deb-goldedplus/goldlib/glibc/regex.cpp

//  Extended regular expression matching and search library,
//  version 0.12.
//  (Implements POSIX draft P1003.2/D11.2, except for some of the
//  internationalization features.)
//  Copyright (C) 1993, 94, 95, 96, 97, 98 Free Software Foundation, Inc.
//
//  The GNU C Library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Library General Public License as
//  published by the Free Software Foundation; either version 2 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
//  Library General Public License for more details.
//
//  You should have received a copy of the GNU Library General Public
//  License along with the GNU C Library; see the file COPYING.LIB.  If not,
//  write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
//  Boston, MA 02111-1307, USA.  */

//  $Id$

/* AIX requires this to be the first thing in the file. */
#if defined _AIX && !defined REGEX_MALLOC
#pragma alloca
#endif

#undef  _GNU_SOURCE
#define _GNU_SOURCE

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#if defined STDC_HEADERS && !defined emacs
# include <stddef.h>
#else
/* We need this for `regex.h', and perhaps for the Emacs include files.  */
# include <sys/types.h>
#endif

#define WIDE_CHAR_SUPPORT (HAVE_WCTYPE_H && HAVE_WCHAR_H && HAVE_BTOWC)

/* For platform which support the ISO C amendement 1 functionality we
support user defined character classes.  */
#if defined _LIBC || WIDE_CHAR_SUPPORT
/* Solaris 2.5 has a bug: <wchar.h> must be included before <wctype.h>.  */
# include <wchar.h>
# include <wctype.h>
#endif

#ifdef _LIBC
/* We have to keep the namespace clean.  */
# define regfree(preg) __regfree (preg)
# define regexec(pr, st, nm, pm, ef) __regexec (pr, st, nm, pm, ef)
# define regcomp(preg, pattern, cflags) __regcomp (preg, pattern, cflags)
# define regerror(errcode, preg, errbuf, errbuf_size) \
  __regerror(errcode, preg, errbuf, errbuf_size)
# define re_set_registers(bu, re, nu, st, en) \
  __re_set_registers (bu, re, nu, st, en)
# define re_match_2(bufp, string1, size1, string2, size2, pos, regs, stop) \
  __re_match_2 (bufp, string1, size1, string2, size2, pos, regs, stop)
# define re_match(bufp, string, size, pos, regs) \
  __re_match (bufp, string, size, pos, regs)
# define re_search(bufp, string, size, startpos, range, regs) \
  __re_search (bufp, string, size, startpos, range, regs)
# define re_compile_pattern(pattern, length, bufp) \
  __re_compile_pattern (pattern, length, bufp)
# define re_set_syntax(syntax) __re_set_syntax (syntax)
# define re_search_2(bufp, st1, s1, st2, s2, startpos, range, regs, stop) \
  __re_search_2 (bufp, st1, s1, st2, s2, startpos, range, regs, stop)
# define re_compile_fastmap(bufp) __re_compile_fastmap (bufp)

#define btowc __btowc
#endif

/* This is for other GNU distributions with internationalized messages.  */
#if HAVE_LIBINTL_H || defined _LIBC
# include <libintl.h>
#else
# define gettext(msgid) (msgid)
#endif

#ifndef gettext_noop
/* This define is so xgettext can find the internationalizable
strings.  */
# define gettext_noop(String) String
#endif

/* The `emacs' switch turns on certain matching commands
that make sense only in Emacs. */
#ifdef emacs

# include "lisp.h"
# include "buffer.h"
# include "syntax.h"

#else  /* not emacs */

/* If we are not linking with Emacs proper,
we can't use the relocating allocator
even if config.h says that we can.  */
# undef REL_ALLOC

# if defined STDC_HEADERS || defined _LIBC
#  include <stdlib.h>
# else
char *malloc ();
char *realloc ();
# endif

/* When used in Emacs's lib-src, we need to get bzero and bcopy somehow.
If nothing else has been done, use the method below.  */
# ifdef INHIBIT_STRING_HEADER
#  if !(defined HAVE_BZERO && defined HAVE_BCOPY)
#   if !defined bzero && !defined bcopy
#    undef INHIBIT_STRING_HEADER
#   endif
#  endif
# endif

/* This is the normal way of making sure we have a bcopy and a bzero.
This is used in most programs--a few other programs avoid this
by defining INHIBIT_STRING_HEADER.  */
# ifndef INHIBIT_STRING_HEADER
#  if defined HAVE_STRING_H || defined STDC_HEADERS || defined _LIBC
#   include <string.h>
#   ifndef bzero
#    ifndef _LIBC
#     define bzero(s, n)    memset (s, '\0', n)
#    else
#     define bzero(s, n)    __bzero (s, n)
#    endif
#   endif
#  else
#   include <strings.h>
#   ifndef memcmp
#    define memcmp(s1, s2, n)   bcmp (s1, s2, n)
#   endif
#   ifndef memcpy
#    define memcpy(d, s, n) (bcopy (s, d, n), (d))
#   endif
#  endif
# endif

/* isalpha etc. are used for the character classes.  */
#include <gctype.h>

/* Define the syntax stuff for \<, \>, etc.  */

/* This must be nonzero for the wordchar and notwordchar pattern
commands in re_match_2.  */
# ifndef Sword
#  define Sword 1
# endif

# ifdef SWITCH_ENUM_BUG
#  define SWITCH_ENUM_CAST(x) ((int)(x))
# else
#  define SWITCH_ENUM_CAST(x) (x)
# endif

/* How many characters in the character set.  */
# define CHAR_SET_SIZE 256

# ifdef SYNTAX_TABLE

extern char *re_syntax_table;

# else /* not SYNTAX_TABLE */

static char re_syntax_table[CHAR_SET_SIZE];

static void
init_syntax_once ()
{
  register int c;
  static int done = 0;

  if (done)
    return;

  bzero (re_syntax_table, sizeof re_syntax_table);

  /* for (c = 'a'; c <= 'z'; c++)
  re_syntax_table[c] = Sword;

  for (c = 'A'; c <= 'Z'; c++)
  re_syntax_table[c] = Sword;

  for (c = '0'; c <= '9'; c++)
  re_syntax_table[c] = Sword; */

  for (c = 0; c < 256; c++)
    re_syntax_table[c] = isxalnum(c) ? Sword : 0;

  re_syntax_table[int('_')] = Sword;

  done = 1;
}

# endif /* not SYNTAX_TABLE */

# define SYNTAX(c) re_syntax_table[c & 0xFF]

#endif /* not emacs */

/* Get the interface, including the syntax bits.  */
#include "regex.h"

/* Jim Meyering writes:

"... Some ctype macros are valid only for character codes that
isascii says are ASCII (SGI's IRIX-4.0.5 is one such system --when
using /bin/cc or gcc but without giving an ansi option).  So, all
ctype uses should be through macros like ISPRINT...  If
STDC_HEADERS is defined, then autoconf has verified that the ctype
macros don't need to be guarded with references to isascii. ...
Defining isascii to 1 should let any compiler worth its salt
eliminate the && through constant folding."
Solaris defines some of these symbols so we must undefine them first.  */

#undef ISASCII
#if defined STDC_HEADERS || (!defined isascii && !defined HAVE_ISASCII)
//# define ISASCII(c) ((c) < 256)
inline bool ISASCII(char) { return true; }
#else
# define ISASCII(c) isascii(c)
#endif

#ifdef isblank
# define ISBLANK(c) (ISASCII (c) && isblank (c))
#else
# define ISBLANK(c) ((c) == ' ' || (c) == '\t')
#endif
#ifdef isgraph
# define ISGRAPH(c) (ISASCII (c) && isgraph (c))
#else
# define ISGRAPH(c) (ISASCII (c) && isprint (c) && !isspace (c))
#endif

#undef ISPRINT
#define ISPRINT(c)  (ISASCII (c) && isprint   (c))
#define ISDIGIT(c)  (ISASCII (c) && isdigit   (c))
#define ISALNUM(c)  (ISASCII (c) && isxalnum  (c))
#define ISALPHA(c)  (ISASCII (c) && g_isalpha (c))
#define ISCNTRL(c)  (ISASCII (c) && iscntrl   (c))
#define ISLOWER(c)  (ISASCII (c) && g_islower (c))
#define ISPUNCT(c)  (ISASCII (c) && ispunct   (c))
#define ISSPACE(c)  (ISASCII (c) && isspace   (c))
#define ISUPPER(c)  (ISASCII (c) && g_isupper (c))
#define ISXDIGIT(c) (ISASCII (c) && isxdigit  (c))

#ifndef NULL
# define NULL (void *)0
#endif

/* We remove any previous definition of `SIGN_EXTEND_CHAR',
since ours (we hope) works properly with all combinations of
machines, compilers, `char' and `unsigned char' argument types.
(Per Bothner suggested the basic approach.)  */
#undef SIGN_EXTEND_CHAR
#if __STDC__
# define SIGN_EXTEND_CHAR(c) ((signed char) (c))
#else  /* not __STDC__ */
/* As in Harbison and Steele.  */
# define SIGN_EXTEND_CHAR(c) ((((unsigned char) (c)) ^ 128) - 128)
#endif

/* Should we use malloc or alloca?  If REGEX_MALLOC is not defined, we
use `alloca' instead of `malloc'.  This is because using malloc in
re_search* or re_match* could cause memory leaks when C-g is used in
Emacs; also, malloc is slower and causes storage fragmentation.  On
the other hand, malloc is more portable, and easier to debug.

Because we sometimes use alloca, some routines have to be macros,
not functions -- `alloca'-allocated space disappears at the end of the
function it is called in.  */

#ifdef REGEX_MALLOC

# define REGEX_ALLOCATE malloc
# define REGEX_REALLOCATE(source, osize, nsize) realloc (source, nsize)
# define REGEX_FREE free

#else /* not REGEX_MALLOC  */

/* Emacs already defines alloca, sometimes.  */
# ifndef alloca

/* Make alloca work the best possible way.  */
#  ifdef __GNUC__
#   define alloca __builtin_alloca
#  else /* not __GNUC__ */
#   if HAVE_ALLOCA_H
#    include <alloca.h>
#   endif /* HAVE_ALLOCA_H */
#   if HAVE_MALLOC_H
#    include <malloc.h>
#   endif /* HAVE_MALLOC_H */
#  endif /* not __GNUC__ */

# endif /* not alloca */

# define REGEX_ALLOCATE alloca

/* Assumes a `char *destination' variable.  */
# define REGEX_REALLOCATE(source, osize, nsize)             \
  (destination = (char *) alloca (nsize),               \
  memcpy (destination, source, osize))

/* No need to do anything to free, after alloca.  */
# define REGEX_FREE(arg) ((void)0) /* Do nothing!  But inhibit gcc warning.  */

#endif /* not REGEX_MALLOC */

/* Define how to allocate the failure stack.  */

#if defined REL_ALLOC && defined REGEX_MALLOC

# define REGEX_ALLOCATE_STACK(size)             \
  r_alloc (&failure_stack_ptr, (size))
# define REGEX_REALLOCATE_STACK(source, osize, nsize)       \
  r_re_alloc (&failure_stack_ptr, (nsize))
# define REGEX_FREE_STACK(ptr)                  \
  r_alloc_free (&failure_stack_ptr)

#else /* not using relocating allocator */

# ifdef REGEX_MALLOC

#  define REGEX_ALLOCATE_STACK malloc
#  define REGEX_REALLOCATE_STACK(source, osize, nsize) realloc (source, nsize)
#  define REGEX_FREE_STACK free

# else /* not REGEX_MALLOC */

#  define REGEX_ALLOCATE_STACK alloca

#  define REGEX_REALLOCATE_STACK(source, osize, nsize)          \
  REGEX_REALLOCATE (source, osize, nsize)
/* No need to explicitly free anything.  */
#  define REGEX_FREE_STACK(arg)

# endif /* not REGEX_MALLOC */
#endif /* not using relocating allocator */


/* True if `size1' is non-NULL and PTR is pointing anywhere inside
`string1' or just past its end.  This works if PTR is NULL, which is
a good thing.  */
#define FIRST_STRING_P(ptr)                     \
  (size1 && string1 <= (ptr) && (ptr) <= string1 + size1)

/* (Re)Allocate N items of type T using malloc, or fail.  */
#define TALLOC(n, t) ((t *) malloc ((n) * sizeof (t)))
#define RETALLOC(addr, n, t) ((addr) = (t *) realloc (addr, (n) * sizeof (t)))
#define RETALLOC_IF(addr, n, t) \
  if (addr) RETALLOC((addr), (n), t); else (addr) = TALLOC ((n), t)
#define REGEX_TALLOC(n, t) ((t *) REGEX_ALLOCATE ((n) * sizeof (t)))

#define BYTEWIDTH 8 /* In bits.  */

#define STREQ(s1, s2) ((strcmp (s1, s2) == 0))

#undef MAX
#undef MIN
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))

static int re_match_2_internal(struct re_pattern_buffer *bufp,
                               const char *string1, int size1,
                               const char *string2, int size2,
                               int pos,
                               struct re_registers *regs,
                               int stop);

/* These are the command codes that appear in compiled regular
expressions.  Some opcodes are followed by argument bytes.  A
command code can specify any interpretation whatsoever for its
arguments.  Zero bytes may appear in the compiled regular expression.  */

typedef enum
{
  no_op = 0,

  /* Succeed right away--no more backtracking.  */
  succeed,

  /* Followed by one byte giving n, then by n literal bytes.  */
  exactn,

  /* Matches any (more or less) character.  */
  anychar,

  /* Matches any one char belonging to specified set.  First
  following byte is number of bitmap bytes.  Then come bytes
  for a bitmap saying which chars are in.  Bits in each byte
  are ordered low-bit-first.  A character is in the set if its
  bit is 1.  A character too large to have a bit in the map is
  automatically not in the set.  */
  charset,

  /* Same parameters as charset, but match any character that is
  not one of those specified.  */
  charset_not,

  /* Start remembering the text that is matched, for storing in a
  register.  Followed by one byte with the register number, in
  the range 0 to one less than the pattern buffer's re_nsub
  field.  Then followed by one byte with the number of groups
  inner to this one.  (This last has to be part of the
  start_memory only because we need it in the on_failure_jump
  of re_match_2.)  */
  start_memory,

  /* Stop remembering the text that is matched and store it in a
  memory register.  Followed by one byte with the register
  number, in the range 0 to one less than `re_nsub' in the
  pattern buffer, and one byte with the number of inner groups,
  just like `start_memory'.  (We need the number of inner
  groups here because we don't have any easy way of finding the
  corresponding start_memory when we're at a stop_memory.)  */
  stop_memory,

  /* Match a duplicate of something remembered. Followed by one
  byte containing the register number.  */
  duplicate,

  /* Fail unless at beginning of line.  */
  begline,

  /* Fail unless at end of line.  */
  endline,

  /* Succeeds if at beginning of buffer (if emacs) or at beginning
  of string to be matched (if not).  */
  begbuf,

  /* Analogously, for end of buffer/string.  */
  endbuf,

  /* Followed by two byte relative address to which to jump.  */
  jump,

  /* Same as jump, but marks the end of an alternative.  */
  jump_past_alt,

  /* Followed by two-byte relative address of place to resume at
  in case of failure.  */
  on_failure_jump,

  /* Like on_failure_jump, but pushes a placeholder instead of the
  current string position when executed.  */
  on_failure_keep_string_jump,

  /* Throw away latest failure point and then jump to following
  two-byte relative address.  */
  pop_failure_jump,

  /* Change to pop_failure_jump if know won't have to backtrack to
  match; otherwise change to jump.  This is used to jump
  back to the beginning of a repeat.  If what follows this jump
  clearly won't match what the repeat does, such that we can be
  sure that there is no use backtracking out of repetitions
  already matched, then we change it to a pop_failure_jump.
  Followed by two-byte address.  */
  maybe_pop_jump,

  /* Jump to following two-byte address, and push a dummy failure
  point. This failure point will be thrown away if an attempt
  is made to use it for a failure.  A `+' construct makes this
  before the first repeat.  Also used as an intermediary kind
  of jump when compiling an alternative.  */
  dummy_failure_jump,

  /* Push a dummy failure point and continue.  Used at the end of
  alternatives.  */
  push_dummy_failure,

  /* Followed by two-byte relative address and two-byte number n.
  After matching N times, jump to the address upon failure.  */
  succeed_n,

  /* Followed by two-byte relative address, and two-byte number n.
  Jump to the address N times, then fail.  */
  jump_n,

  /* Set the following two-byte relative address to the
  subsequent two-byte number.  The address *includes* the two
  bytes of number.  */
  set_number_at,

  wordchar, /* Matches any word-constituent character.  */
  notwordchar,  /* Matches any char that is not a word-constituent.  */

  wordbeg,  /* Succeeds if at word beginning.  */
  wordend,  /* Succeeds if at word end.  */

  wordbound,    /* Succeeds if at a word boundary.  */
  notwordbound  /* Succeeds if not at a word boundary.  */

#ifdef emacs
  ,before_dot,  /* Succeeds if before point.  */
  at_dot,   /* Succeeds if at point.  */
  after_dot,    /* Succeeds if after point.  */

  /* Matches any character whose syntax is specified.  Followed by
  a byte which contains a syntax code, e.g., Sword.  */
  syntaxspec,

  /* Matches any character whose syntax is not that specified.  */
  notsyntaxspec
#endif /* emacs */
} re_opcode_t;

/* Common operations on the compiled pattern.  */

/* Store NUMBER in two contiguous bytes starting at DESTINATION.  */

#define STORE_NUMBER(destination, number) \
{                                       \
  (destination)[0] = (number) & 0377;   \
  (destination)[1] = (number) >> 8;     \
  }

/* Same as STORE_NUMBER, except increment DESTINATION to
the byte after where the number is stored.  Therefore, DESTINATION
must be an lvalue.  */

#define STORE_NUMBER_AND_INCR(destination, number)  \
{                                                 \
  STORE_NUMBER (destination, number);             \
  (destination) += 2;                             \
  }

/* Put into DESTINATION a number stored in two contiguous bytes starting
at SOURCE.  */

#define EXTRACT_NUMBER(destination, source)                   \
{                                                           \
  (destination) = *(source) & 0377;                         \
  (destination) += SIGN_EXTEND_CHAR (*((source) + 1)) << 8; \
  }

/* Same as EXTRACT_NUMBER, except increment SOURCE to after the number.
SOURCE must be an lvalue.  */

#define EXTRACT_NUMBER_AND_INCR(destination, source)  \
{                                                   \
  EXTRACT_NUMBER (destination, source);             \
  (source) += 2;                                    \
  }

/* Set by `re_set_syntax' to the current regexp syntax to recognize.  Can
also be assigned to arbitrarily: each pattern buffer stores its own
syntax, so it can be changed between regex compilations.  */
/* This has no initializer because initialized variables in Emacs
become read-only after dumping.  */
reg_syntax_t re_syntax_options;


/* Specify the precise syntax of regexps for compilation.  This provides
for compatibility for various utilities which historically have
different, incompatible syntaxes.

The argument SYNTAX is a bit mask comprised of the various bits
defined in regex.h.  We return the old syntax.  */

reg_syntax_t
re_set_syntax (reg_syntax_t syntax)
{
  reg_syntax_t ret = re_syntax_options;

  re_syntax_options = syntax;
  return ret;
}
#ifdef _LIBC
weak_alias (__re_set_syntax, re_set_syntax)
#endif

/* This table gives an error message for each of the error codes listed
in regex.h.  Obviously the order here has to be same as there.
POSIX doesn't require that we do anything for REG_NOERROR,
but why not be nice?  */

static const char *re_error_msgid[] =
{
  gettext_noop ("Success"),   /* REG_NOERROR */
  gettext_noop ("No match"),  /* REG_NOMATCH */
  gettext_noop ("Invalid regular expression"), /* REG_BADPAT */
  gettext_noop ("Invalid collation character"), /* REG_ECOLLATE */
  gettext_noop ("Invalid character class name"), /* REG_ECTYPE */
  gettext_noop ("Trailing backslash"), /* REG_EESCAPE */
  gettext_noop ("Invalid back reference"), /* REG_ESUBREG */
  gettext_noop ("Unmatched [ or [^"), /* REG_EBRACK */
  gettext_noop ("Unmatched ( or \\("), /* REG_EPAREN */
  gettext_noop ("Unmatched \\{"), /* REG_EBRACE */
  gettext_noop ("Invalid content of \\{\\}"), /* REG_BADBR */
  gettext_noop ("Invalid range end"), /* REG_ERANGE */
  gettext_noop ("Memory exhausted"), /* REG_ESPACE */
  gettext_noop ("Invalid preceding regular expression"), /* REG_BADRPT */
  gettext_noop ("Premature end of regular expression"), /* REG_EEND */
  gettext_noop ("Regular expression too big"), /* REG_ESIZE */
  gettext_noop ("Unmatched ) or \\)"), /* REG_ERPAREN */
};

/* Avoiding alloca during matching, to placate r_alloc.  */

/* Define MATCH_MAY_ALLOCATE unless we need to make sure that the
searching and matching functions should not call alloca.  On some
systems, alloca is implemented in terms of malloc, and if we're
using the relocating allocator routines, then malloc could cause a
relocation, which might (if the strings being searched are in the
ralloc heap) shift the data out from underneath the regexp
routines.

Here's another reason to avoid allocation: Emacs
processes input from X in a signal handler; processing X input may
call malloc; if input arrives while a matching routine is calling
malloc, then we're scrod.  But Emacs can't just block input while
calling matching routines; then we don't notice interrupts when
they come in.  So, Emacs blocks input around all regexp calls
except the matching calls, which it leaves unprotected, in the
faith that they will not malloc.  */

/* Normally, this is fine.  */
#define MATCH_MAY_ALLOCATE

/* When using GNU C, we are not REALLY using the C alloca, no matter
what config.h may say.  So don't take precautions for it.  */
#ifdef __GNUC__
# undef C_ALLOCA
#endif

/* The match routines may not allocate if (1) they would do it with malloc
and (2) it's not safe for them to use malloc.
Note that if REL_ALLOC is defined, matching would not use malloc for the
failure stack, but we would still use it for the register vectors;
so REL_ALLOC should not affect this.  */
#if (defined C_ALLOCA || defined REGEX_MALLOC) && defined emacs
# undef MATCH_MAY_ALLOCATE
#endif


/* Failure stack declarations and macros; both re_compile_fastmap and
re_match_2 use a failure stack.  These have to be macros because of
REGEX_ALLOCATE_STACK.  */


/* Number of failure points for which to initially allocate space
when matching.  If this number is exceeded, we allocate more
space, so it is not a hard limit.  */
#ifndef INIT_FAILURE_ALLOC
# define INIT_FAILURE_ALLOC 5
#endif

/* Roughly the maximum number of failure points on the stack.  Would be
exactly that if always used MAX_FAILURE_ITEMS items each time we failed.
This is a variable only so users of regex can assign to it; we never
change it ourselves.  */

#ifdef INT_IS_16BIT

# if defined MATCH_MAY_ALLOCATE
/* 4400 was enough to cause a crash on Alpha OSF/1,
whose default stack limit is 2mb.  */
long int re_max_failures = 4000;
# else
long int re_max_failures = 2000;
# endif

union fail_stack_elt
{
  unsigned char *pointer;
  long int integer;
};

typedef union fail_stack_elt fail_stack_elt_t;

typedef struct
{
  fail_stack_elt_t *stack;
  unsigned long int size;
  unsigned long int avail;      /* Offset of next open position.  */
} fail_stack_type;

#else /* not INT_IS_16BIT */

# if defined MATCH_MAY_ALLOCATE
/* 4400 was enough to cause a crash on Alpha OSF/1,
whose default stack limit is 2mb.  */
int re_max_failures = 20000;
# else
int re_max_failures = 2000;
# endif

union fail_stack_elt
{
  unsigned char *pointer;
  int integer;
};

typedef union fail_stack_elt fail_stack_elt_t;

typedef struct
{
  fail_stack_elt_t *stack;
  unsigned size;
  unsigned avail;           /* Offset of next open position.  */
} fail_stack_type;

#endif /* INT_IS_16BIT */

#define FAIL_STACK_EMPTY()     (fail_stack.avail == 0)
#define FAIL_STACK_PTR_EMPTY() (fail_stack_ptr->avail == 0)
#define FAIL_STACK_FULL()      (fail_stack.avail == fail_stack.size)


/* Define macros to initialize and free the failure stack.
Do `return -2' if the alloc fails.  */

#ifdef MATCH_MAY_ALLOCATE
# define INIT_FAIL_STACK()                                                    \
{                                                                           \
  fail_stack.stack = (fail_stack_elt_t *)                                   \
  REGEX_ALLOCATE_STACK (INIT_FAILURE_ALLOC * sizeof (fail_stack_elt_t));  \
  if (fail_stack.stack == NULL) return -2;                                  \
  fail_stack.size = INIT_FAILURE_ALLOC;                                     \
  fail_stack.avail = 0;                                                     \
}

# define RESET_FAIL_STACK()  REGEX_FREE_STACK (fail_stack.stack)
#else
# define INIT_FAIL_STACK()                      \
  do {                                  \
  fail_stack.avail = 0;                       \
  } while (0)

# define RESET_FAIL_STACK()
#endif


/* Double the size of FAIL_STACK, up to approximately `re_max_failures' items.

Return 1 if succeeds, and 0 if either ran out of memory
allocating space for it or it was already too large.

REGEX_REALLOCATE_STACK requires `destination' be declared.   */

#define DOUBLE_FAIL_STACK(fail_stack)                   \
  ((fail_stack).size > (unsigned) (re_max_failures * MAX_FAILURE_ITEMS) \
  ? 0                                  \
  : ((fail_stack).stack = (fail_stack_elt_t *)             \
  REGEX_REALLOCATE_STACK ((fail_stack).stack,             \
  (fail_stack).size * sizeof (fail_stack_elt_t),        \
  ((fail_stack).size << 1) * sizeof (fail_stack_elt_t)),    \
  \
  (fail_stack).stack == NULL                    \
  ? 0                               \
  : ((fail_stack).size <<= 1,                   \
  1)))


/* Push pointer POINTER on FAIL_STACK.
Return 1 if was able to do so and 0 if ran out of memory allocating
space to do so.  */
#define PUSH_PATTERN_OP(POINTER, FAIL_STACK)                \
  ((FAIL_STACK_FULL ()                          \
  && !DOUBLE_FAIL_STACK (FAIL_STACK))                 \
  ? 0                                  \
  : ((FAIL_STACK).stack[(FAIL_STACK).avail++].pointer = POINTER,   \
  1))

/* Push a pointer value onto the failure stack.
Assumes the variable `fail_stack'.  Probably should only
be called from within `PUSH_FAILURE_POINT'.  */
#define PUSH_FAILURE_POINTER(item)                  \
  fail_stack.stack[fail_stack.avail++].pointer = (unsigned char *) (item)

/* This pushes an integer-valued item onto the failure stack.
Assumes the variable `fail_stack'.  Probably should only
be called from within `PUSH_FAILURE_POINT'.  */
#define PUSH_FAILURE_INT(item)                  \
  fail_stack.stack[fail_stack.avail++].integer = (item)

/* Push a fail_stack_elt_t value onto the failure stack.
Assumes the variable `fail_stack'.  Probably should only
be called from within `PUSH_FAILURE_POINT'.  */
#define PUSH_FAILURE_ELT(item)                  \
  fail_stack.stack[fail_stack.avail++] =  (item)

/* These three POP... operations complement the three PUSH... operations.
All assume that `fail_stack' is nonempty.  */
#define POP_FAILURE_POINTER() fail_stack.stack[--fail_stack.avail].pointer
#define POP_FAILURE_INT() fail_stack.stack[--fail_stack.avail].integer
#define POP_FAILURE_ELT() fail_stack.stack[--fail_stack.avail]


/* Push the information about the state we will need
if we ever fail back to it.

Requires variables fail_stack, regstart, regend, reg_info, and
num_regs_pushed be declared.  DOUBLE_FAIL_STACK requires `destination'
be declared.

Does `return FAILURE_CODE' if runs out of memory.  */

#define PUSH_FAILURE_POINT(pattern_place, string_place, failure_code)   \
{                                                                    \
  char *destination;                                                  \
  /* Must be int, so when we don't save any registers, the arithmetic \
of 0 + -1 isn't done as unsigned.  */                            \
  /* Can't be int, since there is not a shred of a guarantee that int \
is wide enough to hold a value of something to which pointer can \
be assigned */                                                   \
  active_reg_t this_reg;                                              \
  \
  /* Ensure we have enough space allocated for what we will push.  */ \
  while (REMAINING_AVAIL_SLOTS < NUM_FAILURE_ITEMS)                   \
{                                                                 \
  if (!DOUBLE_FAIL_STACK (fail_stack))                            \
  return failure_code;                                          \
}                                                                 \
  \
  for (this_reg = lowest_active_reg; this_reg <= highest_active_reg;  \
  this_reg++)                                                      \
{                                                                   \
  PUSH_FAILURE_POINTER (regstart[this_reg]);                        \
  PUSH_FAILURE_POINTER (regend[this_reg]);                          \
  PUSH_FAILURE_ELT (reg_info[this_reg].word);                       \
}                                                                   \
  \
  PUSH_FAILURE_INT (lowest_active_reg);                               \
  PUSH_FAILURE_INT (highest_active_reg);                              \
  PUSH_FAILURE_POINTER (pattern_place);                               \
  PUSH_FAILURE_POINTER (string_place);                                \
}

/* This is the number of items that are pushed and popped on the stack
for each register.  */
#define NUM_REG_ITEMS  3

/* Individual items aside from the registers.  */
#define NUM_NONREG_ITEMS 4

/* We push at most this many items on the stack.  */
/* We used to use (num_regs - 1), which is the number of registers
this regexp will save; but that was changed to 5
to avoid stack overflow for a regexp with lots of parens.  */
#define MAX_FAILURE_ITEMS (5 * NUM_REG_ITEMS + NUM_NONREG_ITEMS)

/* We actually push this many items.  */
#define NUM_FAILURE_ITEMS               \
  (((0                          \
  ? 0 : highest_active_reg - lowest_active_reg + 1)  \
  * NUM_REG_ITEMS)                    \
  + NUM_NONREG_ITEMS)

/* How many items can still be added to the stack without overflowing it.  */
#define REMAINING_AVAIL_SLOTS ((fail_stack).size - (fail_stack).avail)


/* Pops what PUSH_FAIL_STACK pushes.

We restore into the parameters, all of which should be lvalues:
STR -- the saved data position.
PAT -- the saved pattern position.
LOW_REG, HIGH_REG -- the highest and lowest active registers.
REGSTART, REGEND -- arrays of string positions.
REG_INFO -- array of information about each subexpression.

Also assumes the variables `fail_stack' and (if debugging), `bufp',
`pend', `string1', `size1', `string2', and `size2'.  */

#define POP_FAILURE_POINT(str, pat, low_reg, high_reg, regstart, regend, reg_info)  \
{                                                                       \
  active_reg_t this_reg;                                                \
  const unsigned char *string_temp;                                     \
  \
  /* If the saved string location is NULL, it came from an              \
on_failure_keep_string_jump opcode, and we want to throw away the  \
saved NULL, thus retaining our current position in the string.  */ \
  string_temp = POP_FAILURE_POINTER ();                                 \
  if (string_temp != NULL)                                              \
  str = (const char *) string_temp;                                   \
  \
  pat = (unsigned char *) POP_FAILURE_POINTER ();                       \
  \
  /* Restore register info.  */                                         \
  high_reg = (active_reg_t) POP_FAILURE_INT ();                         \
  low_reg = (active_reg_t) POP_FAILURE_INT ();                          \
  \
  for (this_reg = high_reg; this_reg >= low_reg; this_reg--)            \
{                                                                     \
  reg_info[this_reg].word = POP_FAILURE_ELT ();                       \
  regend[this_reg] = (const char *) POP_FAILURE_POINTER ();           \
  regstart[this_reg] = (const char *) POP_FAILURE_POINTER ();         \
}                                                                     \
  \
  set_regs_matched_done = 0;                                            \
} /* POP_FAILURE_POINT */



/* Structure for per-register (a.k.a. per-group) information.
Other register information, such as the
starting and ending positions (which are addresses), and the list of
inner groups (which is a bits list) are maintained in separate
variables.

We are making a (strictly speaking) nonportable assumption here: that
the compiler will pack our bit fields into something that fits into
the type of `word', i.e., is something that fits into one item on the
failure stack.  */


/* Declarations and macros for re_match_2.  */

typedef union
{
  fail_stack_elt_t word;
  struct
  {
    /* This field is one if this group can match the empty string,
    zero if not.  If not yet determined,  `MATCH_NULL_UNSET_VALUE'.  */
#define MATCH_NULL_UNSET_VALUE 3
    unsigned match_null_string_p : 2;
    unsigned is_active : 1;
    unsigned matched_something : 1;
    unsigned ever_matched_something : 1;
  } bits;
} register_info_type;

#define REG_MATCH_NULL_STRING_P(R)  ((R).bits.match_null_string_p)
#define IS_ACTIVE(R)  ((R).bits.is_active)
#define MATCHED_SOMETHING(R)  ((R).bits.matched_something)
#define EVER_MATCHED_SOMETHING(R)  ((R).bits.ever_matched_something)


/* Call this when have matched a real character; it sets `matched' flags
for the subexpressions which we are currently inside.  Also records
that those subexprs have matched.  */
#define SET_REGS_MATCHED()                                      \
{                                                           \
  if (!set_regs_matched_done)                               \
{                                                           \
  active_reg_t r;                                           \
  set_regs_matched_done = 1;                                \
  for (r = lowest_active_reg; r <= highest_active_reg; r++) \
{                                                       \
  MATCHED_SOMETHING (reg_info[r])                       \
  = EVER_MATCHED_SOMETHING (reg_info[r])                  \
  = 1;                                                    \
}                                                       \
}                                                           \
}

/* Registers are set to a sentinel when they haven't yet matched.  */
static char reg_unset_dummy;
#define REG_UNSET_VALUE (&reg_unset_dummy)
#define REG_UNSET(e) ((e) == REG_UNSET_VALUE)

/* Subroutine declarations and macros for regex_compile.  */

static reg_errcode_t regex_compile(const char *pattern, size_t size,
                                   reg_syntax_t syntax, struct re_pattern_buffer *bufp);
static void store_op1(re_opcode_t op, unsigned char *loc, int arg);
static void store_op2(re_opcode_t op, unsigned char *loc, int arg1, int arg2);
static void insert_op1(re_opcode_t op, unsigned char *loc,
                       int arg, unsigned char *end);
static void insert_op2(re_opcode_t op, unsigned char *loc,
                       int arg1, int arg2, unsigned char *end);
static bool at_begline_loc_p(const char *pattern, const char *p,
                             reg_syntax_t syntax);
static bool at_endline_loc_p(const char *p, const char *pend,
                             reg_syntax_t syntax);
static reg_errcode_t compile_range(const char **p_ptr, const char *pend,
                                   char *translate, reg_syntax_t syntax,
                                   unsigned char *b);

/* Fetch the next character in the uncompiled pattern---translating it
if necessary.  Also cast from a signed character in the constant
string passed to us by the user to an unsigned char that we can use
as an array index (in, e.g., `translate').  */
#ifndef PATFETCH
# define PATFETCH(c)                                  \
{                                                   \
  if (p == pend) return REG_EEND;                   \
  c = (unsigned char) *p++;                         \
  if (translate) c = (unsigned char) translate[c];  \
}
#endif

/* Fetch the next character in the uncompiled pattern, with no
translation.  */
#define PATFETCH_RAW(c)             \
{                                 \
  if (p == pend) return REG_EEND; \
  c = (unsigned char) *p++;       \
}

/* Go backwards one character in the pattern.  */
#define PATUNFETCH p--


/* If `translate' is non-null, return translate[D], else just D.  We
cast the subscript to translate because some data is declared as
`char *', to avoid warnings when a string constant is passed.  But
when we use a character as a subscript we must make it unsigned.  */
#ifndef TRANSLATE
# define TRANSLATE(d) \
  (translate ? (char) translate[(unsigned char) (d)] : (d))
#endif


/* Macros for outputting the compiled pattern into `buffer'.  */

/* If the buffer isn't allocated when it comes in, use this.  */
#define INIT_BUF_SIZE  32

/* Make sure we have at least N more bytes of space in buffer.  */
#define GET_BUFFER_SPACE(n)                     \
  while ((unsigned long) (b - bufp->buffer + (n)) > bufp->allocated)  \
  EXTEND_BUFFER ()

/* Make sure we have one more byte of buffer space and then add C to it.  */
#define BUF_PUSH(c)             \
{                             \
  GET_BUFFER_SPACE (1);       \
  *b++ = (unsigned char) (c); \
}


/* Ensure we have two more bytes of buffer space and then append C1 and C2.  */
#define BUF_PUSH_2(c1, c2)        \
{                               \
  GET_BUFFER_SPACE (2);         \
  *b++ = (unsigned char) (c1);  \
  *b++ = (unsigned char) (c2);  \
}


/* As with BUF_PUSH_2, except for three bytes.  */
#define BUF_PUSH_3(c1, c2, c3)    \
{                               \
  GET_BUFFER_SPACE (3);         \
  *b++ = (unsigned char) (c1);  \
  *b++ = (unsigned char) (c2);  \
  *b++ = (unsigned char) (c3);  \
}


/* Store a jump with opcode OP at LOC to location TO.  We store a
relative address offset by the three bytes the jump itself occupies.  */
#define STORE_JUMP(op, loc, to) \
  store_op1 (op, loc, (int) ((to) - (loc) - 3))

/* Likewise, for a two-argument jump.  */
#define STORE_JUMP2(op, loc, to, arg) \
  store_op2 (op, loc, (int) ((to) - (loc) - 3), arg)

/* Like `STORE_JUMP', but for inserting.  Assume `b' is the buffer end.  */
#define INSERT_JUMP(op, loc, to) \
  insert_op1 (op, loc, (int) ((to) - (loc) - 3), b)

/* Like `STORE_JUMP2', but for inserting.  Assume `b' is the buffer end.  */
#define INSERT_JUMP2(op, loc, to, arg) \
  insert_op2 (op, loc, (int) ((to) - (loc) - 3), arg, b)


/* This is not an arbitrary limit: the arguments which represent offsets
into the pattern are two bytes long.  So if 2^16 bytes turns out to
be too small, many things would have to change.  */
/* Any other compiler which, like MSC, has allocation limit below 2^16
bytes will have to use approach similar to what was done below for
MSC and drop MAX_BUF_SIZE a bit.  Otherwise you may end up
reallocating to 0 bytes.  Such thing is not going to work too well.
You have been warned!!  */
#if defined _MSC_VER  && !defined WIN32
/* Microsoft C 16-bit versions limit malloc to approx 65512 bytes.
The REALLOC define eliminates a flurry of conversion warnings,
but is not required. */
# define MAX_BUF_SIZE  65500L
# define REALLOC(p,s) realloc ((p), (size_t) (s))
#else
# define MAX_BUF_SIZE (1L << 16)
# define REALLOC(p,s) realloc ((p), (s))
#endif

/* Extend the buffer by twice its current size via realloc and
reset the pointers that pointed into the old block to point to the
correct places in the new one.  If extending the buffer results in it
being larger than MAX_BUF_SIZE, then flag memory exhausted.  */
#define EXTEND_BUFFER()                                                       \
{                                                                           \
  unsigned char *old_buffer = bufp->buffer;                                 \
  if (bufp->allocated == MAX_BUF_SIZE)                                      \
  return REG_ESIZE;                                                       \
  bufp->allocated <<= 1;                                                    \
  if (bufp->allocated > MAX_BUF_SIZE)                                       \
  bufp->allocated = MAX_BUF_SIZE;                                         \
  bufp->buffer = (unsigned char *) REALLOC (bufp->buffer, bufp->allocated); \
  if (bufp->buffer == NULL)                                                 \
  return REG_ESPACE;                                                      \
  /* If the buffer moved, move all the pointers into it.  */                \
  if (old_buffer != bufp->buffer)                                           \
{                                                                       \
  b = (b - old_buffer) + bufp->buffer;                                  \
  begalt = (begalt - old_buffer) + bufp->buffer;                        \
  if (fixup_alt_jump)                                                   \
  fixup_alt_jump = (fixup_alt_jump - old_buffer) + bufp->buffer;      \
  if (laststart)                                                        \
  laststart = (laststart - old_buffer) + bufp->buffer;                \
  if (pending_exact)                                                    \
  pending_exact = (pending_exact - old_buffer) + bufp->buffer;        \
}                                                                       \
}


/* Since we have one byte reserved for the register number argument to
{start,stop}_memory, the maximum number of groups we can report
things about is what fits in that byte.  */
#define MAX_REGNUM 255

/* But patterns can have more than `MAX_REGNUM' registers.  We just
ignore the excess.  */
typedef unsigned regnum_t;


/* Macros for the compile stack.  */

/* Since offsets can go either forwards or backwards, this type needs to
be able to hold values from -(MAX_BUF_SIZE - 1) to MAX_BUF_SIZE - 1.  */
/* int may be not enough when sizeof(int) == 2.  */
typedef long pattern_offset_t;

typedef struct
{
  pattern_offset_t begalt_offset;
  pattern_offset_t fixup_alt_jump;
  pattern_offset_t inner_group_offset;
  pattern_offset_t laststart_offset;
  regnum_t regnum;
} compile_stack_elt_t;


typedef struct
{
  compile_stack_elt_t *stack;
  unsigned size;
  unsigned avail;           /* Offset of next open position.  */
} compile_stack_type;


#define INIT_COMPILE_STACK_SIZE 32

#define COMPILE_STACK_EMPTY  (compile_stack.avail == 0)
#define COMPILE_STACK_FULL  (compile_stack.avail == compile_stack.size)

/* The next available element.  */
#define COMPILE_STACK_TOP (compile_stack.stack[compile_stack.avail])


/* Set the bit for character C in a list.  */
#define SET_LIST_BIT(c)                               \
  (b[((unsigned char) (c)) / BYTEWIDTH]               \
  |= 1 << (((unsigned char) c) % BYTEWIDTH))


/* Get the next unsigned number in the uncompiled pattern.  */
#define GET_UNSIGNED_NUMBER(num)                    \
{ if (p != pend)                          \
{                                  \
  PATFETCH (c);                            \
  while (ISDIGIT (c))                      \
{                              \
  if (num < 0)                         \
  num = 0;                          \
  num = num * 10 + c - '0';                    \
  if (p == pend)                       \
  break;                            \
  PATFETCH (c);                        \
}                              \
}                                \
}

#if defined _LIBC || WIDE_CHAR_SUPPORT
/* The GNU C library provides support for user-defined character classes
and the functions from ISO C amendement 1.  */
# ifdef CHARCLASS_NAME_MAX
#  define CHAR_CLASS_MAX_LENGTH CHARCLASS_NAME_MAX
# else
/* This shouldn't happen but some implementation might still have this
problem.  Use a reasonable default value.  */
#  define CHAR_CLASS_MAX_LENGTH 256
# endif

# ifdef _LIBC
#  define IS_CHAR_CLASS(string) __wctype (string)
# else
#  define IS_CHAR_CLASS(string) wctype (string)
# endif
#else
# define CHAR_CLASS_MAX_LENGTH  6 /* Namely, `xdigit'.  */

# define IS_CHAR_CLASS(string)                      \
  (STREQ (string, "alpha") || STREQ (string, "upper")          \
  || STREQ (string, "lower") || STREQ (string, "digit")       \
  || STREQ (string, "alnum") || STREQ (string, "xdigit")      \
  || STREQ (string, "space") || STREQ (string, "print")       \
  || STREQ (string, "punct") || STREQ (string, "graph")       \
  || STREQ (string, "cntrl") || STREQ (string, "blank"))
#endif

#ifndef MATCH_MAY_ALLOCATE

/* If we cannot allocate large objects within re_match_2_internal,
we make the fail stack and register vectors global.
The fail stack, we grow to the maximum size when a regexp
is compiled.
The register vectors, we adjust in size each time we
compile a regexp, according to the number of registers it needs.  */

static fail_stack_type fail_stack;

/* Size with which the following vectors are currently allocated.
That is so we can make them bigger as needed,
but never make them smaller.  */
static int regs_allocated_size;

static const char **     regstart, **     regend;
static const char ** old_regstart, ** old_regend;
static const char **best_regstart, **best_regend;
static register_info_type *reg_info;
static const char **reg_dummy;
static register_info_type *reg_info_dummy;

/* Make the register vectors big enough for NUM_REGS registers,
but don't make them smaller.  */

static
regex_grow_registers (num_regs)
int num_regs;
{
  if (num_regs > regs_allocated_size)
  {
    RETALLOC_IF (regstart,     num_regs, const char *);
    RETALLOC_IF (regend,   num_regs, const char *);
    RETALLOC_IF (old_regstart, num_regs, const char *);
    RETALLOC_IF (old_regend,   num_regs, const char *);
    RETALLOC_IF (best_regstart, num_regs, const char *);
    RETALLOC_IF (best_regend,  num_regs, const char *);
    RETALLOC_IF (reg_info,     num_regs, register_info_type);
    RETALLOC_IF (reg_dummy,    num_regs, const char *);
    RETALLOC_IF (reg_info_dummy, num_regs, register_info_type);

    regs_allocated_size = num_regs;
  }
}

#endif /* not MATCH_MAY_ALLOCATE */

static bool group_in_compile_stack(compile_stack_type compile_stack,
                                   regnum_t regnum);

/* `regex_compile' compiles PATTERN (of length SIZE) according to SYNTAX.
Returns one of error codes defined in `regex.h', or zero for success.

Assumes the `allocated' (and perhaps `buffer') and `translate'
fields are set in BUFP on entry.

If it succeeds, results are put in BUFP (if it returns an error, the
contents of BUFP are undefined):
`buffer' is the compiled pattern;
`syntax' is set to SYNTAX;
`used' is set to the length of the compiled pattern;
`fastmap_accurate' is zero;
`re_nsub' is the number of subexpressions in PATTERN;
`not_bol' and `not_eol' are zero;

The `fastmap' and `newline_anchor' fields are neither
examined nor set.  */

/* Return, freeing storage we allocated.  */
#define FREE_STACK_RETURN(value)        \
  return (free (compile_stack.stack), value)

static reg_errcode_t
regex_compile (const char *pattern,
               size_t size,
               reg_syntax_t syntax,
struct re_pattern_buffer *bufp)
{
  /* We fetch characters from PATTERN here.  Even though PATTERN is
  `char *' (i.e., signed), we declare these variables as unsigned, so
  they can be reliably used as array indices.  */
  register unsigned char c, c1;

  /* A random temporary spot in PATTERN.  */
  const char *p1;

  /* Points to the end of the buffer, where we should append.  */
  register unsigned char *b;

  /* Keeps track of unclosed groups.  */
  compile_stack_type compile_stack;

  /* Points to the current (ending) position in the pattern.  */
  const char *p = pattern;
  const char *pend = pattern + size;

  /* How to translate the characters in the pattern.  */
  RE_TRANSLATE_TYPE translate = bufp->translate;

  /* Address of the count-byte of the most recently inserted `exactn'
  command.  This makes it possible to tell if a new exact-match
  character can be added to that command or if the character requires
  a new `exactn' command.  */
  unsigned char *pending_exact = 0;

  /* Address of start of the most recently finished expression.
  This tells, e.g., postfix * where to find the start of its
  operand.  Reset at the beginning of groups and alternatives.  */
  unsigned char *laststart = 0;

  /* Address of beginning of regexp, or inside of last group.  */
  unsigned char *begalt;

  /* Place in the uncompiled pattern (i.e., the {) to
  which to go back if the interval is invalid.  */
  const char *beg_interval;

  /* Address of the place where a forward jump should go to the end of
  the containing expression.  Each alternative of an `or' -- except the
  last -- ends with a forward jump of this sort.  */
  unsigned char *fixup_alt_jump = 0;

  /* Counts open-groups as they are encountered.  Remembered for the
  matching close-group on the compile stack, so the same register
  number is put in the stop_memory as the start_memory.  */
  regnum_t regnum = 0;

  /* Initialize the compile stack.  */
  compile_stack.stack = TALLOC (INIT_COMPILE_STACK_SIZE, compile_stack_elt_t);
  if (compile_stack.stack == NULL)
    return REG_ESPACE;

  compile_stack.size = INIT_COMPILE_STACK_SIZE;
  compile_stack.avail = 0;

  /* Initialize the pattern buffer.  */
  bufp->syntax = syntax;
  bufp->fastmap_accurate = 0;
  bufp->not_bol = bufp->not_eol = 0;

  /* Set `used' to zero, so that if we return an error, the pattern
  printer (for debugging) will think there's no pattern.  We reset it
  at the end.  */
  bufp->used = 0;

  /* Always count groups, whether or not bufp->no_sub is set.  */
  bufp->re_nsub = 0;

#if !defined emacs && !defined SYNTAX_TABLE
  /* Initialize the syntax table.  */
  init_syntax_once ();
#endif

  if (bufp->allocated == 0)
  {
    if (bufp->buffer)
    { /* If zero allocated, but buffer is non-null, try to realloc
      enough space.  This loses if buffer's address is bogus, but
      that is the user's responsibility.  */
      RETALLOC (bufp->buffer, INIT_BUF_SIZE, unsigned char);
    }
    else
    { /* Caller did not allocate a buffer.  Do it for them.  */
      bufp->buffer = TALLOC (INIT_BUF_SIZE, unsigned char);
    }
    if (!bufp->buffer) FREE_STACK_RETURN (REG_ESPACE);

    bufp->allocated = INIT_BUF_SIZE;
  }

  begalt = b = bufp->buffer;

  /* Loop through the uncompiled pattern until we're at the end.  */
  while (p != pend)
  {
    PATFETCH (c);

    switch (c)
    {
    case '^':
      {
        if (   /* If at start of pattern, it's an operator.  */
          p == pattern + 1
          /* If context independent, it's an operator.  */
          || syntax & RE_CONTEXT_INDEP_ANCHORS
          /* Otherwise, depends on what's come before.  */
          || at_begline_loc_p (pattern, p, syntax))
        {
          BUF_PUSH (begline);
        }
        else
          goto normal_char;
      }
      break;


    case '$':
      {
        if (   /* If at end of pattern, it's an operator.  */
          p == pend
          /* If context independent, it's an operator.  */
          || syntax & RE_CONTEXT_INDEP_ANCHORS
          /* Otherwise, depends on what's next.  */
          || at_endline_loc_p (p, pend, syntax))
        {
          BUF_PUSH (endline);
        }
        else
          goto normal_char;
      }
      break;


    case '+':
    case '?':
      if ((syntax & RE_BK_PLUS_QM)
        || (syntax & RE_LIMITED_OPS))
        goto normal_char;
handle_plus:
    case '*':
      /* If there is no previous pattern... */
      if (!laststart)
      {
        if (syntax & RE_CONTEXT_INVALID_OPS)
          FREE_STACK_RETURN (REG_BADRPT);
        else if (!(syntax & RE_CONTEXT_INDEP_OPS))
          goto normal_char;
      }

      {
        /* Are we optimizing this jump?  */
        bool keep_string_p = false;

        /* 1 means zero (many) matches is allowed.  */
        char zero_times_ok = 0, many_times_ok = 0;

        /* If there is a sequence of repetition chars, collapse it
        down to just one (the right one).  We can't combine
        interval operators with these because of, e.g., `a{2}*',
        which should only match an even number of `a's.  */

        for (;;)
        {
          zero_times_ok |= c != '+';
          many_times_ok |= c != '?';

          if (p == pend)
            break;

          PATFETCH (c);

          if (c == '*'
            || (!(syntax & RE_BK_PLUS_QM) && (c == '+' || c == '?')))
            ;

          else if (syntax & RE_BK_PLUS_QM  &&  c == '\\')
          {
            if (p == pend) FREE_STACK_RETURN (REG_EESCAPE);

            PATFETCH (c1);
            if (!(c1 == '+' || c1 == '?'))
            {
              PATUNFETCH;
              PATUNFETCH;
              break;
            }

            c = c1;
          }
          else
          {
            PATUNFETCH;
            break;
          }

          /* If we get here, we found another repeat character.  */
        }

        /* Star, etc. applied to an empty pattern is equivalent
        to an empty pattern.  */
        if (!laststart)
          break;

        /* Now we know whether or not zero matches is allowed
        and also whether or not two or more matches is allowed.  */
        if (many_times_ok)
        { /* More than one repetition is allowed, so put in at the
          end a backward relative jump from `b' to before the next
          jump we're going to put in below (which jumps from
          laststart to after this jump).

          But if we are at the `*' in the exact sequence `.*\n',
          insert an unconditional jump backwards to the .,
          instead of the beginning of the loop.  This way we only
          push a failure point once, instead of every time
          through the loop.  */

          /* Allocate the space for the jump.  */
          GET_BUFFER_SPACE (3);

          /* We know we are not at the first character of the pattern,
          because laststart was nonzero.  And we've already
          incremented `p', by the way, to be the character after
          the `*'.  Do we have to do something analogous here
          for null bytes, because of RE_DOT_NOT_NULL?  */
          if (TRANSLATE (*(p - 2)) == TRANSLATE ('.')
            && zero_times_ok
            && p < pend && TRANSLATE (*p) == TRANSLATE ('\n')
            && !(syntax & RE_DOT_NEWLINE))
          { /* We have .*\n.  */
            STORE_JUMP (jump, b, laststart);
            keep_string_p = true;
          }
          else
            /* Anything else.  */
            STORE_JUMP (maybe_pop_jump, b, laststart - 3);

          /* We've added more stuff to the buffer.  */
          b += 3;
        }

        /* On failure, jump from laststart to b + 3, which will be the
        end of the buffer after this jump is inserted.  */
        GET_BUFFER_SPACE (3);
        INSERT_JUMP (keep_string_p ? on_failure_keep_string_jump
          : on_failure_jump,
          laststart, b + 3);
        pending_exact = 0;
        b += 3;

        if (!zero_times_ok)
        {
          /* At least one repetition is required, so insert a
          `dummy_failure_jump' before the initial
          `on_failure_jump' instruction of the loop. This
          effects a skip over that instruction the first time
          we hit that loop.  */
          GET_BUFFER_SPACE (3);
          INSERT_JUMP (dummy_failure_jump, laststart, laststart + 6);
          b += 3;
        }
      }
      break;


    case '.':
      laststart = b;
      BUF_PUSH (anychar);
      break;


    case '[':
      {
        bool had_char_class = false;

        if (p == pend) FREE_STACK_RETURN (REG_EBRACK);

        /* Ensure that we have enough space to push a charset: the
        opcode, the length count, and the bitset; 34 bytes in all.  */
        GET_BUFFER_SPACE (34);

        laststart = b;

        /* We test `*p == '^' twice, instead of using an if
        statement, so we only need one BUF_PUSH.  */
        BUF_PUSH (*p == '^' ? charset_not : charset);
        if (*p == '^')
          p++;

        /* Remember the first position in the bracket expression.  */
        p1 = p;

        /* Push the number of bytes in the bitmap.  */
        BUF_PUSH ((1 << BYTEWIDTH) / BYTEWIDTH);

        /* Clear the whole map.  */
        bzero (b, (1 << BYTEWIDTH) / BYTEWIDTH);

        /* charset_not matches newline according to a syntax bit.  */
        if ((re_opcode_t) b[-2] == charset_not
          && (syntax & RE_HAT_LISTS_NOT_NEWLINE))
          SET_LIST_BIT ('\n');

        /* Read in characters and ranges, setting map bits.  */
        for (;;)
        {
          if (p == pend) FREE_STACK_RETURN (REG_EBRACK);

          PATFETCH (c);

          /* \ might escape characters inside [...] and [^...].  */
          if ((syntax & RE_BACKSLASH_ESCAPE_IN_LISTS) && c == '\\')
          {
            if (p == pend) FREE_STACK_RETURN (REG_EESCAPE);

            PATFETCH (c1);
            SET_LIST_BIT (c1);
            continue;
          }

          /* Could be the end of the bracket expression.  If it's
          not (i.e., when the bracket expression is `[]' so
          far), the ']' character bit gets set way below.  */
          if (c == ']' && p != p1 + 1)
            break;

          /* Look ahead to see if it's a range when the last thing
          was a character class.  */
          if (had_char_class && c == '-' && *p != ']')
            FREE_STACK_RETURN (REG_ERANGE);

          /* Look ahead to see if it's a range when the last thing
          was a character: if this is a hyphen not at the
          beginning or the end of a list, then it's the range
          operator.  */
          if (c == '-'
            && !(p - 2 >= pattern && p[-2] == '[')
            && !(p - 3 >= pattern && p[-3] == '[' && p[-2] == '^')
            && *p != ']')
          {
            reg_errcode_t ret
              = compile_range (&p, pend, translate, syntax, b);
            if (ret != REG_NOERROR) FREE_STACK_RETURN (ret);
          }

          else if (p[0] == '-' && p[1] != ']')
          { /* This handles ranges made up of characters only.  */
            reg_errcode_t ret;

            /* Move past the `-'.  */
            PATFETCH (c1);

            ret = compile_range (&p, pend, translate, syntax, b);
            if (ret != REG_NOERROR) FREE_STACK_RETURN (ret);
          }

          /* See if we're at the beginning of a possible character
          class.  */

          else if (syntax & RE_CHAR_CLASSES && c == '[' && *p == ':')
          { /* Leave room for the null.  */
            char str[CHAR_CLASS_MAX_LENGTH + 1];

            PATFETCH (c);
            c1 = 0;

            /* If pattern is `[[:'.  */
            if (p == pend) FREE_STACK_RETURN (REG_EBRACK);

            for (;;)
            {
              PATFETCH (c);
              if ((c == ':' && *p == ']') || p == pend)
                break;
              if (c1 < CHAR_CLASS_MAX_LENGTH)
                str[c1++] = c;
              else
                /* This is in any case an invalid class name.  */
                str[0] = '\0';
            }
            str[c1] = '\0';

            /* If isn't a word bracketed by `[:' and `:]':
            undo the ending character, the letters, and leave
            the leading `:' and `[' (but set bits for them).  */
            if (c == ':' && *p == ']')
            {
#if defined _LIBC || WIDE_CHAR_SUPPORT
              bool is_lower = STREQ (str, "lower");
              bool is_upper = STREQ (str, "upper");
              wctype_t wt;
              int ch;

              wt = IS_CHAR_CLASS (str);
              if (wt == 0)
                FREE_STACK_RETURN (REG_ECTYPE);

              /* Throw away the ] at the end of the character
              class.  */
              PATFETCH (c);

              if (p == pend) FREE_STACK_RETURN (REG_EBRACK);

              for (ch = 0; ch < 1 << BYTEWIDTH; ++ch)
              {
# ifdef _LIBC
                if (__iswctype (__btowc (ch), wt))
                  SET_LIST_BIT (ch);
# else
                if (iswctype (btowc (ch), wt))
                  SET_LIST_BIT (ch);
# endif

                if (translate && (is_upper || is_lower)
                  && (ISUPPER (ch) || ISLOWER (ch)))
                  SET_LIST_BIT (ch);
              }

              had_char_class = true;
#else
              int ch;
              bool is_alnum = STREQ (str, "alnum");
              bool is_alpha = STREQ (str, "alpha");
              bool is_blank = STREQ (str, "blank");
              bool is_cntrl = STREQ (str, "cntrl");
              bool is_digit = STREQ (str, "digit");
              bool is_graph = STREQ (str, "graph");
              bool is_lower = STREQ (str, "lower");
              bool is_print = STREQ (str, "print");
              bool is_punct = STREQ (str, "punct");
              bool is_space = STREQ (str, "space");
              bool is_upper = STREQ (str, "upper");
              bool is_xdigit = STREQ (str, "xdigit");

              if (!IS_CHAR_CLASS (str))
                FREE_STACK_RETURN (REG_ECTYPE);

              /* Throw away the ] at the end of the character
              class.  */
              PATFETCH (c);

              if (p == pend) FREE_STACK_RETURN (REG_EBRACK);

              for (ch = 0; ch < 1 << BYTEWIDTH; ch++)
              {
                /* This was split into 3 if's to
                avoid an arbitrary limit in some compiler.  */
                if (   (is_alnum  && ISALNUM (ch))
                  || (is_alpha  && ISALPHA (ch))
                  || (is_blank  && ISBLANK (ch))
                  || (is_cntrl  && ISCNTRL (ch)))
                  SET_LIST_BIT (ch);
                if (   (is_digit  && ISDIGIT (ch))
                  || (is_graph  && ISGRAPH (ch))
                  || (is_lower  && ISLOWER (ch))
                  || (is_print  && ISPRINT (ch)))
                  SET_LIST_BIT (ch);
                if (   (is_punct  && ISPUNCT (ch))
                  || (is_space  && ISSPACE (ch))
                  || (is_upper  && ISUPPER (ch))
                  || (is_xdigit && ISXDIGIT (ch)))
                  SET_LIST_BIT (ch);
                if (   translate && (is_upper || is_lower)
                  && (ISUPPER (ch) || ISLOWER (ch)))
                  SET_LIST_BIT (ch);
              }
              had_char_class = true;
#endif  /* libc || wctype.h */
            }
            else
            {
              c1++;
              while (c1--)
                PATUNFETCH;
              SET_LIST_BIT ('[');
              SET_LIST_BIT (':');
              had_char_class = false;
            }
          }
          else
          {
            had_char_class = false;
            SET_LIST_BIT (c);
          }
        }

        /* Discard any (non)matching list bytes that are all 0 at the
        end of the map.  Decrease the map-length byte too.  */
        while ((int) b[-1] > 0 && b[b[-1] - 1] == 0)
          b[-1]--;
        b += b[-1];
      }
      break;


    case '(':
      if (syntax & RE_NO_BK_PARENS)
        goto handle_open;
      else
        goto normal_char;


    case ')':
      if (syntax & RE_NO_BK_PARENS)
        goto handle_close;
      else
        goto normal_char;


    case '\n':
      if (syntax & RE_NEWLINE_ALT)
        goto handle_alt;
      else
        goto normal_char;


    case '|':
      if (syntax & RE_NO_BK_VBAR)
        goto handle_alt;
      else
        goto normal_char;


    case '{':
      if (syntax & RE_INTERVALS && syntax & RE_NO_BK_BRACES)
        goto handle_interval;
      else
        goto normal_char;


    case '\\':
      if (p == pend) FREE_STACK_RETURN (REG_EESCAPE);

      /* Do not translate the character after the \, so that we can
      distinguish, e.g., \B from \b, even if we normally would
      translate, e.g., B to b.  */
      PATFETCH_RAW (c);

      switch (c)
      {
      case '(':
        if (syntax & RE_NO_BK_PARENS)
          goto normal_backslash;

handle_open:
        bufp->re_nsub++;
        regnum++;

        if (COMPILE_STACK_FULL)
        {
          RETALLOC (compile_stack.stack, compile_stack.size << 1,
            compile_stack_elt_t);
          if (compile_stack.stack == NULL) return REG_ESPACE;

          compile_stack.size <<= 1;
        }

        /* These are the values to restore when we hit end of this
        group.  They are all relative offsets, so that if the
        whole pattern moves because of realloc, they will still
        be valid.  */
        COMPILE_STACK_TOP.begalt_offset = begalt - bufp->buffer;
        COMPILE_STACK_TOP.fixup_alt_jump
          = fixup_alt_jump ? fixup_alt_jump - bufp->buffer + 1 : 0;
        COMPILE_STACK_TOP.laststart_offset = b - bufp->buffer;
        COMPILE_STACK_TOP.regnum = regnum;

        /* We will eventually replace the 0 with the number of
        groups inner to this one.  But do not push a
        start_memory for groups beyond the last one we can
        represent in the compiled pattern.  */
        if (regnum <= MAX_REGNUM)
        {
          COMPILE_STACK_TOP.inner_group_offset = b - bufp->buffer + 2;
          BUF_PUSH_3 (start_memory, regnum, 0);
        }

        compile_stack.avail++;

        fixup_alt_jump = 0;
        laststart = 0;
        begalt = b;
        /* If we've reached MAX_REGNUM groups, then this open
        won't actually generate any code, so we'll have to
        clear pending_exact explicitly.  */
        pending_exact = 0;
        break;


      case ')':
        if (syntax & RE_NO_BK_PARENS) goto normal_backslash;

        if (COMPILE_STACK_EMPTY)
        {
          if (syntax & RE_UNMATCHED_RIGHT_PAREN_ORD)
            goto normal_backslash;
          else
            FREE_STACK_RETURN (REG_ERPAREN);
        }

handle_close:
        if (fixup_alt_jump)
        { /* Push a dummy failure point at the end of the
          alternative for a possible future
          `pop_failure_jump' to pop.  See comments at
          `push_dummy_failure' in `re_match_2'.  */
          BUF_PUSH (push_dummy_failure);

          /* We allocated space for this jump when we assigned
          to `fixup_alt_jump', in the `handle_alt' case below.  */
          STORE_JUMP (jump_past_alt, fixup_alt_jump, b - 1);
        }

        /* See similar code for backslashed left paren above.  */
        if (COMPILE_STACK_EMPTY)
        {
          if (syntax & RE_UNMATCHED_RIGHT_PAREN_ORD)
            goto normal_char;
          else
            FREE_STACK_RETURN (REG_ERPAREN);
        }

        {
          /* We don't just want to restore into `regnum', because
          later groups should continue to be numbered higher,
          as in `(ab)c(de)' -- the second group is #2.  */
          regnum_t this_group_regnum;

          compile_stack.avail--;
          begalt = bufp->buffer + COMPILE_STACK_TOP.begalt_offset;
          fixup_alt_jump
            = COMPILE_STACK_TOP.fixup_alt_jump
            ? bufp->buffer + COMPILE_STACK_TOP.fixup_alt_jump - 1
            : 0;
          laststart = bufp->buffer + COMPILE_STACK_TOP.laststart_offset;
          this_group_regnum = COMPILE_STACK_TOP.regnum;
          /* If we've reached MAX_REGNUM groups, then this open
          won't actually generate any code, so we'll have to
          clear pending_exact explicitly.  */
          pending_exact = 0;

          /* We're at the end of the group, so now we know how many
          groups were inside this one.  */
          if (this_group_regnum <= MAX_REGNUM)
          {
            unsigned char *inner_group_loc
              = bufp->buffer + COMPILE_STACK_TOP.inner_group_offset;

            *inner_group_loc = regnum - this_group_regnum;
            BUF_PUSH_3 (stop_memory, this_group_regnum,
              regnum - this_group_regnum);
          }
        }
        break;


      case '|':                   /* `\|'.  */
        if (syntax & RE_LIMITED_OPS || syntax & RE_NO_BK_VBAR)
          goto normal_backslash;
handle_alt:
        if (syntax & RE_LIMITED_OPS)
          goto normal_char;

        /* Insert before the previous alternative a jump which
        jumps to this alternative if the former fails.  */
        GET_BUFFER_SPACE (3);
        INSERT_JUMP (on_failure_jump, begalt, b + 6);
        pending_exact = 0;
        b += 3;

        /* The alternative before this one has a jump after it
        which gets executed if it gets matched.  Adjust that
        jump so it will jump to this alternative's analogous
        jump (put in below, which in turn will jump to the next
        (if any) alternative's such jump, etc.).  The last such
        jump jumps to the correct final destination.  A picture:
        _____ _____
        |   | |   |
        |   v |   v
        a | b   | c

        If we are at `b', then fixup_alt_jump right now points to a
        three-byte space after `a'.  We'll put in the jump, set
        fixup_alt_jump to right after `b', and leave behind three
        bytes which we'll fill in when we get to after `c'.  */

        if (fixup_alt_jump)
          STORE_JUMP (jump_past_alt, fixup_alt_jump, b);

        /* Mark and leave space for a jump after this alternative,
        to be filled in later either by next alternative or
        when know we're at the end of a series of alternatives.  */
        fixup_alt_jump = b;
        GET_BUFFER_SPACE (3);
        b += 3;

        laststart = 0;
        begalt = b;
        break;


      case '{':
        /* If \{ is a literal.  */
        if (!(syntax & RE_INTERVALS)
          /* If we're at `\{' and it's not the open-interval
          operator.  */
          || ((syntax & RE_INTERVALS) && (syntax & RE_NO_BK_BRACES))
          || (p - 2 == pattern  &&  p == pend))
          goto normal_backslash;

handle_interval:
        {
          /* If got here, then the syntax allows intervals.  */

          /* At least (most) this many matches must be made.  */
          int lower_bound = -1, upper_bound = -1;

          beg_interval = p - 1;

          if (p == pend)
          {
            if (syntax & RE_NO_BK_BRACES)
              goto unfetch_interval;
            else
              FREE_STACK_RETURN (REG_EBRACE);
          }

          GET_UNSIGNED_NUMBER (lower_bound);

          if (c == ',')
          {
            GET_UNSIGNED_NUMBER (upper_bound);
            if (upper_bound < 0) upper_bound = RE_DUP_MAX;
          }
          else
            /* Interval such as `{1}' => match exactly once. */
            upper_bound = lower_bound;

          if (lower_bound < 0 || upper_bound > RE_DUP_MAX
            || lower_bound > upper_bound)
          {
            if (syntax & RE_NO_BK_BRACES)
              goto unfetch_interval;
            else
              FREE_STACK_RETURN (REG_BADBR);
          }

          if (!(syntax & RE_NO_BK_BRACES))
          {
            if (c != '\\') FREE_STACK_RETURN (REG_EBRACE);

            PATFETCH (c);
          }

          if (c != '}')
          {
            if (syntax & RE_NO_BK_BRACES)
              goto unfetch_interval;
            else
              FREE_STACK_RETURN (REG_BADBR);
          }

          /* We just parsed a valid interval.  */

          /* If it's invalid to have no preceding re.  */
          if (!laststart)
          {
            if (syntax & RE_CONTEXT_INVALID_OPS)
              FREE_STACK_RETURN (REG_BADRPT);
            else if (syntax & RE_CONTEXT_INDEP_OPS)
              laststart = b;
            else
              goto unfetch_interval;
          }

          /* If the upper bound is zero, don't want to succeed at
          all; jump from `laststart' to `b + 3', which will be
          the end of the buffer after we insert the jump.  */
          if (upper_bound == 0)
          {
            GET_BUFFER_SPACE (3);
            INSERT_JUMP (jump, laststart, b + 3);
            b += 3;
          }

          /* Otherwise, we have a nontrivial interval.  When
          we're all done, the pattern will look like:
          set_number_at <jump count> <upper bound>
          set_number_at <succeed_n count> <lower bound>
          succeed_n <after jump addr> <succeed_n count>
          <body of loop>
          jump_n <succeed_n addr> <jump count>
          (The upper bound and `jump_n' are omitted if
          `upper_bound' is 1, though.)  */
          else
          { /* If the upper bound is > 1, we need to insert
            more at the end of the loop.  */
            unsigned nbytes = 10 + (upper_bound > 1) * 10;

            GET_BUFFER_SPACE (nbytes);

            /* Initialize lower bound of the `succeed_n', even
            though it will be set during matching by its
            attendant `set_number_at' (inserted next),
            because `re_compile_fastmap' needs to know.
            Jump to the `jump_n' we might insert below.  */
            INSERT_JUMP2 (succeed_n, laststart,
              b + 5 + (upper_bound > 1) * 5,
              lower_bound);
            b += 5;

            /* Code to initialize the lower bound.  Insert
            before the `succeed_n'.  The `5' is the last two
            bytes of this `set_number_at', plus 3 bytes of
            the following `succeed_n'.  */
            insert_op2 (set_number_at, laststart, 5, lower_bound, b);
            b += 5;

            if (upper_bound > 1)
            { /* More than one repetition is allowed, so
              append a backward jump to the `succeed_n'
              that starts this interval.

              When we've reached this during matching,
              we'll have matched the interval once, so
              jump back only `upper_bound - 1' times.  */
              STORE_JUMP2 (jump_n, b, laststart + 5,
                upper_bound - 1);
              b += 5;

              /* The location we want to set is the second
              parameter of the `jump_n'; that is `b-2' as
              an absolute address.  `laststart' will be
              the `set_number_at' we're about to insert;
              `laststart+3' the number to set, the source
              for the relative address.  But we are
              inserting into the middle of the pattern --
              so everything is getting moved up by 5.
              Conclusion: (b - 2) - (laststart + 3) + 5,
              i.e., b - laststart.

              We insert this at the beginning of the loop
              so that if we fail during matching, we'll
              reinitialize the bounds.  */
              insert_op2 (set_number_at, laststart, b - laststart,
                upper_bound - 1, b);
              b += 5;
            }
          }
          pending_exact = 0;
          beg_interval = NULL;
        }
        break;

unfetch_interval:
        /* If an invalid interval, match the characters as literals.  */
        p = beg_interval;
        beg_interval = NULL;

        /* normal_char and normal_backslash need `c'.  */
        PATFETCH (c);

        if (!(syntax & RE_NO_BK_BRACES))
        {
          if (p > pattern  &&  p[-1] == '\\')
            goto normal_backslash;
        }
        goto normal_char;

#ifdef emacs
        /* There is no way to specify the before_dot and after_dot
        operators.  rms says this is ok.  --karl  */
      case '=':
        BUF_PUSH (at_dot);
        break;

      case 's':
        laststart = b;
        PATFETCH (c);
        BUF_PUSH_2 (syntaxspec, syntax_spec_code[c]);
        break;

      case 'S':
        laststart = b;
        PATFETCH (c);
        BUF_PUSH_2 (notsyntaxspec, syntax_spec_code[c]);
        break;
#endif /* emacs */


      case 'w':
        if (syntax & RE_NO_GNU_OPS)
          goto normal_char;
        laststart = b;
        BUF_PUSH (wordchar);
        break;


      case 'W':
        if (syntax & RE_NO_GNU_OPS)
          goto normal_char;
        laststart = b;
        BUF_PUSH (notwordchar);
        break;


      case '<':
        if (syntax & RE_NO_GNU_OPS)
          goto normal_char;
        BUF_PUSH (wordbeg);
        break;

      case '>':
        if (syntax & RE_NO_GNU_OPS)
          goto normal_char;
        BUF_PUSH (wordend);
        break;

      case 'b':
        if (syntax & RE_NO_GNU_OPS)
          goto normal_char;
        BUF_PUSH (wordbound);
        break;

      case 'B':
        if (syntax & RE_NO_GNU_OPS)
          goto normal_char;
        BUF_PUSH (notwordbound);
        break;

      case '`':
        if (syntax & RE_NO_GNU_OPS)
          goto normal_char;
        BUF_PUSH (begbuf);
        break;

      case '\'':
        if (syntax & RE_NO_GNU_OPS)
          goto normal_char;
        BUF_PUSH (endbuf);
        break;

      case '1': case '2': case '3': case '4': case '5':
      case '6': case '7': case '8': case '9':
        if (syntax & RE_NO_BK_REFS)
          goto normal_char;

        c1 = c - '0';

        if (c1 > regnum)
          FREE_STACK_RETURN (REG_ESUBREG);

        /* Can't back reference to a subexpression if inside of it.  */
        if (group_in_compile_stack (compile_stack, (regnum_t) c1))
          goto normal_char;

        laststart = b;
        BUF_PUSH_2 (duplicate, c1);
        break;


      case '+':
      case '?':
        if (syntax & RE_BK_PLUS_QM)
          goto handle_plus;
        else
          goto normal_backslash;

      default:
normal_backslash:
        /* You might think it would be useful for \ to mean
        not to translate; but if we don't translate it
        it will never match anything.  */
        c = TRANSLATE (c);
        goto normal_char;
      }
      break;


    default:
      /* Expects the character in `c'.  */
normal_char:
      /* If no exactn currently being built.  */
      if (!pending_exact

        /* If last exactn not at current position.  */
        || pending_exact + *pending_exact + 1 != b

        /* We have only one byte following the exactn for the count.  */
        || *pending_exact == (1 << BYTEWIDTH) - 1

        /* If followed by a repetition operator.  */
        || *p == '*' || *p == '^'
        || ((syntax & RE_BK_PLUS_QM)
        ? *p == '\\' && (p[1] == '+' || p[1] == '?')
        : (*p == '+' || *p == '?'))
        || ((syntax & RE_INTERVALS)
        && ((syntax & RE_NO_BK_BRACES)
        ? *p == '{'
        : (p[0] == '\\' && p[1] == '{'))))
      {
        /* Start building a new exactn.  */

        laststart = b;

        BUF_PUSH_2 (exactn, 0);
        pending_exact = b - 1;
      }

      BUF_PUSH (c);
      (*pending_exact)++;
      break;
    } /* switch (c) */
  } /* while p != pend */


  /* Through the pattern now.  */

  if (fixup_alt_jump)
    STORE_JUMP (jump_past_alt, fixup_alt_jump, b);

  if (!COMPILE_STACK_EMPTY)
    FREE_STACK_RETURN (REG_EPAREN);

  /* If we don't want backtracking, force success
  the first time we reach the end of the compiled pattern.  */
  if (syntax & RE_NO_POSIX_BACKTRACKING)
    BUF_PUSH (succeed);

  free (compile_stack.stack);

  /* We have succeeded; set the length of the buffer.  */
  bufp->used = b - bufp->buffer;

#ifndef MATCH_MAY_ALLOCATE
  /* Initialize the failure stack to the largest possible stack.  This
  isn't necessary unless we're trying to avoid calling alloca in
  the search and match routines.  */
  {
    int num_regs = bufp->re_nsub + 1;

    /* Since DOUBLE_FAIL_STACK refuses to double only if the current size
    is strictly greater than re_max_failures, the largest possible stack
    is 2 * re_max_failures failure points.  */
    if (fail_stack.size < (2 * re_max_failures * MAX_FAILURE_ITEMS))
    {
      fail_stack.size = (2 * re_max_failures * MAX_FAILURE_ITEMS);

# ifdef emacs
      if (! fail_stack.stack)
        fail_stack.stack
        = (fail_stack_elt_t *) xmalloc (fail_stack.size
        * sizeof (fail_stack_elt_t));
      else
        fail_stack.stack
        = (fail_stack_elt_t *) xrealloc (fail_stack.stack,
        (fail_stack.size
        * sizeof (fail_stack_elt_t)));
# else /* not emacs */
      if (! fail_stack.stack)
        fail_stack.stack
        = (fail_stack_elt_t *) malloc (fail_stack.size
        * sizeof (fail_stack_elt_t));
      else
        fail_stack.stack
        = (fail_stack_elt_t *) realloc (fail_stack.stack,
        (fail_stack.size
        * sizeof (fail_stack_elt_t)));
# endif /* not emacs */
    }

    regex_grow_registers (num_regs);
  }
#endif /* not MATCH_MAY_ALLOCATE */

  return REG_NOERROR;
} /* regex_compile */

/* Subroutines for `regex_compile'.  */

/* Store OP at LOC followed by two-byte integer parameter ARG.  */

static void
store_op1 (re_opcode_t op,
           unsigned char *loc,
           int arg)
{
  *loc = (unsigned char) op;
  STORE_NUMBER (loc + 1, arg);
}


/* Like `store_op1', but for two two-byte parameters ARG1 and ARG2.  */

static void
store_op2 (re_opcode_t op,
           unsigned char *loc,
           int arg1,
           int arg2)
{
  *loc = (unsigned char) op;
  STORE_NUMBER (loc + 1, arg1);
  STORE_NUMBER (loc + 3, arg2);
}


/* Copy the bytes from LOC to END to open up three bytes of space at LOC
for OP followed by two-byte integer parameter ARG.  */

static void
insert_op1 (re_opcode_t op,
            unsigned char *loc,
            int arg,
            unsigned char *end)
{
  register unsigned char *pfrom = end;
  register unsigned char *pto = end + 3;

  while (pfrom != loc)
    *--pto = *--pfrom;

  store_op1 (op, loc, arg);
}


/* Like `insert_op1', but for two two-byte parameters ARG1 and ARG2.  */

static void
insert_op2 (re_opcode_t op,
            unsigned char *loc,
            int arg1,
            int arg2,
            unsigned char *end)
{
  register unsigned char *pfrom = end;
  register unsigned char *pto = end + 5;

  while (pfrom != loc)
    *--pto = *--pfrom;

  store_op2 (op, loc, arg1, arg2);
}


/* P points to just after a ^ in PATTERN.  Return true if that ^ comes
after an alternative or a begin-subexpression.  We assume there is at
least one character before the ^.  */

static bool
at_begline_loc_p (const char *pattern,
                  const char *p,
                  reg_syntax_t syntax)
{
  const char *prev = p - 2;
  bool prev_prev_backslash = prev > pattern && prev[-1] == '\\';

  return
    /* After a subexpression?  */
    (*prev == '(' && (syntax & RE_NO_BK_PARENS || prev_prev_backslash))
    /* After an alternative?  */
    || (*prev == '|' && (syntax & RE_NO_BK_VBAR || prev_prev_backslash));
}


/* The dual of at_begline_loc_p.  This one is for $.  We assume there is
at least one character after the $, i.e., `P < PEND'.  */

static bool
at_endline_loc_p (const char *p,
                  const char *pend,
                  reg_syntax_t syntax)
{
  const char *next = p;
  bool next_backslash = *next == '\\';
  const char *next_next = p + 1 < pend ? p + 1 : 0;

  return
    /* Before a subexpression?  */
    (syntax & RE_NO_BK_PARENS ? *next == ')'
    : next_backslash && next_next && *next_next == ')')
    /* Before an alternative?  */
    || (syntax & RE_NO_BK_VBAR ? *next == '|'
    : next_backslash && next_next && *next_next == '|');
}


/* Returns true if REGNUM is in one of COMPILE_STACK's elements and
false if it's not.  */

static bool
group_in_compile_stack (compile_stack_type compile_stack,
                        regnum_t regnum)
{
  int this_element;

  for (this_element = compile_stack.avail - 1;
    this_element >= 0;
    this_element--)
    if (compile_stack.stack[this_element].regnum == regnum)
      return true;

  return false;
}


/* Read the ending character of a range (in a bracket expression) from the
uncompiled pattern *P_PTR (which ends at PEND).  We assume the
starting character is in `P[-2]'.  (`P[-1]' is the character `-'.)
Then we set the translation of all bits between the starting and
ending characters (inclusive) in the compiled pattern B.

Return an error code.

We use these short variable names so we can use the same macros as
`regex_compile' itself.  */

static reg_errcode_t
compile_range (const char **p_ptr,
               const char *pend,
               RE_TRANSLATE_TYPE translate,
               reg_syntax_t syntax,
               unsigned char *b)
{
  unsigned this_char;

  const char *p = *p_ptr;
  unsigned int range_start, range_end;

  if (p == pend)
    return REG_ERANGE;

  /* Even though the pattern is a signed `char *', we need to fetch
  with unsigned char *'s; if the high bit of the pattern character
  is set, the range endpoints will be negative if we fetch using a
  signed char *.

  We also want to fetch the endpoints without translating them; the
  appropriate translation is done in the bit-setting loop below.  */
  /* The SVR4 compiler on the 3B2 had trouble with unsigned const char *.  */
  range_start = ((const unsigned char *) p)[-2];
  range_end   = ((const unsigned char *) p)[0];

  /* Have to increment the pointer into the pattern string, so the
  caller isn't still at the ending character.  */
  (*p_ptr)++;

  /* If the start is after the end, the range is empty.  */
  if (range_start > range_end)
    return syntax & RE_NO_EMPTY_RANGES ? REG_ERANGE : REG_NOERROR;

  /* Here we see why `this_char' has to be larger than an `unsigned
  char' -- the range is inclusive, so if `range_end' == 0xff
  (assuming 8-bit characters), we would otherwise go into an infinite
  loop, since all characters <= 0xff.  */
  for (this_char = range_start; this_char <= range_end; this_char++)
  {
    SET_LIST_BIT (TRANSLATE (this_char));
  }

  return REG_NOERROR;
}

/* re_compile_fastmap computes a ``fastmap'' for the compiled pattern in
BUFP.  A fastmap records which of the (1 << BYTEWIDTH) possible
characters can start a string that matches the pattern.  This fastmap
is used by re_search to skip quickly over impossible starting points.

The caller must supply the address of a (1 << BYTEWIDTH)-byte data
area as BUFP->fastmap.

We set the `fastmap', `fastmap_accurate', and `can_be_null' fields in
the pattern buffer.

Returns 0 if we succeed, -2 if an internal error.   */

int
re_compile_fastmap (struct re_pattern_buffer *bufp)
{
  int j, k;
#ifdef MATCH_MAY_ALLOCATE
  fail_stack_type fail_stack;
#endif
#ifndef REGEX_MALLOC
  char *destination;
#endif

  register char *fastmap = bufp->fastmap;
  unsigned char *pattern = bufp->buffer;
  unsigned char *p = pattern;
  register unsigned char *pend = pattern + bufp->used;

#ifdef REL_ALLOC
  /* This holds the pointer to the failure stack, when
  it is allocated relocatably.  */
  fail_stack_elt_t *failure_stack_ptr;
#endif

  /* Assume that each path through the pattern can be null until
  proven otherwise.  We set this false at the bottom of switch
  statement, to which we get only if a particular path doesn't
  match the empty string.  */
  bool path_can_be_null = true;

  /* We aren't doing a `succeed_n' to begin with.  */
  bool succeed_n_p = false;

  INIT_FAIL_STACK ();
  bzero (fastmap, 1 << BYTEWIDTH);  /* Assume nothing's valid.  */
  bufp->fastmap_accurate = 1;       /* It will be when we're done.  */
  bufp->can_be_null = 0;

  while (true)
  {
    if (p == pend || *p == succeed)
    {
      /* We have reached the (effective) end of pattern.  */
      if (!FAIL_STACK_EMPTY ())
      {
        bufp->can_be_null |= path_can_be_null;

        /* Reset for next path.  */
        path_can_be_null = true;

        p = fail_stack.stack[--fail_stack.avail].pointer;

        continue;
      }
      else
        break;
    }

    switch (SWITCH_ENUM_CAST ((re_opcode_t) *p++))
    {

      /* I guess the idea here is to simply not bother with a fastmap
      if a backreference is used, since it's too hard to figure out
      the fastmap for the corresponding group.  Setting
      `can_be_null' stops `re_search_2' from using the fastmap, so
      that is all we do.  */
    case duplicate:
      bufp->can_be_null = 1;
      goto done;


      /* Following are the cases which match a character.  These end
      with `break'.  */

    case exactn:
      fastmap[p[1]] = 1;
      break;


    case charset:
      for (j = *p++ * BYTEWIDTH - 1; j >= 0; j--)
        if (p[j / BYTEWIDTH] & (1 << (j % BYTEWIDTH)))
          fastmap[j] = 1;
      break;


    case charset_not:
      /* Chars beyond end of map must be allowed.  */
      for (j = *p * BYTEWIDTH; j < (1 << BYTEWIDTH); j++)
        fastmap[j] = 1;

      for (j = *p++ * BYTEWIDTH - 1; j >= 0; j--)
        if (!(p[j / BYTEWIDTH] & (1 << (j % BYTEWIDTH))))
          fastmap[j] = 1;
      break;


    case wordchar:
      for (j = 0; j < (1 << BYTEWIDTH); j++)
        if (SYNTAX (j) == Sword)
          fastmap[j] = 1;
      break;


    case notwordchar:
      for (j = 0; j < (1 << BYTEWIDTH); j++)
        if (SYNTAX (j) != Sword)
          fastmap[j] = 1;
      break;


    case anychar:
      {
        int fastmap_newline = fastmap['\n'];

        /* `.' matches anything ...  */
        for (j = 0; j < (1 << BYTEWIDTH); j++)
          fastmap[j] = 1;

        /* ... except perhaps newline.  */
        if (!(bufp->syntax & RE_DOT_NEWLINE))
          fastmap['\n'] = fastmap_newline;

        /* Return if we have already set `can_be_null'; if we have,
        then the fastmap is irrelevant.  Something's wrong here.  */
        else if (bufp->can_be_null)
          goto done;

        /* Otherwise, have to check alternative paths.  */
        break;
      }

#ifdef emacs
    case syntaxspec:
      k = *p++;
      for (j = 0; j < (1 << BYTEWIDTH); j++)
        if (SYNTAX (j) == (enum syntaxcode) k)
          fastmap[j] = 1;
      break;


    case notsyntaxspec:
      k = *p++;
      for (j = 0; j < (1 << BYTEWIDTH); j++)
        if (SYNTAX (j) != (enum syntaxcode) k)
          fastmap[j] = 1;
      break;


      /* All cases after this match the empty string.  These end with
      `continue'.  */


    case before_dot:
    case at_dot:
    case after_dot:
      continue;
#endif /* emacs */


    case no_op:
    case begline:
    case endline:
    case begbuf:
    case endbuf:
    case wordbound:
    case notwordbound:
    case wordbeg:
    case wordend:
    case push_dummy_failure:
      continue;


    case jump_n:
    case pop_failure_jump:
    case maybe_pop_jump:
    case jump:
    case jump_past_alt:
    case dummy_failure_jump:
      EXTRACT_NUMBER_AND_INCR (j, p);
      p += j;
      if (j > 0)
        continue;

      /* Jump backward implies we just went through the body of a
      loop and matched nothing.  Opcode jumped to should be
      `on_failure_jump' or `succeed_n'.  Just treat it like an
      ordinary jump.  For a * loop, it has pushed its failure
      point already; if so, discard that as redundant.  */
      if ((re_opcode_t) *p != on_failure_jump
        && (re_opcode_t) *p != succeed_n)
        continue;

      p++;
      EXTRACT_NUMBER_AND_INCR (j, p);
      p += j;

      /* If what's on the stack is where we are now, pop it.  */
      if (!FAIL_STACK_EMPTY ()
        && fail_stack.stack[fail_stack.avail - 1].pointer == p)
        fail_stack.avail--;

      continue;


    case on_failure_jump:
    case on_failure_keep_string_jump:
handle_on_failure_jump:
      EXTRACT_NUMBER_AND_INCR (j, p);

      /* For some patterns, e.g., `(a?)?', `p+j' here points to the
      end of the pattern.  We don't want to push such a point,
      since when we restore it above, entering the switch will
      increment `p' past the end of the pattern.  We don't need
      to push such a point since we obviously won't find any more
      fastmap entries beyond `pend'.  Such a pattern can match
      the null string, though.  */
      if (p + j < pend)
      {
        if (!PUSH_PATTERN_OP (p + j, fail_stack))
        {
          RESET_FAIL_STACK ();
          return -2;
        }
      }
      else
        bufp->can_be_null = 1;

      if (succeed_n_p)
      {
        EXTRACT_NUMBER_AND_INCR (k, p);   /* Skip the n.  */
        succeed_n_p = false;
      }

      continue;


    case succeed_n:
      /* Get to the number of times to succeed.  */
      p += 2;

      /* Increment p past the n for when k != 0.  */
      EXTRACT_NUMBER_AND_INCR (k, p);
      if (k == 0)
      {
        p -= 4;
        succeed_n_p = true;  /* Spaghetti code alert.  */
        goto handle_on_failure_jump;
      }
      continue;


    case set_number_at:
      p += 4;
      continue;


    case start_memory:
    case stop_memory:
      p += 2;
      continue;


    default:
      abort (); /* We have listed all the cases.  */
    } /* switch *p++ */

    /* Getting here means we have found the possible starting
    characters for one path of the pattern -- and that the empty
    string does not match.  We need not follow this path further.
    Instead, look at the next alternative (remembered on the
    stack), or quit if no more.  The test at the top of the loop
    does these things.  */
    path_can_be_null = false;
    p = pend;
  } /* while p */

  /* Set `can_be_null' for the last path (also the first path, if the
  pattern is empty).  */
  bufp->can_be_null |= path_can_be_null;

done:
  RESET_FAIL_STACK ();
  return 0;
} /* re_compile_fastmap */
#ifdef _LIBC
weak_alias (__re_compile_fastmap, re_compile_fastmap)
#endif

/* Set REGS to hold NUM_REGS registers, storing them in STARTS and
ENDS.  Subsequent matches using PATTERN_BUFFER and REGS will use
this memory for recording register information.  STARTS and ENDS
must be allocated using the malloc library routine, and must each
be at least NUM_REGS * sizeof (regoff_t) bytes long.

If NUM_REGS == 0, then subsequent matches should allocate their own
register data.

Unless this function is called, the first search or match using
PATTERN_BUFFER will allocate its own register data, without
freeing the old data.  */

void
re_set_registers (struct re_pattern_buffer *bufp,
struct re_registers *regs,
  unsigned num_regs,
  regoff_t *starts,
  regoff_t *ends)
{
  if (num_regs)
  {
    bufp->regs_allocated = REGS_REALLOCATE;
    regs->num_regs = num_regs;
    regs->start = starts;
    regs->end = ends;
  }
  else
  {
    bufp->regs_allocated = REGS_UNALLOCATED;
    regs->num_regs = 0;
    regs->start = regs->end = (regoff_t *) 0;
  }
}
#ifdef _LIBC
weak_alias (__re_set_registers, re_set_registers)
#endif

/* Searching routines.  */

/* Like re_search_2, below, but only one string is specified, and
doesn't let you say where to stop matching. */

int
re_search (struct re_pattern_buffer *bufp,
           const char *string,
           int size,
           int startpos,
           int range,
struct re_registers *regs)
{
  return re_search_2 (bufp, NULL, 0, string, size, startpos, range,
    regs, size);
}
#ifdef _LIBC
weak_alias (__re_search, re_search)
#endif


/* Using the compiled pattern in BUFP->buffer, first tries to match the
virtual concatenation of STRING1 and STRING2, starting first at index
STARTPOS, then at STARTPOS + 1, and so on.

STRING1 and STRING2 have length SIZE1 and SIZE2, respectively.

RANGE is how far to scan while trying to match.  RANGE = 0 means try
only at STARTPOS; in general, the last start tried is STARTPOS +
RANGE.

In REGS, return the indices of the virtual concatenation of STRING1
and STRING2 that matched the entire BUFP->buffer and its contained
subexpressions.

Do not consider matching one past the index STOP in the virtual
concatenation of STRING1 and STRING2.

We return either the position in the strings at which the match was
found, -1 if no match, or -2 if error (such as failure
stack overflow).  */

int
re_search_2 (struct re_pattern_buffer *bufp,
             const char *string1,
             int size1,
             const char *string2,
             int size2,
             int startpos,
             int range,
struct re_registers *regs,
  int stop)
{
  int val;
  register char *fastmap = bufp->fastmap;
  register RE_TRANSLATE_TYPE translate = bufp->translate;
  int total_size = size1 + size2;
  int endpos = startpos + range;

  /* Check for out-of-range STARTPOS.  */
  if (startpos < 0 || startpos > total_size)
    return -1;

  /* Fix up RANGE if it might eventually take us outside
  the virtual concatenation of STRING1 and STRING2.
  Make sure we won't move STARTPOS below 0 or above TOTAL_SIZE.  */
  if (endpos < 0)
    range = 0 - startpos;
  else if (endpos > total_size)
    range = total_size - startpos;

  /* If the search isn't to be a backwards one, don't waste time in a
  search for a pattern that must be anchored.  */
  if (bufp->used > 0 && range > 0
    && ((re_opcode_t) bufp->buffer[0] == begbuf
    /* `begline' is like `begbuf' if it cannot match at newlines.  */
    || ((re_opcode_t) bufp->buffer[0] == begline
    && !bufp->newline_anchor)))
  {
    if (startpos > 0)
      return -1;
    else
      range = 1;
  }

#ifdef emacs
  /* In a forward search for something that starts with \=.
  don't keep searching past point.  */
  if (bufp->used > 0 && (re_opcode_t) bufp->buffer[0] == at_dot && range > 0)
  {
    range = PT - startpos;
    if (range <= 0)
      return -1;
  }
#endif /* emacs */

  /* Update the fastmap now if not correct already.  */
  if (fastmap && !bufp->fastmap_accurate)
    if (re_compile_fastmap (bufp) == -2)
      return -2;

  /* Loop through the string, looking for a place to start matching.  */
  for (;;)
  {
    /* If a fastmap is supplied, skip quickly over characters that
    cannot be the start of a match.  If the pattern can match the
    null string, however, we don't need to skip characters; we want
    the first null string.  */
    if (fastmap && startpos < total_size && !bufp->can_be_null)
    {
      if (range > 0)    /* Searching forwards.  */
      {
        register const char *d;
        register int lim = 0;
        int irange = range;

        if (startpos < size1 && startpos + range >= size1)
          lim = range - (size1 - startpos);

        d = (startpos >= size1 ? string2 - size1 : string1) + startpos;

        /* Written out as an if-else to avoid testing `translate'
        inside the loop.  */
        if (translate)
          while (range > lim
            && !fastmap[(unsigned char)
            translate[(unsigned char) *d++]])
            range--;
        else
          while (range > lim && !fastmap[(unsigned char) *d++])
            range--;

        startpos += irange - range;
      }
      else              /* Searching backwards.  */
      {
        register char c = (size1 == 0 || startpos >= size1
          ? string2[startpos - size1]
        : string1[startpos]);

        if (!fastmap[(unsigned char) TRANSLATE (c)])
          goto advance;
      }
    }

    /* If can't match the null string, and that's all we have left, fail.  */
    if (range >= 0 && startpos == total_size && fastmap
      && !bufp->can_be_null)
      return -1;

    val = re_match_2_internal (bufp, string1, size1, string2, size2,
      startpos, regs, stop);
#ifndef REGEX_MALLOC
# ifdef C_ALLOCA
    alloca (0);
# endif
#endif

    if (val >= 0)
      return startpos;

    if (val == -2)
      return -2;

advance:
    if (!range)
      break;
    else if (range > 0)
    {
      range--;
      startpos++;
    }
    else
    {
      range++;
      startpos--;
    }
  }
  return -1;
} /* re_search_2 */
#ifdef _LIBC
weak_alias (__re_search_2, re_search_2)
#endif

/* This converts PTR, a pointer into one of the search strings `string1'
and `string2' into an offset from the beginning of that string.  */
#define POINTER_TO_OFFSET(ptr)          \
  (FIRST_STRING_P (ptr)             \
  ? ((regoff_t) ((ptr) - string1))     \
  : ((regoff_t) ((ptr) - string2 + size1)))

/* Macros for dealing with the split strings in re_match_2.  */

#define MATCHING_IN_FIRST_STRING  (dend == end_match_1)

/* Call before fetching a character with *d.  This switches over to
string2 if necessary.  */
#define PREFETCH()                          \
  while (d == dend)                             \
{                                   \
  /* End of string2 => fail.  */                    \
  if (dend == end_match_2)                      \
  goto fail;                          \
  /* End of string1 => advance to string2.  */          \
  d = string2;                              \
  dend = end_match_2;                       \
}


/* Test if at very beginning or at very end of the virtual concatenation
of `string1' and `string2'.  If only one string, it's `string2'.  */
#define AT_STRINGS_BEG(d) ((d) == (size1 ? string1 : string2) || !size2)
#define AT_STRINGS_END(d) ((d) == end2)


/* Test if D points to a character which is word-constituent.  We have
two special cases to check for: if past the end of string1, look at
the first character in string2; and if before the beginning of
string2, look at the last character in string1.  */
#define WORDCHAR_P(d)                           \
  (SYNTAX ((d) == end1 ? *string2                   \
  : (d) == string2 - 1 ? *(end1 - 1) : *(d))           \
  == Sword)

/* Disabled due to a compiler bug -- see comment at case wordbound */
#if 0
/* Test if the character before D and the one at D differ with respect
to being word-constituent.  */
#define AT_WORD_BOUNDARY(d)                     \
  (AT_STRINGS_BEG (d) || AT_STRINGS_END (d)             \
  || WORDCHAR_P (d - 1) != WORDCHAR_P (d))
#endif

/* Free everything we malloc.  */
#ifdef MATCH_MAY_ALLOCATE
# define FREE_VAR(var) if (var) REGEX_FREE (var); var = NULL
# define FREE_VARIABLES()                 \
{                                       \
  REGEX_FREE_STACK (fail_stack.stack);  \
  FREE_VAR (regstart);                  \
  FREE_VAR (regend);                    \
  FREE_VAR (old_regstart);              \
  FREE_VAR (old_regend);                \
  FREE_VAR (best_regstart);             \
  FREE_VAR (best_regend);               \
  FREE_VAR (reg_info);                  \
  FREE_VAR (reg_dummy);                 \
  FREE_VAR (reg_info_dummy);            \
}
#else
# define FREE_VARIABLES() ((void)0) /* Do nothing!  But inhibit gcc warning. */
#endif /* not MATCH_MAY_ALLOCATE */

/* These values must meet several constraints.  They must not be valid
register values; since we have a limit of 255 registers (because
we use only one byte in the pattern for the register number), we can
use numbers larger than 255.  They must differ by 1, because of
NUM_FAILURE_ITEMS above.  And the value for the lowest register must
be larger than the value for the highest register, so we do not try
to actually save any registers when none are active.  */
#define NO_HIGHEST_ACTIVE_REG (1 << BYTEWIDTH)
#define NO_LOWEST_ACTIVE_REG (NO_HIGHEST_ACTIVE_REG + 1)

/* Matching routines.  */

#ifndef emacs   /* Emacs never uses this.  */
/* re_match is like re_match_2 except it takes only a single string.  */

int
re_match (struct re_pattern_buffer *bufp,
          const char *string,
          int size,
          int pos,
struct re_registers *regs)
{
  int result = re_match_2_internal (bufp, NULL, 0, string, size,
    pos, regs, size);
# ifndef REGEX_MALLOC
#  ifdef C_ALLOCA
  alloca (0);
#  endif
# endif
  return result;
}
# ifdef _LIBC
weak_alias (__re_match, re_match)
# endif
#endif /* not emacs */

static bool group_match_null_string_p(unsigned char **p, unsigned char *end,
                                      register_info_type *reg_info);
static bool alt_match_null_string_p(unsigned char *p, unsigned char *end,
                                    register_info_type *reg_info);
static bool common_op_match_null_string_p(unsigned char **p,
                                          unsigned char *end, register_info_type *reg_info);
static int bcmp_translate(const char *s1, const char *s2,
                          int len, char *translate);

/* re_match_2 matches the compiled pattern in BUFP against the
the (virtual) concatenation of STRING1 and STRING2 (of length SIZE1
and SIZE2, respectively).  We start matching at POS, and stop
matching at STOP.

If REGS is non-null and the `no_sub' field of BUFP is nonzero, we
store offsets for the substring each group matched in REGS.  See the
documentation for exactly how many groups we fill.

We return -1 if no match, -2 if an internal error (such as the
failure stack overflowing).  Otherwise, we return the length of the
matched substring.  */

int
re_match_2 (struct re_pattern_buffer *bufp,
            const char *string1,
            int size1,
            const char *string2,
            int size2,
            int pos,
struct re_registers *regs,
  int stop)
{
  int result = re_match_2_internal (bufp, string1, size1, string2, size2,
    pos, regs, stop);
#ifndef REGEX_MALLOC
# ifdef C_ALLOCA
  alloca (0);
# endif
#endif
  return result;
}
#ifdef _LIBC
weak_alias (__re_match_2, re_match_2)
#endif

/* This is a separate function so that we can force an alloca cleanup
afterwards.  */
static int
re_match_2_internal (struct re_pattern_buffer *bufp,
                     const char *string1,
                     int size1,
                     const char *string2,
                     int size2,
                     int pos,
struct re_registers *regs,
  int stop)
{
  /* General temporaries.  */
  int mcnt;
  unsigned char *p1;

  /* Just past the end of the corresponding string.  */
  const char *end1, *end2;

  /* Pointers into string1 and string2, just past the last characters in
  each to consider matching.  */
  const char *end_match_1, *end_match_2;

  /* Where we are in the data, and the end of the current string.  */
  const char *d, *dend;

  /* Where we are in the pattern, and the end of the pattern.  */
  unsigned char *p = bufp->buffer;
  register unsigned char *pend = p + bufp->used;

  /* Mark the opcode just after a start_memory, so we can test for an
  empty subpattern when we get to the stop_memory.  */
  unsigned char *just_past_start_mem = 0;

  /* We use this to map every character in the string.  */
  RE_TRANSLATE_TYPE translate = bufp->translate;

  /* Failure point stack.  Each place that can handle a failure further
  down the line pushes a failure point on this stack.  It consists of
  restart, regend, and reg_info for all registers corresponding to
  the subexpressions we're currently inside, plus the number of such
  registers, and, finally, two char *'s.  The first char * is where
  to resume scanning the pattern; the second one is where to resume
  scanning the strings.  If the latter is zero, the failure point is
  a ``dummy''; if a failure happens and the failure point is a dummy,
  it gets discarded and the next next one is tried.  */
#ifdef MATCH_MAY_ALLOCATE /* otherwise, this is global.  */
  fail_stack_type fail_stack;
#endif

#ifdef REL_ALLOC
  /* This holds the pointer to the failure stack, when
  it is allocated relocatably.  */
  fail_stack_elt_t *failure_stack_ptr;
#endif

  /* We fill all the registers internally, independent of what we
  return, for use in backreferences.  The number here includes
  an element for register zero.  */
  size_t num_regs = bufp->re_nsub + 1;

  /* The currently active registers.  */
  active_reg_t lowest_active_reg = NO_LOWEST_ACTIVE_REG;
  active_reg_t highest_active_reg = NO_HIGHEST_ACTIVE_REG;

  /* Information on the contents of registers. These are pointers into
  the input strings; they record just what was matched (on this
  attempt) by a subexpression part of the pattern, that is, the
  regnum-th regstart pointer points to where in the pattern we began
  matching and the regnum-th regend points to right after where we
  stopped matching the regnum-th subexpression.  (The zeroth register
  keeps track of what the whole pattern matches.)  */
#ifdef MATCH_MAY_ALLOCATE /* otherwise, these are global.  */
  const char **regstart, **regend;
#endif

  /* If a group that's operated upon by a repetition operator fails to
  match anything, then the register for its start will need to be
  restored because it will have been set to wherever in the string we
  are when we last see its open-group operator.  Similarly for a
  register's end.  */
#ifdef MATCH_MAY_ALLOCATE /* otherwise, these are global.  */
  const char **old_regstart, **old_regend;
#endif

  /* The is_active field of reg_info helps us keep track of which (possibly
  nested) subexpressions we are currently in. The matched_something
  field of reg_info[reg_num] helps us tell whether or not we have
  matched any of the pattern so far this time through the reg_num-th
  subexpression.  These two fields get reset each time through any
  loop their register is in.  */
#ifdef MATCH_MAY_ALLOCATE /* otherwise, this is global.  */
  register_info_type *reg_info;
#endif

  /* The following record the register info as found in the above
  variables when we find a match better than any we've seen before.
  This happens as we backtrack through the failure points, which in
  turn happens only if we have not yet matched the entire string. */
  unsigned best_regs_set = false;
#ifdef MATCH_MAY_ALLOCATE /* otherwise, these are global.  */
  const char **best_regstart, **best_regend;
#endif

  /* Logically, this is `best_regend[0]'.  But we don't want to have to
  allocate space for that if we're not allocating space for anything
  else (see below).  Also, we never need info about register 0 for
  any of the other register vectors, and it seems rather a kludge to
  treat `best_regend' differently than the rest.  So we keep track of
  the end of the best match so far in a separate variable.  We
  initialize this to NULL so that when we backtrack the first time
  and need to test it, it's not garbage.  */
  const char *match_end = NULL;

  /* This helps SET_REGS_MATCHED avoid doing redundant work.  */
  int set_regs_matched_done = 0;

  /* Used when we pop values we don't care about.  */
#ifdef MATCH_MAY_ALLOCATE /* otherwise, these are global.  */
  const char **reg_dummy;
  register_info_type *reg_info_dummy;
#endif

  INIT_FAIL_STACK ();

#ifdef MATCH_MAY_ALLOCATE
  /* Do not bother to initialize all the register variables if there are
  no groups in the pattern, as it takes a fair amount of time.  If
  there are groups, we include space for register 0 (the whole
  pattern), even though we never use it, since it simplifies the
  array indexing.  We should fix this.  */
  if (bufp->re_nsub)
  {
    regstart = REGEX_TALLOC (num_regs, const char *);
    regend = REGEX_TALLOC (num_regs, const char *);
    old_regstart = REGEX_TALLOC (num_regs, const char *);
    old_regend = REGEX_TALLOC (num_regs, const char *);
    best_regstart = REGEX_TALLOC (num_regs, const char *);
    best_regend = REGEX_TALLOC (num_regs, const char *);
    reg_info = REGEX_TALLOC (num_regs, register_info_type);
    reg_dummy = REGEX_TALLOC (num_regs, const char *);
    reg_info_dummy = REGEX_TALLOC (num_regs, register_info_type);

    if (!(regstart && regend && old_regstart && old_regend && reg_info
      && best_regstart && best_regend && reg_dummy && reg_info_dummy))
    {
      FREE_VARIABLES ();
      return -2;
    }
  }
  else
  {
    /* We must initialize all our variables to NULL, so that
    `FREE_VARIABLES' doesn't try to free them.  */
    regstart = regend = old_regstart = old_regend = best_regstart
      = best_regend = reg_dummy = NULL;
    reg_info = reg_info_dummy = (register_info_type *) NULL;
  }
#endif /* MATCH_MAY_ALLOCATE */

  /* The starting position is bogus.  */
  if (pos < 0 || pos > size1 + size2)
  {
    FREE_VARIABLES ();
    return -1;
  }

  /* Initialize subexpression text positions to -1 to mark ones that no
  start_memory/stop_memory has been seen for. Also initialize the
  register information struct.  */
  for (mcnt = 1; (unsigned) mcnt < num_regs; mcnt++)
  {
    regstart[mcnt] = regend[mcnt]
    = old_regstart[mcnt] = old_regend[mcnt] = REG_UNSET_VALUE;

    REG_MATCH_NULL_STRING_P (reg_info[mcnt]) = MATCH_NULL_UNSET_VALUE;
    IS_ACTIVE (reg_info[mcnt]) = 0;
    MATCHED_SOMETHING (reg_info[mcnt]) = 0;
    EVER_MATCHED_SOMETHING (reg_info[mcnt]) = 0;
  }

  /* We move `string1' into `string2' if the latter's empty -- but not if
  `string1' is null.  */
  if (size2 == 0 && string1 != NULL)
  {
    string2 = string1;
    size2 = size1;
    string1 = 0;
    size1 = 0;
  }
  end1 = string1 + size1;
  end2 = string2 + size2;

  /* Compute where to stop matching, within the two strings.  */
  if (stop <= size1)
  {
    end_match_1 = string1 + stop;
    end_match_2 = string2;
  }
  else
  {
    end_match_1 = end1;
    end_match_2 = string2 + stop - size1;
  }

  /* `p' scans through the pattern as `d' scans through the data.
  `dend' is the end of the input string that `d' points within.  `d'
  is advanced into the following input string whenever necessary, but
  this happens before fetching; therefore, at the beginning of the
  loop, `d' can be pointing at the end of a string, but it cannot
  equal `string2'.  */
  if (size1 > 0 && pos <= size1)
  {
    d = string1 + pos;
    dend = end_match_1;
  }
  else
  {
    d = string2 + pos - size1;
    dend = end_match_2;
  }

  /* This loops over pattern commands.  It exits by returning from the
  function if the match is complete, or it drops through if the match
  fails at this starting point in the input data.  */
  for (;;)
  {
    if (p == pend)
    { /* End of pattern means we might have succeeded.  */

      /* If we haven't matched the entire string, and we want the
      longest match, try backtracking.  */
      if (d != end_match_2)
      {
        /* 1 if this match is the best seen so far.  */
        bool best_match_p;

        /* 1 if this match ends in the same string (string1 or string2)
        as the best previous match.  */
        if ((FIRST_STRING_P (match_end) == MATCHING_IN_FIRST_STRING))
          best_match_p = d > match_end;
        else
          best_match_p = !MATCHING_IN_FIRST_STRING;

        if (!FAIL_STACK_EMPTY ())
        { /* More failure points to try.  */

          /* If exceeds best match so far, save it.  */
          if (!best_regs_set || best_match_p)
          {
            best_regs_set = true;
            match_end = d;

            for (mcnt = 1; (unsigned) mcnt < num_regs; mcnt++)
            {
              best_regstart[mcnt] = regstart[mcnt];
              best_regend[mcnt] = regend[mcnt];
            }
          }
          goto fail;
        }

        /* If no failure points, don't restore garbage.  And if
        last match is real best match, don't restore second
        best one. */
        else if (best_regs_set && !best_match_p)
        {
restore_best_regs:
          /* Restore best match.  It may happen that `dend ==
          end_match_1' while the restored d is in string2.
          For example, the pattern `x.*y.*z' against the
          strings `x-' and `y-z-', if the two strings are
          not consecutive in memory.  */
          d = match_end;
          dend = ((d >= string1 && d <= end1)
            ? end_match_1 : end_match_2);

          for (mcnt = 1; (unsigned) mcnt < num_regs; mcnt++)
          {
            regstart[mcnt] = best_regstart[mcnt];
            regend[mcnt] = best_regend[mcnt];
          }
        }
      } /* d != end_match_2 */

succeed_label:
      /* If caller wants register contents data back, do it.  */
      if (regs && !bufp->no_sub)
      {
        /* Have the register data arrays been allocated?  */
        if (bufp->regs_allocated == REGS_UNALLOCATED)
        { /* No.  So allocate them with malloc.  We need one
          extra element beyond `num_regs' for the `-1' marker
          GNU code uses.  */
          regs->num_regs = MAX (RE_NREGS, num_regs + 1);
          regs->start = TALLOC (regs->num_regs, regoff_t);
          regs->end = TALLOC (regs->num_regs, regoff_t);
          if (regs->start == NULL || regs->end == NULL)
          {
            FREE_VARIABLES ();
            return -2;
          }
          bufp->regs_allocated = REGS_REALLOCATE;
        }
        else if (bufp->regs_allocated == REGS_REALLOCATE)
        { /* Yes.  If we need more elements than were already
          allocated, reallocate them.  If we need fewer, just
          leave it alone.  */
          if (regs->num_regs < num_regs + 1)
          {
            regs->num_regs = num_regs + 1;
            RETALLOC (regs->start, regs->num_regs, regoff_t);
            RETALLOC (regs->end, regs->num_regs, regoff_t);
            if (regs->start == NULL || regs->end == NULL)
            {
              FREE_VARIABLES ();
              return -2;
            }
          }
        }

        /* Convert the pointer data in `regstart' and `regend' to
        indices.  Register zero has to be set differently,
        since we haven't kept track of any info for it.  */
        if (regs->num_regs > 0)
        {
          regs->start[0] = pos;
          regs->end[0] = (MATCHING_IN_FIRST_STRING
            ? ((regoff_t) (d - string1))
            : ((regoff_t) (d - string2 + size1)));
        }

        /* Go through the first `min (num_regs, regs->num_regs)'
        registers, since that is all we initialized.  */
        for (mcnt = 1; (unsigned) mcnt < MIN (num_regs, regs->num_regs);
          mcnt++)
        {
          if (REG_UNSET (regstart[mcnt]) || REG_UNSET (regend[mcnt]))
            regs->start[mcnt] = regs->end[mcnt] = -1;
          else
          {
            regs->start[mcnt]
            = (regoff_t) POINTER_TO_OFFSET (regstart[mcnt]);
            regs->end[mcnt]
            = (regoff_t) POINTER_TO_OFFSET (regend[mcnt]);
          }
        }

        /* If the regs structure we return has more elements than
        were in the pattern, set the extra elements to -1.  If
        we (re)allocated the registers, this is the case,
        because we always allocate enough to have at least one
        -1 at the end.  */
        for (mcnt = num_regs; (unsigned) mcnt < regs->num_regs; mcnt++)
          regs->start[mcnt] = regs->end[mcnt] = -1;
      } /* regs && !bufp->no_sub */

      mcnt = d - pos - (MATCHING_IN_FIRST_STRING
        ? string1
        : string2 - size1);

      FREE_VARIABLES ();
      return mcnt;
    }

    /* Otherwise match next pattern command.  */
    switch (SWITCH_ENUM_CAST ((re_opcode_t) *p++))
    {
      /* Ignore these.  Used to ignore the n of succeed_n's which
      currently have n == 0.  */
    case no_op:
      break;

    case succeed:
      goto succeed_label;

      /* Match the next n pattern characters exactly.  The following
      byte in the pattern defines n, and the n bytes after that
      are the characters to match.  */
    case exactn:
      mcnt = *p++;
      /* This is written out as an if-else so we don't waste time
      testing `translate' inside the loop.  */
      if (translate)
      {
        do
        {
          PREFETCH ();
          if ((unsigned char) translate[(unsigned char) *d++]
          != (unsigned char) *p++)
            goto fail;
        }
        while (--mcnt);
      }
      else
      {
        do
        {
          PREFETCH ();
          if (*d++ != (char) *p++) goto fail;
        }
        while (--mcnt);
      }
      SET_REGS_MATCHED ();
      break;


      /* Match any character except possibly a newline or a null.  */
    case anychar:
      PREFETCH ();

      if ((!(bufp->syntax & RE_DOT_NEWLINE) && TRANSLATE (*d) == '\n')
        || (bufp->syntax & RE_DOT_NOT_NULL && TRANSLATE (*d) == '\000'))
        goto fail;

      SET_REGS_MATCHED ();
      d++;
      break;


    case charset:
    case charset_not:
      {
        register unsigned char c;
        bool not_bool = (re_opcode_t) *(p - 1) == charset_not;
        PREFETCH ();
        c = TRANSLATE (*d); /* The character to match.  */

        /* Cast to `unsigned' instead of `unsigned char' in case the
        bit list is a full 32 bytes long.  */
        if (c < (unsigned) (*p * BYTEWIDTH)
          && p[1 + c / BYTEWIDTH] & (1 << (c % BYTEWIDTH)))
          not_bool = !not_bool;

        p += 1 + *p;

        if (!not_bool) goto fail;

        SET_REGS_MATCHED ();
        d++;
        break;
      }


      /* The beginning of a group is represented by start_memory.
      The arguments are the register number in the next byte, and the
      number of groups inner to this one in the next.  The text
      matched within the group is recorded (in the internal
      registers data structure) under the register number.  */
    case start_memory:
      /* Find out if this group can match the empty string.  */
      p1 = p;       /* To send to group_match_null_string_p.  */

      if (REG_MATCH_NULL_STRING_P (reg_info[*p]) == MATCH_NULL_UNSET_VALUE)
        REG_MATCH_NULL_STRING_P (reg_info[*p])
        = group_match_null_string_p (&p1, pend, reg_info);

      /* Save the position in the string where we were the last time
      we were at this open-group operator in case the group is
      operated upon by a repetition operator, e.g., with `(a*)*b'
      against `ab'; then we want to ignore where we are now in
      the string in case this attempt to match fails.  */
      old_regstart[*p] = REG_MATCH_NULL_STRING_P (reg_info[*p])
        ? REG_UNSET (regstart[*p]) ? d : regstart[*p]
      : regstart[*p];
      regstart[*p] = d;
      IS_ACTIVE (reg_info[*p]) = 1;
      MATCHED_SOMETHING (reg_info[*p]) = 0;

      /* Clear this whenever we change the register activity status.  */
      set_regs_matched_done = 0;

      /* This is the new highest active register.  */
      highest_active_reg = *p;

      /* If nothing was active before, this is the new lowest active
      register.  */
      if (lowest_active_reg == NO_LOWEST_ACTIVE_REG)
        lowest_active_reg = *p;

      /* Move past the register number and inner group count.  */
      p += 2;
      just_past_start_mem = p;

      break;


      /* The stop_memory opcode represents the end of a group.  Its
      arguments are the same as start_memory's: the register
      number, and the number of inner groups.  */
    case stop_memory:
      /* We need to save the string position the last time we were at
      this close-group operator in case the group is operated
      upon by a repetition operator, e.g., with `((a*)*(b*)*)*'
      against `aba'; then we want to ignore where we are now in
      the string in case this attempt to match fails.  */
      old_regend[*p] = REG_MATCH_NULL_STRING_P (reg_info[*p])
        ? REG_UNSET (regend[*p]) ? d : regend[*p]
      : regend[*p];

      regend[*p] = d;

      /* This register isn't active anymore.  */
      IS_ACTIVE (reg_info[*p]) = 0;

      /* Clear this whenever we change the register activity status.  */
      set_regs_matched_done = 0;

      /* If this was the only register active, nothing is active
      anymore.  */
      if (lowest_active_reg == highest_active_reg)
      {
        lowest_active_reg = NO_LOWEST_ACTIVE_REG;
        highest_active_reg = NO_HIGHEST_ACTIVE_REG;
      }
      else
      { /* We must scan for the new highest active register, since
        it isn't necessarily one less than now: consider
        (a(b)c(d(e)f)g).  When group 3 ends, after the f), the
        new highest active register is 1.  */
        unsigned char r = *p - 1;
        while (r > 0 && !IS_ACTIVE (reg_info[r]))
          r--;

        /* If we end up at register zero, that means that we saved
        the registers as the result of an `on_failure_jump', not
        a `start_memory', and we jumped to past the innermost
        `stop_memory'.  For example, in ((.)*) we save
        registers 1 and 2 as a result of the *, but when we pop
        back to the second ), we are at the stop_memory 1.
        Thus, nothing is active.  */
        if (r == 0)
        {
          lowest_active_reg = NO_LOWEST_ACTIVE_REG;
          highest_active_reg = NO_HIGHEST_ACTIVE_REG;
        }
        else
          highest_active_reg = r;
      }

      /* If just failed to match something this time around with a
      group that's operated on by a repetition operator, try to
      force exit from the ``loop'', and restore the register
      information for this group that we had before trying this
      last match.  */
      if ((!MATCHED_SOMETHING (reg_info[*p])
        || just_past_start_mem == p - 1)
        && (p + 2) < pend)
      {
        bool is_a_jump_n = false;

        p1 = p + 2;
        mcnt = 0;
        switch ((re_opcode_t) *p1++)
        {
        case jump_n:
          is_a_jump_n = true;
        case pop_failure_jump:
        case maybe_pop_jump:
        case jump:
        case dummy_failure_jump:
          EXTRACT_NUMBER_AND_INCR (mcnt, p1);
          if (is_a_jump_n)
            p1 += 2;
          break;

        default:
          /* do nothing */ ;
        }
        p1 += mcnt;

        /* If the next operation is a jump backwards in the pattern
        to an on_failure_jump right before the start_memory
        corresponding to this stop_memory, exit from the loop
        by forcing a failure after pushing on the stack the
        on_failure_jump's jump in the pattern, and d.  */
        if (mcnt < 0 && (re_opcode_t) *p1 == on_failure_jump
          && (re_opcode_t) p1[3] == start_memory && p1[4] == *p)
        {
          /* If this group ever matched anything, then restore
          what its registers were before trying this last
          failed match, e.g., with `(a*)*b' against `ab' for
          regstart[1], and, e.g., with `((a*)*(b*)*)*'
          against `aba' for regend[3].

          Also restore the registers for inner groups for,
          e.g., `((a*)(b*))*' against `aba' (register 3 would
          otherwise get trashed).  */

          if (EVER_MATCHED_SOMETHING (reg_info[*p]))
          {
            unsigned r;

            EVER_MATCHED_SOMETHING (reg_info[*p]) = 0;

            /* Restore this and inner groups' (if any) registers.  */
            for (r = *p; r < (unsigned) *p + (unsigned) *(p + 1);
              r++)
            {
              regstart[r] = old_regstart[r];

              /* xx why this test?  */
              if (old_regend[r] >= regstart[r])
                regend[r] = old_regend[r];
            }
          }
          p1++;
          EXTRACT_NUMBER_AND_INCR (mcnt, p1);
          PUSH_FAILURE_POINT (p1 + mcnt, d, -2);

          goto fail;
        }
      }

      /* Move past the register number and the inner group count.  */
      p += 2;
      break;


      /* \<digit> has been turned into a `duplicate' command which is
      followed by the numeric value of <digit> as the register number.  */
    case duplicate:
      {
        register const char *d2, *dend2;
        int regno = *p++;   /* Get which register to match against.  */

        /* Can't back reference a group which we've never matched.  */
        if (REG_UNSET (regstart[regno]) || REG_UNSET (regend[regno]))
          goto fail;

        /* Where in input to try to start matching.  */
        d2 = regstart[regno];

        /* Where to stop matching; if both the place to start and
        the place to stop matching are in the same string, then
        set to the place to stop, otherwise, for now have to use
        the end of the first string.  */

        dend2 = ((FIRST_STRING_P (regstart[regno])
          == FIRST_STRING_P (regend[regno]))
          ? regend[regno] : end_match_1);
        for (;;)
        {
          /* If necessary, advance to next segment in register
          contents.  */
          while (d2 == dend2)
          {
            if (dend2 == end_match_2) break;
            if (dend2 == regend[regno]) break;

            /* End of string1 => advance to string2. */
            d2 = string2;
            dend2 = regend[regno];
          }
          /* At end of register contents => success */
          if (d2 == dend2) break;

          /* If necessary, advance to next segment in data.  */
          PREFETCH ();

          /* How many characters left in this segment to match.  */
          mcnt = dend - d;

          /* Want how many consecutive characters we can match in
          one shot, so, if necessary, adjust the count.  */
          if (mcnt > dend2 - d2)
            mcnt = dend2 - d2;

          /* Compare that many; failure if mismatch, else move
          past them.  */
          if (translate
            ? bcmp_translate (d, d2, mcnt, translate)
            : memcmp (d, d2, mcnt))
            goto fail;
          d += mcnt, d2 += mcnt;

          /* Do this because we've match some characters.  */
          SET_REGS_MATCHED ();
        }
      }
      break;


      /* begline matches the empty string at the beginning of the string
      (unless `not_bol' is set in `bufp'), and, if
      `newline_anchor' is set, after newlines.  */
    case begline:
      if (AT_STRINGS_BEG (d))
      {
        if (!bufp->not_bol) break;
      }
      else if (d[-1] == '\n' && bufp->newline_anchor)
      {
        break;
      }
      /* In all other cases, we fail.  */
      goto fail;


      /* endline is the dual of begline.  */
    case endline:
      if (AT_STRINGS_END (d))
      {
        if (!bufp->not_eol) break;
      }

      /* We have to ``prefetch'' the next character.  */
      else if ((d == end1 ? *string2 : *d) == '\n'
        && bufp->newline_anchor)
      {
        break;
      }
      goto fail;


      /* Match at the very beginning of the data.  */
    case begbuf:
      if (AT_STRINGS_BEG (d))
        break;
      goto fail;


      /* Match at the very end of the data.  */
    case endbuf:
      if (AT_STRINGS_END (d))
        break;
      goto fail;


      /* on_failure_keep_string_jump is used to optimize `.*\n'.  It
      pushes NULL as the value for the string on the stack.  Then
      `pop_failure_point' will keep the current value for the
      string, instead of restoring it.  To see why, consider
      matching `foo\nbar' against `.*\n'.  The .* matches the foo;
      then the . fails against the \n.  But the next thing we want
      to do is match the \n against the \n; if we restored the
      string value, we would be back at the foo.

      Because this is used only in specific cases, we don't need to
      check all the things that `on_failure_jump' does, to make
      sure the right things get saved on the stack.  Hence we don't
      share its code.  The only reason to push anything on the
      stack at all is that otherwise we would have to change
      `anychar's code to do something besides goto fail in this
      case; that seems worse than this.  */
    case on_failure_keep_string_jump:
      EXTRACT_NUMBER_AND_INCR (mcnt, p);
      PUSH_FAILURE_POINT (p + mcnt, NULL, -2);
      break;


      /* Uses of on_failure_jump:

      Each alternative starts with an on_failure_jump that points
      to the beginning of the next alternative.  Each alternative
      except the last ends with a jump that in effect jumps past
      the rest of the alternatives.  (They really jump to the
      ending jump of the following alternative, because tensioning
      these jumps is a hassle.)

      Repeats start with an on_failure_jump that points past both
      the repetition text and either the following jump or
      pop_failure_jump back to this on_failure_jump.  */
    case on_failure_jump:
on_failure:
      EXTRACT_NUMBER_AND_INCR (mcnt, p);

      /* If this on_failure_jump comes right before a group (i.e.,
      the original * applied to a group), save the information
      for that group and all inner ones, so that if we fail back
      to this point, the group's information will be correct.
      For example, in \(a*\)*\1, we need the preceding group,
      and in \(zz\(a*\)b*\)\2, we need the inner group.  */

      /* We can't use `p' to check ahead because we push
      a failure point to `p + mcnt' after we do this.  */
      p1 = p;

      /* We need to skip no_op's before we look for the
      start_memory in case this on_failure_jump is happening as
      the result of a completed succeed_n, as in \(a\)\{1,3\}b\1
      against aba.  */
      while (p1 < pend && (re_opcode_t) *p1 == no_op)
        p1++;

      if (p1 < pend && (re_opcode_t) *p1 == start_memory)
      {
        /* We have a new highest active register now.  This will
        get reset at the start_memory we are about to get to,
        but we will have saved all the registers relevant to
        this repetition op, as described above.  */
        highest_active_reg = *(p1 + 1) + *(p1 + 2);
        if (lowest_active_reg == NO_LOWEST_ACTIVE_REG)
          lowest_active_reg = *(p1 + 1);
      }

      PUSH_FAILURE_POINT (p + mcnt, d, -2);
      break;


      /* A smart repeat ends with `maybe_pop_jump'.
      We change it to either `pop_failure_jump' or `jump'.  */
    case maybe_pop_jump:
      EXTRACT_NUMBER_AND_INCR (mcnt, p);
      {
        register unsigned char *p2 = p;

        /* Compare the beginning of the repeat with what in the
        pattern follows its end. If we can establish that there
        is nothing that they would both match, i.e., that we
        would have to backtrack because of (as in, e.g., `a*a')
        then we can change to pop_failure_jump, because we'll
        never have to backtrack.

        This is not true in the case of alternatives: in
        `(a|ab)*' we do need to backtrack to the `ab' alternative
        (e.g., if the string was `ab').  But instead of trying to
        detect that here, the alternative has put on a dummy
        failure point which is what we will end up popping.  */

        /* Skip over open/close-group commands.
        If what follows this loop is a ...+ construct,
        look at what begins its body, since we will have to
        match at least one of that.  */
        while (true)
        {
          if (p2 + 2 < pend
            && ((re_opcode_t) *p2 == stop_memory
            || (re_opcode_t) *p2 == start_memory))
            p2 += 3;
          else if (p2 + 6 < pend
            && (re_opcode_t) *p2 == dummy_failure_jump)
            p2 += 6;
          else
            break;
        }

        p1 = p + mcnt;
        /* p1[0] ... p1[2] are the `on_failure_jump' corresponding
        to the `maybe_finalize_jump' of this case.  Examine what
        follows.  */

        /* If we're at the end of the pattern, we can change.  */
        if (p2 == pend)
        {
          /* Consider what happens when matching ":\(.*\)"
          against ":/".  I don't really understand this code
          yet.  */
          p[-3] = (unsigned char) pop_failure_jump;
        }

        else if ((re_opcode_t) *p2 == exactn
          || (bufp->newline_anchor && (re_opcode_t) *p2 == endline))
        {
          register unsigned char c
            = *p2 == (unsigned char) endline ? '\n' : p2[2];

          if ((re_opcode_t) p1[3] == exactn && p1[5] != c)
          {
            p[-3] = (unsigned char) pop_failure_jump;
          }

          else if ((re_opcode_t) p1[3] == charset
            || (re_opcode_t) p1[3] == charset_not)
          {
            int not_int = (re_opcode_t) p1[3] == charset_not;

            if (c < (unsigned char) (p1[4] * BYTEWIDTH)
              && p1[5 + c / BYTEWIDTH] & (1 << (c % BYTEWIDTH)))
              not_int = !not_int;

            /* `not' is equal to 1 if c would match, which means
            that we can't change to pop_failure_jump.  */
            if (!not_int)
            {
              p[-3] = (unsigned char) pop_failure_jump;
            }
          }
        }
        else if ((re_opcode_t) *p2 == charset)
        {
          if ((re_opcode_t) p1[3] == exactn
            && ! ((int) p2[1] * BYTEWIDTH > (int) p1[4]
          && (p2[2 + p1[4] / BYTEWIDTH]
          & (1 << (p1[4] % BYTEWIDTH)))))
          {
            p[-3] = (unsigned char) pop_failure_jump;
          }

          else if ((re_opcode_t) p1[3] == charset_not)
          {
            int idx;
            /* We win if the charset_not inside the loop
            lists every character listed in the charset after.  */
            for (idx = 0; idx < (int) p2[1]; idx++)
              if (! (p2[2 + idx] == 0
                || (idx < (int) p1[4]
              && ((p2[2 + idx] & ~ p1[5 + idx]) == 0))))
                break;

              if (idx == p2[1])
              {
                p[-3] = (unsigned char) pop_failure_jump;
              }
          }
          else if ((re_opcode_t) p1[3] == charset)
          {
            int idx;
            /* We win if the charset inside the loop
            has no overlap with the one after the loop.  */
            for (idx = 0;
              idx < (int) p2[1] && idx < (int) p1[4];
              idx++)
              if ((p2[2 + idx] & p1[5 + idx]) != 0)
                break;

            if (idx == p2[1] || idx == p1[4])
            {
              p[-3] = (unsigned char) pop_failure_jump;
            }
          }
        }
      }
      p -= 2;       /* Point at relative address again.  */
      if ((re_opcode_t) p[-1] != pop_failure_jump)
      {
        p[-1] = (unsigned char) jump;
        goto unconditional_jump;
      }
      /* Note fall through.  */


      /* The end of a simple repeat has a pop_failure_jump back to
      its matching on_failure_jump, where the latter will push a
      failure point.  The pop_failure_jump takes off failure
      points put on by this pop_failure_jump's matching
      on_failure_jump; we got through the pattern to here from the
      matching on_failure_jump, so didn't fail.  */
    case pop_failure_jump:
      {
        /* We need to pass separate storage for the lowest and
        highest registers, even though we don't care about the
        actual values.  Otherwise, we will restore only one
        register from the stack, since lowest will == highest in
        `pop_failure_point'.  */
        active_reg_t dummy_low_reg, dummy_high_reg;
        unsigned char *pdummy;
        const char *sdummy;

        POP_FAILURE_POINT (sdummy, pdummy,
          dummy_low_reg, dummy_high_reg,
          reg_dummy, reg_dummy, reg_info_dummy);
      }
      /* Note fall through.  */

unconditional_jump:
      /* Note fall through.  */

      /* Unconditionally jump (without popping any failure points).  */
    case jump:
      EXTRACT_NUMBER_AND_INCR (mcnt, p);    /* Get the amount to jump.  */
      p += mcnt;                /* Do the jump.  */
      break;


      /* We need this opcode so we can detect where alternatives end
      in `group_match_null_string_p' et al.  */
    case jump_past_alt:
      goto unconditional_jump;


      /* Normally, the on_failure_jump pushes a failure point, which
      then gets popped at pop_failure_jump.  We will end up at
      pop_failure_jump, also, and with a pattern of, say, `a+', we
      are skipping over the on_failure_jump, so we have to push
      something meaningless for pop_failure_jump to pop.  */
    case dummy_failure_jump:
      /* It doesn't matter what we push for the string here.  What
      the code at `fail' tests is the value for the pattern.  */
      PUSH_FAILURE_POINT (NULL, NULL, -2);
      goto unconditional_jump;


      /* At the end of an alternative, we need to push a dummy failure
      point in case we are followed by a `pop_failure_jump', because
      we don't want the failure point for the alternative to be
      popped.  For example, matching `(a|ab)*' against `aab'
      requires that we match the `ab' alternative.  */
    case push_dummy_failure:
      /* See comments just above at `dummy_failure_jump' about the
      two zeroes.  */
      PUSH_FAILURE_POINT (NULL, NULL, -2);
      break;

      /* Have to succeed matching what follows at least n times.
      After that, handle like `on_failure_jump'.  */
    case succeed_n:
      EXTRACT_NUMBER (mcnt, p + 2);

      /* Originally, this is how many times we HAVE to succeed.  */
      if (mcnt > 0)
      {
        mcnt--;
        p += 2;
        STORE_NUMBER_AND_INCR (p, mcnt);
      }
      else if (mcnt == 0)
      {
        p[2] = (unsigned char) no_op;
        p[3] = (unsigned char) no_op;
        goto on_failure;
      }
      break;

    case jump_n:
      EXTRACT_NUMBER (mcnt, p + 2);

      /* Originally, this is how many times we CAN jump.  */
      if (mcnt)
      {
        mcnt--;
        STORE_NUMBER (p + 2, mcnt);
        goto unconditional_jump;
      }
      /* If don't have to jump any more, skip over the rest of command.  */
      else
        p += 4;
      break;

    case set_number_at:
      {
        EXTRACT_NUMBER_AND_INCR (mcnt, p);
        p1 = p + mcnt;
        EXTRACT_NUMBER_AND_INCR (mcnt, p);
        STORE_NUMBER (p1, mcnt);
        break;
      }

    case wordbound:
      {
        bool prevchar, thischar;

        if (AT_STRINGS_BEG (d) || AT_STRINGS_END (d))
          break;

        prevchar = WORDCHAR_P (d - 1);
        thischar = WORDCHAR_P (d);
        if (prevchar != thischar)
          break;
        goto fail;
      }

    case notwordbound:
      {
        bool prevchar, thischar;

        if (AT_STRINGS_BEG (d) || AT_STRINGS_END (d))
          goto fail;

        prevchar = WORDCHAR_P (d - 1);
        thischar = WORDCHAR_P (d);
        if (prevchar != thischar)
          goto fail;
        break;
      }

    case wordbeg:
      if (WORDCHAR_P (d) && (AT_STRINGS_BEG (d) || !WORDCHAR_P (d - 1)))
        break;
      goto fail;

    case wordend:
      if (!AT_STRINGS_BEG (d) && WORDCHAR_P (d - 1)
        && (!WORDCHAR_P (d) || AT_STRINGS_END (d)))
        break;
      goto fail;

#ifdef emacs
    case before_dot:
      if (PTR_CHAR_POS ((unsigned char *) d) >= point)
        goto fail;
      break;

    case at_dot:
      if (PTR_CHAR_POS ((unsigned char *) d) != point)
        goto fail;
      break;

    case after_dot:
      if (PTR_CHAR_POS ((unsigned char *) d) <= point)
        goto fail;
      break;

    case syntaxspec:
      mcnt = *p++;
      goto matchsyntax;

    case wordchar:
      mcnt = (int) Sword;
matchsyntax:
      PREFETCH ();
      /* Can't use *d++ here; SYNTAX may be an unsafe macro.  */
      d++;
      if (SYNTAX (d[-1]) != (enum syntaxcode) mcnt)
        goto fail;
      SET_REGS_MATCHED ();
      break;

    case notsyntaxspec:
      mcnt = *p++;
      goto matchnotsyntax;

    case notwordchar:
      mcnt = (int) Sword;
matchnotsyntax:
      PREFETCH ();
      /* Can't use *d++ here; SYNTAX may be an unsafe macro.  */
      d++;
      if (SYNTAX (d[-1]) == (enum syntaxcode) mcnt)
        goto fail;
      SET_REGS_MATCHED ();
      break;

#else /* not emacs */
    case wordchar:
      PREFETCH ();
      if (!WORDCHAR_P (d))
        goto fail;
      SET_REGS_MATCHED ();
      d++;
      break;

    case notwordchar:
      PREFETCH ();
      if (WORDCHAR_P (d))
        goto fail;
      SET_REGS_MATCHED ();
      d++;
      break;
#endif /* not emacs */

    default:
      abort ();
    }
    continue;  /* Successfully executed one pattern command; keep going.  */


    /* We goto here if a matching operation fails. */
fail:
    if (!FAIL_STACK_EMPTY ())
    { /* A restart point is known.  Restore to that state.  */
      POP_FAILURE_POINT (d, p,
        lowest_active_reg, highest_active_reg,
        regstart, regend, reg_info);

      /* If this failure point is a dummy, try the next one.  */
      if (!p)
        goto fail;

      /* If we failed to the end of the pattern, don't examine *p.  */
      if (p < pend)
      {
        bool is_a_jump_n = false;

        /* If failed to a backwards jump that's part of a repetition
        loop, need to pop this failure point and use the next one.  */
        switch ((re_opcode_t) *p)
        {
        case jump_n:
          is_a_jump_n = true;
        case maybe_pop_jump:
        case pop_failure_jump:
        case jump:
          p1 = p + 1;
          EXTRACT_NUMBER_AND_INCR (mcnt, p1);
          p1 += mcnt;

          if ((is_a_jump_n && (re_opcode_t) *p1 == succeed_n)
            || (!is_a_jump_n
            && (re_opcode_t) *p1 == on_failure_jump))
            goto fail;
          break;
        default:
          /* do nothing */ ;
        }
      }

      if (d >= string1 && d <= end1)
        dend = end_match_1;
    }
    else
      break;   /* Matching at this starting point really fails.  */
  } /* for (;;) */

  if (best_regs_set)
    goto restore_best_regs;

  FREE_VARIABLES ();

  return -1;                    /* Failure to match.  */
} /* re_match_2 */

/* Subroutine definitions for re_match_2.  */


/* We are passed P pointing to a register number after a start_memory.

Return true if the pattern up to the corresponding stop_memory can
match the empty string, and false otherwise.

If we find the matching stop_memory, sets P to point to one past its number.
Otherwise, sets P to an undefined byte less than or equal to END.

We don't handle duplicates properly (yet).  */

static bool
group_match_null_string_p (unsigned char **p,
                           unsigned char *end,
                           register_info_type *reg_info)
{
  int mcnt;
  /* Point to after the args to the start_memory.  */
  unsigned char *p1 = *p + 2;

  while (p1 < end)
  {
    /* Skip over opcodes that can match nothing, and return true or
    false, as appropriate, when we get to one that can't, or to the
    matching stop_memory.  */

    switch ((re_opcode_t) *p1)
    {
      /* Could be either a loop or a series of alternatives.  */
    case on_failure_jump:
      p1++;
      EXTRACT_NUMBER_AND_INCR (mcnt, p1);

      /* If the next operation is not a jump backwards in the
      pattern.  */

      if (mcnt >= 0)
      {
        /* Go through the on_failure_jumps of the alternatives,
        seeing if any of the alternatives cannot match nothing.
        The last alternative starts with only a jump,
        whereas the rest start with on_failure_jump and end
        with a jump, e.g., here is the pattern for `a|b|c':

        /on_failure_jump/0/6/exactn/1/a/jump_past_alt/0/6
        /on_failure_jump/0/6/exactn/1/b/jump_past_alt/0/3
        /exactn/1/c

        So, we have to first go through the first (n-1)
        alternatives and then deal with the last one separately.  */


        /* Deal with the first (n-1) alternatives, which start
        with an on_failure_jump (see above) that jumps to right
        past a jump_past_alt.  */

        while ((re_opcode_t) p1[mcnt-3] == jump_past_alt)
        {
          /* `mcnt' holds how many bytes long the alternative
          is, including the ending `jump_past_alt' and
          its number.  */

          if (!alt_match_null_string_p (p1, p1 + mcnt - 3,
            reg_info))
            return false;

          /* Move to right after this alternative, including the
          jump_past_alt.  */
          p1 += mcnt;

          /* Break if it's the beginning of an n-th alternative
          that doesn't begin with an on_failure_jump.  */
          if ((re_opcode_t) *p1 != on_failure_jump)
            break;

          /* Still have to check that it's not an n-th
          alternative that starts with an on_failure_jump.  */
          p1++;
          EXTRACT_NUMBER_AND_INCR (mcnt, p1);
          if ((re_opcode_t) p1[mcnt-3] != jump_past_alt)
          {
            /* Get to the beginning of the n-th alternative.  */
            p1 -= 3;
            break;
          }
        }

        /* Deal with the last alternative: go back and get number
        of the `jump_past_alt' just before it.  `mcnt' contains
        the length of the alternative.  */
        EXTRACT_NUMBER (mcnt, p1 - 2);

        if (!alt_match_null_string_p (p1, p1 + mcnt, reg_info))
          return false;

        p1 += mcnt;   /* Get past the n-th alternative.  */
      } /* if mcnt > 0 */
      break;


    case stop_memory:
      *p = p1 + 2;
      return true;


    default:
      if (!common_op_match_null_string_p (&p1, end, reg_info))
        return false;
    }
  } /* while p1 < end */

  return false;
} /* group_match_null_string_p */


/* Similar to group_match_null_string_p, but doesn't deal with alternatives:
It expects P to be the first byte of a single alternative and END one
byte past the last. The alternative can contain groups.  */

static bool
alt_match_null_string_p (unsigned char *p,
                         unsigned char *end,
                         register_info_type *reg_info)
{
  int mcnt;
  unsigned char *p1 = p;

  while (p1 < end)
  {
    /* Skip over opcodes that can match nothing, and break when we get
    to one that can't.  */

    switch ((re_opcode_t) *p1)
    {
      /* It's a loop.  */
    case on_failure_jump:
      p1++;
      EXTRACT_NUMBER_AND_INCR (mcnt, p1);
      p1 += mcnt;
      break;

    default:
      if (!common_op_match_null_string_p (&p1, end, reg_info))
        return false;
    }
  }  /* while p1 < end */

  return true;
} /* alt_match_null_string_p */


/* Deals with the ops common to group_match_null_string_p and
alt_match_null_string_p.

Sets P to one after the op and its arguments, if any.  */

static bool
common_op_match_null_string_p (unsigned char **p,
                               unsigned char *end,
                               register_info_type *reg_info)
{
  int mcnt;
  bool ret;
  int reg_no;
  unsigned char *p1 = *p;

  switch ((re_opcode_t) *p1++)
  {
  case no_op:
  case begline:
  case endline:
  case begbuf:
  case endbuf:
  case wordbeg:
  case wordend:
  case wordbound:
  case notwordbound:
#ifdef emacs
  case before_dot:
  case at_dot:
  case after_dot:
#endif
    break;

  case start_memory:
    reg_no = *p1;
    ret = group_match_null_string_p (&p1, end, reg_info);

    /* Have to set this here in case we're checking a group which
    contains a group and a back reference to it.  */

    if (REG_MATCH_NULL_STRING_P (reg_info[reg_no]) == MATCH_NULL_UNSET_VALUE)
      REG_MATCH_NULL_STRING_P (reg_info[reg_no]) = ret;

    if (!ret)
      return false;
    break;

    /* If this is an optimized succeed_n for zero times, make the jump.  */
  case jump:
    EXTRACT_NUMBER_AND_INCR (mcnt, p1);
    if (mcnt >= 0)
      p1 += mcnt;
    else
      return false;
    break;

  case succeed_n:
    /* Get to the number of times to succeed.  */
    p1 += 2;
    EXTRACT_NUMBER_AND_INCR (mcnt, p1);

    if (mcnt == 0)
    {
      p1 -= 4;
      EXTRACT_NUMBER_AND_INCR (mcnt, p1);
      p1 += mcnt;
    }
    else
      return false;
    break;

  case duplicate:
    if (!REG_MATCH_NULL_STRING_P (reg_info[*p1]))
      return false;
    break;

  case set_number_at:
    p1 += 4;

  default:
    /* All other opcodes mean we cannot match the empty string.  */
    return false;
  }

  *p = p1;
  return true;
} /* common_op_match_null_string_p */


/* Return zero if TRANSLATE[S1] and TRANSLATE[S2] are identical for LEN
bytes; nonzero otherwise.  */

static int
bcmp_translate (const char *s1,
                const char *s2,
                register int len,
                RE_TRANSLATE_TYPE translate)
{
  register const unsigned char *p1 = (const unsigned char *) s1;
  register const unsigned char *p2 = (const unsigned char *) s2;
  while (len)
  {
    if (translate[*p1++] != translate[*p2++]) return 1;
    len--;
  }
  return 0;
}

/* Entry points for GNU code.  */

/* re_compile_pattern is the GNU regular expression compiler: it
compiles PATTERN (of length SIZE) and puts the result in BUFP.
Returns 0 if the pattern was valid, otherwise an error string.

Assumes the `allocated' (and perhaps `buffer') and `translate' fields
are set in BUFP on entry.

We call regex_compile to do the actual compilation.  */

const char *
re_compile_pattern (const char *pattern,
                    size_t length,
struct re_pattern_buffer *bufp)
{
  reg_errcode_t ret;

  /* GNU code is written to assume at least RE_NREGS registers will be set
  (and at least one extra will be -1).  */
  bufp->regs_allocated = REGS_UNALLOCATED;

  /* And GNU code determines whether or not to get register information
  by passing null for the REGS argument to re_match, etc., not by
  setting no_sub.  */
  bufp->no_sub = 0;

  /* Match anchors at newline.  */
  bufp->newline_anchor = 1;

  ret = regex_compile (pattern, length, re_syntax_options, bufp);

  if (!ret)
    return NULL;
  return gettext (re_error_msgid[(int) ret]);
}
#ifdef _LIBC
weak_alias (__re_compile_pattern, re_compile_pattern)
#endif

/* Entry points compatible with 4.2 BSD regex library.  We don't define
them unless specifically requested.  */

#if defined _REGEX_RE_COMP || defined _LIBC

/* BSD has one and only one pattern buffer.  */
static struct re_pattern_buffer re_comp_buf;

char *
#ifdef _LIBC
/* Make these definitions weak in libc, so POSIX programs can redefine
these names if they don't use our functions, and still use
regcomp/regexec below without link errors.  */
weak_function
#endif
re_comp (s)
const char *s;
{
  reg_errcode_t ret;

  if (!s)
  {
    if (!re_comp_buf.buffer)
      return gettext ("No previous regular expression");
    return 0;
  }

  if (!re_comp_buf.buffer)
  {
    re_comp_buf.buffer = (unsigned char *) malloc (200);
    if (re_comp_buf.buffer == NULL)
      return (char *) gettext (re_error_msgid[(int) REG_ESPACE]);
    re_comp_buf.allocated = 200;

    re_comp_buf.fastmap = (char *) malloc (1 << BYTEWIDTH);
    if (re_comp_buf.fastmap == NULL)
      return (char *) gettext (re_error_msgid[(int) REG_ESPACE]);
  }

  /* Since `re_exec' always passes NULL for the `regs' argument, we
  don't need to initialize the pattern buffer fields which affect it.  */

  /* Match anchors at newlines.  */
  re_comp_buf.newline_anchor = 1;

  ret = regex_compile (s, strlen (s), re_syntax_options, &re_comp_buf);

  if (!ret)
    return NULL;

  /* Yes, we're discarding `const' here if !HAVE_LIBINTL.  */
  return (char *) gettext (re_error_msgid[(int) ret]);
}


int
#ifdef _LIBC
weak_function
#endif
re_exec (s)
const char *s;
{
  const int len = strlen (s);
  return
    0 <= re_search (&re_comp_buf, s, len, 0, len, (struct re_registers *) 0);
}

#endif /* _REGEX_RE_COMP */

/* POSIX.2 functions.  Don't define these for Emacs.  */

#ifndef emacs

/* regcomp takes a regular expression as a string and compiles it.

PREG is a regex_t *.  We do not expect any fields to be initialized,
since POSIX says we shouldn't.  Thus, we set

`buffer' to the compiled pattern;
`used' to the length of the compiled pattern;
`syntax' to RE_SYNTAX_POSIX_EXTENDED if the
REG_EXTENDED bit in CFLAGS is set; otherwise, to
RE_SYNTAX_POSIX_BASIC;
`newline_anchor' to REG_NEWLINE being set in CFLAGS;
`fastmap' to an allocated space for the fastmap;
`fastmap_accurate' to zero;
`re_nsub' to the number of subexpressions in PATTERN.

PATTERN is the address of the pattern string.

CFLAGS is a series of bits which affect compilation.

If REG_EXTENDED is set, we use POSIX extended syntax; otherwise, we
use POSIX basic syntax.

If REG_NEWLINE is set, then . and [^...] don't match newline.
Also, regexec will try a match beginning after every newline.

If REG_ICASE is set, then we considers upper- and lowercase
versions of letters to be equivalent when matching.

If REG_NOSUB is set, then when PREG is passed to regexec, that
routine will report only success or failure, and nothing about the
registers.

It returns 0 if it succeeds, nonzero if it doesn't.  (See regex.h for
the return codes and their meanings.)  */

int
regcomp (regex_t *preg,
         const char *pattern,
         int cflags)
{
  reg_errcode_t ret;
  reg_syntax_t syntax
    = (cflags & REG_EXTENDED) ?
RE_SYNTAX_POSIX_EXTENDED : RE_SYNTAX_POSIX_BASIC;

  /* regex_compile will allocate the space for the compiled pattern.  */
  preg->buffer = 0;
  preg->allocated = 0;
  preg->used = 0;

  /* Try to allocate space for the fastmap.  */
  preg->fastmap = (char *) malloc (1 << BYTEWIDTH);

  if (cflags & REG_ICASE)
  {
    unsigned i;

    preg->translate
      = (RE_TRANSLATE_TYPE) malloc (CHAR_SET_SIZE
      * sizeof (*(RE_TRANSLATE_TYPE)0));
    if (preg->translate == NULL)
      return (int) REG_ESPACE;

    /* Map uppercase characters to corresponding lowercase ones.  */
    for (i = 0; i < CHAR_SET_SIZE; i++)
      preg->translate[i] = ISUPPER (i) ? g_tolower (i) : i;
  }
  else
    preg->translate = NULL;

  /* If REG_NEWLINE is set, newlines are treated differently.  */
  if (cflags & REG_NEWLINE)
  { /* REG_NEWLINE implies neither . nor [^...] match newline.  */
    syntax &= ~RE_DOT_NEWLINE;
    syntax |= RE_HAT_LISTS_NOT_NEWLINE;
    /* It also changes the matching behavior.  */
    preg->newline_anchor = 1;
  }
  else
    preg->newline_anchor = 0;

  preg->no_sub = !!(cflags & REG_NOSUB);

  /* POSIX says a null character in the pattern terminates it, so we
  can use strlen here in compiling the pattern.  */
  ret = regex_compile (pattern, strlen (pattern), syntax, preg);

  /* POSIX doesn't distinguish between an unmatched open-group and an
  unmatched close-group: both are REG_EPAREN.  */
  if (ret == REG_ERPAREN) ret = REG_EPAREN;

  if (ret == REG_NOERROR && preg->fastmap)
  {
    /* Compute the fastmap now, since regexec cannot modify the pattern
    buffer.  */
    if (re_compile_fastmap (preg) == -2)
    {
      /* Some error occured while computing the fastmap, just forget
      about it.  */
      free (preg->fastmap);
      preg->fastmap = NULL;
    }
  }

  return (int) ret;
}
#ifdef _LIBC
weak_alias (__regcomp, regcomp)
#endif


/* regexec searches for a given pattern, specified by PREG, in the
string STRING.

If NMATCH is zero or REG_NOSUB was set in the cflags argument to
`regcomp', we ignore PMATCH.  Otherwise, we assume PMATCH has at
least NMATCH elements, and we set them to the offsets of the
corresponding matched substrings.

EFLAGS specifies `execution flags' which affect matching: if
REG_NOTBOL is set, then ^ does not match at the beginning of the
string; if REG_NOTEOL is set, then $ does not match at the end.

We return 0 if we find a match and REG_NOMATCH if not.  */

int
regexec (const regex_t *preg,
         const char *string,
         size_t nmatch,
         regmatch_t pmatch[],
         int eflags)
{
  int ret;
  struct re_registers regs;
  regex_t private_preg;
  int len = strlen (string);
  bool want_reg_info = !preg->no_sub && nmatch > 0;

  private_preg = *preg;

  private_preg.not_bol = !!(eflags & REG_NOTBOL);
  private_preg.not_eol = !!(eflags & REG_NOTEOL);

  /* The user has told us exactly how many registers to return
  information about, via `nmatch'.  We have to pass that on to the
  matching routines.  */
  private_preg.regs_allocated = REGS_FIXED;

  if (want_reg_info)
  {
    regs.num_regs = nmatch;
    regs.start = TALLOC (nmatch * 2, regoff_t);
    if (regs.start == NULL)
      return (int) REG_NOMATCH;
    regs.end = regs.start + nmatch;
  }

  /* Perform the searching operation.  */
  ret = re_search (&private_preg, string, len,
    /* start: */ 0, /* range: */ len,
    want_reg_info ? &regs : (struct re_registers *) 0);

  /* Copy the register information to the POSIX structure.  */
  if (want_reg_info)
  {
    if (ret >= 0)
    {
      unsigned r;

      for (r = 0; r < nmatch; r++)
      {
        pmatch[r].rm_so = regs.start[r];
        pmatch[r].rm_eo = regs.end[r];
      }
    }

    /* If we needed the temporary register info, free the space now.  */
    free (regs.start);
  }

  /* We want zero return to mean success, unlike `re_search'.  */
  return ret >= 0 ? (int) REG_NOERROR : (int) REG_NOMATCH;
}
#ifdef _LIBC
weak_alias (__regexec, regexec)
#endif


/* Returns a message corresponding to an error code, ERRCODE, returned
from either regcomp or regexec.   We don't use PREG here.  */

size_t
regerror (int errcode, const regex_t *preg, char *errbuf, size_t errbuf_size)
{
  const char *msg;
  size_t msg_size;

  if (errcode < 0
    || errcode >= (int) (sizeof (re_error_msgid)
    / sizeof (re_error_msgid[0])))
    /* Only error codes returned by the rest of the code should be passed
    to this routine.  If we are given anything else, or if other regex
    code generates an invalid error code, then the program has a bug.
    Dump core so we can fix it.  */
    abort ();

  msg = gettext (re_error_msgid[errcode]);

  msg_size = strlen (msg) + 1; /* Includes the null.  */

  if (errbuf_size != 0)
  {
    if (msg_size > errbuf_size)
    {
#if defined HAVE_MEMPCPY || defined _LIBC
      *((char *) __mempcpy (errbuf, msg, errbuf_size - 1)) = '\0';
#else
      memcpy (errbuf, msg, errbuf_size - 1);
      errbuf[errbuf_size - 1] = 0;
#endif
    }
    else
      memcpy (errbuf, msg, msg_size);
  }

  return msg_size;
}
#ifdef _LIBC
weak_alias (__regerror, regerror)
#endif


/* Free dynamically allocated space used by PREG.  */

void
regfree (regex_t *preg)
{
  if (preg->buffer != NULL)
    free (preg->buffer);
  preg->buffer = NULL;

  preg->allocated = 0;
  preg->used = 0;

  if (preg->fastmap != NULL)
    free (preg->fastmap);
  preg->fastmap = NULL;
  preg->fastmap_accurate = 0;

  if (preg->translate != NULL)
    free (preg->translate);
  preg->translate = NULL;
}
#ifdef _LIBC
weak_alias (__regfree, regfree)
#endif

#endif /* not emacs  */