Tcl_RegExpMatch(3) Tcl Library Procedures Tcl_RegExpMatch(3)
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NAME
Tcl_RegExpMatch, Tcl_RegExpCompile, Tcl_RegExpExec, Tcl_RegExpRange, Tcl_GetRegExpFromObj, Tcl_Reg-ExpMatchObj, Tcl_RegExpMatchObj,
ExpMatchObj, Tcl_RegExpExecObj, Tcl_RegExpGetInfo - Pattern matching with regular expressions
SYNOPSIS
#include <tcl.h>
int
Tcl_RegExpMatchObj(interp, strObj, patObj)
int
Tcl_RegExpMatch(interp, string, pattern)
Tcl_RegExp
Tcl_RegExpCompile(interp, pattern)
int
Tcl_RegExpExec(interp, regexp, string, start)
Tcl_RegExpRange(regexp, index, startPtr, endPtr)
Tcl_RegExp |
Tcl_GetRegExpFromObj(interp, patObj, cflags) |
int |
Tcl_RegExpExecObj(interp, regexp, objPtr, offset, nmatches, eflags) |
Tcl_RegExpGetInfo(regexp, infoPtr) |
ARGUMENTS
Tcl_Interp *interp (in) Tcl interpreter to use for error reporting. The interpreter may be
NULL if no error reporting is desired. |
Tcl_Obj *strObj (in/out) ||
Refers to the object from which to get the string to search. The |
internal representation of the object may be converted to a form |
that can be efficiently searched. |
Tcl_Obj *patObj (in/out) ||
Refers to the object from which to get a regular expression. The |
compiled regular expression is cached in the object.
char *string (in) String to check for a match with a regular expression.
CONST char *pattern (in) String in the form of a regular expression pattern.
Tcl_RegExp regexp (in) Compiled regular expression. Must have been returned previously by
Tcl_GetRegExpFromObj or Tcl_RegExpCompile.
char *start (in) If string is just a portion of some other string, this argument
identifies the beginning of the larger string. If it isn't the same
as string, then no ^ matches will be allowed.
int index (in) Specifies which range is desired: 0 means the range of the entire
match, 1 or greater means the range that matched a parenthesized
sub-expression. |
CONST |
char **startPtr(out) | |
The address of the first character in the range is stored here, or |
NULL if there is no such range. |
CONST |
char **endPtr (out) | |
The address of the character just after the last one in the range is |
stored here, or NULL if there is no such range. |
int cflags (in) ||
OR-ed combination of compilation flags. See below for more informa- |
tion. |
Tcl_Obj *objPtr (in/out) ||
An object which contains the string to check for a match with a reg- |
ular expression. |
int off- |
set (in) | |
The character offset into the string where matching should begin. |
The value of the offset has no impact on ^ matches. This behavior |
is controlled by eflags. |
int nmatches (in) ||
The number of matching subexpressions that should be remembered for |
later use. If this value is 0, then no subexpression match informa- |
tion 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. |
int eflags (in) ||
OR-ed combination of the values TCL_REG_NOTBOL and TCL_REG_NOTEOL. |
See below for more information. |
Tcl_RegEx- |
pInfo *infoPtr(out) | |
The address of the location where information about a previous match |
should be stored by Tcl_RegExpGetInfo.
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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 regular expression) then Tcl_RegExpMatch returns
-1 and leaves an error message in the interpreter result. Tcl_RegExpMatchObj is similar to Tcl_Reg- |
ExpMatch except it operates on the Tcl objects strObj and patObj instead of UTF strings. Tcl_RegExp- |
MatchObj 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_RegExpCompile 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 com-piling compiling
piling the regular expression then Tcl_RegExpCompile returns NULL and leaves an error message in the
interpreter result. Note: the return value from Tcl_RegExpCompile 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 string 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 string 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 doesn't allow ^ atoms in the pattern to match. The start argument provides this
information by pointing to the start of the overall string containing string. Start will be less
than or equal to string; if it is less than string then no ^ matches will be allowed.
Tcl_RegExpRange may be invoked after Tcl_RegExpExec returns; it provides 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 characters that matched the index'th parenthe-sized parenthesized
sized 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 compil- |
ing 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 representation |
of patObj refers to the compiled form. The eflags argument is a bitwise OR of zero or more of the |
following flags that control the compilation of patObj: |
TCL_REG_ADVANCED ||
Compile advanced regular expressions (`AREs'). This mode corresponds to the normal regular |
expression syntax accepted by the Tcl regexp and regsub commands. |
TCL_REG_EXTENDED ||
Compile extended regular expressions (`EREs'). This mode corresponds to the regular expres- |
sion syntax recognized by Tcl 8.0 and earlier versions. |
TCL_REG_BASIC ||
Compile basic regular expressions (`BREs'). 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 specified. |
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 ordinary characters. |
TCL_REG_NOCASE ||
Compile for matching that ignores upper/lower case distinctions. |
TCL_REG_NEW- |
LINE | |
Compile for newline-sensitive matching. By default, newline is a completely ordinary char- |
acter 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 `$' matches an empty string before any new- |
line in addition to its normal function. REG_NEWLINE is the bitwise OR of REG_NLSTOP and |
REG_NLANCH. |
TCL_REG_NLSTOP ||
Compile for partial newline-sensitive matching, with the behavior of `[^' bracket expres- |
sions and `.' affected, but not the behavior of `^' and `$'. In this mode, `[^' bracket |
expressions and `.' never match newline. |
TCL_REG_NLANCH ||
Compile for inverse partial newline-sensitive matching, with the behavior of of `^' and `$' |
(the ``anchors'') affected, but not the behavior of `[^' bracket expressions and `.'. In |
this mode `^' matches an empty string after any newline in addition to its normal function, |
and `$' 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_CAN- |
MATCH | |
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 subexpressions are of interest. If nmatches is 0, then no |
subexpression match information is recorded, which may allow the matcher to make various optimiza- |
tions. 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 |
controlled by the eflags argument, which is a bitwise OR of zero or more of the following flags: |
TCL_REG_NOT- |
BOL | |
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 `\A' |
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 `\Z' matches. |
Tcl_RegExpGetInfo retrieves information about the last match performed with a given regular expres- |
sion 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 subexpressions 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 ele- |
ment in the array refers to the range matched by the entire regular expression, and subsequent ele- |
ments refer to the parenthesized subexpressions in the order that they appear in the pattern. 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_CANMATCH flag was used. It indi- |
cates 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 ear- |
liest 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_RegExpIndices, Tcl_RegExpInfo
Tcl 8.1 Tcl_RegExpMatch(3)
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