/* kwset.c - search for any of a set of keywords.

   Copyright (C) 1989, 1998, 2000, 2005, 2007, 2009-2017 Free Software

   Foundation, Inc.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3, or (at your option)

   any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA

   02110-1301, USA.  */

/* Written August 1989 by Mike Haertel.  */

/* For the Aho-Corasick algorithm, see:

   Aho AV, Corasick MJ. Efficient string matching: an aid to

   bibliographic search. CACM 18, 6 (1975), 333-40

   <http://dx.doi.org/10.1145/360825.360855>, which describes the

   failure function used below.

   For the Boyer-Moore algorithm, see: Boyer RS, Moore JS.

   A fast string searching algorithm. CACM 20, 10 (1977), 762-72

   <http://dx.doi.org/10.1145/359842.359859>.

   For a survey of more-recent string matching algorithms that might

   help improve performance, see: Faro S, Lecroq T. The exact online

   string matching problem: a review of the most recent results.

   ACM Computing Surveys 45, 2 (2013), 13

   <http://dx.doi.org/10.1145/2431211.2431212>.  */

#include <config.h>

#include "kwset.h"

#include <stdint.h>

#include <sys/types.h>

#include "system.h"

#include "intprops.h"

#include "memchr2.h"

#include "obstack.h"

#include "xalloc.h"

#include "verify.h"

#define obstack_chunk_alloc xmalloc

#define obstack_chunk_free free

static unsigned char

U (char ch)

{

  return to_uchar (ch);

}

/* Balanced tree of edges and labels leaving a given trie node.  */

struct tree

{

  struct tree *llink;		/* Left link; MUST be first field.  */

  struct tree *rlink;		/* Right link (to larger labels).  */

  struct trie *trie;		/* Trie node pointed to by this edge.  */

  unsigned char label;		/* Label on this edge.  */

  char balance;			/* Difference in depths of subtrees.  */

};

/* Node of a trie representing a set of keywords.  */

struct trie

{

  /* If an accepting node, this is either 2*W + 1 where W is the word

     index, or is SIZE_MAX if Aho-Corasick is in use and FAIL

     specifies where to look for more info.  If not an accepting node,

     this is zero.  */

  size_t accepting;

  struct tree *links;		/* Tree of edges leaving this node.  */

  struct trie *parent;		/* Parent of this node.  */

  struct trie *next;		/* List of all trie nodes in level order.  */

  struct trie *fail;		/* Aho-Corasick failure function.  */

  ptrdiff_t depth;		/* Depth of this node from the root.  */

  ptrdiff_t shift;		/* Shift function for search failures.  */

  ptrdiff_t maxshift;		/* Max shift of self and descendants.  */

};

/* Structure returned opaquely to the caller, containing everything.  */

struct kwset

{

  struct obstack obstack;	/* Obstack for node allocation.  */

  ptrdiff_t words;		/* Number of words in the trie.  */

  struct trie *trie;		/* The trie itself.  */

  ptrdiff_t mind;		/* Minimum depth of an accepting node.  */

  ptrdiff_t maxd;		/* Maximum depth of any node.  */

  unsigned char delta[NCHAR];	/* Delta table for rapid search.  */

  struct trie *next[NCHAR];	/* Table of children of the root.  */

  char *target;			/* Target string if there's only one.  */

  ptrdiff_t *shift;		/* Used in Boyer-Moore search for one

                                   string.  */

  char const *trans;		/* Character translation table.  */

  /* This helps to match a terminal byte, which is the first byte

     for Aho-Corasick, and the last byte for Boyer-More.  If all the

     patterns have the same terminal byte (after translation via TRANS

     if TRANS is nonnull), then this is that byte as an unsigned char.

     Otherwise this is -1 if there is disagreement among the strings

     about terminal bytes, and -2 if there are no terminal bytes and

     no disagreement because all the patterns are empty.  */

  int gc1;

  /* This helps to match a terminal byte.  If 0 <= GC1HELP, B is

     terminal when B == GC1 || B == GC1HELP (note that GC1 == GCHELP

     is common here).  This is typically faster than evaluating

     to_uchar (TRANS[B]) == GC1.  */

  int gc1help;

  /* If the string has two or more bytes, this is the penultimate byte,

     after translation via TRANS if TRANS is nonnull.  This variable

     is used only by Boyer-Moore.  */

  char gc2;

  /* kwsexec implementation.  */

  ptrdiff_t (*kwsexec) (kwset_t, char const *, ptrdiff_t,

                        struct kwsmatch *, bool);

};

/* Use TRANS to transliterate C.  A null TRANS does no transliteration.  */

static inline char

tr (char const *trans, char c)

{

  return trans ? trans[U(c)] : c;

}

static ptrdiff_t acexec (kwset_t, char const *, ptrdiff_t,

                         struct kwsmatch *, bool);

static ptrdiff_t bmexec (kwset_t, char const *, ptrdiff_t,

                         struct kwsmatch *, bool);

/* Return a newly allocated keyword set.  A nonnull TRANS specifies a

   table of character translations to be applied to all pattern and

   search text.  */

kwset_t

kwsalloc (char const *trans)

{

  struct kwset *kwset = xmalloc (sizeof *kwset);

  obstack_init (&kwset->obstack);

  kwset->words = 0;

  kwset->trie = obstack_alloc (&kwset->obstack, sizeof *kwset->trie);

  kwset->trie->accepting = 0;

  kwset->trie->links = NULL;

  kwset->trie->parent = NULL;

  kwset->trie->next = NULL;

  kwset->trie->fail = NULL;

  kwset->trie->depth = 0;

  kwset->trie->shift = 0;

  kwset->mind = PTRDIFF_MAX;

  kwset->maxd = -1;

  kwset->target = NULL;

  kwset->trans = trans;

  kwset->kwsexec = acexec;

  return kwset;

}

/* This upper bound is valid for CHAR_BIT >= 4 and

   exact for CHAR_BIT in { 4..11, 13, 15, 17, 19 }.  */

enum { DEPTH_SIZE = CHAR_BIT + CHAR_BIT / 2 };

/* Add the given string to the contents of the keyword set.  */

void

kwsincr (kwset_t kwset, char const *text, ptrdiff_t len)

{

  assume (0 <= len);

  struct trie *trie = kwset->trie;

  char const *trans = kwset->trans;

  bool reverse = kwset->kwsexec == bmexec;

  if (reverse)

    text += len;

  /* Descend the trie (built of keywords) character-by-character,

     installing new nodes when necessary.  */

  while (len--)

    {

      unsigned char uc = reverse ? *--text : *text++;

      unsigned char label = trans ? trans[uc] : uc;

      /* Descend the tree of outgoing links for this trie node,

         looking for the current character and keeping track

         of the path followed.  */

      struct tree *cur = trie->links;

      struct tree *links[DEPTH_SIZE];

      enum { L, R } dirs[DEPTH_SIZE];

      links[0] = (struct tree *) &trie->links;

      dirs[0] = L;

      ptrdiff_t depth = 1;

      while (cur && label != cur->label)

        {

          links[depth] = cur;

          if (label < cur->label)

            dirs[depth++] = L, cur = cur->llink;

          else

            dirs[depth++] = R, cur = cur->rlink;

        }

      /* The current character doesn't have an outgoing link at

         this trie node, so build a new trie node and install

         a link in the current trie node's tree.  */

      if (!cur)

        {

          cur = obstack_alloc (&kwset->obstack, sizeof *cur);

          cur->llink = NULL;

          cur->rlink = NULL;

          cur->trie = obstack_alloc (&kwset->obstack, sizeof *cur->trie);

          cur->trie->accepting = 0;

          cur->trie->links = NULL;

          cur->trie->parent = trie;

          cur->trie->next = NULL;

          cur->trie->fail = NULL;

          cur->trie->depth = trie->depth + 1;

          cur->trie->shift = 0;

          cur->label = label;

          cur->balance = 0;

          /* Install the new tree node in its parent.  */

          if (dirs[--depth] == L)

            links[depth]->llink = cur;

          else

            links[depth]->rlink = cur;

          /* Back up the tree fixing the balance flags.  */

          while (depth && !links[depth]->balance)

            {

              if (dirs[depth] == L)

                --links[depth]->balance;

              else

                ++links[depth]->balance;

              --depth;

            }

          /* Rebalance the tree by pointer rotations if necessary.  */

          if (depth && ((dirs[depth] == L && --links[depth]->balance)

                        || (dirs[depth] == R && ++links[depth]->balance)))

            {

              struct tree *t, *r, *l, *rl, *lr;

              switch (links[depth]->balance)

                {

                case (char) -2:

                  switch (dirs[depth + 1])

                    {

                    case L:

                      r = links[depth], t = r->llink, rl = t->rlink;

                      t->rlink = r, r->llink = rl;

                      t->balance = r->balance = 0;

                      break;

                    case R:

                      r = links[depth], l = r->llink, t = l->rlink;

                      rl = t->rlink, lr = t->llink;

                      t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;

                      l->balance = t->balance != 1 ? 0 : -1;

                      r->balance = t->balance != (char) -1 ? 0 : 1;

                      t->balance = 0;

                      break;

                    default:

                      abort ();

                    }

                  break;

                case 2:

                  switch (dirs[depth + 1])

                    {

                    case R:

                      l = links[depth], t = l->rlink, lr = t->llink;

                      t->llink = l, l->rlink = lr;

                      t->balance = l->balance = 0;

                      break;

                    case L:

                      l = links[depth], r = l->rlink, t = r->llink;

                      lr = t->llink, rl = t->rlink;

                      t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;

                      l->balance = t->balance != 1 ? 0 : -1;

                      r->balance = t->balance != (char) -1 ? 0 : 1;

                      t->balance = 0;

                      break;

                    default:

                      abort ();

                    }

                  break;

                default:

                  abort ();

                }

              if (dirs[depth - 1] == L)

                links[depth - 1]->llink = t;

              else

                links[depth - 1]->rlink = t;

            }

        }

      trie = cur->trie;

    }

  /* Mark the node finally reached as accepting, encoding the

     index number of this word in the keyword set so far.  */

  if (!trie->accepting)

    {

      size_t words = kwset->words;

      trie->accepting = 2 * words + 1;

    }

  ++kwset->words;

  /* Keep track of the longest and shortest string of the keyword set.  */

  if (trie->depth < kwset->mind)

    kwset->mind = trie->depth;

  if (trie->depth > kwset->maxd)

    kwset->maxd = trie->depth;

}

ptrdiff_t

kwswords (kwset_t kwset)

{

  return kwset->words;

}

/* Enqueue the trie nodes referenced from the given tree in the

   given queue.  */

static void

enqueue (struct tree *tree, struct trie **last)

{

  if (!tree)

    return;

  enqueue (tree->llink, last);

  enqueue (tree->rlink, last);

  (*last) = (*last)->next = tree->trie;

}

/* Compute the Aho-Corasick failure function for the trie nodes referenced

   from the given tree, given the failure function for their parent as

   well as a last resort failure node.  */

static void

treefails (struct tree const *tree, struct trie const *fail,

           struct trie *recourse, bool reverse)

{

  struct tree *cur;

  if (!tree)

    return;

  treefails (tree->llink, fail, recourse, reverse);

  treefails (tree->rlink, fail, recourse, reverse);

  /* Find, in the chain of fails going back to the root, the first

     node that has a descendant on the current label.  */

  while (fail)

    {

      cur = fail->links;

      while (cur && tree->label != cur->label)

        if (tree->label < cur->label)

          cur = cur->llink;

        else

          cur = cur->rlink;

      if (cur)

        {

          tree->trie->fail = cur->trie;

          if (!reverse && cur->trie->accepting && !tree->trie->accepting)

            tree->trie->accepting = SIZE_MAX;

          return;

        }

      fail = fail->fail;

    }

  tree->trie->fail = recourse;

}

/* Set delta entries for the links of the given tree such that

   the preexisting delta value is larger than the current depth.  */

static void

treedelta (struct tree const *tree, ptrdiff_t depth, unsigned char delta[])

{

  if (!tree)

    return;

  treedelta (tree->llink, depth, delta);

  treedelta (tree->rlink, depth, delta);

  if (depth < delta[tree->label])

    delta[tree->label] = depth;

}

/* Return true if A has every label in B.  */

static bool _GL_ATTRIBUTE_PURE

hasevery (struct tree const *a, struct tree const *b)

{

  if (!b)

    return true;

  if (!hasevery (a, b->llink))

    return false;

  if (!hasevery (a, b->rlink))

    return false;

  while (a && b->label != a->label)

    if (b->label < a->label)

      a = a->llink;

    else

      a = a->rlink;

  return !!a;

}

/* Compute a vector, indexed by character code, of the trie nodes

   referenced from the given tree.  */

static void

treenext (struct tree const *tree, struct trie *next[])

{

  if (!tree)

    return;

  treenext (tree->llink, next);

  treenext (tree->rlink, next);

  next[tree->label] = tree->trie;

}

/* Prepare a built keyword set for use.  */

void

kwsprep (kwset_t kwset)

{

  char const *trans = kwset->trans;

  ptrdiff_t i;

  unsigned char deltabuf[NCHAR];

  unsigned char *delta = trans ? deltabuf : kwset->delta;

  struct trie *curr, *last;

  /* Use Boyer-Moore if just one pattern, Aho-Corasick otherwise.  */

  bool reverse = kwset->words == 1;

  if (reverse)

    {

      kwset_t new_kwset;

      /* Enqueue the immediate descendants in the level order queue.  */

      for (curr = last = kwset->trie; curr; curr = curr->next)

        enqueue (curr->links, &last);

      /* Looking for just one string.  Extract it from the trie.  */

      kwset->target = obstack_alloc (&kwset->obstack, kwset->mind);

      for (i = 0, curr = kwset->trie; i < kwset->mind; ++i)

        {

          kwset->target[i] = curr->links->label;

          curr = curr->next;

        }

      new_kwset = kwsalloc (kwset->trans);

      new_kwset->kwsexec = bmexec;

      kwsincr (new_kwset, kwset->target, kwset->mind);

      obstack_free (&kwset->obstack, NULL);

      *kwset = *new_kwset;

      free (new_kwset);

    }

  /* Initial values for the delta table; will be changed later.  The

     delta entry for a given character is the smallest depth of any

     node at which an outgoing edge is labeled by that character.  */

  memset (delta, MIN (kwset->mind, UCHAR_MAX), sizeof deltabuf);

  /* Traverse the nodes of the trie in level order, simultaneously

     computing the delta table, failure function, and shift function.  */

  for (curr = last = kwset->trie; curr; curr = curr->next)

    {

      /* Enqueue the immediate descendants in the level order queue.  */

      enqueue (curr->links, &last);

      /* Update the delta table for the descendants of this node.  */

      treedelta (curr->links, curr->depth, delta);

      /* Compute the failure function for the descendants of this node.  */

      treefails (curr->links, curr->fail, kwset->trie, reverse);

      if (reverse)

        {

          curr->shift = kwset->mind;

          curr->maxshift = kwset->mind;

          /* Update the shifts at each node in the current node's chain

             of fails back to the root.  */

          struct trie *fail;

          for (fail = curr->fail; fail; fail = fail->fail)

            {

              /* If the current node has some outgoing edge that the fail

                 doesn't, then the shift at the fail should be no larger

                 than the difference of their depths.  */

              if (!hasevery (fail->links, curr->links))

                if (curr->depth - fail->depth < fail->shift)

                  fail->shift = curr->depth - fail->depth;

              /* If the current node is accepting then the shift at the

                 fail and its descendants should be no larger than the

                 difference of their depths.  */

              if (curr->accepting && fail->maxshift > curr->depth - fail->depth)

                fail->maxshift = curr->depth - fail->depth;

            }

        }

    }

  if (reverse)

    {

      /* Traverse the trie in level order again, fixing up all nodes whose

         shift exceeds their inherited maxshift.  */

      for (curr = kwset->trie->next; curr; curr = curr->next)

        {

          if (curr->maxshift > curr->parent->maxshift)

            curr->maxshift = curr->parent->maxshift;

          if (curr->shift > curr->maxshift)

            curr->shift = curr->maxshift;

        }

    }

  /* Create a vector, indexed by character code, of the outgoing links

     from the root node.  Accumulate GC1 and GC1HELP.  */

  struct trie *nextbuf[NCHAR];

  struct trie **next = trans ? nextbuf : kwset->next;

  memset (next, 0, sizeof nextbuf);

  treenext (kwset->trie->links, next);

  int gc1 = -2;

  int gc1help = -1;

  for (i = 0; i < NCHAR; i++)

    {

      int ti = i;

      if (trans)

        {

          ti = U(trans[i]);

          kwset->next[i] = next[ti];

        }

      if (kwset->next[i])

        {

          if (gc1 < -1)

            {

              gc1 = ti;

              gc1help = i;

            }

          else if (gc1 == ti)

            gc1help = gc1help == ti ? i : -1;

          else if (i == ti && gc1 == gc1help)

            gc1help = i;

          else

            gc1 = -1;

        }

    }

  kwset->gc1 = gc1;

  kwset->gc1help = gc1help;

  if (reverse)

    {

      /* Looking for just one string.  Extract it from the trie.  */

      kwset->target = obstack_alloc (&kwset->obstack, kwset->mind);

      for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i)

        {

          kwset->target[i] = curr->links->label;

          curr = curr->next;

        }

      if (kwset->mind > 1)

        {

          /* Looking for the delta2 shift that might be made after a

             backwards match has failed.  Extract it from the trie.  */

          kwset->shift

            = obstack_alloc (&kwset->obstack,

                             sizeof *kwset->shift * (kwset->mind - 1));

          for (i = 0, curr = kwset->trie->next; i < kwset->mind - 1; ++i)

            {

              kwset->shift[i] = curr->shift;

              curr = curr->next;

            }

          /* The penultimate byte.  */

          kwset->gc2 = tr (trans, kwset->target[kwset->mind - 2]);

        }

    }

  /* Fix things up for any translation table.  */

  if (trans)

    for (i = 0; i < NCHAR; ++i)

      kwset->delta[i] = delta[U(trans[i])];

}

/* Delta2 portion of a Boyer-Moore search.  *TP is the string text

   pointer; it is updated in place.  EP is the end of the string text,

   and SP the end of the pattern.  LEN is the pattern length; it must

   be at least 2.  TRANS, if nonnull, is the input translation table.

   GC1 and GC2 are the last and second-from last bytes of the pattern,

   transliterated by TRANS; the caller precomputes them for

   efficiency.  If D1 is nonnull, it is a delta1 table for shifting *TP

   when failing.  KWSET->shift says how much to shift.  */

static inline bool

bm_delta2_search (char const **tpp, char const *ep, char const *sp,

                  ptrdiff_t len,

                  char const *trans, char gc1, char gc2,

                  unsigned char const *d1, kwset_t kwset)

{

  char const *tp = *tpp;

  ptrdiff_t d = len, skip = 0;

  while (true)

    {

      ptrdiff_t i = 2;

      if (tr (trans, tp[-2]) == gc2)

        {

          while (++i <= d)

            if (tr (trans, tp[-i]) != tr (trans, sp[-i]))

              break;

          if (i > d)

            {

              for (i = d + skip + 1; i <= len; ++i)

                if (tr (trans, tp[-i]) != tr (trans, sp[-i]))

                  break;

              if (i > len)

                {

                  *tpp = tp - len;

                  return true;

                }

            }

        }

      tp += d = kwset->shift[i - 2];

      if (tp > ep)

        break;

      if (tr (trans, tp[-1]) != gc1)

        {

          if (d1)

            tp += d1[U(tp[-1])];

          break;

        }

      skip = i - 1;

    }

  *tpp = tp;

  return false;

}

/* Return the address of the first byte in the buffer S (of size N)

   that matches the terminal byte specified by KWSET, or NULL if there

   is no match.  KWSET->gc1 should be nonnegative.  */

static char const *

memchr_kwset (char const *s, ptrdiff_t n, kwset_t kwset)

{

  char const *slim = s + n;

  if (kwset->gc1help < 0)

    {

      for (; s < slim; s++)

        if (kwset->next[U(*s)])

          return s;

    }

  else

    {

      int small_heuristic = 2;

      size_t small_bytes = small_heuristic * sizeof (unsigned long int);

      while (s < slim)

        {

          if (kwset->next[U(*s)])

            return s;

          s++;

          if ((uintptr_t) s % small_bytes == 0)

            return memchr2 (s, kwset->gc1, kwset->gc1help, slim - s);

        }

    }

  return NULL;

}

/* Fast Boyer-Moore search (inlinable version).  */

static inline ptrdiff_t

bmexec_trans (kwset_t kwset, char const *text, ptrdiff_t size)

{

  assume (0 <= size);

  unsigned char const *d1;

  char const *ep, *sp, *tp;

  int d;

  ptrdiff_t len = kwset->mind;

  char const *trans = kwset->trans;

  if (len == 0)

    return 0;

  if (len > size)

    return -1;

  if (len == 1)

    {

      tp = memchr_kwset (text, size, kwset);

      return tp ? tp - text : -1;

    }

  d1 = kwset->delta;

  sp = kwset->target + len;

  tp = text + len;

  char gc1 = kwset->gc1;

  char gc2 = kwset->gc2;

  /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2).  */

  ptrdiff_t len12;

  if (!INT_MULTIPLY_WRAPV (len, 12, &len12) && len12 < size)

    /* 11 is not a bug, the initial offset happens only once.  */

    for (ep = text + size - 11 * len; tp <= ep; )

      {

        char const *tp0 = tp;

        d = d1[U(tp[-1])], tp += d;

        d = d1[U(tp[-1])], tp += d;

        if (d != 0)

          {

            d = d1[U(tp[-1])], tp += d;

            d = d1[U(tp[-1])], tp += d;

            d = d1[U(tp[-1])], tp += d;

            if (d != 0)

              {

                d = d1[U(tp[-1])], tp += d;

                d = d1[U(tp[-1])], tp += d;

                d = d1[U(tp[-1])], tp += d;

                if (d != 0)

                  {

                    d = d1[U(tp[-1])], tp += d;

                    d = d1[U(tp[-1])], tp += d;

                    /* As a heuristic, prefer memchr to seeking by

                       delta1 when the latter doesn't advance much.  */

                    int advance_heuristic = 16 * sizeof (long);

                    if (advance_heuristic <= tp - tp0)

                      continue;

                    tp--;

                    tp = memchr_kwset (tp, text + size - tp, kwset);

                    if (! tp)

                      return -1;

                    tp++;

                    if (ep <= tp)

                      break;

                  }

              }

          }

        if (bm_delta2_search (&tp, ep, sp, len, trans, gc1, gc2, d1, kwset))

          return tp - text;

      }

  /* Now only a few characters are left to search.  Carefully avoid

     ever producing an out-of-bounds pointer.  */

  ep = text + size;

  d = d1[U(tp[-1])];

  while (d <= ep - tp)

    {

      d = d1[U((tp += d)[-1])];

      if (d != 0)

        continue;

      if (bm_delta2_search (&tp, ep, sp, len, trans, gc1, gc2, NULL, kwset))

        return tp - text;

    }

  return -1;

}

/* Fast Boyer-Moore search.  */

static ptrdiff_t

bmexec (kwset_t kwset, char const *text, ptrdiff_t size,

        struct kwsmatch *kwsmatch, bool longest)

{

  /* Help the compiler inline in two ways, depending on whether

     kwset->trans is null.  */

  ptrdiff_t ret = (IGNORE_DUPLICATE_BRANCH_WARNING

                   (kwset->trans

                    ? bmexec_trans (kwset, text, size)

                    : bmexec_trans (kwset, text, size)));

  if (0 <= ret)

    {

       kwsmatch->index = 0;

       kwsmatch->offset[0] = ret;

       kwsmatch->size[0] = kwset->mind;

    }

  return ret;

}

/* Hairy multiple string search with the Aho-Corasick algorithm.

   (inlinable version)  */

static inline ptrdiff_t

acexec_trans (kwset_t kwset, char const *text, ptrdiff_t len,

              struct kwsmatch *kwsmatch, bool longest)

{

  struct trie const *trie, *accept;

  char const *tp, *left, *lim;

  struct tree const *tree;

  char const *trans;

  /* Initialize register copies and look for easy ways out.  */

  if (len < kwset->mind)

    return -1;

  trans = kwset->trans;

  trie = kwset->trie;

  lim = text + len;

  tp = text;

  if (!trie->accepting)

    {

      unsigned char c;

      int gc1 = kwset->gc1;

      while (true)

        {

          if (gc1 < 0)

            {

              while (! (trie = kwset->next[c = tr (trans, *tp++)]))

                if (tp >= lim)

                  return -1;

            }

          else

            {

              tp = memchr_kwset (tp, lim - tp, kwset);

              if (!tp)

                return -1;

              c = tr (trans, *tp++);

              trie = kwset->next[c];

            }

          while (true)

            {

              if (trie->accepting)

                goto match;

              if (tp >= lim)

                return -1;

              c = tr (trans, *tp++);

              for (tree = trie->links; c != tree->label; )

                {

                  tree = c < tree->label ? tree->llink : tree->rlink;

                  if (! tree)

                    {

                      trie = trie->fail;

                      if (!trie)

                        {

                          trie = kwset->next[c];

                          if (trie)

                            goto have_trie;

                          if (tp >= lim)

                            return -1;

                          goto next_c;

                        }

                      if (trie->accepting)

                        {

                          --tp;

                          goto match;

                        }

                      tree = trie->links;

                    }

                }

              trie = tree->trie;

            have_trie:;

            }

        next_c:;

        }

    }

 match:

  accept = trie;

  while (accept->accepting == SIZE_MAX)

    accept = accept->fail;

  left = tp - accept->depth;

  /* Try left-most longest match.  */

  if (longest)

    {

      while (tp < lim)

        {

          struct trie const *accept1;

          char const *left1;

          unsigned char c = tr (trans, *tp++);

          do

            {

              tree = trie->links;

              while (tree && c != tree->label)

                tree = c < tree->label ? tree->llink : tree->rlink;

            }

          while (!tree && (trie = trie->fail) && accept->depth <= trie->depth);

          if (!tree)

            break;

          trie = tree->trie;

          if (trie->accepting)

            {

              accept1 = trie;