pcre2test(1) General Commands Manual pcre2test(1)
NAME
pcre2test - a program for testing Perl-compatible regular expressions.
SYNOPSIS
pcre2test [options] [input file [output file]]
pcre2test is a test program for the PCRE2 regular expression libraries,
but it can also be used for experimenting with regular expressions.
This document describes the features of the test program; for details
of the regular expressions themselves, see the pcre2pattern
documentation. For details of the PCRE2 library function calls and
their options, see the pcre2api documentation.
The input for pcre2test is a sequence of regular expression patterns
and subject strings to be matched. There are also command lines for
setting defaults and controlling some special actions. The output shows
the result of each match attempt. Modifiers on external or internal
command lines, the patterns, and the subject lines specify PCRE2
function options, control how the subject is processed, and what output
is produced.
There are many obscure modifiers, some of which are specifically
designed for use in conjunction with the test script and data files
that are distributed as part of PCRE2. All the modifiers are documented
here, some without much justification, but many of them are unlikely to
be of use except when testing the libraries.
PCRE2's 8-BIT, 16-BIT AND 32-BIT LIBRARIES
Different versions of the PCRE2 library can be built to support
character strings that are encoded in 8-bit, 16-bit, or 32-bit code
units. One, two, or all three of these libraries may be simultaneously
installed. The pcre2test program can be used to test all the libraries.
However, its own input and output are always in 8-bit format. When
testing the 16-bit or 32-bit libraries, patterns and subject strings
are converted to 16-bit or 32-bit format before being passed to the
library functions. Results are converted back to 8-bit code units for
output.
In the rest of this document, the names of library functions and
structures are given in generic form, for example, pcre2_compile(). The
actual names used in the libraries have a suffix _8, _16, or _32, as
appropriate.
INPUT ENCODING
Input to pcre2test is processed line by line, either by calling the C
library's fgets() function, or via the libreadline or libedit library.
In some Windows environments character 26 (hex 1A) causes an immediate
end of file, and no further data is read, so this character should be
avoided unless you really want that action.
The input is processed using C's string functions, so must not contain
binary zeros, even though in Unix-like environments, fgets() treats any
bytes other than newline as data characters. An error is generated if a
binary zero is encountered. By default subject lines are processed for
backslash escapes, which makes it possible to include any data value in
strings that are passed to the library for matching. For patterns,
there is a facility for specifying some or all of the 8-bit input
characters as hexadecimal pairs, which makes it possible to include
binary zeros.
Input for the 16-bit and 32-bit libraries
When testing the 16-bit or 32-bit libraries, there is a need to be able
to generate character code points greater than 255 in the strings that
are passed to the library. For subject lines and some patterns,
backslash escapes can be used. In addition, when the utf modifier (see
"Setting compilation options" below) is set, the pattern and any
following subject lines are interpreted as UTF-8 strings and translated
to UTF-16 or UTF-32 as appropriate.
For non-UTF testing of wide characters, the utf8_input modifier can be
used. This is mutually exclusive with utf, and is allowed only in
16-bit or 32-bit mode. It causes the pattern and following subject
lines to be treated as UTF-8 according to the original definition (RFC
2279), which allows for character values up to 0x7fffffff. Each
character is placed in one 16-bit or 32-bit code unit (in the 16-bit
case, values greater than 0xffff cause an error to occur).
UTF-8 (in its original definition) is not capable of encoding values
greater than 0x7fffffff, but such values can be handled by the 32-bit
library. When testing this library in non-UTF mode with utf8_input set,
if any character is preceded by the byte 0xff (which is an invalid byte
in UTF-8) 0x80000000 is added to the character's value. For subject
strings, using an escape sequence is preferable.
COMMAND LINE OPTIONS
-8 If the 8-bit library has been built, this option causes it to
be used (this is the default). If the 8-bit library has not
been built, this option causes an error.
-16 If the 16-bit library has been built, this option causes it
to be used. If the 8-bit library has not been built, this is
the default. If the 16-bit library has not been built, this
option causes an error.
-32 If the 32-bit library has been built, this option causes it
to be used. If no other library has been built, this is the
default. If the 32-bit library has not been built, this
option causes an error.
-ac Behave as if each pattern has the auto_callout modifier, that
is, insert automatic callouts into every pattern that is
compiled.
-AC As for -ac, but in addition behave as if each subject line
has the callout_extra modifier, that is, show additional
information from callouts.
-b Behave as if each pattern has the fullbincode modifier; the
full internal binary form of the pattern is output after
compilation.
-C Output the version number of the PCRE2 library, and all
available information about the optional features that are
included, and then exit with zero exit code. All other
options are ignored. If both -C and -LM are present,
whichever is first is recognized.
-C option Output information about a specific build-time option, then
exit. This functionality is intended for use in scripts such
as RunTest. The following options output the value and set
the exit code as indicated:
ebcdic-nl the code for LF (= NL) in an EBCDIC environment:
either 0x15 or 0x25
0 if used in an ASCII/Unicode environment
exit code is always 0
linksize the configured internal link size (2, 3, or 4)
exit code is set to the link size
newline the default newline setting:
CR, LF, CRLF, ANYCRLF, ANY, or NUL
exit code is always 0
bsr the default setting for what \R matches:
ANYCRLF or ANY
exit code is always 0
The following options output 1 for true or 0 for false, and
set the exit code to the same value:
backslash-C \C is supported (not locked out)
ebcdic compiled for an EBCDIC environment
jit just-in-time support is available
pcre2-16 the 16-bit library was built
pcre2-32 the 32-bit library was built
pcre2-8 the 8-bit library was built
unicode Unicode support is available
Note that the availability of JIT support in the library does
not guarantee that it can actually be used because in some
environments it is unable to allocate executable memory. The
option "jitusable" gives more detailed information. It
returns one of the following values:
0 JIT is available and usable
1 JIT is available but cannot allocate executable memory
2 JIT is not available
3 Unexpected return from test call to pcre2_jit_compile()
If an unknown option is given, an error message is output;
the exit code is 0.
-d Behave as if each pattern has the debug modifier; the
internal form and information about the compiled pattern is
output after compilation; -d is equivalent to -b -i.
-dfa Behave as if each subject line has the dfa modifier; matching
is done using the pcre2_dfa_match() function instead of the
default pcre2_match().
-error number[,number,...]
Call pcre2_get_error_message() for each of the error numbers
in the comma-separated list, display the resulting messages
on the standard output, then exit with zero exit code. The
numbers may be positive or negative. This is a convenience
facility for PCRE2 maintainers.
-help Output a brief summary these options and then exit.
-i Behave as if each pattern has the info modifier; information
about the compiled pattern is given after compilation.
-jit Behave as if each pattern line has the jit modifier; after
successful compilation, each pattern is passed to the just-
in-time compiler, if available.
-jitfast Behave as if each pattern line has the jitfast modifier;
after successful compilation, each pattern is passed to the
just-in-time compiler, if available, and each subject line is
passed directly to the JIT matcher via its "fast path".
-jitverify
Behave as if each pattern line has the jitverify modifier;
after successful compilation, each pattern is passed to the
just-in-time compiler, if available, and the use of JIT for
matching is verified.
-LM List modifiers: write a list of available pattern and subject
modifiers to the standard output, then exit with zero exit
code. All other options are ignored. If both -C and any -Lx
options are present, whichever is first is recognized.
-LP List properties: write a list of recognized Unicode
properties to the standard output, then exit with zero exit
code. All other options are ignored. If both -C and any -Lx
options are present, whichever is first is recognized.
-LS List scripts: write a list of recognized Unicode script names
to the standard output, then exit with zero exit code. All
other options are ignored. If both -C and any -Lx options are
present, whichever is first is recognized.
-pattern modifier-list
Behave as if each pattern line contains the given modifiers.
-q Do not output the version number of pcre2test at the start of
execution.
-S size On Unix-like systems, set the size of the run-time stack to
size mebibytes (units of 1024*1024 bytes).
-subject modifier-list
Behave as if each subject line contains the given modifiers.
-t Run each compile and match many times with a timer, and
output the resulting times per compile or match. When JIT is
used, separate times are given for the initial compile and
the JIT compile. You can control the number of iterations
that are used for timing by following -t with a number (as a
separate item on the command line). For example, "-t 1000"
iterates 1000 times. The default is to iterate 500,000 times.
-tm This is like -t except that it times only the matching phase,
not the compile phase.
-T -TM These behave like -t and -tm, but in addition, at the end of
a run, the total times for all compiles and matches are
output.
-version Output the PCRE2 version number and then exit.
DESCRIPTION
If pcre2test is given two filename arguments, it reads from the first
and writes to the second. If the first name is "-", input is taken from
the standard input. If pcre2test is given only one argument, it reads
from that file and writes to stdout. Otherwise, it reads from stdin and
writes to stdout.
When pcre2test is built, a configuration option can specify that it
should be linked with the libreadline or libedit library. When this is
done, if the input is from a terminal, it is read using the readline()
function. This provides line-editing and history facilities. The output
from the -help option states whether or not readline() will be used.
The program handles any number of tests, each of which consists of a
set of input lines. Each set starts with a regular expression pattern,
followed by any number of subject lines to be matched against that
pattern. In between sets of test data, command lines that begin with #
may appear. This file format, with some restrictions, can also be
processed by the perltest.sh script that is distributed with PCRE2 as a
means of checking that the behaviour of PCRE2 and Perl is the same. For
a specification of perltest.sh, see the comments near its beginning.
See also the #perltest command below.
When the input is a terminal, pcre2test prompts for each line of input,
using "re>" to prompt for regular expression patterns, and "data>" to
prompt for subject lines. Command lines starting with # can be entered
only in response to the "re>" prompt.
Each subject line is matched separately and independently. If you want
to do multi-line matches, you have to use the \n escape sequence (or \r
or \r\n, etc., depending on the newline setting) in a single line of
input to encode the newline sequences. There is no limit on the length
of subject lines; the input buffer is automatically extended if it is
too small. There are replication features that makes it possible to
generate long repetitive pattern or subject lines without having to
supply them explicitly.
An empty line or the end of the file signals the end of the subject
lines for a test, at which point a new pattern or command line is
expected if there is still input to be read.
COMMAND LINES
In between sets of test data, a line that begins with # is interpreted
as a command line. If the first character is followed by white space or
an exclamation mark, the line is treated as a comment, and ignored.
Otherwise, the following commands are recognized:
#forbid_utf
Subsequent patterns automatically have the PCRE2_NEVER_UTF and
PCRE2_NEVER_UCP options set, which locks out the use of the PCRE2_UTF
and PCRE2_UCP options and the use of (*UTF) and (*UCP) at the start of
patterns. This command also forces an error if a subsequent pattern
contains any occurrences of \P, \p, or \X, which are still supported
when PCRE2_UTF is not set, but which require Unicode property support
to be included in the library.
This is a trigger guard that is used in test files to ensure that UTF
or Unicode property tests are not accidentally added to files that are
used when Unicode support is not included in the library. Setting
PCRE2_NEVER_UTF and PCRE2_NEVER_UCP as a default can also be obtained
by the use of #pattern; the difference is that #forbid_utf cannot be
unset, and the automatic options are not displayed in pattern
information, to avoid cluttering up test output.
#load <filename>
This command is used to load a set of precompiled patterns from a file,
as described in the section entitled "Saving and restoring compiled
patterns" below.
#loadtables <filename>
This command is used to load a set of binary character tables that can
be accessed by the tables=3 qualifier. Such tables can be created by
the pcre2_dftables program with the -b option.
#newline_default [<newline-list>]
When PCRE2 is built, a default newline convention can be specified.
This determines which characters and/or character pairs are recognized
as indicating a newline in a pattern or subject string. The default can
be overridden when a pattern is compiled. The standard test files
contain tests of various newline conventions, but the majority of the
tests expect a single linefeed to be recognized as a newline by
default. Without special action the tests would fail when PCRE2 is
compiled with either CR or CRLF as the default newline.
The #newline_default command specifies a list of newline types that are
acceptable as the default. The types must be one of CR, LF, CRLF,
ANYCRLF, ANY, or NUL (in upper or lower case), for example:
#newline_default LF Any anyCRLF
If the default newline is in the list, this command has no effect.
Otherwise, except when testing the POSIX API, a newline modifier that
specifies the first newline convention in the list (LF in the above
example) is added to any pattern that does not already have a newline
modifier. If the newline list is empty, the feature is turned off. This
command is present in a number of the standard test input files.
When the POSIX API is being tested there is no way to override the
default newline convention, though it is possible to set the newline
convention from within the pattern. A warning is given if the posix or
posix_nosub modifier is used when #newline_default would set a default
for the non-POSIX API.
#pattern <modifier-list>
This command sets a default modifier list that applies to all
subsequent patterns. Modifiers on a pattern can change these settings.
#perltest
This line is used in test files that can also be processed by
perltest.sh to confirm that Perl gives the same results as PCRE2.
Subsequent tests are checked for the use of pcre2test features that are
incompatible with the perltest.sh script.
Patterns must use '/' as their delimiter, and only certain modifiers
are supported. Comment lines, #pattern commands, and #subject commands
that set or unset "mark" are recognized and acted on. The #perltest,
#forbid_utf, and #newline_default commands, which are needed in the
relevant pcre2test files, are silently ignored. All other command lines
are ignored, but give a warning message. The #perltest command helps
detect tests that are accidentally put in the wrong file or use the
wrong delimiter. For more details of the perltest.sh script see the
comments it contains.
#pop [<modifiers>]
#popcopy [<modifiers>]
These commands are used to manipulate the stack of compiled patterns,
as described in the section entitled "Saving and restoring compiled
patterns" below.
#save <filename>
This command is used to save a set of compiled patterns to a file, as
described in the section entitled "Saving and restoring compiled
patterns" below.
#subject <modifier-list>
This command sets a default modifier list that applies to all
subsequent subject lines. Modifiers on a subject line can change these
settings.
MODIFIER SYNTAX
Modifier lists are used with both pattern and subject lines. Items in a
list are separated by commas followed by optional white space. Trailing
whitespace in a modifier list is ignored. Some modifiers may be given
for both patterns and subject lines, whereas others are valid only for
one or the other. Each modifier has a long name, for example
"anchored", and some of them must be followed by an equals sign and a
value, for example, "offset=12". Values cannot contain comma
characters, but may contain spaces. Modifiers that do not take values
may be preceded by a minus sign to turn off a previous setting.
A few of the more common modifiers can also be specified as single
letters, for example "i" for "caseless". In documentation, following
the Perl convention, these are written with a slash ("the /i modifier")
for clarity. Abbreviated modifiers must all be concatenated in the
first item of a modifier list. If the first item is not recognized as a
long modifier name, it is interpreted as a sequence of these
abbreviations. For example:
/abc/ig,newline=cr,jit=3
This is a pattern line whose modifier list starts with two one-letter
modifiers (/i and /g). The lower-case abbreviated modifiers are the
same as used in Perl.
PATTERN SYNTAX
A pattern line must start with one of the following characters (common
symbols, excluding pattern meta-characters):
/ ! " ' ` - = _ : ; , % & @ ~
This is interpreted as the pattern's delimiter. A regular expression
may be continued over several input lines, in which case the newline
characters are included within it. It is possible to include the
delimiter as a literal within the pattern by escaping it with a
backslash, for example
/abc\/def/
If you do this, the escape and the delimiter form part of the pattern,
but since the delimiters are all non-alphanumeric, the inclusion of the
backslash does not affect the pattern's interpretation. Note, however,
that this trick does not work within \Q...\E literal bracketing because
the backslash will itself be interpreted as a literal. If the
terminating delimiter is immediately followed by a backslash, for
example,
/abc/\
a backslash is added to the end of the pattern. This is done to provide
a way of testing the error condition that arises if a pattern finishes
with a backslash, because
/abc\/
is interpreted as the first line of a pattern that starts with "abc/",
causing pcre2test to read the next line as a continuation of the
regular expression.
A pattern can be followed by a modifier list (details below).
SUBJECT LINE SYNTAX
Before each subject line is passed to pcre2_match(), pcre2_dfa_match(),
or pcre2_jit_match(), leading and trailing white space is removed, and
the line is scanned for backslash escapes, unless the subject_literal
modifier was set for the pattern. The following provide a means of
encoding non-printing characters in a visible way:
\a alarm (BEL, \x07)
\b backspace (\x08)
\e escape (\x27)
\f form feed (\x0c)
\n newline (\x0a)
\N{U+hh...} unicode character (any number of hex digits)
\r carriage return (\x0d)
\t tab (\x09)
\v vertical tab (\x0b)
\ddd octal number (up to 3 octal digits); represent a single
code point unless larger than 255 with the 8-bit
library
\o{dd...} octal number (any number of octal digits} representing a
character in UTF mode or a code point
\xhh hexadecimal byte (up to 2 hex digits)
\x{hh...} hexadecimal number (up to 8 hex digits) representing a
character in UTF mode or a code point
Invoking \N{U+hh...} or \x{hh...} doesn't require the use of the utf
modifier on the pattern. It is always recognized. There may be any
number of hexadecimal digits inside the braces; invalid values provoke
error messages but when using \N{U+hh...} with some invalid unicode
characters they will be accepted with a warning instead.
Note that even in UTF-8 mode, \xhh (and depending of how large, \ddd)
describe one byte rather than one character; this makes it possible to
construct invalid UTF-8 sequences for testing purposes. On the other
hand, \x{hh...} is interpreted as a UTF-8 character in UTF-8 mode, only
generating more than one byte if the value is greater than 127. To
avoid the ambiguity it is preferred to use \N{U+hh...} when describing
characters. When testing the 8-bit library not in UTF-8 mode, \x{hh}
generates one byte for values that could fit on it, and causes an error
for greater values.
When testing the 16-bit library, not in UTF-16 mode, all 4-digit
\x{hhhh} values are accepted. This makes it possible to construct
invalid UTF-16 sequences for testing purposes.
When testing the 32-bit library, not in UTF-32 mode, all 4 to 8-digit
\x{...} values are accepted. This makes it possible to construct
invalid UTF-32 sequences for testing purposes.
There is a special backslash sequence that specifies replication of one
or more characters:
\[<characters>]{<count>}
This makes it possible to test long strings without having to provide
them as part of the file. For example:
\[abc]{4}
is converted to "abcabcabcabc". This feature does not support nesting.
To include a closing square bracket in the characters, code it as \x5D.
A backslash followed by an equals sign marks the end of the subject
string and the start of a modifier list. For example:
abc\=notbol,notempty
If the subject string is empty and \= is followed by whitespace, the
line is treated as a comment line, and is not used for matching. For
example:
\= This is a comment.
abc\= This is an invalid modifier list.
A backslash followed by any other non-alphanumeric character just
escapes that character. A backslash followed by anything else causes an
error. However, if the very last character in the line is a backslash
(and there is no modifier list), it is ignored. This gives a way of
passing an empty line as data, since a real empty line terminates the
data input.
If the subject_literal modifier is set for a pattern, all subject lines
that follow are treated as literals, with no special treatment of
backslashes. No replication is possible, and any subject modifiers
must be set as defaults by a #subject command.
PATTERN MODIFIERS
There are several types of modifier that can appear in pattern lines.
Except where noted below, they may also be used in #pattern commands. A
pattern's modifier list can add to or override default modifiers that
were set by a previous #pattern command.
Setting compilation options
The following modifiers set options for pcre2_compile(). Most of them
set bits in the options argument of that function, but those whose
names start with PCRE2_EXTRA are additional options that are set in the
compile context. Some of these options have single-letter
abbreviations. There is special handling for /x: if a second x is
present, PCRE2_EXTENDED is converted into PCRE2_EXTENDED_MORE as in
Perl. A third appearance adds PCRE2_EXTENDED as well, though this makes
no difference to the way pcre2_compile() behaves. See pcre2api for a
description of the effects of these options.
allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS
allow_lookaround_bsk set PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK
allow_surrogate_escapes set PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
alt_bsux set PCRE2_ALT_BSUX
alt_circumflex set PCRE2_ALT_CIRCUMFLEX
alt_extended_class set PCRE2_ALT_EXTENDED_CLASS
alt_verbnames set PCRE2_ALT_VERBNAMES
anchored set PCRE2_ANCHORED
/a ascii_all set all ASCII options
ascii_bsd set PCRE2_EXTRA_ASCII_BSD
ascii_bss set PCRE2_EXTRA_ASCII_BSS
ascii_bsw set PCRE2_EXTRA_ASCII_BSW
ascii_digit set PCRE2_EXTRA_ASCII_DIGIT
ascii_posix set PCRE2_EXTRA_ASCII_POSIX
auto_callout set PCRE2_AUTO_CALLOUT
bad_escape_is_literal set PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
/i caseless set PCRE2_CASELESS
/r caseless_restrict set PCRE2_EXTRA_CASELESS_RESTRICT
dollar_endonly set PCRE2_DOLLAR_ENDONLY
/s dotall set PCRE2_DOTALL
dupnames set PCRE2_DUPNAMES
endanchored set PCRE2_ENDANCHORED
escaped_cr_is_lf set PCRE2_EXTRA_ESCAPED_CR_IS_LF
/x extended set PCRE2_EXTENDED
/xx extended_more set PCRE2_EXTENDED_MORE
extra_alt_bsux set PCRE2_EXTRA_ALT_BSUX
firstline set PCRE2_FIRSTLINE
literal set PCRE2_LITERAL
match_line set PCRE2_EXTRA_MATCH_LINE
match_invalid_utf set PCRE2_MATCH_INVALID_UTF
match_unset_backref set PCRE2_MATCH_UNSET_BACKREF
match_word set PCRE2_EXTRA_MATCH_WORD
/m multiline set PCRE2_MULTILINE
never_backslash_c set PCRE2_NEVER_BACKSLASH_C
never_callout set PCRE2_EXTRA_NEVER_CALLOUT
never_ucp set PCRE2_NEVER_UCP
never_utf set PCRE2_NEVER_UTF
/n no_auto_capture set PCRE2_NO_AUTO_CAPTURE
no_auto_possess set PCRE2_NO_AUTO_POSSESS
no_bs0 set PCRE2_EXTRA_NO_BS0
no_dotstar_anchor set PCRE2_NO_DOTSTAR_ANCHOR
no_start_optimize set PCRE2_NO_START_OPTIMIZE
no_utf_check set PCRE2_NO_UTF_CHECK
python_octal set PCRE2_EXTRA_PYTHON_OCTAL
turkish_casing set PCRE2_EXTRA_TURKISH_CASING
ucp set PCRE2_UCP
ungreedy set PCRE2_UNGREEDY
use_offset_limit set PCRE2_USE_OFFSET_LIMIT
utf set PCRE2_UTF
As well as turning on the PCRE2_UTF option, the utf modifier causes all
non-printing characters in output strings to be printed using the
\x{hh...} notation. Otherwise, those less than 0x100 are output in hex
without the curly brackets. Setting utf in 16-bit or 32-bit mode also
causes pattern and subject strings to be translated to UTF-16 or
UTF-32, respectively, before being passed to library functions.
The following modifiers enable or disable performance optimizations by
calling pcre2_set_optimize() before invoking the regex compiler.
optimization_full enable all optional optimizations
optimization_none disable all optional optimizations
auto_possess auto-possessify variable quantifiers
auto_possess_off don't auto-possessify variable quantifiers
dotstar_anchor anchor patterns starting with .*
dotstar_anchor_off don't anchor patterns starting with .*
start_optimize enable pre-scan of subject string
start_optimize_off disable pre-scan of subject string
See the pcre2_set_optimize documentation for details on these
optimizations.
Setting compilation controls
The following modifiers affect the compilation process or request
information about the pattern. There are single-letter abbreviations
for some that are heavily used in the test files.
/B bincode show binary code without lengths
bsr=[anycrlf|unicode] specify \R handling
callout_info show callout information
convert=<options> request foreign pattern conversion
convert_glob_escape=c set glob escape character
convert_glob_separator=c set glob separator character
convert_length set convert buffer length
debug same as info,fullbincode
expand expand repetition syntax in pattern
framesize show matching frame size
fullbincode show binary code with lengths
/I info show info about compiled pattern
hex unquoted characters are hexadecimal
jit[=<number>] use JIT
jitfast use JIT fast path
jitverify verify JIT use
locale=<name> use this locale
max_pattern_compiled ) set maximum compiled pattern
_length=<n> ) length (bytes)
max_pattern_length=<n> set maximum pattern length (code units)
max_varlookbehind=<n> set maximum variable lookbehind length
memory show memory used
newline=<type> set newline type
null_context compile with a NULL context
null_pattern pass pattern as NULL
parens_nest_limit=<n> set maximum parentheses depth
posix use the POSIX API
posix_nosub use the POSIX API with REG_NOSUB
push push compiled pattern onto the stack
pushcopy push a copy onto the stack
pushtablescopy push a copy with tables onto the stack
stackguard=<number> test the stackguard feature
subject_literal treat all subject lines as literal
tables=[0|1|2|3] select internal tables
use_length do not zero-terminate the pattern
utf8_input treat input as UTF-8
The effects of these modifiers are described in the following sections.
Newline and \R handling
The bsr modifier specifies what \R in a pattern should match. If it is
set to "anycrlf", \R matches CR, LF, or CRLF only. If it is set to
"unicode", \R matches any Unicode newline sequence. The default can be
specified when PCRE2 is built; if it is not, the default is set to
Unicode.
The newline modifier specifies which characters are to be interpreted
as newlines, both in the pattern and in subject lines. The type must be
one of CR, LF, CRLF, ANYCRLF, ANY, or NUL (in upper or lower case).
Information about a pattern
The debug modifier is a shorthand for info,fullbincode, requesting all
available information.
The bincode modifier causes a representation of the compiled code to be
output after compilation. This information does not contain length and
offset values, which ensures that the same output is generated for
different internal link sizes and different code unit widths. By using
bincode, the same regression tests can be used in different
environments.
The fullbincode modifier, by contrast, does include length and offset
values. This is used in a few special tests that run only for specific
code unit widths and link sizes, and is also useful for one-off tests.
The info modifier requests information about the compiled pattern
(whether it is anchored, has a fixed first character, and so on). The
information is obtained from the pcre2_pattern_info() function. Here
are some typical examples:
re> /(?i)(^a|^b)/m,info
Capture group count = 1
Compile options: multiline
Overall options: caseless multiline
First code unit at start or follows newline
Subject length lower bound = 1
re> /(?i)abc/info
Capture group count = 0
Compile options: <none>
Overall options: caseless
First code unit = 'a' (caseless)
Last code unit = 'c' (caseless)
Subject length lower bound = 3
"Compile options" are those specified by modifiers; "overall options"
have added options that are taken or deduced from the pattern. If both
sets of options are the same, just a single "options" line is output;
if there are no options, the line is omitted. "First code unit" is
where any match must start; if there is more than one they are listed
as "starting code units". "Last code unit" is the last literal code
unit that must be present in any match. This is not necessarily the
last character. These lines are omitted if no starting or ending code
units are recorded. The subject length line is omitted when
no_start_optimize is set because the minimum length is not calculated
when it can never be used.
The framesize modifier shows the size, in bytes, of each storage frame
used by pcre2_match() for handling backtracking. The size depends on
the number of capturing parentheses in the pattern. A vector of these
frames is used at matching time; its overall size is shown when the
heaframes_size subject modifier is set.
The callout_info modifier requests information about all the callouts
in the pattern. A list of them is output at the end of any other
information that is requested. For each callout, either its number or
string is given, followed by the item that follows it in the pattern.
Passing a NULL context
Normally, pcre2test passes a context block to pcre2_compile(). If the
null_context modifier is set, however, NULL is passed. This is for
testing that pcre2_compile() behaves correctly in this case (it uses
default values).
Passing a NULL pattern
The null_pattern modifier is for testing the behaviour of
pcre2_compile() when the pattern argument is NULL. The length value
passed is the default PCRE2_ZERO_TERMINATED unless use_length is set.
Any length other than zero causes an error.
Specifying pattern characters in hexadecimal
The hex modifier specifies that the characters of the pattern, except
for substrings enclosed in single or double quotes, are to be
interpreted as pairs of hexadecimal digits. This feature is provided as
a way of creating patterns that contain binary zeros and other non-
printing characters. White space is permitted between pairs of digits.
For example, this pattern contains three characters:
/ab 32 59/hex
Parts of such a pattern are taken literally if quoted. This pattern
contains nine characters, only two of which are specified in
hexadecimal:
/ab "literal" 32/hex
Either single or double quotes may be used. There is no way of
including the delimiter within a substring. The hex and expand
modifiers are mutually exclusive.
Specifying the pattern's length
By default, patterns are passed to the compiling functions as zero-
terminated strings but can be passed by length instead of being zero-
terminated. The use_length modifier causes this to happen. Using a
length happens automatically (whether or not use_length is set) when
hex is set, because patterns specified in hexadecimal may contain
binary zeros.
If hex or use_length is used with the POSIX wrapper API (see "Using the
POSIX wrapper API" below), the REG_PEND extension is used to pass the
pattern's length.
Specifying a maximum for variable lookbehinds
Variable lookbehind assertions are supported only if, for each one,
there is a maximum length (in characters) that it can match. There is a
limit on this, whose default can be set at build time, with an ultimate
default of 255. The max_varlookbehind modifier uses the
pcre2_set_max_varlookbehind() function to change the limit. Lookbehinds
whose branches each match a fixed length are limited to 65535
characters per branch.
Specifying wide characters in 16-bit and 32-bit modes
In 16-bit and 32-bit modes, all input is automatically treated as UTF-8
and translated to UTF-16 or UTF-32 when the utf modifier is set. For
testing the 16-bit and 32-bit libraries in non-UTF mode, the utf8_input
modifier can be used. It is mutually exclusive with utf. Input lines
are interpreted as UTF-8 as a means of specifying wide characters. More
details are given in "Input encoding" above.
Generating long repetitive patterns
Some tests use long patterns that are very repetitive. Instead of
creating a very long input line for such a pattern, you can use a
special repetition feature, similar to the one described for subject
lines above. If the expand modifier is present on a pattern, parts of
the pattern that have the form
\[<characters>]{<count>}
are expanded before the pattern is passed to pcre2_compile(). For
example, \[AB]{6000} is expanded to "ABAB..." 6000 times. This
construction cannot be nested. An initial "\[" sequence is recognized
only if "]{" followed by decimal digits and "}" is found later in the
pattern. If not, the characters remain in the pattern unaltered. The
expand and hex modifiers are mutually exclusive.
If part of an expanded pattern looks like an expansion, but is really
part of the actual pattern, unwanted expansion can be avoided by giving
two values in the quantifier. For example, \[AB]{6000,6000} is not
recognized as an expansion item.
If the info modifier is set on an expanded pattern, the result of the
expansion is included in the information that is output.
JIT compilation
Just-in-time (JIT) compiling is a heavyweight optimization that can
greatly speed up pattern matching. See the pcre2jit documentation for
details. JIT compiling happens, optionally, after a pattern has been
successfully compiled into an internal form. The JIT compiler converts
this to optimized machine code. It needs to know whether the match-time
options PCRE2_PARTIAL_HARD and PCRE2_PARTIAL_SOFT are going to be used,
because different code is generated for the different cases. See the
partial modifier in "Subject Modifiers" below for details of how these
options are specified for each match attempt.
JIT compilation is requested by the jit pattern modifier, which may
optionally be followed by an equals sign and a number in the range 0 to
7. The three bits that make up the number specify which of the three
JIT operating modes are to be compiled:
1 compile JIT code for non-partial matching
2 compile JIT code for soft partial matching
4 compile JIT code for hard partial matching
The possible values for the jit modifier are therefore:
0 disable JIT
1 normal matching only
2 soft partial matching only
3 normal and soft partial matching
4 hard partial matching only
6 soft and hard partial matching only
7 all three modes
If no number is given, 7 is assumed. The phrase "partial matching"
means a call to pcre2_match() with either the PCRE2_PARTIAL_SOFT or the
PCRE2_PARTIAL_HARD option set. Note that such a call may return a
complete match; the options enable the possibility of a partial match,
but do not require it. Note also that if you request JIT compilation
only for partial matching (for example, jit=2) but do not set the
partial modifier on a subject line, that match will not use JIT code
because none was compiled for non-partial matching.
If JIT compilation is successful, the compiled JIT code will
automatically be used when an appropriate type of match is run, except
when incompatible run-time options are specified. For more details, see
the pcre2jit documentation. See also the jitstack modifier below for a
way of setting the size of the JIT stack.
If the jitfast modifier is specified, matching is done using the JIT
"fast path" interface, pcre2_jit_match(), which skips some of the
sanity checks that are done by pcre2_match(), and of course does not
work when JIT is not supported. If jitfast is specified without jit,
jit=7 is assumed.
If the jitverify modifier is specified, information about the compiled
pattern shows whether JIT compilation was or was not successful. If
jitverify is specified without jit, jit=7 is assumed. If JIT
compilation is successful when jitverify is set, the text "(JIT)" is
added to the first output line after a match or non match when JIT-
compiled code was actually used in the match.
Setting a locale
The locale modifier must specify the name of a locale, for example:
/pattern/locale=fr_FR
The given locale is set, pcre2_maketables() is called to build a set of
character tables for the locale, and this is then passed to
pcre2_compile() when compiling the regular expression. The same tables
are used when matching the following subject lines. The locale modifier
applies only to the pattern on which it appears, but can be given in a
#pattern command if a default is needed. Setting a locale and alternate
character tables are mutually exclusive.
Showing pattern memory
The memory modifier causes the size in bytes of the memory used to hold
the compiled pattern to be output. This does not include the size of
the pcre2_code block; it is just the actual compiled data. If the
pattern is subsequently passed to the JIT compiler, the size of the JIT
compiled code is also output. Here is an example:
re> /a(b)c/jit,memory
Memory allocation (code space): 21
Memory allocation (JIT code): 1910
Limiting nested parentheses
The parens_nest_limit modifier sets a limit on the depth of nested
parentheses in a pattern. Breaching the limit causes a compilation
error. The default for the library is set when PCRE2 is built, but
pcre2test sets its own default of 220, which is required for running
the standard test suite.
Limiting the pattern length
The max_pattern_length modifier sets a limit, in code units, to the
length of pattern that pcre2_compile() will accept. Breaching the limit
causes a compilation error. The default is the largest number a
PCRE2_SIZE variable can hold (essentially unlimited).
Limiting the size of a compiled pattern
The max_pattern_compiled_length modifier sets a limit, in bytes, to the
amount of memory used by a compiled pattern. Breaching the limit causes
a compilation error. The default is the largest number a PCRE2_SIZE
variable can hold (essentially unlimited).
Using the POSIX wrapper API
The posix and posix_nosub modifiers cause pcre2test to call PCRE2 via
the POSIX wrapper API rather than its native API. When posix_nosub is
used, the POSIX option REG_NOSUB is passed to regcomp(). The POSIX
wrapper supports only the 8-bit library. Note that it does not imply
POSIX matching semantics; for more detail see the pcre2posix
documentation. The following pattern modifiers set options for the
regcomp() function:
caseless REG_ICASE
multiline REG_NEWLINE
dotall REG_DOTALL )
ungreedy REG_UNGREEDY ) These options are not part of
ucp REG_UCP ) the POSIX standard
utf REG_UTF8 )
The regerror_buffsize modifier specifies a size for the error buffer
that is passed to regerror() in the event of a compilation error. For
example:
/abc/posix,regerror_buffsize=20
This provides a means of testing the behaviour of regerror() when the
buffer is too small for the error message. If this modifier has not
been set, a large buffer is used.
The aftertext and allaftertext subject modifiers work as described
below. All other modifiers are either ignored, with a warning message,
or cause an error.
The pattern is passed to regcomp() as a zero-terminated string by
default, but if the use_length or hex modifiers are set, the REG_PEND
extension is used to pass it by length.
Testing the stack guard feature
The stackguard modifier is used to test the use of
pcre2_set_compile_recursion_guard(), a function that is provided to
enable stack availability to be checked during compilation (see the
pcre2api documentation for details). If the number specified by the
modifier is greater than zero, pcre2_set_compile_recursion_guard() is
called to set up callback from pcre2_compile() to a local function. The
argument it receives is the current nesting parenthesis depth; if this
is greater than the value given by the modifier, non-zero is returned,
causing the compilation to be aborted.
Using alternative character tables
The value specified for the tables modifier must be one of the digits
0, 1, 2, or 3. It causes a specific set of built-in character tables to
be passed to pcre2_compile(). This is used in the PCRE2 tests to check
behaviour with different character tables. The digit specifies the
tables as follows:
0 do not pass any special character tables
1 the default ASCII tables, as distributed in
pcre2_chartables.c.dist
2 a set of tables defining ISO 8859 characters
3 a set of tables loaded by the #loadtables command
In tables 2, some characters whose codes are greater than 128 are
identified as letters, digits, spaces, etc. Tables 3 can be used only
after a #loadtables command has loaded them from a binary file. Setting
alternate character tables and a locale are mutually exclusive.
Setting certain match controls
The following modifiers are really subject modifiers, and are described
under "Subject Modifiers" below. However, they may be included in a
pattern's modifier list, in which case they are applied to every
subject line that is processed with that pattern. These modifiers do
not affect the compilation process.
aftertext show text after match
allaftertext show text after captures
allcaptures show all captures
allvector show the entire ovector
allusedtext show all consulted text
altglobal alternative global matching
/g global global matching
heapframes_size show match data heapframes size
jitstack=<n> set size of JIT stack
mark show mark values
replace=<string> specify a replacement string
startchar show starting character when relevant
substitute_callout use substitution callouts
substitute_case_callout use substitution case callouts
substitute_extended use PCRE2_SUBSTITUTE_EXTENDED
substitute_literal use PCRE2_SUBSTITUTE_LITERAL
substitute_matched use PCRE2_SUBSTITUTE_MATCHED
substitute_overflow_length use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
substitute_replacement_only use PCRE2_SUBSTITUTE_REPLACEMENT_ONLY
substitute_skip=<n> skip substitution <n>
substitute_stop=<n> skip substitution <n> and following
substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY
These modifiers may not appear in a #pattern command. If you want them
as defaults, set them in a #subject command.
Specifying literal subject lines
If the subject_literal modifier is present on a pattern, all the
subject lines that it matches are taken as literal strings, with no
interpretation of backslashes. It is not possible to set subject
modifiers on such lines, but any that are set as defaults by a #subject
command are recognized.
Saving a compiled pattern
When a pattern with the push modifier is successfully compiled, it is
pushed onto a stack of compiled patterns, and pcre2test expects the
next line to contain a new pattern (or a command) instead of a subject
line. This facility is used when saving compiled patterns to a file, as
described in the section entitled "Saving and restoring compiled
patterns" below. If pushcopy is used instead of push, a copy of the
compiled pattern is stacked, leaving the original as current, ready to
match the following input lines. This provides a way of testing the
pcre2_code_copy() function. The push and pushcopy modifiers are
incompatible with compilation modifiers such as global that act at
match time. Any that are specified are ignored (for the stacked copy),
with a warning message, except for replace, which causes an error. Note
that jitverify, which is allowed, does not carry through to any
subsequent matching that uses a stacked pattern.
Testing foreign pattern conversion
The experimental foreign pattern conversion functions in PCRE2 can be
tested by setting the convert modifier. Its argument is a colon-
separated list of options, which set the equivalent option for the
pcre2_pattern_convert() function:
glob PCRE2_CONVERT_GLOB
glob_no_starstar PCRE2_CONVERT_GLOB_NO_STARSTAR
glob_no_wild_separator PCRE2_CONVERT_GLOB_NO_WILD_SEPARATOR
posix_basic PCRE2_CONVERT_POSIX_BASIC
posix_extended PCRE2_CONVERT_POSIX_EXTENDED
unset Unset all options
The "unset" value is useful for turning off a default that has been set
by a #pattern command. When one of these options is set, the input
pattern is passed to pcre2_pattern_convert(). If the conversion is
successful, the result is reflected in the output and then passed to
pcre2_compile(). The normal utf and no_utf_check options, if set, cause
the PCRE2_CONVERT_UTF and PCRE2_CONVERT_NO_UTF_CHECK options to be
passed to pcre2_pattern_convert().
By default, the conversion function is allowed to allocate a buffer for
its output. However, if the convert_length modifier is set to a value
greater than zero, pcre2test passes a buffer of the given length. This
makes it possible to test the length check.
The convert_glob_escape and convert_glob_separator modifiers can be
used to specify the escape and separator characters for glob
processing, overriding the defaults, which are operating-system
dependent.
SUBJECT MODIFIERS
The modifiers that can appear in subject lines and the #subject command
are of two types.
Setting match options
The following modifiers set options for pcre2_match() or
pcre2_dfa_match(). See pcre2api for a description of their effects.
anchored set PCRE2_ANCHORED
copy_matched_subject set PCRE2_COPY_MATCHED_SUBJECT
endanchored set PCRE2_ENDANCHORED
dfa_restart set PCRE2_DFA_RESTART
dfa_shortest set PCRE2_DFA_SHORTEST
disable_recurseloop_check set PCRE2_DISABLE_RECURSELOOP_CHECK
no_jit set PCRE2_NO_JIT
no_utf_check set PCRE2_NO_UTF_CHECK
notbol set PCRE2_NOTBOL
notempty set PCRE2_NOTEMPTY
notempty_atstart set PCRE2_NOTEMPTY_ATSTART
noteol set PCRE2_NOTEOL
partial_hard (or ph) set PCRE2_PARTIAL_HARD
partial_soft (or ps) set PCRE2_PARTIAL_SOFT
The partial matching modifiers are provided with abbreviations because
they appear frequently in tests.
If the posix or posix_nosub modifier was present on the pattern,
causing the POSIX wrapper API to be used, the only option-setting
modifiers that have any effect are notbol, notempty, and noteol,
causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively, to be
passed to regexec(). The other modifiers are ignored, with a warning
message.
There is one additional modifier that can be used with the POSIX
wrapper. It is ignored (with a warning) if used for non-POSIX matching.
posix_startend=<n>[:<m>]
This causes the subject string to be passed to regexec() using the
REG_STARTEND option, which uses offsets to specify which part of the
string is searched. If only one number is given, the end offset is
passed as the end of the subject string. For more detail of
REG_STARTEND, see the pcre2posix documentation. If the subject string
contains binary zeros (coded as escapes such as \x{00} because
pcre2test does not support actual binary zeros in its input), you must
use posix_startend to specify its length.
Setting match controls
The following modifiers affect the matching process or request
additional information. Some of them may also be specified on a pattern
line (see above), in which case they apply to every subject line that
is matched against that pattern, but can be overridden by modifiers on
the subject.
aftertext show text after match
allaftertext show text after captures
allcaptures show all captures
allusedtext show all consulted text (non-JIT only)
allvector show the entire ovector
altglobal alternative global matching
callout_capture show captures at callout time
callout_data=<n> set a value to pass via callouts
callout_error=<n>[:<m>] control callout error
callout_extra show extra callout information
callout_fail=<n>[:<m>] control callout failure
callout_no_where do not show position of a callout
callout_none do not supply a callout function
copy=<number or name> copy captured substring
depth_limit=<n> set a depth limit
dfa use pcre2_dfa_match()
find_limits find heap, match and depth limits
find_limits_noheap find match and depth limits
get=<number or name> extract captured substring
getall extract all captured substrings
/g global global matching
heapframes_size show match data heapframes size
heap_limit=<n> set a limit on heap memory (Kbytes)
jitstack=<n> set size of JIT stack
mark show mark values
match_limit=<n> set a match limit
memory show heap memory usage
null_context match with a NULL context
null_replacement substitute with NULL replacement
null_subject match with NULL subject
offset=<n> set starting offset
offset_limit=<n> set offset limit
ovector=<n> set size of output vector
recursion_limit=<n> obsolete synonym for depth_limit
replace=<string> specify a replacement string
startchar show startchar when relevant
startoffset=<n> same as offset=<n>
substitute_callout use substitution callouts
substitute_case_callout use substitution case callouts
substitute_extended use PCRE2_SUBSTITUTE_EXTENDED
substitute_literal use PCRE2_SUBSTITUTE_LITERAL
substitute_matched use PCRE2_SUBSTITUTE_MATCHED
substitute_overflow_length use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
substitute_replacement_only use PCRE2_SUBSTITUTE_REPLACEMENT_ONLY
substitute_skip=<n> skip substitution number n
substitute_stop=<n> skip substitution number n and greater
substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY
zero_terminate pass the subject as zero-terminated
The effects of these modifiers are described in the following sections.
When matching via the POSIX wrapper API, the aftertext, allaftertext,
and ovector subject modifiers work as described below. All other
modifiers are either ignored, with a warning message, or cause an
error.
Showing more text
The aftertext modifier requests that as well as outputting the part of
the subject string that matched the entire pattern, pcre2test should in
addition output the remainder of the subject string. This is useful for
tests where the subject contains multiple copies of the same substring.
The allaftertext modifier requests the same action for captured
substrings as well as the main matched substring. In each case the
remainder is output on the following line with a plus character
following the capture number.
The allusedtext modifier requests that all the text that was consulted
during a successful pattern match by the interpreter should be shown,
for both full and partial matches. This feature is not supported for
JIT matching, and if requested with JIT it is ignored (with a warning
message). Setting this modifier affects the output if there is a
lookbehind at the start of a match, or, for a complete match, a
lookahead at the end, or if \K is used in the pattern. Characters that
precede or follow the start and end of the actual match are indicated
in the output by '<' or '>' characters underneath them. Here is an
example:
re> /(?<=pqr)abc(?=xyz)/
data> 123pqrabcxyz456\=allusedtext
0: pqrabcxyz
<<< >>>
data> 123pqrabcxy\=ph,allusedtext
Partial match: pqrabcxy
<<<
The first, complete match shows that the matched string is "abc", with
the preceding and following strings "pqr" and "xyz" having been
consulted during the match (when processing the assertions). The
partial match can indicate only the preceding string.
The startchar modifier requests that the starting character for the
match be indicated, if it is different to the start of the matched
string. The only time when this occurs is when \K has been processed as
part of the match. In this situation, the output for the matched string
is displayed from the starting character instead of from the match
point, with circumflex characters under the earlier characters. For
example:
re> /abc\Kxyz/
data> abcxyz\=startchar
0: abcxyz
^^^
Unlike allusedtext, the startchar modifier can be used with JIT.
However, these two modifiers are mutually exclusive.
Showing the value of all capture groups
The allcaptures modifier requests that the values of all potential
captured parentheses be output after a match. By default, only those up
to the highest one actually used in the match are output (corresponding
to the return code from pcre2_match()). Groups that did not take part
in the match are output as "<unset>". This modifier is not relevant for
DFA matching (which does no capturing) and does not apply when replace
is specified; it is ignored, with a warning message, if present.
Showing the entire ovector, for all outcomes
The allvector modifier requests that the entire ovector be shown,
whatever the outcome of the match. Compare allcaptures, which shows
only up to the maximum number of capture groups for the pattern, and
then only for a successful complete non-DFA match. This modifier, which
acts after any match result, and also for DFA matching, provides a
means of checking that there are no unexpected modifications to ovector
fields. Before each match attempt, the ovector is filled with a special
value, and if this is found in both elements of a capturing pair,
"<unchanged>" is output. After a successful match, this applies to all
groups after the maximum capture group for the pattern. In other cases
it applies to the entire ovector. After a partial match, the first two
elements are the only ones that should be set. After a DFA match, the
amount of ovector that is used depends on the number of matches that
were found.
Testing pattern callouts
A callout function is supplied when pcre2test calls the library
matching functions, unless callout_none is specified. Its behaviour can
be controlled by various modifiers listed above whose names begin with
callout_. Details are given in the section entitled "Callouts" below.
Testing callouts from pcre2_substitute() is described separately in
"Testing the substitution function" below.
Finding all matches in a string
Searching for all possible matches within a subject can be requested by
the global or altglobal modifier. After finding a match, the matching
function is called again to search the remainder of the subject. The
difference between global and altglobal is that the former uses the
start_offset argument to pcre2_match() or pcre2_dfa_match() to start
searching at a new point within the entire string (which is what Perl
does), whereas the latter passes over a shortened subject. This makes a
difference to the matching process if the pattern begins with a
lookbehind assertion (including \b or \B).
If an empty string is matched, the next match is done with the
PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED flags set, in order to search
for another, non-empty, match at the same point in the subject. If this
match fails, the start offset is advanced, and the normal match is
retried. This imitates the way Perl handles such cases when using the
/g modifier or the split() function. Normally, the start offset is
advanced by one character, but if the newline convention recognizes
CRLF as a newline, and the current character is CR followed by LF, an
advance of two characters occurs.
Testing substring extraction functions
The copy and get modifiers can be used to test the
pcre2_substring_copy_xxx() and pcre2_substring_get_xxx() functions.
They can be given more than once, and each can specify a capture group
name or number, for example:
abcd\=copy=1,copy=3,get=G1
If the #subject command is used to set default copy and/or get lists,
these can be unset by specifying a negative number to cancel all
numbered groups and an empty name to cancel all named groups.
The getall modifier tests pcre2_substring_list_get(), which extracts
all captured substrings.
If the subject line is successfully matched, the substrings extracted
by the convenience functions are output with C, G, or L after the
string number instead of a colon. This is in addition to the normal
full list. The string length (that is, the return from the extraction
function) is given in parentheses after each substring, followed by the
name when the extraction was by name.
Testing the substitution function
If the replace modifier is set, the pcre2_substitute() function is
called instead of one of the matching functions (or after one call of
pcre2_match() in the case of PCRE2_SUBSTITUTE_MATCHED). Note that
replacement strings cannot contain commas, because a comma signifies
the end of a modifier. This is not thought to be an issue in a test
program.
Specifying a completely empty replacement string disables this
modifier. However, it is possible to specify an empty replacement by
providing a buffer length, as described below, for an otherwise empty
replacement.
Unlike subject strings, pcre2test does not process replacement strings
for escape sequences. In UTF mode, a replacement string is checked to
see if it is a valid UTF-8 string. If so, it is correctly converted to
a UTF string of the appropriate code unit width. If it is not a valid
UTF-8 string, the individual code units are copied directly. This
provides a means of passing an invalid UTF-8 string for testing
purposes.
The following modifiers set options (in additional to the normal match
options) for pcre2_substitute():
global PCRE2_SUBSTITUTE_GLOBAL
substitute_extended PCRE2_SUBSTITUTE_EXTENDED
substitute_literal PCRE2_SUBSTITUTE_LITERAL
substitute_matched PCRE2_SUBSTITUTE_MATCHED
substitute_overflow_length PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
substitute_replacement_only PCRE2_SUBSTITUTE_REPLACEMENT_ONLY
substitute_unknown_unset PCRE2_SUBSTITUTE_UNKNOWN_UNSET
substitute_unset_empty PCRE2_SUBSTITUTE_UNSET_EMPTY
See the pcre2api documentation for details of these options.
After a successful substitution, the modified string is output,
preceded by the number of replacements. This may be zero if there were
no matches. Here is a simple example of a substitution test:
/abc/replace=xxx
=abc=abc=
1: =xxx=abc=
=abc=abc=\=global
2: =xxx=xxx=
Subject and replacement strings should be kept relatively short (fewer
than 256 characters) for substitution tests, as fixed-size buffers are
used. To make it easy to test for buffer overflow, if the replacement
string starts with a number in square brackets, that number is passed
to pcre2_substitute() as the size of the output buffer, with the
replacement string starting at the next character. Here is an example
that tests the edge case:
/abc/
123abc123\=replace=[10]XYZ
1: 123XYZ123
123abc123\=replace=[9]XYZ
Failed: error -47: no more memory
The default action of pcre2_substitute() is to return
PCRE2_ERROR_NOMEMORY when the output buffer is too small. However, if
the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using the
substitute_overflow_length modifier), pcre2_substitute() continues to
go through the motions of matching and substituting (but not doing any
callouts), in order to compute the size of buffer that is required.
When this happens, pcre2test shows the required buffer length (which
includes space for the trailing zero) as part of the error message. For
example:
/abc/substitute_overflow_length
123abc123\=replace=[9]XYZ
Failed: error -47: no more memory: 10 code units are needed
A replacement string is ignored with POSIX and DFA matching. Specifying
partial matching provokes an error return ("bad option value") from
pcre2_substitute().
Testing substitute callouts
If the substitute_callout modifier is set, a substitution callout
function is set up. The null_context modifier must not be set, because
the address of the callout function is passed in a match context. When
the callout function is called (after each substitution), details of
the input and output strings are output. For example:
/abc/g,replace=<$0>,substitute_callout
abcdefabcpqr
1(1) Old 0 3 "abc" New 0 5 "<abc>"
2(1) Old 6 9 "abc" New 8 13 "<abc>"
2: <abc>def<abc>pqr
The first number on each callout line is the count of matches. The
parenthesized number is the number of pairs that are set in the ovector
(that is, one more than the number of capturing groups that were set).
Then are listed the offsets of the old substring, its contents, and the
same for the replacement.
By default, the substitution callout function returns zero, which
accepts the replacement and causes matching to continue if /g was used.
Two further modifiers can be used to test other return values. If
substitute_skip is set to a value greater than zero the callout
function returns +1 for the match of that number, and similarly
substitute_stop returns -1. These cause the replacement to be rejected,
and -1 causes no further matching to take place. If either of them are
set, substitute_callout is assumed. For example:
/abc/g,replace=<$0>,substitute_skip=1
abcdefabcpqr
1(1) Old 0 3 "abc" New 0 5 "<abc> SKIPPED"
2(1) Old 6 9 "abc" New 6 11 "<abc>"
2: abcdef<abc>pqr
abcdefabcpqr\=substitute_stop=1
1(1) Old 0 3 "abc" New 0 5 "<abc> STOPPED"
1: abcdefabcpqr
If both are set for the same number, stop takes precedence. Only a
single skip or stop is supported, which is sufficient for testing that
the feature works.
Testing substitute case callouts
If the substitute_case_callout modifier is set, a substitution case
callout function is set up. The callout function is called for each
substituted chunk which is to be case-transformed.
The callout function passed is a fixed function with implementation for
certain behaviours: inputs which shrink when case-transformed; inputs
which grow; inputs with distinct upper/lower/titlecase forms. The
characters which are not special-cased for testing purposes are left
unmodified, as if they are caseless characters.
Setting the JIT stack size
The jitstack modifier provides a way of setting the maximum stack size
that is used by the just-in-time optimization code. It is ignored if
JIT optimization is not being used. The value is a number of kibibytes
(units of 1024 bytes). Setting zero reverts to the default of 32KiB.
Providing a stack that is larger than the default is necessary only for
very complicated patterns. If jitstack is set non-zero on a subject
line it overrides any value that was set on the pattern.
Setting heap, match, and depth limits
The heap_limit, match_limit, and depth_limit modifiers set the
appropriate limits in the match context. These values are ignored when
the find_limits or find_limits_noheap modifier is specified.
Finding minimum limits
If the find_limits modifier is present on a subject line, pcre2test
calls the relevant matching function several times, setting different
values in the match context via pcre2_set_heap_limit(),
pcre2_set_match_limit(), or pcre2_set_depth_limit() until it finds the
smallest value for each parameter that allows the match to complete
without a "limit exceeded" error. The match itself may succeed or fail.
An alternative modifier, find_limits_noheap, omits the heap limit. This
is used in the standard tests, because the minimum heap limit varies
between systems. If JIT is being used, only the match limit is
relevant, and the other two are automatically omitted.
When using this modifier, the pattern should not contain any limit
settings such as (*LIMIT_MATCH=...) within it. If such a setting is
present and is lower than the minimum matching value, the minimum value
cannot be found because pcre2_set_match_limit() etc. are only able to
reduce the value of an in-pattern limit; they cannot increase it.
For non-DFA matching, the minimum depth_limit number is a measure of
how much nested backtracking happens (that is, how deeply the pattern's
tree is searched). In the case of DFA matching, depth_limit controls
the depth of recursive calls of the internal function that is used for
handling pattern recursion, lookaround assertions, and atomic groups.
For non-DFA matching, the match_limit number is a measure of the amount
of backtracking that takes place, and learning the minimum value can be
instructive. For most simple matches, the number is quite small, but
for patterns with very large numbers of matching possibilities, it can
become large very quickly with increasing length of subject string. In
the case of DFA matching, match_limit controls the total number of
calls, both recursive and non-recursive, to the internal matching
function, thus controlling the overall amount of computing resource
that is used.
For both kinds of matching, the heap_limit number, which is in
kibibytes (units of 1024 bytes), limits the amount of heap memory used
for matching.
Showing MARK names
The mark modifier causes the names from backtracking control verbs that
are returned from calls to pcre2_match() to be displayed. If a mark is
returned for a match, non-match, or partial match, pcre2test shows it.
For a match, it is on a line by itself, tagged with "MK:". Otherwise,
it is added to the non-match message.
Showing memory usage
The memory modifier causes pcre2test to log the sizes of all heap
memory allocation and freeing calls that occur during a call to
pcre2_match() or pcre2_dfa_match(). In the latter case, heap memory is
used only when a match requires more internal workspace that the
default allocation on the stack, so in many cases there will be no
output. No heap memory is allocated during matching with JIT. For this
modifier to work, the null_context modifier must not be set on both the
pattern and the subject, though it can be set on one or the other.
Showing the heap frame overall vector size
The heapframes_size modifier is relevant for matches using
pcre2_match() without JIT. After a match has run (whether successful or
not) the size, in bytes, of the allocated heap frames vector that is
left attached to the match data block is shown. If the matching action
involved several calls to pcre2_match() (for example, global matching
or for timing) only the final value is shown.
This modifier is ignored, with a warning, for POSIX or DFA matching.
JIT matching does not use the heap frames vector, so the size is always
zero, unless there was a previous non-JIT match. Note that specifing a
size of zero for the output vector (see below) causes pcre2test to free
its match data block (and associated heap frames vector) and allocate a
new one.
Setting a starting offset
The offset modifier sets an offset in the subject string at which
matching starts. Its value is a number of code units, not characters.
Setting an offset limit
The offset_limit modifier sets a limit for unanchored matches. If a
match cannot be found starting at or before this offset in the subject,
a "no match" return is given. The data value is a number of code units,
not characters. When this modifier is used, the use_offset_limit
modifier must have been set for the pattern; if not, an error is
generated.
Setting the size of the output vector
The ovector modifier applies only to the subject line in which it
appears, though of course it can also be used to set a default in a
#subject command. It specifies the number of pairs of offsets that are
available for storing matching information. The default is 15.
A value of zero is useful when testing the POSIX API because it causes
regexec() to be called with a NULL capture vector. When not testing the
POSIX API, a value of zero is used to cause
pcre2_match_data_create_from_pattern() to be called, in order to create
a new match block of exactly the right size for the pattern. (It is not
possible to create a match block with a zero-length ovector; there is
always at least one pair of offsets.) The old match data block is
freed.
Passing the subject as zero-terminated
By default, the subject string is passed to a native API matching
function with its correct length. In order to test the facility for
passing a zero-terminated string, the zero_terminate modifier is
provided. It causes the length to be passed as PCRE2_ZERO_TERMINATED.
When matching via the POSIX interface, this modifier is ignored, with a
warning.
When testing pcre2_substitute(), this modifier also has the effect of
passing the replacement string as zero-terminated.
Passing a NULL context, subject, or replacement
Normally, pcre2test passes a context block to pcre2_match(),
pcre2_dfa_match(), pcre2_jit_match() or pcre2_substitute(). If the
null_context modifier is set, however, NULL is passed. This is for
testing that the matching and substitution functions behave correctly
in this case (they use default values). This modifier cannot be used
with the find_limits, find_limits_noheap, or substitute_callout
modifiers.
Similarly, for testing purposes, if the null_subject or
null_replacement modifier is set, the subject or replacement string
pointers are passed as NULL, respectively, to the relevant functions.
THE ALTERNATIVE MATCHING FUNCTION
By default, pcre2test uses the standard PCRE2 matching function,
pcre2_match() to match each subject line. PCRE2 also supports an
alternative matching function, pcre2_dfa_match(), which operates in a
different way, and has some restrictions. The differences between the
two functions are described in the pcre2matching documentation.
If the dfa modifier is set, the alternative matching function is used.
This function finds all possible matches at a given point in the
subject. If, however, the dfa_shortest modifier is set, processing
stops after the first match is found. This is always the shortest
possible match.
DEFAULT OUTPUT FROM pcre2test
This section describes the output when the normal matching function,
pcre2_match(), is being used.
When a match succeeds, pcre2test outputs the list of captured
substrings, starting with number 0 for the string that matched the
whole pattern. Otherwise, it outputs "No match" when the return is
PCRE2_ERROR_NOMATCH, or "Partial match:" followed by the partially
matching substring when the return is PCRE2_ERROR_PARTIAL. (Note that
this is the entire substring that was inspected during the partial
match; it may include characters before the actual match start if a
lookbehind assertion, \K, \b, or \B was involved.)
For any other return, pcre2test outputs the PCRE2 negative error number
and a short descriptive phrase. If the error is a failed UTF string
check, the code unit offset of the start of the failing character is
also output. Here is an example of an interactive pcre2test run.
$ pcre2test
PCRE2 version 10.22 2016-07-29
re> /^abc(\d+)/
data> abc123
0: abc123
1: 123
data> xyz
No match
Unset capturing substrings that are not followed by one that is set are
not shown by pcre2test unless the allcaptures modifier is specified. In
the following example, there are two capturing substrings, but when the
first data line is matched, the second, unset substring is not shown.
An "internal" unset substring is shown as "<unset>", as for the second
data line.
re> /(a)|(b)/
data> a
0: a
1: a
data> b
0: b
1: <unset>
2: b
If the strings contain any non-printing characters, they are output as
\xhh escapes if the value is less than 256 and UTF mode is not set.
Otherwise they are output as \x{hh...} escapes. See below for the
definition of non-printing characters. If the aftertext modifier is
set, the output for substring 0 is followed by the rest of the subject
string, identified by "0+" like this:
re> /cat/aftertext
data> cataract
0: cat
0+ aract
If global matching is requested, the results of successive matching
attempts are output in sequence, like this:
re> /\Bi(\w\w)/g
data> Mississippi
0: iss
1: ss
0: iss
1: ss
0: ipp
1: pp
"No match" is output only if the first match attempt fails. Here is an
example of a failure message (the offset 4 that is specified by the
offset modifier is past the end of the subject string):
re> /xyz/
data> xyz\=offset=4
Error -24 (bad offset value)
Note that whereas patterns can be continued over several lines (a plain
">" prompt is used for continuations), subject lines may not. However
newlines can be included in a subject by means of the \n escape (or \r,
\r\n, etc., depending on the newline sequence setting).
OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
When the alternative matching function, pcre2_dfa_match(), is used, the
output consists of a list of all the matches that start at the first
point in the subject where there is at least one match. For example:
re> /(tang|tangerine|tan)/
data> yellow tangerine\=dfa
0: tangerine
1: tang
2: tan
Using the normal matching function on this data finds only "tang". The
longest matching string is always given first (and numbered zero).
After a PCRE2_ERROR_PARTIAL return, the output is "Partial match:",
followed by the partially matching substring. Note that this is the
entire substring that was inspected during the partial match; it may
include characters before the actual match start if a lookbehind
assertion, \b, or \B was involved. (\K is not supported for DFA
matching.)
If global matching is requested, the search for further matches resumes
at the end of the longest match. For example:
re> /(tang|tangerine|tan)/g
data> yellow tangerine and tangy sultana\=dfa
0: tangerine
1: tang
2: tan
0: tang
1: tan
0: tan
The alternative matching function does not support substring capture,
so the modifiers that are concerned with captured substrings are not
relevant.
RESTARTING AFTER A PARTIAL MATCH
When the alternative matching function has given the
PCRE2_ERROR_PARTIAL return, indicating that the subject partially
matched the pattern, you can restart the match with additional subject
data by means of the dfa_restart modifier. For example:
re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
data> 23ja\=ps,dfa
Partial match: 23ja
data> n05\=dfa,dfa_restart
0: n05
For further information about partial matching, see the pcre2partial
documentation.
CALLOUTS
If the pattern contains any callout requests, pcre2test's callout
function is called during matching unless callout_none is specified.
This works with both matching functions, and with JIT, though there are
some differences in behaviour. The output for callouts with numerical
arguments and those with string arguments is slightly different.
Callouts with numerical arguments
By default, the callout function displays the callout number, the start
and current positions in the subject text at the callout time, and the
next pattern item to be tested. For example:
--->pqrabcdef
0 ^ ^ \d
This output indicates that callout number 0 occurred for a match
attempt starting at the fourth character of the subject string, when
the pointer was at the seventh character, and when the next pattern
item was \d. Just one circumflex is output if the start and current
positions are the same, or if the current position precedes the start
position, which can happen if the callout is in a lookbehind assertion.
Callouts numbered 255 are assumed to be automatic callouts, inserted as
a result of the auto_callout pattern modifier. In this case, instead of
showing the callout number, the offset in the pattern, preceded by a
plus, is output. For example:
re> /\d?[A-E]\*/auto_callout
data> E*
--->E*
+0 ^ \d?
+3 ^ [A-E]
+8 ^^ \*
+10 ^ ^
0: E*
If a pattern contains (*MARK) items, an additional line is output
whenever a change of latest mark is passed to the callout function. For
example:
re> /a(*MARK:X)bc/auto_callout
data> abc
--->abc
+0 ^ a
+1 ^^ (*MARK:X)
+10 ^^ b
Latest Mark: X
+11 ^ ^ c
+12 ^ ^
0: abc
The mark changes between matching "a" and "b", but stays the same for
the rest of the match, so nothing more is output. If, as a result of
backtracking, the mark reverts to being unset, the text "<unset>" is
output.
Callouts with string arguments
The output for a callout with a string argument is similar, except that
instead of outputting a callout number before the position indicators,
the callout string and its offset in the pattern string are output
before the reflection of the subject string, and the subject string is
reflected for each callout. For example:
re> /^ab(?C'first')cd(?C"second")ef/
data> abcdefg
Callout (7): 'first'
--->abcdefg
^ ^ c
Callout (20): "second"
--->abcdefg
^ ^ e
0: abcdef
Callout modifiers
The callout function in pcre2test returns zero (carry on matching) by
default, but you can use a callout_fail modifier in a subject line to
change this and other parameters of the callout (see below).
If the callout_capture modifier is set, the current captured groups are
output when a callout occurs. This is useful only for non-DFA matching,
as pcre2_dfa_match() does not support capturing, so no captures are
ever shown.
The normal callout output, showing the callout number or pattern offset
(as described above) is suppressed if the callout_no_where modifier is
set.
When using the interpretive matching function pcre2_match() without
JIT, setting the callout_extra modifier causes additional output from
pcre2test's callout function to be generated. For the first callout in
a match attempt at a new starting position in the subject, "New match
attempt" is output. If there has been a backtrack since the last
callout (or start of matching if this is the first callout),
"Backtrack" is output, followed by "No other matching paths" if the
backtrack ended the previous match attempt. For example:
re> /(a+)b/auto_callout,no_start_optimize,no_auto_possess
data> aac\=callout_extra
New match attempt
--->aac
+0 ^ (
+1 ^ a+
+3 ^ ^ )
+4 ^ ^ b
Backtrack
--->aac
+3 ^^ )
+4 ^^ b
Backtrack
No other matching paths
New match attempt
--->aac
+0 ^ (
+1 ^ a+
+3 ^^ )
+4 ^^ b
Backtrack
No other matching paths
New match attempt
--->aac
+0 ^ (
+1 ^ a+
Backtrack
No other matching paths
New match attempt
--->aac
+0 ^ (
+1 ^ a+
No match
Notice that various optimizations must be turned off if you want all
possible matching paths to be scanned. If no_start_optimize is not
used, there is an immediate "no match", without any callouts, because
the starting optimization fails to find "b" in the subject, which it
knows must be present for any match. If no_auto_possess is not used,
the "a+" item is turned into "a++", which reduces the number of
backtracks.
The callout_extra modifier has no effect if used with the DFA matching
function, or with JIT.
Return values from callouts
The default return from the callout function is zero, which allows
matching to continue. The callout_fail modifier can be given one or two
numbers. If there is only one number, 1 is returned instead of 0
(causing matching to backtrack) when a callout of that number is
reached. If two numbers (<n>:<m>) are given, 1 is returned when callout
<n> is reached and there have been at least <m> callouts. The
callout_error modifier is similar, except that PCRE2_ERROR_CALLOUT is
returned, causing the entire matching process to be aborted. If both
these modifiers are set for the same callout number, callout_error
takes precedence. Note that callouts with string arguments are always
given the number zero.
The callout_data modifier can be given an unsigned or a negative
number. This is set as the "user data" that is passed to the matching
function, and passed back when the callout function is invoked. Any
value other than zero is used as a return from pcre2test's callout
function.
Inserting callouts can be helpful when using pcre2test to check
complicated regular expressions. For further information about
callouts, see the pcre2callout documentation.
NON-PRINTING CHARACTERS
When pcre2test is outputting text in the compiled version of a pattern,
bytes other than 32-126 are always treated as non-printing characters
and are therefore shown as hex escapes.
When pcre2test is outputting text that is a matched part of a subject
string, it behaves in the same way, unless a different locale has been
set for the pattern (using the locale modifier). In this case, the
isprint() function is used to distinguish printing and non-printing
characters.
SAVING AND RESTORING COMPILED PATTERNS
It is possible to save compiled patterns on disc or elsewhere, and
reload them later, subject to a number of restrictions. JIT data cannot
be saved. The host on which the patterns are reloaded must be running
the same version of PCRE2, with the same code unit width, and must also
have the same endianness, pointer width and PCRE2_SIZE type. Before
compiled patterns can be saved they must be serialized, that is,
converted to a stream of bytes. A single byte stream may contain any
number of compiled patterns, but they must all use the same character
tables. A single copy of the tables is included in the byte stream (its
size is 1088 bytes).
The functions whose names begin with pcre2_serialize_ are used for
serializing and de-serializing. They are described in the
pcre2serialize documentation. In this section we describe the features
of pcre2test that can be used to test these functions.
Note that "serialization" in PCRE2 does not convert compiled patterns
to an abstract format like Java or .NET. It just makes a reloadable
byte code stream. Hence the restrictions on reloading mentioned above.
In pcre2test, when a pattern with push modifier is successfully
compiled, it is pushed onto a stack of compiled patterns, and pcre2test
expects the next line to contain a new pattern (or command) instead of
a subject line. By contrast, the pushcopy modifier causes a copy of the
compiled pattern to be stacked, leaving the original available for
immediate matching. By using push and/or pushcopy, a number of patterns
can be compiled and retained. These modifiers are incompatible with
posix, and control modifiers that act at match time are ignored (with a
message) for the stacked patterns. The jitverify modifier applies only
at compile time.
The command
#save <filename>
causes all the stacked patterns to be serialized and the result written
to the named file. Afterwards, all the stacked patterns are freed. The
command
#load <filename>
reads the data in the file, and then arranges for it to be de-
serialized, with the resulting compiled patterns added to the pattern
stack. The pattern on the top of the stack can be retrieved by the #pop
command, which must be followed by lines of subjects that are to be
matched with the pattern, terminated as usual by an empty line or end
of file. This command may be followed by a modifier list containing
only control modifiers that act after a pattern has been compiled. In
particular, hex, posix, posix_nosub, push, and pushcopy are not
allowed, nor are any option-setting modifiers. The JIT modifiers are,
however permitted. Here is an example that saves and reloads two
patterns.
/abc/push
/xyz/push
#save tempfile
#load tempfile
#pop info
xyz
#pop jit,bincode
abc
If jitverify is used with #pop, it does not automatically imply jit,
which is different behaviour from when it is used on a pattern.
The #popcopy command is analogous to the pushcopy modifier in that it
makes current a copy of the topmost stack pattern, leaving the original
still on the stack.
SEE ALSO
pcre2(3), pcre2api(3), pcre2callout(3), pcre2jit, pcre2matching(3),
pcre2partial(d), pcre2pattern(3), pcre2serialize(3).
AUTHOR
Philip Hazel
Retired from University Computing Service
Cambridge, England.
REVISION
Last updated: 26 December 2024
Copyright (c) 1997-2024 University of Cambridge.
PCRE2 10.45 26 December 2024 pcre2test(1)
pcre2 10.45 - Generated Tue Feb 25 13:17:06 CST 2025