open
       do_open9
       do_openn
       do_pmop_dump
       do_spawn
       do_spawn_nowait
       do_sprintf
       do_sv_dump
       doing_taint
       doref
       dounwind
       dowantarray
       dump_eval
       dump_form
       dump_indent
       dump_mstats
       dump_sub
       dump_vindent
       filter_add
       filter_del
       filter_read
       foldEQ_latin1
       form_nocontext
       fp_dup
       fprintf_nocontext
       free_global_struct
       free_tmps
       get_context
       get_mstats
       get_op_descs
       get_op_names
       get_ppaddr
       get_vtbl
       gp_dup
       gp_free
       gp_ref
       gv_AVadd
       gv_HVadd
       gv_IOadd
       gv_SVadd
       gv_add_by_type
       gv_autoload4
       gv_autoload_pv
       gv_autoload_pvn
       gv_autoload_sv
       gv_check
       gv_dump
       gv_efullname
       gv_efullname3
       gv_efullname4
       gv_fetchfile
       gv_fetchfile_flags
       gv_fetchpv
       gv_fetchpvn_flags
       gv_fetchsv
       gv_fullname
       gv_fullname3
       gv_fullname4
       gv_handler
       gv_name_set
       he_dup
       hek_dup
       hv_common
       hv_common_key_len
       hv_delayfree_ent
       hv_eiter_p
       hv_eiter_set
       hv_free_ent
       hv_ksplit
       hv_name_set
       hv_placeholders_get
       hv_placeholders_set
       hv_rand_set
       hv_riter_p
       hv_riter_set
       init_global_struct
       init_stacks
       init_tm
       instr
       is_lvalue_sub
       leave_scope
       load_module_nocontext
       magic_dump
       malloc
       markstack_grow
       mess_nocontext
       mfree
       mg_dup
       mg_size
       mini_mktime
       moreswitches
       mro_get_from_name
       mro_get_private_data
       mro_set_mro
       mro_set_private_data
       my_atof
       my_atof2
       my_bcopy
       my_bzero
       my_chsize
       my_cxt_index
       my_cxt_init
       my_dirfd
       my_exit
       my_failure_exit
       my_fflush_all
       my_fork
       my_lstat
       my_memcmp
       my_memset
       my_pclose
       my_popen
       my_popen_list
       my_setenv
       my_socketpair
       my_stat
       my_strftime
       newANONATTRSUB
       newANONHASH
       newANONLIST
       newANONSUB
       newATTRSUB
       newAVREF
       newCVREF
       newFORM
       newGVREF
       newGVgen
       newGVgen_flags
       newHVREF
       newHVhv
       newIO
       newMYSUB
       newPROG
       newRV
       newSUB
       newSVREF
       newSVpvf_nocontext
       new_stackinfo
       ninstr
       op_refcnt_lock
       op_refcnt_unlock
       parser_dup
       perl_alloc_using
       perl_clone_using
       pmop_dump
       pop_scope
       pregcomp
       pregexec
       pregfree
       pregfree2
       printf_nocontext
       ptr_table_fetch
       ptr_table_free
       ptr_table_new
       ptr_table_split
       ptr_table_store
       push_scope
       re_compile
       re_dup_guts
       re_intuit_start
       re_intuit_string
       realloc
       reentrant_free
       reentrant_init
       reentrant_retry
       reentrant_size
       ref
       reg_named_buff_all
       reg_named_buff_exists
       reg_named_buff_fetch
       reg_named_buff_firstkey
       reg_named_buff_nextkey
       reg_named_buff_scalar
       regclass_swash
       regdump
       regdupe_internal
       regexec_flags
       regfree_internal
       reginitcolors
       regnext
       repeatcpy
       rninstr
       rsignal
       rsignal_state
       runops_debug
       runops_standard
       rvpv_dup
       safesyscalloc
       safesysfree
       safesysmalloc
       safesysrealloc
       save_I16
       save_I32
       save_I8
       save_adelete
       save_aelem
       save_aelem_flags
       save_alloc
       save_aptr
       save_ary
       save_bool
       save_clearsv
       save_delete
       save_destructor
       save_destructor_x
       save_freeop
       save_freepv
       save_freesv
       save_generic_pvref
       save_generic_svref
       save_gp
       save_hash
       save_hdelete
       save_helem
       save_helem_flags
       save_hints
       save_hptr
       save_int
       save_item
       save_iv
       save_list
       save_long
       save_mortalizesv
       save_nogv
       save_op
       save_padsv_and_mortalize
       save_pptr
       save_pushi32ptr
       save_pushptr
       save_pushptrptr
       save_re_context
       save_scalar
       save_set_svflags
       save_shared_pvref
       save_sptr
       save_svref
       save_vptr
       savestack_grow
       savestack_grow_cnt
       scan_num
       scan_vstring
       screaminstr
       seed
       set_context
       set_numeric_local
       set_numeric_radix
       set_numeric_standard
       share_hek
       si_dup
       ss_dup
       stack_grow
       start_subparse
       str_to_version
       sv_2iv
       sv_2pv
       sv_2uv
       sv_catpvf_mg_nocontext
       sv_catpvf_nocontext
       sv_dup
       sv_dup_inc
       sv_peek
       sv_pvn_nomg
       sv_setpvf_mg_nocontext
       sv_setpvf_nocontext
       swash_fetch
       swash_init
       sys_init
       sys_init3
       sys_intern_clear
       sys_intern_dup
       sys_intern_init
       sys_term
       taint_env
       taint_proper
       tmps_grow
       unlnk
       unsharepvn
       utf16_to_utf8
       utf16_to_utf8_reversed
       uvuni_to_utf8
       vdeb
       vform
       vload_module
       vnewSVpvf
       vwarner
       warn_nocontext
       warner
       warner_nocontext
       whichsig
       whichsig_pv
       whichsig_pvn
       whichsig_sv


AUTHORS

       Until May 1997, this document was maintained by Jeff Okamoto
       <okamoto@corp.hp.com>.  It is now maintained as part of Perl itself.

       With lots of help and suggestions from Dean Roehrich, Malcolm Beattie,
       Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil
       Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer,
       Stephen McCamant, and Gurusamy Sarathy.

       API Listing originally by Dean Roehrich <roehrich@cray.com>.

       Updated to be autogenerated from comments in the source by Benjamin
       Stuhl.


SEE ALSO

       perlguts(1), perlxs(1), perlxstut(1), perlintern(1)



perl v5.20.0                      2014-05-30                        perlapi(1)

perl 5.20.0 - Generated Fri May 30 16:42:54 CDT 2014