path: root/posix/regex.h

/* Definitions for data structures and routines for the regular
   expression library.
   Copyright (C) 1985, 1989-2025 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef _REGEX_H
#define _REGEX_H 1

#include <sys/types.h>

/* Allow the use in C++ code.  */
#ifdef __cplusplus
extern "C" {
#endif

/* Define __USE_GNU to declare GNU extensions that violate the
   POSIX name space rules.  */
#ifdef _GNU_SOURCE
# define __USE_GNU 1
#endif

#ifdef _REGEX_LARGE_OFFSETS

/* Use types and values that are wide enough to represent signed and
   unsigned byte offsets in memory.  This currently works only when
   the regex code is used outside of the GNU C library; it is not yet
   supported within glibc itself, and glibc users should not define
   _REGEX_LARGE_OFFSETS.  */

/* The type of object sizes.  */
typedef size_t __re_size_t;

/* The type of object sizes, in places where the traditional code
   uses unsigned long int.  */
typedef size_t __re_long_size_t;

#else

/* The traditional GNU regex implementation mishandles strings longer
   than INT_MAX.  */
typedef unsigned int __re_size_t;
typedef unsigned long int __re_long_size_t;

#endif

/* The following two types have to be signed and unsigned integer type
   wide enough to hold a value of a pointer.  For most ANSI compilers
   ptrdiff_t and size_t should be likely OK.  Still size of these two
   types is 2 for Microsoft C.  Ugh... */
typedef long int s_reg_t;
typedef unsigned long int active_reg_t;

/* The following bits are used to determine the regexp syntax we
   recognize.  The set/not-set meanings are chosen so that Emacs syntax
   remains the value 0.  The bits are given in alphabetical order, and
   the definitions shifted by one from the previous bit; thus, when we
   add or remove a bit, only one other definition need change.  */
typedef unsigned long int reg_syntax_t;

#ifdef __USE_GNU
/* If this bit is not set, then \ inside a bracket expression is literal.
   If set, then such a \ quotes the following character.  */
# define RE_BACKSLASH_ESCAPE_IN_LISTS ((unsigned long int) 1)

/* If this bit is not set, then + and ? are operators, and \+ and \? are
     literals.
   If set, then \+ and \? are operators and + and ? are literals.  */
# define RE_BK_PLUS_QM (RE_BACKSLASH_ESCAPE_IN_LISTS << 1)

/* If this bit is set, then character classes are supported.  They are:
     [:alpha:], [:upper:], [:lower:],  [:digit:], [:alnum:], [:xdigit:],
     [:space:], [:print:], [:punct:], [:graph:], and [:cntrl:].
   If not set, then character classes are not supported.  */
# define RE_CHAR_CLASSES (RE_BK_PLUS_QM << 1)

/* If this bit is set, then ^ and $ are always anchors (outside bracket
     expressions, of course).
   If this bit is not set, then it depends:
	^  is an anchor if it is at the beginning of a regular
	   expression or after an open-group or an alternation operator;
	$  is an anchor if it is at the end of a regular expression, or
	   before a close-group or an alternation operator.

   This bit could be (re)combined with RE_CONTEXT_INDEP_OPS, because
   POSIX draft 11.2 says that * etc. in leading positions is undefined.
   We already implemented a previous draft which made those constructs
   invalid, though, so we haven't changed the code back.  */
# define RE_CONTEXT_INDEP_ANCHORS (RE_CHAR_CLASSES << 1)

/* If this bit is set, then special characters are always special
     regardless of where they are in the pattern.
   If this bit is not set, then special characters are special only in
     some contexts; otherwise they are ordinary.  Specifically,
     * + ? and intervals are only special when not after the beginning,
     open-group, or alternation operator.  */
# define RE_CONTEXT_INDEP_OPS (RE_CONTEXT_INDEP_ANCHORS << 1)

/* If this bit is set, then *, +, ?, and { cannot be first in an re or
     immediately after an alternation or begin-group operator.  */
# define RE_CONTEXT_INVALID_OPS (RE_CONTEXT_INDEP_OPS << 1)

/* If this bit is set, then . matches newline.
   If not set, then it doesn't.  */
# define RE_DOT_NEWLINE (RE_CONTEXT_INVALID_OPS << 1)

/* If this bit is set, then . doesn't match NUL.
   If not set, then it does.  */
# define RE_DOT_NOT_NULL (RE_DOT_NEWLINE << 1)

/* If this bit is set, nonmatching lists [^...] do not match newline.
   If not set, they do.  */
# define RE_HAT_LISTS_NOT_NEWLINE (RE_DOT_NOT_NULL << 1)

/* If this bit is set, either \{...\} or {...} defines an
     interval, depending on RE_NO_BK_BRACES.
   If not set, \{, \}, {, and } are literals.  */
# define RE_INTERVALS (RE_HAT_LISTS_NOT_NEWLINE << 1)

/* If this bit is set, +, ? and | aren't recognized as operators.
   If not set, they are.  */
# define RE_LIMITED_OPS (RE_INTERVALS << 1)

/* If this bit is set, newline is an alternation operator.
   If not set, newline is literal.  */
# define RE_NEWLINE_ALT (RE_LIMITED_OPS << 1)

/* If this bit is set, then '{...}' defines an interval, and \{ and \}
     are literals.
  If not set, then '\{...\}' defines an interval.  */
# define RE_NO_BK_BRACES (RE_NEWLINE_ALT << 1)

/* If this bit is set, (...) defines a group, and \( and \) are literals.
   If not set, \(...\) defines a group, and ( and ) are literals.  */
# define RE_NO_BK_PARENS (RE_NO_BK_BRACES << 1)

/* If this bit is set, then \<digit> matches <digit>.
   If not set, then \<digit> is a back-reference.  */
# define RE_NO_BK_REFS (RE_NO_BK_PARENS << 1)

/* If this bit is set, then | is an alternation operator, and \| is literal.
   If not set, then \| is an alternation operator, and | is literal.  */
# define RE_NO_BK_VBAR (RE_NO_BK_REFS << 1)

/* If this bit is set, then an ending range point collating higher
     than the starting range point, as in [z-a], is invalid.
   If not set, then when ending range point collates higher than the
     starting range point, the range is ignored.  */
# define RE_NO_EMPTY_RANGES (RE_NO_BK_VBAR << 1)

/* If this bit is set, then an unmatched ) is ordinary.
   If not set, then an unmatched ) is invalid.  */
# define RE_UNMATCHED_RIGHT_PAREN_ORD (RE_NO_EMPTY_RANGES << 1)

/* If this bit is set, succeed as soon as we match the whole pattern,
   without further backtracking.  */
# define RE_NO_POSIX_BACKTRACKING (RE_UNMATCHED_RIGHT_PAREN_ORD << 1)

/* If this bit is set, do not process the GNU regex operators.
   If not set, then the GNU regex operators are recognized. */
# define RE_NO_GNU_OPS (RE_NO_POSIX_BACKTRACKING << 1)

/* If this bit is set, turn on internal regex debugging.
   If not set, and debugging was on, turn it off.
   This only works if regex.c is compiled -DDEBUG.
   We define this bit always, so that all that's needed to turn on
   debugging is to recompile regex.c; the calling code can always have
   this bit set, and it won't affect anything in the normal case. */
# define RE_DEBUG (RE_NO_GNU_OPS << 1)

/* If this bit is set, a syntactically invalid interval is treated as
   a string of ordinary characters.  For example, the ERE 'a{1' is
   treated as 'a\{1'.  */
# define RE_INVALID_INTERVAL_ORD (RE_DEBUG << 1)

/* If this bit is set, then ignore case when matching.
   If not set, then case is significant.  */
# define RE_ICASE (RE_INVALID_INTERVAL_ORD << 1)

/* This bit is used internally like RE_CONTEXT_INDEP_ANCHORS but only
   for ^, because it is difficult to scan the regex backwards to find
   whether ^ should be special.  */
# define RE_CARET_ANCHORS_HERE (RE_ICASE << 1)

/* If this bit is set, then \{ cannot be first in a regex or
   immediately after an alternation, open-group or \} operator.  */
# define RE_CONTEXT_INVALID_DUP (RE_CARET_ANCHORS_HERE << 1)

/* If this bit is set, then no_sub will be set to 1 during
   re_compile_pattern.  */
# define RE_NO_SUB (RE_CONTEXT_INVALID_DUP << 1)
#endif

/* This global variable defines the particular regexp syntax to use (for
   some interfaces).  When a regexp is com