Tcl_RegExpMatch(3) Tcl Library Procedures Tcl_RegExpMatch(3)
NAME
Tcl_RegExpMatch, Tcl_RegExpCompile, Tcl_RegExpExec, Tcl_RegExpRange,
Tcl_GetRegExpFromObj, Tcl_RegExpMatchObj, Tcl_RegExpExecObj, Tcl_Reg-
ExpGetInfo - Pattern matching with regular expressions
SYNOPSIS
#include <tcl.h>
int
Tcl_RegExpMatchObj(interp, textObj, patObj)
int
Tcl_RegExpMatch(interp, text, pattern)
Tcl_RegExp
Tcl_RegExpCompile(interp, pattern)
int
Tcl_RegExpExec(interp, regexp, text, start)
void
Tcl_RegExpRange(regexp, index, startPtr, endPtr)
Tcl_RegExp
Tcl_GetRegExpFromObj(interp, patObj, cflags)
int
Tcl_RegExpExecObj(interp, regexp, textObj, offset, nmatches, eflags)
void
Tcl_RegExpGetInfo(regexp, infoPtr)
ARGUMENTS
Tcl interpreter to use for error reporting. The interpreter may be
NULL if no error reporting is desired. Refers to the object from which
to get the text to search. The internal representation of the object
may be converted to a form that can be efficiently searched. Refers to
the object from which to get a regular expression. The compiled regular
expression is cached in the object. Text to search for a match with a
regular expression. String in the form of a regular expression pat-
tern. Compiled regular expression. Must have been returned previously
by Tcl_GetRegExpFromObj or Tcl_RegExpCompile. If text is just a por-
tion of some other string, this argument identifies the beginning of
the larger string. If it is not the same as text, then no matches will
be allowed. Specifies which range is desired: 0 means the range of
the entire match, 1 or greater means the range that matched a parenthe-
sized sub-expression. The address of the first character in the range
is stored here, or NULL if there is no such range. The address of the
character just after the last one in the range is stored here, or NULL
if there is no such range. OR-ed combination of the compilation flags
TCL_REG_ADVANCED, TCL_REG_EXTENDED, TCL_REG_BASIC, TCL_REG_EXPANDED,
TCL_REG_QUOTE, TCL_REG_NOCASE, TCL_REG_NEWLINE, TCL_REG_NLSTOP,
TCL_REG_NLANCH, TCL_REG_NOSUB, and TCL_REG_CANMATCH. See below for more
information. The character offset into the text where matching should
begin. The value of the offset has no impact on ^ matches. This
behavior is controlled by eflags. The number of matching subexpres-
sions that should be remembered for later use. If this value is 0,
then no subexpression match information will be computed. If the value
is -1, then all of the matching subexpressions will be remembered. Any
other value will be taken as the maximum number of subexpressions to
remember. OR-ed combination of the execution flags TCL_REG_NOTBOL and
TCL_REG_NOTEOL. See below for more information. The address of the
location where information about a previous match should be stored by
Tcl_RegExpGetInfo.
DESCRIPTION
Tcl_RegExpMatch determines whether its pattern argument matches regexp,
where regexp is interpreted as a regular expression using the rules in
the re_syntax reference page. If there is a match then Tcl_RegExpMatch
returns 1. If there is no match then Tcl_RegExpMatch returns 0. If an
error occurs in the matching process (e.g. pattern is not a valid regu-
lar expression) then Tcl_RegExpMatch returns -1 and leaves an error
message in the interpreter result. Tcl_RegExpMatchObj is similar to
Tcl_RegExpMatch except it operates on the Tcl objects textObj and
patObj instead of UTF strings. Tcl_RegExpMatchObj is generally more
efficient than Tcl_RegExpMatch, so it is the preferred interface.
Tcl_RegExpCompile, Tcl_RegExpExec, and Tcl_RegExpRange provide lower-
level access to the regular expression pattern matcher. Tcl_RegExpCom-
pile compiles a regular expression string into the internal form used
for efficient pattern matching. The return value is a token for this
compiled form, which can be used in subsequent calls to Tcl_RegExpExec
or Tcl_RegExpRange. If an error occurs while compiling the regular
expression then Tcl_RegExpCompile returns NULL and leaves an error mes-
sage in the interpreter result. Note: the return value from Tcl_Reg-
ExpCompile is only valid up to the next call to Tcl_RegExpCompile; it
is not safe to retain these values for long periods of time.
Tcl_RegExpExec executes the regular expression pattern matcher. It
returns 1 if text contains a range of characters that match regexp, 0
if no match is found, and -1 if an error occurs. In the case of an
error, Tcl_RegExpExec leaves an error message in the interpreter
result. When searching a string for multiple matches of a pattern, it
is important to distinguish between the start of the original string
and the start of the current search. For example, when searching for
the second occurrence of a match, the text argument might point to the
character just after the first match; however, it is important for the
pattern matcher to know that this is not the start of the entire
string, so that it does not allow atoms in the pattern to match. The
start argument provides this information by pointing to the start of
the overall string containing text. Start will be less than or equal
to text; if it is less than text then no ^ matches will be allowed.
Tcl_RegExpRange may be invoked after Tcl_RegExpExec returns; it pro-
vides detailed information about what ranges of the string matched what
parts of the pattern. Tcl_RegExpRange returns a pair of pointers in
*startPtr and *endPtr that identify a range of characters in the source
string for the most recent call to Tcl_RegExpExec. Index indicates
which of several ranges is desired: if index is 0, information is
returned about the overall range of characters that matched the entire
pattern; otherwise, information is returned about the range of charac-
ters that matched the index'th parenthesized subexpression within the
pattern. If there is no range corresponding to index then NULL is
stored in *startPtr and *endPtr.
Tcl_GetRegExpFromObj, Tcl_RegExpExecObj, and Tcl_RegExpGetInfo are
object interfaces that provide the most direct control of Henry
Spencer's regular expression library. For users that need to modify
compilation and execution options directly, it is recommended that you
use these interfaces instead of calling the internal regexp functions.
These interfaces handle the details of UTF to Unicode translations as
well as providing improved performance through caching in the pattern
and string objects.
Tcl_GetRegExpFromObj attempts to return a compiled regular expression
from the patObj. If the object does not already contain a compiled
regular expression it will attempt to create one from the string in the
object and assign it to the internal representation of the patObj. The
return value of this function is of type Tcl_RegExp. The return value
is a token for this compiled form, which can be used in subsequent
calls to Tcl_RegExpExecObj or Tcl_RegExpGetInfo. If an error occurs
while compiling the regular expression then Tcl_GetRegExpFromObj
returns NULL and leaves an error message in the interpreter result.
The regular expression token can be used as long as the internal repre-
sentation of patObj refers to the compiled form. The cflags argument
is a bit-wise OR of zero or more of the following flags that control
the compilation of patObj:
TCL_REG_ADVANCED
Compile advanced regular expressions This mode corresponds to
the normal regular expression syntax accepted by the Tcl reg-
exp and regsub commands.
TCL_REG_EXTENDED
Compile extended regular expressions This mode corresponds to
the regular expression syntax recognized by Tcl 8.0 and ear-
lier versions.
TCL_REG_BASIC
Compile basic regular expressions This mode corresponds to the
regular expression syntax recognized by common Unix utilities
like sed and grep. This is the default if no flags are speci-
fied.
TCL_REG_EXPANDED
Compile the regular expression (basic, extended, or advanced)
using an expanded syntax that allows comments and whitespace.
This mode causes non-backslashed non-bracket-expression white
space and #-to-end-of-line comments to be ignored.
TCL_REG_QUOTE
Compile a literal string, with all characters treated as ordi-
nary characters.
TCL_REG_NOCASE
Compile for matching that ignores upper/lower case distinc-
tions.
TCL_REG_NEWLINE
Compile for newline-sensitive matching. By default, newline
is a completely ordinary character with no special meaning in
either regular expressions or strings. With this flag,
bracket expressions and never match newline, matches an empty
string after any newline in addition to its normal function,
and matches an empty string before any newline in addition to
its normal function. REG_NEWLINE is the bit-wise OR of
REG_NLSTOP and REG_NLANCH.
TCL_REG_NLSTOP
Compile for partial newline-sensitive matching, with the
behavior of bracket expressions and affected, but not the
behavior of and In this mode, bracket expressions and never
match newline.
TCL_REG_NLANCH
Compile for inverse partial newline-sensitive matching, with
the behavior of and (the affected, but not the behavior of
bracket expressions and In this mode matches an empty string
after any newline in addition to its normal function, and
matches an empty string before any newline in addition to its
normal function.
TCL_REG_NOSUB
Compile for matching that reports only success or failure, not
what was matched. This reduces compile overhead and may
improve performance. Subsequent calls to Tcl_RegExpGetInfo or
Tcl_RegExpRange will not report any match information.
TCL_REG_CANMATCH
Compile for matching that reports the potential to complete a
partial match given more text (see below).
Only one of TCL_REG_EXTENDED, TCL_REG_ADVANCED, TCL_REG_BASIC, and
TCL_REG_QUOTE may be specified.
Tcl_RegExpExecObj executes the regular expression pattern matcher. It
returns 1 if objPtr contains a range of characters that match regexp, 0
if no match is found, and -1 if an error occurs. In the case of an
error, Tcl_RegExpExecObj leaves an error message in the interpreter
result. The nmatches value indicates to the matcher how many subex-
pressions are of interest. If nmatches is 0, then no subexpression
match information is recorded, which may allow the matcher to make var-
ious optimizations. If the value is -1, then all of the subexpressions
in the pattern are remembered. If the value is a positive integer,
then only that number of subexpressions will be remembered. Matching
begins at the specified Unicode character index given by offset.
Unlike Tcl_RegExpExec, the behavior of anchors is not affected by the
offset value. Instead the behavior of the anchors is explicitly con-
trolled by the eflags argument, which is a bit-wise OR of zero or more
of the following flags:
TCL_REG_NOTBOL
The starting character will not be treated as the beginning of
a line or the beginning of the string, so will not match
there. Note that this flag has no effect on how matches.
TCL_REG_NOTEOL
The last character in the string will not be treated as the
end of a line or the end of the string, so will not match
there. Note that this flag has no effect on how matches.
Tcl_RegExpGetInfo retrieves information about the last match performed
with a given regular expression regexp. The infoPtr argument contains
a pointer to a structure that is defined as follows:
typedef struct Tcl_RegExpInfo {
int nsubs;
Tcl_RegExpIndices *matches;
long extendStart; } Tcl_RegExpInfo;
The nsubs field contains a count of the number of parenthesized subex-
pressions within the regular expression. If the TCL_REG_NOSUB was
used, then this value will be zero. The matches field points to an
array of nsubs values that indicate the bounds of each subexpression
matched. The first element in the array refers to the range matched by
the entire regular expression, and subsequent elements refer to the
parenthesized subexpressions in the order that they appear in the pat-
tern. Each element is a structure that is defined as follows:
typedef struct Tcl_RegExpIndices {
long start;
long end; } Tcl_RegExpIndices;
The start and end values are Unicode character indices relative to the
offset location within objPtr where matching began. The start index
identifies the first character of the matched subexpression. The end
index identifies the first character after the matched subexpression.
If the subexpression matched the empty string, then start and end will
be equal. If the subexpression did not participate in the match, then
start and end will be set to -1.
The extendStart field in Tcl_RegExpInfo is only set if the TCL_REG_CAN-
MATCH flag was used. It indicates the first character in the string
where a match could occur. If a match was found, this will be the same
as the beginning of the current match. If no match was found, then it
indicates the earliest point at which a match might occur if additional
text is appended to the string. If it is no match is possible even
with further text, this field will be set to -1.
SEE ALSO
re_syntax(n)
KEYWORDS
match, pattern, regular expression, string, subexpression, Tcl_RegEx-
pIndices, Tcl_RegExpInfo
Tcl 8.1 Tcl_RegExpMatch(3)
RegExp 8.5.4 - Generated Wed Aug 20 18:47:20 CDT 2008