Update.

	* posix/Makefile (distribute): Add regcomp.c, regexec.c,
	regex_internal.c, and regex_internal.h.
	(CFLAGS-regex.c): Replace -DMBS_SUPPORT with -DRE_ENABLE_I18N.
	* posix/regex.c: Complete rewrite.
	* posix/regexec.c: New file.
	* posix/regcomp.c: New file.
	* posix/regex_internal.c: New file.
	* posix/regex_internal.h: New file.
	* posix/regex.h (RE_ICASE): New macro.
	Contributed by Isamu Hasegawa <isamu@yamato.ibm.com>.

1 files changed, 2076 insertions, 0 deletions

diff --git a/posix/regexec.c b/posix/regexec.c
new file mode 100644
index 0000000..cf8f304
--- /dev/null
+++ b/posix/regexec.c
@@ -0,0 +1,2076 @@
+/* Extended regular expression matching and search library.
+   Copyright (C) 2002 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Isamu Hasegawa <isamu@yamato.ibm.com>.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <assert.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <wctype.h>
+
+#ifdef _LIBC
+# ifndef _RE_DEFINE_LOCALE_FUNCTIONS
+#  define _RE_DEFINE_LOCALE_FUNCTIONS 1
+#  include <locale/localeinfo.h>
+#  include <locale/elem-hash.h>
+#  include <locale/coll-lookup.h>
+# endif
+#endif
+
+#include "regex.h"
+#include "regex_internal.h"
+
+static void match_ctx_init (re_match_context_t *cache, int eflags, int n);
+static void match_ctx_free (re_match_context_t *cache);
+static void match_ctx_add_entry (re_match_context_t *cache, int node, int from,
+                                 int to);
+static int re_search_internal (const regex_t *preg, const char *string,
+                               int length, int start, int range, size_t nmatch,
+                               regmatch_t pmatch[], int eflags);
+static inline re_dfastate_t *acquire_init_state_context (const regex_t *preg,
+                                const re_string_t *input, int idx, int eflags);
+static int check_matching (const regex_t *preg, re_string_t *input,
+                           re_match_context_t *mctx, re_dfastate_t **state_log,
+                           int start_idx, int fl_search, int fl_longest_match);
+static int check_halt_node_context (const re_dfa_t *dfa, int node,
+                                    unsigned int context);
+static int check_halt_state_context (const regex_t *preg,
+                                     const re_dfastate_t *state,
+                                     const re_string_t *input, int idx,
+                                     int eflags);
+static int proceed_next_node (const regex_t *preg,
+                              re_dfastate_t **state_log,
+                              const re_match_context_t *mctx,
+                              const re_string_t *input,
+                              int *pidx, int node, re_node_set *eps_via_nodes);
+static void set_regs (const regex_t *preg, re_dfastate_t **state_log,
+                      const re_match_context_t *mctx, const re_string_t *input,
+                      size_t nmatch, regmatch_t *pmatch, int last);
+static int sift_states_iter_mb (const regex_t *preg, re_dfastate_t **state_log,
+                                const re_match_context_t *mctx,
+                                const re_string_t *input, int node_idx,
+                                int str_idx, int max_str_idx);
+static int sift_states_iter_bkref (const re_dfa_t *dfa,
+                                   re_dfastate_t **state_log,
+                                   struct re_backref_cache_entry *mctx_entry,
+                                   int node_idx, int idx, int match_first,
+                                   int match_last);
+static void sift_states_backward (const regex_t *preg,
+                                  re_dfastate_t **state_log,
+                                  const re_match_context_t *mctx,
+                                  const re_string_t *input, int last_node);
+static void add_epsilon_backreference (const re_dfa_t *dfa,
+                                       const re_match_context_t *mctx,
+                                       const re_node_set *plog, int idx,
+                                       re_node_set *state_buf);
+static re_dfastate_t *transit_state (const regex_t *preg, re_dfastate_t *state,
+                                     re_string_t *input, int fl_search,
+                                     re_dfastate_t **state_log,
+                                     re_match_context_t *mctx);
+static re_dfastate_t *transit_state_sb (const regex_t *preg,
+                                        re_dfastate_t *pstate,
+                                        re_string_t *input, int fl_search,
+                                        re_match_context_t *mctx);
+static void transit_state_mb (const regex_t *preg, re_dfastate_t *pstate,
+                              const re_string_t *input,
+                              re_dfastate_t **state_log,
+                              re_match_context_t *mctx);
+static void transit_state_bkref (const regex_t *preg, re_dfastate_t *pstate,
+                                 const re_string_t *input,
+                                 re_dfastate_t **state_log,
+                                 re_match_context_t *mctx);
+static void transit_state_bkref_loop (const regex_t *preg,
+                                      const re_string_t *input,
+                                      re_node_set *nodes,
+                                      re_dfastate_t **work_state_log,
+                                      re_dfastate_t **state_log,
+                                      re_match_context_t *mctx);
+static re_dfastate_t **build_trtable (const regex_t *dfa,
+                                      const re_dfastate_t *state,
+                                      int fl_search);
+static int check_node_accept_bytes (const regex_t *preg, int node_idx,
+                                    const re_string_t *input, int idx);
+static unsigned int find_collation_sequence_value (const unsigned char *mbs,
+                                                   size_t name_len);
+static int group_nodes_into_DFAstates (const regex_t *dfa,
+                                       const re_dfastate_t *state,
+                                       re_node_set *states_node,
+                                       bitset *states_ch);
+static int check_node_accept (const regex_t *preg, const re_token_t *node,
+                              const re_string_t *input, int idx, int eflags);
+
+/* Entry point for POSIX code.  */
+
+/* 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 (preg, string, nmatch, pmatch, eflags)
+    const regex_t *preg;
+    const char *string;
+    size_t nmatch;
+    regmatch_t pmatch[];
+    int eflags;
+{
+  int length = strlen (string);
+  if (preg->no_sub)
+    return re_search_internal (preg, string, length, 0, length, 0,
+                               NULL, eflags);
+  else
+    return re_search_internal (preg, string, length, 0, length, nmatch,
+                               pmatch, eflags);
+}
+#ifdef _LIBC
+weak_alias (__regexec, regexec)
+#endif
+
+/* Entry points for GNU code.  */
+
+/* re_match is like re_match_2 except it takes only a single string.  */
+
+int
+re_match (buffer, string, length, start, regs)
+    struct re_pattern_buffer *buffer;
+    const char *string;
+    int length, start;
+    struct re_registers *regs;
+{
+  int i, nregs, result, rval, eflags = 0;
+  regmatch_t *pmatch;
+
+  eflags |= (buffer->not_bol) ? REG_NOTBOL : 0;
+  eflags |= (buffer->not_eol) ? REG_NOTEOL : 0;
+
+  /* We need at least 1 register.  */
+  nregs = ((regs == NULL) ? 1
+           : ((regs->num_regs > buffer->re_nsub) ? buffer->re_nsub + 1
+              : regs->num_regs + 1));
+  pmatch = re_malloc (regmatch_t, nregs);
+  if (pmatch == NULL)
+    return -2;
+  result = re_search_internal (buffer, string, length, start, 0,
+                               nregs, pmatch, eflags);
+
+  /* If caller wants register contents data back, do it.  */
+  if (regs && !buffer->no_sub)
+    {
+      /* Have the register data arrays been allocated?  */
+      if (buffer->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 = ((RE_NREGS > buffer->re_nsub + 1) ? RE_NREGS
+                            : buffer->re_nsub + 1);
+          regs->start = re_malloc (regoff_t, regs->num_regs);
+          regs->end = re_malloc (regoff_t, regs->num_regs);
+          if (regs->start == NULL || regs->end == NULL)
+            {
+              re_free (pmatch);
+              return -2;
+            }
+          buffer->regs_allocated = REGS_REALLOCATE;
+        }
+      else if (buffer->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 < buffer->re_nsub + 1)
+            {
+              regs->num_regs = buffer->re_nsub + 1;
+              regs->start = re_realloc (regs->start, regoff_t, regs->num_regs);
+              regs->end = re_realloc (regs->end, regoff_t, regs->num_regs);
+              if (regs->start == NULL || regs->end == NULL)
+                {
+                  re_free (pmatch);
+                  return -2;
+                }
+            }
+        }
+      else
+        {
+          /* These braces fend off a "empty body in an else-statement"
+             warning under GCC when assert expands to nothing.  */
+          assert (buffer->regs_allocated == REGS_FIXED);
+        }
+    }
+
+  /* Restore registers.  */
+  if (regs != NULL)
+    {
+      for (i = 0; i <= nregs; ++i)
+        {
+          regs->start[i] = pmatch[i].rm_so;
+          regs->end[i] = pmatch[i].rm_eo;
+        }
+      for ( ; i < regs->num_regs; ++i)
+        {
+          regs->start[i] = -1;
+          regs->end[i] = -1;
+        }
+    }
+  /* Return value is -1 if not match, the length of mathing otherwise.  */
+  rval = (result) ? -1 : pmatch[0].rm_eo - pmatch[0].rm_so;
+  re_free (pmatch);
+  return rval;
+}
+#ifdef _LIBC
+weak_alias (__re_match, re_match)
+#endif
+
+/* 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.
+   Otherwise, we return the length of the matched substring.  */
+
+int
+re_match_2 (buffer, string1, length1, string2, length2, start, regs, stop)
+     struct re_pattern_buffer *buffer;
+     const char *string1, *string2;
+     int length1, length2, start, stop;
+     struct re_registers *regs;
+{
+  int len, ret;
+  char *str = re_malloc (char, length1 + length2);
+  if (str == NULL)
+    return -2;
+  memcpy (str, string1, length1);
+  memcpy (str + length1, string2, length2);
+  len = (length1 + length2 < stop) ? length1 + length2 : stop;
+  ret = re_match (buffer, str, len, start, regs);
+  re_free (str);
+  return ret;
+}
+#ifdef _LIBC
+weak_alias (__re_match_2, re_match_2)
+#endif
+
+/* Like re_search_2, below, but only one string is specified, and
+   doesn't let you say where to stop matching.  */
+
+int
+re_search (bufp, string, size, startpos, range, regs)
+     struct re_pattern_buffer *bufp;
+     const char *string;
+     int size, startpos, range;
+     struct re_registers *regs;
+{
+  int i, nregs, result, real_range, rval, eflags = 0;
+  regmatch_t *pmatch;
+
+  eflags |= (bufp->not_bol) ? REG_NOTBOL : 0;
+  eflags |= (bufp->not_eol) ? REG_NOTEOL : 0;
+
+  /* Check for out-of-range.  */
+  if (startpos < 0 || startpos > size)
+    return -1;
+
+  /* We need at least 1 register.  */
+  nregs = ((regs == NULL) ? 1
+           : ((regs->num_regs > bufp->re_nsub) ? bufp->re_nsub + 1
+              : regs->num_regs + 1));
+  pmatch = re_malloc (regmatch_t, nregs);
+
+  /* Correct range if we need.  */
+  real_range = ((startpos + range > size) ? size - startpos
+                : ((startpos + range < 0) ? -startpos : range));
+
+  /* Compile fastmap if we haven't yet.  */
+  if (bufp->fastmap != NULL && !bufp->fastmap_accurate)
+    re_compile_fastmap (bufp);
+
+  result = re_search_internal (bufp, string, size, startpos, real_range,
+                               nregs, pmatch, eflags);
+
+  /* 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 = ((RE_NREGS > bufp->re_nsub + 1) ? RE_NREGS
+                            : bufp->re_nsub + 1);
+          regs->start = re_malloc (regoff_t, regs->num_regs);
+          regs->end = re_malloc (regoff_t, regs->num_regs);
+          if (regs->start == NULL || regs->end == NULL)
+            {
+              re_free (pmatch);
+              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 < bufp->re_nsub + 1)
+            {
+              regs->num_regs = bufp->re_nsub + 1;
+              regs->start = re_realloc (regs->start, regoff_t, regs->num_regs);
+              regs->end = re_realloc (regs->end, regoff_t, regs->num_regs);
+              if (regs->start == NULL || regs->end == NULL)
+                {
+                  re_free (pmatch);
+                  return -2;
+                }
+            }
+        }
+      else
+        {
+          /* These braces fend off a "empty body in an else-statement"
+             warning under GCC when assert expands to nothing.  */
+          assert (bufp->regs_allocated == REGS_FIXED);
+        }
+    }
+
+  /* Restore registers.  */
+  if (regs != NULL)
+    {
+      for (i = 0; i <= bufp->re_nsub; ++i)
+        {
+          regs->start[i] = pmatch[i].rm_so;
+          regs->end[i] = pmatch[i].rm_eo;
+        }
+      for ( ; i < regs->num_regs; ++i)
+        {
+          regs->start[i] = -1;
+          regs->end[i] = -1;
+        }
+    }
+  /* Return value is -1 if not match, the position where the mathing starts
+     otherwise.  */
+  rval = (result) ? -1 : pmatch[0].rm_so;
+  re_free (pmatch);
+  return rval;
+}
+#ifdef _LIBC
+weak_alias (__re_search, re_search)
+#endif
+
+/* Using the compiled pattern in BUFP, 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.  */
+
+int
+re_search_2 (bufp, string1, length1, string2, length2, start, range, regs,
+             stop)
+    struct re_pattern_buffer *bufp;
+    const char *string1, *string2;
+    int length1, length2, start, range, stop;
+    struct re_registers *regs;
+{
+  int len, ret;
+  char *str = re_malloc (char, length1 + length2);
+  memcpy (str, string1, length1);
+  memcpy (str + length1, string2, length2);
+  len = (length1 + length2 < stop) ? length1 + length2 : stop;
+  ret = re_search (bufp, str, len, start, range, regs);
+  re_free (str);
+  return ret;
+}
+#ifdef _LIBC
+weak_alias (__re_search_2, re_search_2)
+#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 (bufp, regs, num_regs, starts, ends)
+    struct re_pattern_buffer *bufp;
+    struct re_registers *regs;
+    unsigned num_regs;
+    regoff_t *starts, *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
+
+/* Entry points compatible with 4.2 BSD regex library.  We don't define
+   them unless specifically requested.  */
+
+#if defined _REGEX_RE_COMP || defined _LIBC
+int
+# ifdef _LIBC
+weak_function
+# endif
+re_exec (s)
+     const char *s;
+{
+  return 0 == regexec (&re_comp_buf, s, 0, NULL, 0);
+}
+#endif /* _REGEX_RE_COMP */
+
+static re_node_set empty_set;
+
+/* Internal entry point.  */
+
+/* Searches for a compiled pattern PREG in the string STRING, whose
+   length is LENGTH.  NMATCH, PMATCH, and EFLAGS have the same
+   mingings with regexec.  START, and RANGE have the same meanings
+   with re_search.
+   Return 0 if we find a match and REG_NOMATCH if not.
+   Note: We assume front end functions already check ranges.
+   (START + RANGE >= 0 && START + RANGE <= LENGTH)  */
+
+static int
+re_search_internal (preg, string, length, start, range, nmatch, pmatch, eflags)
+    const regex_t *preg;
+    const char *string;
+    int length, start, range, eflags;
+    size_t nmatch;
+    regmatch_t pmatch[];
+{
+  re_dfa_t *dfa = (re_dfa_t *)preg->buffer;
+  re_string_t input;
+  re_dfastate_t **state_log;
+  int fl_longest_match, match_first, match_last = -1;
+  re_match_context_t mctx;
+  char *fastmap = ((preg->fastmap != NULL && preg->fastmap_accurate)
+                   ? preg->fastmap : NULL);
+
+  /* Check if the DFA haven't been compiled.  */
+  if (preg->used == 0 || dfa->init_state == NULL
+      || dfa->init_state_word == NULL || dfa->init_state_nl == NULL
+      || dfa->init_state_begbuf == NULL)
+    return 1;
+
+  re_node_set_init_empty (&empty_set);
+
+  /* We must check the longest matching, if nmatch > 0.  */
+  fl_longest_match = (nmatch != 0);
+
+  /* We will log all the DFA states through which the dfa pass,
+     if nmatch > 1, or this dfa has "multibyte node", which is a
+     back-reference or a node which can accept multibyte character or
+     multi character collating element.  */
+  if (nmatch > 1 || dfa->has_mb_node)
+    state_log = re_malloc (re_dfastate_t *, length + 1);
+  else
+    state_log = NULL;
+
+  if (preg->syntax & RE_ICASE)
+    re_string_construct_toupper (&input, string, length, preg->translate);
+  else
+    re_string_construct (&input, string, length, preg->translate);
+
+  match_ctx_init (&mctx, eflags, dfa->nbackref * 2);
+
+#ifdef DEBUG
+  /* We assume front-end functions already check them.  */
+  assert (start + range >= 0 && start + range <= length);
+#endif
+
+  /* Check incrementally whether of not the input string match.  */
+  for (match_first = start; ;)
+    {
+      if ((match_first < length
+           && (fastmap == NULL
+               || fastmap[re_string_byte_at (&input, match_first)]))
+          || preg->can_be_null)
+        {
+#ifdef RE_ENABLE_I18N
+          if (MB_CUR_MAX == 1 || re_string_first_byte (&input, match_first))
+#endif
+            {
+              /* We assume that the matching starts from `match_first'.  */
+              re_string_set_index (&input, match_first);
+              mctx.match_first = mctx.state_log_top = match_first;
+              mctx.nbkref_ents = mctx.max_bkref_len = 0;
+              match_last = check_matching (preg, &input, &mctx, state_log,
+                                           match_first, 0, fl_longest_match);
+              if (match_last != -1)
+                break;
+            }
+        }
+      /* Update counter.  */
+      if (range < 0)
+        {
+          --match_first;
+          if (match_first < start + range)
+            break;
+        }
+      else
+        {
+          ++match_first;
+          if (match_first > start + range)
+            break;
+        }
+    }
+
+  /* Set pmatch[] if we need.  */
+  if (match_last != -1 && nmatch > 0)
+    {
+      int reg_idx;
+
+      /* Initialize registers.  */
+      for (reg_idx = 0; reg_idx < nmatch; ++reg_idx)
+        pmatch[reg_idx].rm_so = pmatch[reg_idx].rm_eo = -1;
+
+      /* Set the points where matching start/end.  */
+      pmatch[0].rm_so = mctx.match_first;
+      mctx.match_last = pmatch[0].rm_eo = match_last;
+
+      if (!preg->no_sub && nmatch > 1)
+        {
+          /* We need the ranges of all the subexpressions.  */
+          int halt_node;
+          re_dfastate_t *pstate = state_log[match_last];
+#ifdef DEBUG
+          assert (state_log != NULL);
+#endif
+          halt_node = check_halt_state_context (preg, pstate, &input,
+                                                match_last, eflags);
+          sift_states_backward (preg, state_log, &mctx, &input, halt_node);
+          set_regs (preg, state_log, &mctx, &input, nmatch, pmatch, halt_node);
+        }
+    }
+
+  re_free (state_log);
+  if (dfa->nbackref)
+    match_ctx_free (&mctx);
+  re_string_destruct (&input);
+  return match_last == -1;
+}
+
+/* Acquire an initial state.
+   We must select appropriate initial state depending on the context,
+   since initial states may have constraints like "\<", "^", etc..  */
+
+static inline re_dfastate_t *
+acquire_init_state_context (preg, input, idx, eflags)
+    const regex_t *preg;
+    const re_string_t *input;
+    int idx, eflags;
+{
+  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+
+  if (dfa->init_state->has_constraint)
+    {
+      unsigned int context;
+      context =  re_string_context_at (input, idx - 1, eflags,
+                                       preg->newline_anchor);
+      if (IS_WORD_CONTEXT (context))
+        return dfa->init_state_word;
+      else if (IS_ORDINARY_CONTEXT (context))
+        return dfa->init_state;
+      else if (IS_BEGBUF_CONTEXT (context) && IS_NEWLINE_CONTEXT (context))
+        return dfa->init_state_begbuf;
+      else if (IS_NEWLINE_CONTEXT (context))
+        return dfa->init_state_nl;
+      else if (IS_BEGBUF_CONTEXT (context))
+        /* It is relatively rare case, then calculate on demand.  */
+        return re_acquire_state_context (dfa, dfa->init_state->entrance_nodes,
+                                         context);
+      else
+        /* Must not happen?  */
+        return dfa->init_state;
+    }
+  else
+    return dfa->init_state;
+}
+
+/* Check whether the regular expression match input string INPUT or not,
+   and return the index where the matching end, or return -1 if not match.
+   FL_SEARCH means we must search where the matching starts,
+   FL_LONGEST_MATCH means we want the POSIX longest matching.  */
+
+static int
+check_matching (preg, input, mctx, state_log, start_idx, fl_search,
+                fl_longest_match)
+    const regex_t *preg;
+    re_string_t *input;
+    re_match_context_t *mctx;
+    re_dfastate_t **state_log;
+    int start_idx, fl_search, fl_longest_match;
+{
+  int match = 0, match_last = -1;
+  re_dfastate_t *cur_state;
+
+  cur_state = acquire_init_state_context (preg, input, start_idx,
+                                          mctx->eflags);
+  if (state_log != NULL)
+    state_log[start_idx] = cur_state;
+  /* If the RE accepts NULL string.  */
+  if (cur_state->halt)
+    {
+      if (!cur_state->has_constraint
+          || check_halt_state_context (preg, cur_state, input, start_idx,
+                                       mctx->eflags))
+        {
+          if (!fl_longest_match)
+            return start_idx;
+          else
+            {
+              match_last = start_idx;
+              match = 1;
+            }
+        }
+    }
+
+  while (!re_string_eoi (input))
+    {
+      cur_state = transit_state (preg, cur_state, input, fl_search && !match,
+                                 state_log, mctx);
+      if (cur_state == NULL) /* Reached at the invalid state.  */
+        {
+          int cur_str_idx = re_string_cur_idx (input);
+          if (fl_search && !match)
+            {
+              /* Restart from initial state, since we are searching
+                 the point from where matching start.  */
+#ifdef RE_ENABLE_I18N
+              if (MB_CUR_MAX == 1 || re_string_first_byte (input, cur_str_idx))
+#endif /* RE_ENABLE_I18N */
+                cur_state = acquire_init_state_context (preg, input,
+                                                        cur_str_idx,
+                                                        mctx->eflags);
+              if (state_log != NULL)
+                state_log[cur_str_idx] = cur_state;
+            }
+          else if (!fl_longest_match && match)
+            break;
+          else /* (fl_longest_match && match) || (!fl_search && !match)  */
+            {
+              if (state_log == NULL)
+                break;
+              else
+                {
+                  int max = mctx->state_log_top;
+                  for (; cur_str_idx <= max; ++cur_str_idx)
+                    if (state_log[cur_str_idx] != NULL)
+                      break;
+                  if (cur_str_idx > max)
+                    break;
+                }
+            }
+        }
+
+      if (cur_state != NULL && cur_state->halt)
+        {
+          /* Reached at a halt state.
+             Check the halt state can satisfy the current context.  */
+          if (!cur_state->has_constraint
+              || check_halt_state_context (preg, cur_state, input,
+                                           re_string_cur_idx (input),
+                                           mctx->eflags))
+            {
+              /* We found an appropriate halt state.  */
+              match_last = re_string_cur_idx (input);
+              match = 1;
+              if (!fl_longest_match)
+                break;
+            }
+        }
+   }
+  return match_last;
+}
+
+/* Check NODE match the current context.  */
+
+static int check_halt_node_context (dfa, node, context)
+    const re_dfa_t *dfa;
+    int node;
+    unsigned int context;
+{
+  int entity;
+  re_token_type_t type = dfa->nodes[node].type;
+  if (type == END_OF_RE)
+    return 1;
+  if (type != OP_CONTEXT_NODE)
+    return 0;
+  entity = dfa->nodes[node].opr.ctx_info->entity;
+  if (dfa->nodes[entity].type != END_OF_RE
+      || NOT_SATISFY_NEXT_CONSTRAINT (dfa->nodes[node].constraint, context))
+    return 0;
+  return 1;
+}
+
+/* Check the halt state STATE match the current context.
+   Return 0 if not match, if the node, STATE has, is a halt node and
+   match the context, return the node.  */
+
+static int
+check_halt_state_context (preg, state, input, idx, eflags)
+    const regex_t *preg;
+    const re_dfastate_t *state;
+    const re_string_t *input;
+    int idx, eflags;
+{
+  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  int i;
+  unsigned int context;
+#ifdef DEBUG
+  assert (state->halt);
+#endif
+  context = re_string_context_at (input, idx, eflags, preg->newline_anchor);
+  for (i = 0; i < state->nodes.nelem; ++i)
+    if (check_halt_node_context (dfa, state->nodes.elems[i], context))
+      return state->nodes.elems[i];
+  return 0;
+}
+
+/* Compute the next node to which "NFA" transit from NODE.
+   Return the destination node, and update EPS_VIA_NODES.
+   ("NFA" is a NFA corresponding to the DFA.  */
+
+static int
+proceed_next_node (preg, state_log, mctx, input, pidx, node, eps_via_nodes)
+    const regex_t *preg;
+    re_dfastate_t **state_log;
+    const re_match_context_t *mctx;
+    const re_string_t *input;
+    int *pidx, node;
+    re_node_set *eps_via_nodes;
+{
+  re_dfa_t *dfa = (re_dfa_t *)preg->buffer;
+  int i, dest_node = -1;
+  if (IS_EPSILON_NODE (dfa->nodes[node].type))
+    {
+      re_node_set_insert (eps_via_nodes, node);
+      for (i = 0; i < state_log[*pidx]->nodes.nelem; ++i)
+        {
+          int candidate = state_log[*pidx]->nodes.elems[i];
+          if (!re_node_set_contains (dfa->edests + node, candidate)
+              && !(dfa->nodes[candidate].type == OP_CONTEXT_NODE
+                   && re_node_set_contains (dfa->edests + node,
+                            dfa->nodes[candidate].opr.ctx_info->entity)))
+            continue;
+          dest_node = candidate;
+          /* In order to avoid infinite loop like "(a*)*".  */
+          if (!re_node_set_contains (eps_via_nodes, dest_node))
+            break;
+        }
+#ifdef DEBUG
+      assert (dest_node != -1);
+#endif
+      return dest_node;
+    }
+  else
+    {
+      int naccepted = 0, entity = node;
+      re_token_type_t type = dfa->nodes[node].type;
+      if (type == OP_CONTEXT_NODE)
+        {
+          entity = dfa->nodes[node].opr.ctx_info->entity;
+          type = dfa->nodes[entity].type;
+        }
+
+      if (ACCEPT_MB_NODE (type))
+        naccepted = check_node_accept_bytes (preg, entity, input, *pidx);
+      else if (type == OP_BACK_REF)
+        {
+          for (i = 0; i < mctx->nbkref_ents; ++i)
+            {
+              if (mctx->bkref_ents[i].node == node
+                  && mctx->bkref_ents[i].from == *pidx)
+                naccepted = mctx->bkref_ents[i].to - *pidx;
+            }
+          if (naccepted == 0)
+            {
+              re_node_set_insert (eps_via_nodes, node);
+              dest_node = dfa->nexts[node];
+              if (re_node_set_contains (&state_log[*pidx]->nodes, dest_node))
+                return dest_node;
+              for (i = 0; i < state_log[*pidx]->nodes.nelem; ++i)
+                {
+                  dest_node = state_log[*pidx]->nodes.elems[i];
+                  if ((dfa->nodes[dest_node].type == OP_CONTEXT_NODE
+                       && (dfa->nexts[node]
+                           == dfa->nodes[dest_node].opr.ctx_info->entity)))
+                    return dest_node;
+                }
+            }
+        }
+
+      if (naccepted != 0
+          || check_node_accept (preg, dfa->nodes + node, input, *pidx,
+                                mctx->eflags))
+        {
+          dest_node = dfa->nexts[node];
+          *pidx = (naccepted == 0) ? *pidx + 1 : *pidx + naccepted;
+#ifdef DEBUG
+          assert (state_log[*pidx] != NULL);
+#endif
+          re_node_set_empty (eps_via_nodes);
+          return dest_node;
+        }
+    }
+  /* Must not reach here.  */
+#ifdef DEBUG
+  assert (0);
+#endif
+  return 0;
+}
+
+/* Set the positions where the subexpressions are starts/ends to registers
+   PMATCH.
+   Note: We assume that pmatch[0] is already set, and
+   pmatch[i].rm_so == pmatch[i].rm_eo == -1 (i > 1).  */
+
+static void
+set_regs (preg, state_log, mctx, input, nmatch, pmatch, last_node)
+    const regex_t *preg;
+    re_dfastate_t **state_log;
+    const re_match_context_t *mctx;
+    const re_string_t *input;
+    size_t nmatch;
+    regmatch_t *pmatch;
+    int last_node;
+{
+  re_dfa_t *dfa = (re_dfa_t *)preg->buffer;
+  int idx, cur_node, node_entity, real_nmatch;
+  re_node_set eps_via_nodes;
+  int i;
+#ifdef DEBUG
+  assert (nmatch > 1);
+  assert (state_log != NULL);
+#endif
+  cur_node = dfa->init_node;
+  real_nmatch = (nmatch <= preg->re_nsub) ? nmatch : preg->re_nsub + 1;
+  re_node_set_init_empty (&eps_via_nodes);
+  for (idx = pmatch[0].rm_so; idx <= pmatch[0].rm_eo ;)
+    {
+      node_entity = ((dfa->nodes[cur_node].type == OP_CONTEXT_NODE)
+                     ? dfa->nodes[cur_node].opr.ctx_info->entity : cur_node);
+      for (i = 1; i < real_nmatch; ++i)
+        {
+          if (dfa->subexps[i - 1].start == dfa->subexps[i - 1].end)
+            {
+              /* In case of the null subexpression like '()'.  */
+              if (dfa->subexps[i - 1].start == node_entity)
+                {
+                  pmatch[i].rm_so = idx;
+                  pmatch[i].rm_eo = idx;
+                }
+            }
+          else if (dfa->subexps[i - 1].start <= node_entity
+                   && node_entity < dfa->subexps[i - 1].end)
+            {
+              if (pmatch[i].rm_so == -1 || pmatch[i].rm_eo != -1)
+                /* We are at the first node of this sub expression.  */
+                {
+                  pmatch[i].rm_so = idx;
+                  pmatch[i].rm_eo = -1;
+                }
+            }
+          else
+            {
+              if (pmatch[i].rm_so != -1 && pmatch[i].rm_eo == -1)
+                /* We are at the last node of this sub expression.  */
+                pmatch[i].rm_eo = idx;
+            }
+        }
+      if (idx == pmatch[0].rm_eo && cur_node == last_node)
+        break;
+
+      /* Proceed to next node.  */
+      cur_node = proceed_next_node (preg, state_log, mctx, input, &idx,
+                                    cur_node, &eps_via_nodes);
+    }
+  re_node_set_free (&eps_via_nodes);
+  return;
+}
+
+#define NUMBER_OF_STATE 1
+
+/* This function checks the STATE_LOG from the MCTX->match_last
+   to MCTX->match_first and sift the nodes in each states according to
+   the following rules.  Updated state_log will be wrote to STATE_LOG.
+
+   Rules: We throw away the Node `a' in the STATE_LOG[STR_IDX] if...
+     1. When STR_IDX == MATCH_LAST(the last index in the state_log):
+        If `a' isn't the LAST_NODE and `a' can't epsilon transit to
+        the LAST_NODE, we throw away the node `a'.
+     2. When MATCH_FIRST <= STR_IDX < MATCH_LAST and `a' accepts
+        string `s' and transit to `b':
+        i. If 'b' isn't in the STATE_LOG[STR_IDX+strlen('s')], we throw
+           away the node `a'.
+        ii. If 'b' is in the STATE_LOG[STR_IDX+strlen('s')] but 'b' is
+            throwed away, we throw away the node `a'.
+     3. When 0 <= STR_IDX < n and 'a' epsilon transit to 'b':
+        i. If 'b' isn't in the STATE_LOG[STR_IDX], we throw away the
+           node `a'.
+        ii. If 'b' is in the STATE_LOG[STR_IDX] but 'b' is throwed away,
+            we throw away the node `a'.  */
+
+#define STATE_NODE_CONTAINS(state,node) \
+  ((state) != NULL && re_node_set_contains (&(state)->nodes, node))
+
+static void
+sift_states_backward (preg, state_log, mctx, input, last_node)
+    const regex_t *preg;
+    re_dfastate_t **state_log;
+    const re_match_context_t *mctx;
+    const re_string_t *input;
+    int last_node;
+{
+  re_dfa_t *dfa = (re_dfa_t *)preg->buffer;
+  re_node_set state_buf;
+  int str_idx = mctx->match_last;
+  re_node_set *plog;	/* Points the state_log[str_idx]->nodes  */
+
+#ifdef DEBUG
+  assert (state_log != NULL && state_log[str_idx] != NULL);
+#endif
+  re_node_set_alloc (&state_buf, NUMBER_OF_STATE);
+  plog = &state_log[str_idx]->nodes;
+
+  /* Build sifted state_log[str_idx].  It has the nodes which can epsilon
+     transit to the last_node and the last_node itself.  */
+  re_node_set_intersect (&state_buf, plog, dfa->inveclosures + last_node);
+
+  if (state_log[str_idx] != NULL && state_log[str_idx]->has_backref)
+    add_epsilon_backreference (dfa, mctx, plog, str_idx, &state_buf);
+
+  /* Update state log.  */
+  state_log[str_idx] = re_acquire_state (dfa, &state_buf);
+
+  /* Then check each states in the state_log.  */
+  while (str_idx > mctx->match_first)
+    {
+      int i, j;
+      /* Update counters.  */
+      re_node_set_empty (&state_buf);
+      --str_idx;
+      plog = ((state_log[str_idx] == NULL) ? &empty_set
+              : &state_log[str_idx]->nodes);
+
+      /* Then build the next sifted state.
+         We build the next sifted state on `state_buf', and update
+         `state_log[str_idx]' with `state_buf'.
+         Note:
+         `state_buf' is the sifted state from `state_log[str_idx + 1]'.
+         `plog' points the node_set of the old `state_log[str_idx]'.  */
+      for (i = 0; i < plog->nelem; i++)
+        {
+          int prev_node = plog->elems[i];
+          int entity = prev_node;
+          int naccepted = 0;
+          re_token_type_t type = dfa->nodes[prev_node].type;
+          if (type == OP_CONTEXT_NODE)
+            {
+              entity = dfa->nodes[prev_node].opr.ctx_info->entity;
+              type = dfa->nodes[entity].type;
+            }
+
+          /* If the node may accept `multi byte'.  */
+          if (ACCEPT_MB_NODE (type))
+            naccepted = sift_states_iter_mb (preg, state_log, mctx, input,
+                                             entity, str_idx,
+                                             mctx->match_last);
+
+          /* If the node is a back reference.  */
+          else if (type == OP_BACK_REF)
+            for (j = 0; j < mctx->nbkref_ents; ++j)
+              {
+                naccepted = sift_states_iter_bkref (dfa, state_log,
+                                                    mctx->bkref_ents + j,
+                                                    prev_node, str_idx,
+                                                    mctx->match_first,
+                                                    mctx->match_last);
+                if (naccepted)
+                  break;
+              }
+
+          if (!naccepted
+              && check_node_accept (preg, dfa->nodes + prev_node, input,
+                                    str_idx, mctx->eflags)
+              && STATE_NODE_CONTAINS (state_log[str_idx + 1],
+                                      dfa->nexts[prev_node]))
+            naccepted = 1;
+
+          if (naccepted == 0)
+            continue;
+
+          /* `prev_node' may point the entity of the OP_CONTEXT_NODE,
+             then we use plog->elems[i] instead.  */
+          re_node_set_add_intersect (&state_buf, plog,
+                                     dfa->inveclosures + prev_node);
+        }
+      if (state_log[str_idx] != NULL && state_log[str_idx]->has_backref)
+        add_epsilon_backreference (dfa, mctx, plog, str_idx, &state_buf);
+
+      /* Update state_log.  */
+      state_log[str_idx] = re_acquire_state (dfa, &state_buf);
+    }
+
+  re_node_set_free (&state_buf);
+}
+
+/* Helper functions.  */
+
+static inline void
+clean_state_log_if_need (state_log, mctx, next_state_log_idx)
+    re_dfastate_t **state_log;
+    re_match_context_t *mctx;
+    int next_state_log_idx;
+{
+  int top = mctx->state_log_top;
+  if (top < next_state_log_idx)
+    {
+      memset (state_log + top + 1, '\0',
+              sizeof (re_dfastate_t *) * (next_state_log_idx - top));
+      mctx->state_log_top = next_state_log_idx;
+    }
+}
+
+static int
+sift_states_iter_mb (preg, state_log, mctx, input, node_idx, str_idx,
+                     max_str_idx)
+    const regex_t *preg;
+    re_dfastate_t **state_log;
+    const re_match_context_t *mctx;
+    const re_string_t *input;
+    int node_idx, str_idx, max_str_idx;
+{
+  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  int naccepted;
+  /* Check the node can accept `multi byte'.  */
+  naccepted = check_node_accept_bytes (preg, node_idx, input, str_idx);
+  if (naccepted > 0 && str_idx + naccepted <= max_str_idx &&
+      !STATE_NODE_CONTAINS (state_log[str_idx + naccepted],
+                            dfa->nexts[node_idx]))
+    /* The node can't accept the `multi byte', or the
+       destination was already throwed away, then the node
+       could't accept the current input `multi byte'.   */
+    naccepted = 0;
+  /* Otherwise, it is sure that the node could accept
+     `naccepted' bytes input.  */
+  return naccepted;
+}
+
+static int
+sift_states_iter_bkref (dfa, state_log, mctx_entry, node_idx, idx, match_first,
+                        match_last)
+    const re_dfa_t *dfa;
+    re_dfastate_t **state_log;
+    struct re_backref_cache_entry *mctx_entry;
+    int node_idx, idx, match_first, match_last;
+{
+  int naccepted = 0;
+  int from_idx, to_idx;
+  from_idx = mctx_entry->from;
+  to_idx = mctx_entry->to;
+  if (mctx_entry->node == node_idx
+      && from_idx == idx && to_idx <= match_last
+      && STATE_NODE_CONTAINS (state_log[to_idx], dfa->nexts[node_idx]))
+    naccepted = to_idx - from_idx;
+  return naccepted;
+}
+
+static void
+add_epsilon_backreference (dfa, mctx, plog, idx, state_buf)
+    const re_dfa_t *dfa;
+    const re_match_context_t *mctx;
+    const re_node_set *plog;
+    int idx;
+    re_node_set *state_buf;
+{
+  int i, j;
+  for (i = 0; i < plog->nelem; ++i)
+    {
+      int node_idx = plog->elems[i];
+      re_token_type_t type = dfa->nodes[node_idx].type;
+      if (type == OP_CONTEXT_NODE)
+        type = dfa->nodes[dfa->nodes[node_idx].opr.ctx_info->entity].type;
+
+      if (type == OP_BACK_REF &&
+          !re_node_set_contains (state_buf, node_idx))
+        {
+          for (j = 0; j < mctx->nbkref_ents; ++j)
+            {
+              struct re_backref_cache_entry *entry;
+              entry = mctx->bkref_ents + j;
+              if (entry->from == entry->to && entry->from == idx)
+                break;
+            }
+          if (j < mctx->nbkref_ents || idx == mctx->match_first)
+            {
+              re_node_set_add_intersect (state_buf, plog,
+                                         dfa->inveclosures + node_idx);
+              i = 0;
+            }
+        }
+    }
+}
+
+/* Functions for state transition.  */
+
+/* Return the next state to which the current state STATE will transit by
+   accepting the current input byte, and update STATE_LOG if necessary.
+   If STATE can accept a multibyte char/collating element/back reference
+   update the destination of STATE_LOG.  */
+
+static re_dfastate_t *
+transit_state (preg, state, input, fl_search, state_log, mctx)
+    const regex_t *preg;
+    re_dfastate_t *state, **state_log;
+    re_string_t *input;
+    int fl_search;
+    re_match_context_t *mctx;
+{
+  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfastate_t **trtable, *next_state;
+  unsigned char ch;
+
+  if (state == NULL)
+    {
+      next_state = state;
+      re_string_skip_bytes (input, 1);
+    }
+  else
+    {
+      /* If the current state can accept multibyte.  */
+      if (state->accept_mb)
+        transit_state_mb (preg, state, input, state_log, mctx);
+
+      /* Then decide the next state with the single byte.  */
+      if (1)
+        {
+          /* Use transition table  */
+          ch = re_string_fetch_byte (input);
+          trtable = fl_search ? state->trtable_search : state->trtable;
+          if (trtable == NULL)
+            {
+              trtable = build_trtable (preg, state, fl_search);
+              if (fl_search)
+                state->trtable_search = trtable;
+              else
+                state->trtable = trtable;
+            }
+          next_state = trtable[ch];
+        }
+      else
+        {
+          /* don't use transition table  */
+          next_state = transit_state_sb (preg, state, input, fl_search, mctx);
+        }
+    }
+
+  /* Update the state_log if we need.  */
+  if (state_log != NULL)
+    {
+      int cur_idx = re_string_cur_idx (input);
+      if (cur_idx > mctx->state_log_top)
+        {
+          state_log[cur_idx] = next_state;
+          mctx->state_log_top = cur_idx;
+        }
+      else if (state_log[cur_idx] == 0)
+        {
+          state_log[cur_idx] = next_state;
+        }
+      else
+        {
+          re_dfastate_t *pstate;
+          unsigned int context;
+          re_node_set next_nodes, *log_nodes, *table_nodes = NULL;
+          /* If (state_log[cur_idx] != 0), it implies that cur_idx is
+             the destination of a multibyte char/collating element/
+             back reference.  Then the next state is the union set of
+             these destinations and the results of the transition table.  */
+          pstate = state_log[cur_idx];
+          log_nodes = pstate->entrance_nodes;
+          if (next_state != NULL)
+            {
+              table_nodes = next_state->entrance_nodes;
+              re_node_set_init_union (&next_nodes, table_nodes, log_nodes);
+            }
+          else
+            next_nodes = *log_nodes;
+          /* Note: We already add the nodes of the initial state,
+                   then we don't need to add them here.  */
+
+          context = re_string_context_at (input, re_string_cur_idx (input) - 1,
+                                          mctx->eflags, preg->newline_anchor);
+          next_state = state_log[cur_idx]
+              = re_acquire_state_context (dfa, &next_nodes, context);
+          if (table_nodes != NULL)
+            re_node_set_free (&next_nodes);
+        }
+      /* If the next state has back references.  */
+      if (next_state != NULL && next_state->has_backref)
+        {
+          transit_state_bkref (preg, next_state, input, state_log, mctx);
+          next_state = state_log[cur_idx];
+        }
+    }
+  return next_state;
+}
+
+/* Helper functions for transit_state.  */
+
+/* Return the next state to which the current state STATE will transit by
+   accepting the current input byte.  */
+
+static re_dfastate_t *
+transit_state_sb (preg, state, input, fl_search, mctx)
+    const regex_t *preg;
+    re_dfastate_t *state;
+    re_string_t *input;
+    int fl_search;
+    re_match_context_t *mctx;
+{
+  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_node_set next_nodes;
+  re_dfastate_t *next_state;
+  int node_cnt, cur_str_idx = re_string_cur_idx (input);
+  unsigned int context;
+
+  re_node_set_alloc (&next_nodes, state->nodes.nelem + 1);
+  for (node_cnt = 0; node_cnt < state->nodes.nelem; ++node_cnt)
+    {
+      int cur_node = state->nodes.elems[node_cnt];
+      if (check_node_accept (preg, dfa->nodes + cur_node, input,
+                             cur_str_idx, mctx->eflags))
+        re_node_set_merge (&next_nodes,
+                           dfa->eclosures + dfa->nexts[cur_node]);
+    }
+  if (fl_search)
+    {
+#ifdef RE_ENABLE_I18N
+      int not_initial = 0;
+      if (MB_CUR_MAX > 1)
+        for (node_cnt = 0; node_cnt < next_nodes.nelem; ++node_cnt)
+          if (dfa->nodes[next_nodes.elems[node_cnt]].type == CHARACTER)
+            {
+              not_initial = dfa->nodes[next_nodes.elems[node_cnt]].mb_partial;
+              break;
+            }
+      if (!not_initial)
+#endif
+        re_node_set_merge (&next_nodes, dfa->init_state->entrance_nodes);
+    }
+  context = re_string_context_at (input, cur_str_idx, mctx->eflags,
+                                  preg->newline_anchor);
+  next_state = re_acquire_state_context (dfa, &next_nodes, context);
+  re_node_set_free (&next_nodes);
+  re_string_skip_bytes (input, 1);
+  return next_state;
+}
+
+static void
+transit_state_mb (preg, pstate, input, state_log, mctx)
+    const regex_t *preg;
+    re_dfastate_t *pstate, **state_log;
+    const re_string_t *input;
+    re_match_context_t *mctx;
+{
+  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  int i;
+
+  for (i = 0; i < pstate->nodes.nelem; ++i)
+    {
+      re_node_set dest_nodes, *new_nodes;
+      int cur_node_idx = pstate->nodes.elems[i];
+      int naccepted = 0, dest_idx;
+      unsigned int context;
+      re_dfastate_t *dest_state;
+
+      if (dfa->nodes[cur_node_idx].type == OP_CONTEXT_NODE)
+        {
+          context = re_string_context_at (input, re_string_cur_idx (input),
+                                          mctx->eflags, preg->newline_anchor);
+          if (NOT_SATISFY_NEXT_CONSTRAINT (dfa->nodes[cur_node_idx].constraint,
+                                        context))
+            continue;
+          cur_node_idx = dfa->nodes[cur_node_idx].opr.ctx_info->entity;
+        }
+
+      /* How many bytes the node can accepts?  */
+      if (ACCEPT_MB_NODE (dfa->nodes[cur_node_idx].type))
+        naccepted = check_node_accept_bytes (preg, cur_node_idx, input,
+                                             re_string_cur_idx (input));
+      if (naccepted == 0)
+        continue;
+
+      /* The node can accepts `naccepted' bytes.  */
+      dest_idx = re_string_cur_idx (input) + naccepted;
+      clean_state_log_if_need (state_log, mctx, dest_idx);
+#ifdef DEBUG
+      assert (dfa->nexts[cur_node_idx] != -1);
+#endif
+      /* `cur_node_idx' may point the entity of the OP_CONTEXT_NODE,
+         then we use pstate->nodes.elems[i] instead.  */
+      new_nodes = dfa->eclosures + dfa->nexts[pstate->nodes.elems[i]];
+
+      dest_state = state_log[dest_idx];
+      if (dest_state == NULL)
+        dest_nodes = *new_nodes;
+      else
+        re_node_set_init_union (&dest_nodes, dest_state->entrance_nodes,
+                                new_nodes);
+      context = re_string_context_at (input, dest_idx - 1, mctx->eflags,
+                                      preg->newline_anchor);
+      state_log[dest_idx] = re_acquire_state_context (dfa, &dest_nodes, context);
+      if (dest_state != NULL)
+        re_node_set_free (&dest_nodes);
+    }
+}
+
+static void
+transit_state_bkref (preg, pstate, input, state_log, mctx)
+    const regex_t *preg;
+    re_dfastate_t *pstate, **state_log;
+    const re_string_t *input;
+    re_match_context_t *mctx;
+{
+  re_dfastate_t **work_state_log;
+
+#ifdef DEBUG
+  assert (mctx->match_first != -1);
+#endif
+  work_state_log = re_malloc (re_dfastate_t *, re_string_cur_idx (input) + 1);
+
+  transit_state_bkref_loop (preg, input, &pstate->nodes, work_state_log,
+                            state_log, mctx);
+
+  re_free (work_state_log);
+}
+
+/* Caller must allocate `work_state_log'.  */
+
+static void
+transit_state_bkref_loop (preg, input, nodes, work_state_log, state_log, mctx)
+    const regex_t *preg;
+    const re_string_t *input;
+    re_node_set *nodes;
+    re_dfastate_t **work_state_log, **state_log;
+    re_match_context_t *mctx;
+{
+  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  int i, j;
+  regmatch_t *cur_regs = re_malloc (regmatch_t, preg->re_nsub + 1);
+  int cur_str_idx = re_string_cur_idx (input);
+
+  for (i = 0; i < nodes->nelem; ++i)
+    {
+      int dest_str_idx, subexp_idx, prev_nelem, subexp_len;
+      int node_idx = nodes->elems[i];
+      unsigned int context;
+      re_token_t *node = dfa->nodes + node_idx;
+      re_dfastate_t *dest_state;
+      re_node_set *new_dest_nodes;
+
+      /* Check whether `node' is a backreference or not.  */
+      if (node->type == OP_BACK_REF)
+        subexp_idx = node->opr.idx;
+      else if (node->type == OP_CONTEXT_NODE &&
+               dfa->nodes[node->opr.ctx_info->entity].type == OP_BACK_REF)
+        {
+          context = re_string_context_at (input, cur_str_idx, mctx->eflags,
+                                          preg->newline_anchor);
+          if (NOT_SATISFY_NEXT_CONSTRAINT (node->constraint, context))
+            continue;
+          subexp_idx = dfa->nodes[node->opr.ctx_info->entity].opr.idx;
+        }
+      else
+        continue;
+
+      /* `node' is a backreference.
+         At first, set registers to check the backreference. */
+      cur_regs[0].rm_so = mctx->match_first;
+      cur_regs[0].rm_eo = cur_str_idx;
+      memcpy (work_state_log + mctx->match_first,
+              state_log + mctx->match_first,
+              sizeof (re_dfastate_t *)
+	      * (cur_str_idx - mctx->match_first + 1));
+      mctx->match_last = cur_str_idx;
+      sift_states_backward (preg, work_state_log, mctx, input, node_idx);
+      if (!STATE_NODE_CONTAINS (work_state_log[mctx->match_first],
+                                dfa->init_node))
+        continue;
+      for (j = 1; j <= preg->re_nsub; ++j)
+        cur_regs[j].rm_so = cur_regs[j].rm_eo = -1;
+      set_regs (preg, work_state_log, mctx, input,
+                subexp_idx + 1, cur_regs, node_idx);
+
+      /* Then check that the backreference can match the input string.  */
+      subexp_len = cur_regs[subexp_idx].rm_eo - cur_regs[subexp_idx].rm_so;
+      if (subexp_len < 0
+          || (strncmp ((re_string_get_buffer (input)
+                        + cur_regs[subexp_idx].rm_so),
+                       re_string_get_buffer (input) + cur_str_idx, subexp_len)
+              != 0))
+        continue;
+
+      /* Successfully matched, add a new cache entry.  */
+      dest_str_idx = cur_str_idx + subexp_len;
+      match_ctx_add_entry (mctx, node_idx, cur_str_idx, dest_str_idx);
+      clean_state_log_if_need (state_log, mctx, dest_str_idx);
+
+      /* And add the epsilon closures (which is `new_dest_nodes') of
+         the backreference to appropriate state_log.  */
+#ifdef DEBUG
+      assert (dfa->nexts[node_idx] != -1);
+#endif
+      if (node->type == OP_CONTEXT_NODE && subexp_len == 0)
+        new_dest_nodes = dfa->nodes[node_idx].opr.ctx_info->bkref_eclosure;
+      else
+        new_dest_nodes = dfa->eclosures + dfa->nexts[node_idx];
+      context = (IS_WORD_CHAR (re_string_byte_at (input, dest_str_idx - 1))
+                 ? CONTEXT_WORD : 0);
+      dest_state = state_log[dest_str_idx];
+
+      prev_nelem = ((state_log[cur_str_idx] == NULL) ? 0
+                    : state_log[cur_str_idx]->nodes.nelem);
+      /* Add `new_dest_node' to state_log.  */
+      if (dest_state == NULL)
+        state_log[dest_str_idx] = re_acquire_state_context (dfa,
+                                                            new_dest_nodes,
+                                                            context);
+      else
+        {
+          re_node_set dest_nodes;
+          re_node_set_init_union (&dest_nodes, dest_state->entrance_nodes,
+                                  new_dest_nodes);
+          state_log[dest_str_idx] = re_acquire_state_context (dfa, &dest_nodes,
+                                                              context);
+          re_node_set_free (&dest_nodes);
+        }
+
+      /* We need to check recursively if the backreference can epsilon
+         transit.  */
+      if (subexp_len == 0 && state_log[cur_str_idx]->nodes.nelem > prev_nelem)
+        transit_state_bkref_loop (preg, input, new_dest_nodes, work_state_log,
+                                  state_log, mctx);
+    }
+  re_free (cur_regs);
+}
+
+/* Build transition table for the state.  */
+
+static re_dfastate_t **
+build_trtable (preg, state, fl_search)
+    const regex_t *preg;
+    const re_dfastate_t *state;
+    int fl_search;
+{
+  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  int i, j, k, ch;
+  int ndests; /* Number of the destination states from `state'.  */
+  re_dfastate_t **trtable, **dest_states, **dest_states_word, **dest_states_nl;
+  re_node_set follows, *dests_node;
+  bitset *dests_ch;
+  bitset acceptable;
+
+  /* We build DFA states which corresponds to the destination nodes
+     from `state'.  `dests_node[i]' represents the nodes which i-th
+     destination state contains, and `dests_ch[i]' represents the
+     characters which i-th destination state accepts.  */
+  dests_node = re_malloc (re_node_set, SBC_MAX);
+  dests_ch = re_malloc (bitset, SBC_MAX);
+
+  /* Initialize transiton table.  */
+  trtable = (re_dfastate_t **) calloc (sizeof (re_dfastate_t *), SBC_MAX);
+
+  /* At first, group all nodes belonging to `state' into several
+     destinations.  */
+  ndests = group_nodes_into_DFAstates (preg, state, dests_node, dests_ch);
+  if (ndests == 0)
+    {
+      re_free (dests_node);
+      re_free (dests_ch);
+      return trtable;
+    }
+
+  dest_states = re_malloc (re_dfastate_t *, ndests);
+  dest_states_word = re_malloc (re_dfastate_t *, ndests);
+  dest_states_nl = re_malloc (re_dfastate_t *, ndests);
+  bitset_empty (acceptable);
+
+  re_node_set_alloc (&follows, ndests + 1);
+  /* Then build the states for all destinations.  */
+  for (i = 0; i < ndests; ++i)
+    {
+      int next_node;
+      re_node_set_empty (&follows);
+      /* Merge the follows of this destination states.  */
+      for (j = 0; j < dests_node[i].nelem; ++j)
+        {
+          next_node = dfa->nexts[dests_node[i].elems[j]];
+          if (next_node != -1)
+            {
+              re_node_set_merge (&follows, dfa->eclosures + next_node);
+            }
+        }
+      /* If search flag is set, merge the initial state.  */
+      if (fl_search)
+        {
+#ifdef RE_ENABLE_I18N
+          int not_initial = 0;
+          for (j = 0; j < follows.nelem; ++j)
+            if (dfa->nodes[follows.elems[j]].type == CHARACTER)
+              {
+                not_initial = dfa->nodes[follows.elems[j]].mb_partial;
+                break;
+              }
+          if (!not_initial)
+#endif
+            re_node_set_merge (&follows, dfa->init_state->entrance_nodes);
+        }
+      dest_states[i] = re_acquire_state_context (dfa, &follows, 0);
+      /* If the new state has context constraint,
+         build appropriate states for these contexts.  */
+      if (dest_states[i]->has_constraint)
+        {
+          dest_states_word[i] = re_acquire_state_context (dfa, &follows,
+                                                          CONTEXT_WORD);
+          dest_states_nl[i] = re_acquire_state_context (dfa, &follows,
+                                                        CONTEXT_NEWLINE);
+        }
+      else
+        {
+          dest_states_word[i] = dest_states[i];
+          dest_states_nl[i] = dest_states[i];
+        }
+      bitset_merge (acceptable, dests_ch[i]);
+    }
+
+  /* Update the transition table.  */
+  for (i = 0, ch = 0; i < BITSET_UINTS; ++i)
+    for (j = 0; j < UINT_BITS; ++j, ++ch)
+      if ((acceptable[i] >> j) & 1)
+        {
+          if (IS_WORD_CHAR (ch))
+            {
+              for (k = 0; k < ndests; ++k)
+                if ((dests_ch[k][i] >> j) & 1)
+                  trtable[ch] = dest_states_word[k];
+            }
+          else /* not WORD_CHAR */
+            {
+              for (k = 0; k < ndests; ++k)
+                if ((dests_ch[k][i] >> j) & 1)
+                  trtable[ch] = dest_states[k];
+            }
+        }
+  /* new line */
+  for (k = 0; k < ndests; ++k)
+    if (bitset_contain (acceptable, NEWLINE_CHAR))
+      trtable[NEWLINE_CHAR] = dest_states_nl[k];
+
+  re_free (dest_states_nl);
+  re_free (dest_states_word);
+  re_free (dest_states);
+
+  re_node_set_free (&follows);
+  for (i = 0; i < ndests; ++i)
+    re_node_set_free (dests_node + i);
+
+  re_free (dests_ch);
+  re_free (dests_node);
+
+  return trtable;
+}
+
+/* Group all nodes belonging to STATE into several destinations.
+   Then for all destinations, set the nodes belonging to the destination
+   to DESTS_NODE[i] and set the characters accepted by the destination
+   to DEST_CH[i].  This function return the number of destinations.  */
+
+static int
+group_nodes_into_DFAstates (preg, state, dests_node, dests_ch)
+    const regex_t *preg;
+    const re_dfastate_t *state;
+    re_node_set *dests_node;
+    bitset *dests_ch;
+{
+  const re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  int i, j, k;
+  int ndests; /* Number of the destinations from `state'.  */
+  bitset accepts; /* Characters a node can accept.  */
+  const re_node_set *cur_nodes = &state->nodes;
+  bitset_empty (accepts);
+  ndests = 0;
+
+  /* For all the nodes belonging to `state',  */
+  for (i = 0; i < cur_nodes->nelem; ++i)
+    {
+      unsigned int constraint = 0;
+      re_token_t *node = &dfa->nodes[cur_nodes->elems[i]];
+      re_token_type_t type = node->type;
+
+      if (type == OP_CONTEXT_NODE)
+        {
+          constraint = node->constraint;
+          node = dfa->nodes + node->opr.ctx_info->entity;
+          type = node->type;
+        }
+
+      /* Enumerate all single byte character this node can accept.  */
+      if (type == CHARACTER)
+        bitset_set (accepts, node->opr.c);
+      else if (type == SIMPLE_BRACKET)
+        {
+          bitset_merge (accepts, node->opr.sbcset);
+        }
+      else if (type == OP_PERIOD)
+        {
+          bitset_set_all (accepts);
+          if (!(preg->syntax & RE_DOT_NEWLINE))
+            bitset_clear (accepts, '\n');
+          if (preg->syntax & RE_DOT_NOT_NULL)
+            bitset_clear (accepts, '\0');
+        }
+      else
+        continue;
+
+      /* Check the `accepts' and sift the characters which are not
+         match it the context.  */
+      if (constraint)
+        {
+          if (constraint & NEXT_WORD_CONSTRAINT)
+            for (j = 0; j < BITSET_UINTS; ++j)
+              accepts[j] &= dfa->word_char[j];
+          else if (constraint & NEXT_NOTWORD_CONSTRAINT)
+            for (j = 0; j < BITSET_UINTS; ++j)
+              accepts[j] &= ~dfa->word_char[j];
+          else if (constraint & NEXT_NEWLINE_CONSTRAINT)
+            {
+              int accepts_newline = bitset_contain (accepts, NEWLINE_CHAR);
+              bitset_empty (accepts);
+              if (accepts_newline)
+                bitset_set (accepts, NEWLINE_CHAR);
+              else
+                continue;
+            }
+        }
+
+      /* Then divide `accepts' into DFA states, or create a new
+         state.  */
+      for (j = 0; j < ndests; ++j)
+        {
+          bitset intersec; /* Intersection sets, see below.  */
+          bitset remains;
+          /* Flags, see below.  */
+          int has_intersec, not_subset, not_consumed;
+
+          /* Optimization, skip if this state doesn't accept the character.  */
+          if (type == CHARACTER && !bitset_contain (dests_ch[j], node->opr.c))
+            continue;
+
+          /* Enumerate the intersection set of this state and `accepts'.  */
+          has_intersec = 0;
+          for (k = 0; k < BITSET_UINTS; ++k)
+            has_intersec |= intersec[k] = accepts[k] & dests_ch[j][k];
+          /* And skip if the intersection set is empty.  */
+          if (!has_intersec)
+            continue;
+
+          /* Then check if this state is a subset of `accepts'.  */
+          not_subset = not_consumed = 0;
+          for (k = 0; k < BITSET_UINTS; ++k)
+            {
+              not_subset |= remains[k] = ~accepts[k] & dests_ch[j][k];
+              not_consumed |= accepts[k] = accepts[k] & ~dests_ch[j][k];
+            }
+
+          /* If this state isn't a subset of `accepts', create a
+             new group state, which has the `remains'. */
+          if (not_subset)
+            {
+              bitset_copy (dests_ch[ndests], remains);
+              bitset_copy (dests_ch[j], intersec);
+              re_node_set_init_copy (dests_node + ndests, &dests_node[j]);
+              ++ndests;
+            }
+
+          /* Put the position in the current group. */
+          re_node_set_insert (&dests_node[j], cur_nodes->elems[i]);
+
+          /* If all characters are consumed, go to next node. */
+          if (!not_consumed)
+            break;
+        }
+      /* Some characters remain, create a new group. */
+      if (j == ndests)
+        {
+          bitset_copy (dests_ch[ndests], accepts);
+          re_node_set_init_1 (dests_node + ndests, cur_nodes->elems[i]);
+          ++ndests;
+          bitset_empty (accepts);
+        }
+    }
+  return ndests;
+}
+
+/* Check how many bytes the node `dfa->nodes[node_idx]' accepts.  */
+
+static int
+check_node_accept_bytes (preg, node_idx, input, str_idx)
+    const regex_t *preg;
+    int node_idx, str_idx;
+    const re_string_t *input;
+{
+  const re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  const re_token_t *node = dfa->nodes + node_idx;
+  int elem_len = re_string_elem_size_at (input, str_idx);
+  int char_len = re_string_char_size_at (input, str_idx);
+  int i, j;
+#ifdef _LIBC
+  uint32_t nrules = _NL_CURRENT_WORD (LC_COLLATE, _NL_COLLATE_NRULES);
+#endif /* _LIBC */
+  if (elem_len <= 1 && char_len <= 1)
+    return 0;
+  if (node->type == OP_PERIOD)
+    {
+      if ((!(preg->syntax & RE_DOT_NEWLINE) &&
+           re_string_byte_at (input, str_idx) == '\n') ||
+          ((preg->syntax & RE_DOT_NOT_NULL) &&
+           re_string_byte_at (input, str_idx) == '\0'))
+        return 0;
+      return char_len;
+    }
+  else if (node->type == COMPLEX_BRACKET)
+    {
+      const re_charset_t *cset = node->opr.mbcset;
+      const unsigned char *pin = re_string_get_buffer (input) + str_idx;
+#ifdef _LIBC
+      if (nrules != 0)
+        {
+          int match_len = 0;
+          unsigned int in_collseq = 0;
+          const int32_t *table, *indirect;
+          const unsigned char *weights, *extra, *collseqwc;
+          int32_t idx;
+          wchar_t wc = 0;
+          /* This #include defines a local function!  */
+# include <locale/weight.h>
+
+          /* match with collating_symbol?  */
+          if (cset->ncoll_syms)
+            extra = (const unsigned char *)
+              _NL_CURRENT (LC_COLLATE, _NL_COLLATE_SYMB_EXTRAMB);
+          for (i = 0; i < cset->ncoll_syms; ++i)
+            {
+              const unsigned char *coll_sym = extra + cset->coll_syms[i];
+              /* Compare the length of input collating element and
+                 the length of current collating element.  */
+              if (*coll_sym != elem_len)
+                continue;
+              /* Compare each bytes.  */
+              for (j = 0; j < *coll_sym; j++)
+                if (pin[j] != coll_sym[1 + j])
+                  break;
+              if (j == *coll_sym)
+                {
+                  /* Match if every bytes is equal.  */
+                  match_len = j;
+                  goto check_node_accept_bytes_match;
+                }
+            }
+
+          if (cset->nranges || cset->nchar_classes || cset->nmbchars)
+            wc = re_string_wchar_at (input, str_idx);
+
+          if (cset->nranges)
+            {
+              if (elem_len <= char_len)
+                {
+                  collseqwc = _NL_CURRENT (LC_COLLATE, _NL_COLLATE_COLLSEQWC);
+                  in_collseq = collseq_table_lookup (collseqwc, wc);
+                }
+              else
+                in_collseq = find_collation_sequence_value (pin, elem_len);
+            }
+          /* match with range expression?  */
+          for (i = 0; i < cset->nranges; ++i)
+            if (cset->range_starts[i] <= in_collseq
+                && in_collseq <= cset->range_ends[i])
+              {
+                match_len = elem_len;
+                goto check_node_accept_bytes_match;
+              }
+
+          /* match with equivalence_class?  */
+          if (cset->nequiv_classes)
+            {
+              const unsigned char *cp = pin;
+              table = (const int32_t *)
+                _NL_CURRENT (LC_COLLATE, _NL_COLLATE_TABLEMB);
+              weights = (const unsigned char *)
+                _NL_CURRENT (LC_COLLATE, _NL_COLLATE_WEIGHTMB);
+              extra = (const unsigned char *)
+                _NL_CURRENT (LC_COLLATE, _NL_COLLATE_EXTRAMB);
+              indirect = (const int32_t *)
+                _NL_CURRENT (LC_COLLATE, _NL_COLLATE_INDIRECTMB);
+              idx = findidx (&cp);
+              if (idx > 0)
+                for (i = 0; i < cset->nequiv_classes; ++i)
+                  {
+                    int32_t equiv_class_idx = cset->equiv_classes[i];
+                    size_t weight_len = weights[idx];
+                    if (weight_len == weights[equiv_class_idx])
+                      {
+                        int cnt = 0;
+                        while (cnt <= weight_len
+                               && (weights[equiv_class_idx + 1 + cnt]
+                                   == weights[idx + 1 + cnt]))
+                          ++cnt;
+                        if (cnt > weight_len)
+                          {
+                            match_len = elem_len;
+                            goto check_node_accept_bytes_match;
+                          }
+                      }
+                  }
+            }
+
+          /* match with multibyte character?  */
+          for (i = 0; i < cset->nmbchars; ++i)
+            if (wc == cset->mbchars[i])
+              {
+                match_len = char_len;
+                goto check_node_accept_bytes_match;
+              }
+
+          /* match with character_class?  */
+          for (i = 0; i < cset->nchar_classes; ++i)
+            {
+              wctype_t wt = cset->char_classes[i];
+              if (__iswctype (wc, wt))
+                {
+                  match_len = char_len;
+                  goto check_node_accept_bytes_match;
+                }
+            }
+
+        check_node_accept_bytes_match:
+          if (!cset->non_match)
+            return match_len;
+          else
+            {
+              if (match_len > 0)
+                return 0;
+              else
+                return re_string_elem_size_at (input, str_idx);
+            }
+        }
+#endif
+    }
+  return 0;
+}
+
+#ifdef _LIBC
+static unsigned int
+find_collation_sequence_value (mbs, mbs_len)
+    const unsigned char *mbs;
+    size_t mbs_len;
+{
+  uint32_t nrules = _NL_CURRENT_WORD (LC_COLLATE, _NL_COLLATE_NRULES);
+  if (nrules == 0)
+    {
+      if (mbs_len == 1)
+        {
+          /* No valid character.  Match it as a single byte character.  */
+          const unsigned char *collseq = (const unsigned char *)
+            _NL_CURRENT (LC_COLLATE, _NL_COLLATE_COLLSEQMB);
+          return collseq[mbs[0]];
+        }
+      return UINT_MAX;
+    }
+  else
+    {
+      int32_t idx;
+      const unsigned char *extra = (const unsigned char *)
+        _NL_CURRENT (LC_COLLATE, _NL_COLLATE_SYMB_EXTRAMB);
+
+      for (idx = 0; ;)
+        {
+          int mbs_cnt, found = 0;
+          int32_t elem_mbs_len;
+          /* Skip the name of collating element name.  */
+          idx = idx + extra[idx] + 1;
+          elem_mbs_len = extra[idx++];
+          if (mbs_len == elem_mbs_len)
+            {
+              for (mbs_cnt = 0; mbs_cnt < elem_mbs_len; ++mbs_cnt)
+                if (extra[idx + mbs_cnt] != mbs[mbs_cnt])
+                  break;
+              if (mbs_cnt == elem_mbs_len)
+                /* Found the entry.  */
+                found = 1;
+            }
+          /* Skip the byte sequence of the collating element.  */
+          idx += elem_mbs_len;
+          /* Adjust for the alignment.  */
+          idx = (idx + 3) & ~3;
+          /* Skip the collation sequence value.  */
+          idx += sizeof (uint32_t);
+          /* Skip the wide char sequence of the collating element.  */
+          idx = idx + sizeof (uint32_t) * (extra[idx] + 1);
+          /* If we found the entry, return the sequence value.  */
+          if (found)
+            return *(uint32_t *) (extra + idx);
+          /* Skip the collation sequence value.  */
+          idx += sizeof (uint32_t);
+        }
+    }
+}
+#endif
+
+/* Check whether the node accepts the byte which is IDX-th
+   byte of the INPUT.  */
+
+static int
+check_node_accept (preg, node, input, idx, eflags)
+    const regex_t *preg;
+    const re_token_t *node;
+    const re_string_t *input;
+    int idx, eflags;
+{
+  const re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  const re_token_t *cur_node;
+  unsigned char ch;
+  if (node->type == OP_CONTEXT_NODE)
+    {
+      /* The node has constraints.  Check whether the current context
+         satisfies the constraints.  */
+      unsigned int context = re_string_context_at (input, idx, eflags,
+                                                   preg->newline_anchor);
+      if (NOT_SATISFY_NEXT_CONSTRAINT (node->constraint, context))
+        return 0;
+      cur_node = dfa->nodes + node->opr.ctx_info->entity;
+    }
+  else
+    cur_node = node;
+
+  ch = re_string_byte_at (input, idx);
+  if (cur_node->type == CHARACTER)
+    return cur_node->opr.c == ch;
+  else if (cur_node->type == SIMPLE_BRACKET)
+    return bitset_contain (cur_node->opr.sbcset, ch);
+  else if (cur_node->type == OP_PERIOD)
+    return !((ch == '\n' && !(preg->syntax & RE_DOT_NEWLINE))
+             || (ch == '\0' && (preg->syntax & RE_DOT_NOT_NULL)));
+  else
+    return 0;
+}
+
+/* Functions for matching context.  */
+
+static void
+match_ctx_init (mctx, eflags, n)
+    re_match_context_t *mctx;
+    int eflags;
+    int n;
+{
+  mctx->eflags = eflags;
+  mctx->match_first = mctx->match_last = -1;
+  if (n > 0)
+    mctx->bkref_ents = re_malloc (struct re_backref_cache_entry, n);
+  else
+    mctx->bkref_ents = NULL;
+  mctx->nbkref_ents = 0;
+  mctx->abkref_ents = n;
+  mctx->max_bkref_len = 0;
+}
+
+static void
+match_ctx_free (mctx)
+    re_match_context_t *mctx;
+{
+  re_free (mctx->bkref_ents);
+}
+
+/* Add a new backreference entry to the cache.  */
+
+static void
+match_ctx_add_entry (mctx, node, from, to)
+    re_match_context_t *mctx;
+    int node, from, to;
+{
+  if (mctx->nbkref_ents >= mctx->abkref_ents)
+    {
+      mctx->bkref_ents = re_realloc (mctx->bkref_ents,
+                                     struct re_backref_cache_entry,
+                                     mctx->abkref_ents * 2);
+      memset (mctx->bkref_ents + mctx->nbkref_ents, '\0',
+             sizeof (struct re_backref_cache_entry) * mctx->abkref_ents);
+      mctx->abkref_ents *= 2;
+    }
+  mctx->bkref_ents[mctx->nbkref_ents].node = node;
+  mctx->bkref_ents[mctx->nbkref_ents].from = from;
+  mctx->bkref_ents[mctx->nbkref_ents++].to = to;
+  if (mctx->max_bkref_len < to - from)
+    mctx->max_bkref_len = to - from;
+}