kwset.con commit Merge branch 'mn/doc-pack-heu-remove-dead-pastebin' (8ee9a18)
   1/*
   2 * This file has been copied from commit e7ac713d^ in the GNU grep git
   3 * repository. A few small changes have been made to adapt the code to
   4 * Git.
   5 */
   6
   7/* kwset.c - search for any of a set of keywords.
   8   Copyright 1989, 1998, 2000, 2005 Free Software Foundation, Inc.
   9
  10   This program is free software; you can redistribute it and/or modify
  11   it under the terms of the GNU General Public License as published by
  12   the Free Software Foundation; either version 2, or (at your option)
  13   any later version.
  14
  15   This program is distributed in the hope that it will be useful,
  16   but WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18   GNU General Public License for more details.
  19
  20   You should have received a copy of the GNU General Public License
  21   along with this program; if not, write to the Free Software
  22   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
  23   02110-1301, USA.  */
  24
  25/* Written August 1989 by Mike Haertel.
  26   The author may be reached (Email) at the address mike@ai.mit.edu,
  27   or (US mail) as Mike Haertel c/o Free Software Foundation. */
  28
  29/* The algorithm implemented by these routines bears a startling resemblance
  30   to one discovered by Beate Commentz-Walter, although it is not identical.
  31   See "A String Matching Algorithm Fast on the Average," Technical Report,
  32   IBM-Germany, Scientific Center Heidelberg, Tiergartenstrasse 15, D-6900
  33   Heidelberg, Germany.  See also Aho, A.V., and M. Corasick, "Efficient
  34   String Matching:  An Aid to Bibliographic Search," CACM June 1975,
  35   Vol. 18, No. 6, which describes the failure function used below. */
  36
  37#include "cache.h"
  38
  39#include "kwset.h"
  40#include "compat/obstack.h"
  41
  42#define NCHAR (UCHAR_MAX + 1)
  43#define obstack_chunk_alloc xmalloc
  44#define obstack_chunk_free free
  45
  46#define U(c) ((unsigned char) (c))
  47
  48/* Balanced tree of edges and labels leaving a given trie node. */
  49struct tree
  50{
  51  struct tree *llink;           /* Left link; MUST be first field. */
  52  struct tree *rlink;           /* Right link (to larger labels). */
  53  struct trie *trie;            /* Trie node pointed to by this edge. */
  54  unsigned char label;          /* Label on this edge. */
  55  char balance;                 /* Difference in depths of subtrees. */
  56};
  57
  58/* Node of a trie representing a set of reversed keywords. */
  59struct trie
  60{
  61  unsigned int accepting;       /* Word index of accepted word, or zero. */
  62  struct tree *links;           /* Tree of edges leaving this node. */
  63  struct trie *parent;          /* Parent of this node. */
  64  struct trie *next;            /* List of all trie nodes in level order. */
  65  struct trie *fail;            /* Aho-Corasick failure function. */
  66  int depth;                    /* Depth of this node from the root. */
  67  int shift;                    /* Shift function for search failures. */
  68  int maxshift;                 /* Max shift of self and descendants. */
  69};
  70
  71/* Structure returned opaquely to the caller, containing everything. */
  72struct kwset
  73{
  74  struct obstack obstack;       /* Obstack for node allocation. */
  75  int words;                    /* Number of words in the trie. */
  76  struct trie *trie;            /* The trie itself. */
  77  int mind;                     /* Minimum depth of an accepting node. */
  78  int maxd;                     /* Maximum depth of any node. */
  79  unsigned char delta[NCHAR];   /* Delta table for rapid search. */
  80  struct trie *next[NCHAR];     /* Table of children of the root. */
  81  char *target;                 /* Target string if there's only one. */
  82  int mind2;                    /* Used in Boyer-Moore search for one string. */
  83  char const *trans;            /* Character translation table. */
  84};
  85
  86/* Allocate and initialize a keyword set object, returning an opaque
  87   pointer to it.  Return NULL if memory is not available. */
  88kwset_t
  89kwsalloc (char const *trans)
  90{
  91  struct kwset *kwset;
  92
  93  kwset = (struct kwset *) xmalloc(sizeof (struct kwset));
  94
  95  obstack_init(&kwset->obstack);
  96  kwset->words = 0;
  97  kwset->trie
  98    = (struct trie *) obstack_alloc(&kwset->obstack, sizeof (struct trie));
  99  if (!kwset->trie)
 100    {
 101      kwsfree((kwset_t) kwset);
 102      return NULL;
 103    }
 104  kwset->trie->accepting = 0;
 105  kwset->trie->links = NULL;
 106  kwset->trie->parent = NULL;
 107  kwset->trie->next = NULL;
 108  kwset->trie->fail = NULL;
 109  kwset->trie->depth = 0;
 110  kwset->trie->shift = 0;
 111  kwset->mind = INT_MAX;
 112  kwset->maxd = -1;
 113  kwset->target = NULL;
 114  kwset->trans = trans;
 115
 116  return (kwset_t) kwset;
 117}
 118
 119/* This upper bound is valid for CHAR_BIT >= 4 and
 120   exact for CHAR_BIT in { 4..11, 13, 15, 17, 19 }. */
 121#define DEPTH_SIZE (CHAR_BIT + CHAR_BIT/2)
 122
 123/* Add the given string to the contents of the keyword set.  Return NULL
 124   for success, an error message otherwise. */
 125const char *
 126kwsincr (kwset_t kws, char const *text, size_t len)
 127{
 128  struct kwset *kwset;
 129  register struct trie *trie;
 130  register unsigned char label;
 131  register struct tree *link;
 132  register int depth;
 133  struct tree *links[DEPTH_SIZE];
 134  enum { L, R } dirs[DEPTH_SIZE];
 135  struct tree *t, *r, *l, *rl, *lr;
 136
 137  kwset = (struct kwset *) kws;
 138  trie = kwset->trie;
 139  text += len;
 140
 141  /* Descend the trie (built of reversed keywords) character-by-character,
 142     installing new nodes when necessary. */
 143  while (len--)
 144    {
 145      label = kwset->trans ? kwset->trans[U(*--text)] : *--text;
 146
 147      /* Descend the tree of outgoing links for this trie node,
 148         looking for the current character and keeping track
 149         of the path followed. */
 150      link = trie->links;
 151      links[0] = (struct tree *) &trie->links;
 152      dirs[0] = L;
 153      depth = 1;
 154
 155      while (link && label != link->label)
 156        {
 157          links[depth] = link;
 158          if (label < link->label)
 159            dirs[depth++] = L, link = link->llink;
 160          else
 161            dirs[depth++] = R, link = link->rlink;
 162        }
 163
 164      /* The current character doesn't have an outgoing link at
 165         this trie node, so build a new trie node and install
 166         a link in the current trie node's tree. */
 167      if (!link)
 168        {
 169          link = (struct tree *) obstack_alloc(&kwset->obstack,
 170                                               sizeof (struct tree));
 171          if (!link)
 172            return "memory exhausted";
 173          link->llink = NULL;
 174          link->rlink = NULL;
 175          link->trie = (struct trie *) obstack_alloc(&kwset->obstack,
 176                                                     sizeof (struct trie));
 177          if (!link->trie)
 178            {
 179              obstack_free(&kwset->obstack, link);
 180              return "memory exhausted";
 181            }
 182          link->trie->accepting = 0;
 183          link->trie->links = NULL;
 184          link->trie->parent = trie;
 185          link->trie->next = NULL;
 186          link->trie->fail = NULL;
 187          link->trie->depth = trie->depth + 1;
 188          link->trie->shift = 0;
 189          link->label = label;
 190          link->balance = 0;
 191
 192          /* Install the new tree node in its parent. */
 193          if (dirs[--depth] == L)
 194            links[depth]->llink = link;
 195          else
 196            links[depth]->rlink = link;
 197
 198          /* Back up the tree fixing the balance flags. */
 199          while (depth && !links[depth]->balance)
 200            {
 201              if (dirs[depth] == L)
 202                --links[depth]->balance;
 203              else
 204                ++links[depth]->balance;
 205              --depth;
 206            }
 207
 208          /* Rebalance the tree by pointer rotations if necessary. */
 209          if (depth && ((dirs[depth] == L && --links[depth]->balance)
 210                        || (dirs[depth] == R && ++links[depth]->balance)))
 211            {
 212              switch (links[depth]->balance)
 213                {
 214                case (char) -2:
 215                  switch (dirs[depth + 1])
 216                    {
 217                    case L:
 218                      r = links[depth], t = r->llink, rl = t->rlink;
 219                      t->rlink = r, r->llink = rl;
 220                      t->balance = r->balance = 0;
 221                      break;
 222                    case R:
 223                      r = links[depth], l = r->llink, t = l->rlink;
 224                      rl = t->rlink, lr = t->llink;
 225                      t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
 226                      l->balance = t->balance != 1 ? 0 : -1;
 227                      r->balance = t->balance != (char) -1 ? 0 : 1;
 228                      t->balance = 0;
 229                      break;
 230                    default:
 231                      abort ();
 232                    }
 233                  break;
 234                case 2:
 235                  switch (dirs[depth + 1])
 236                    {
 237                    case R:
 238                      l = links[depth], t = l->rlink, lr = t->llink;
 239                      t->llink = l, l->rlink = lr;
 240                      t->balance = l->balance = 0;
 241                      break;
 242                    case L:
 243                      l = links[depth], r = l->rlink, t = r->llink;
 244                      lr = t->llink, rl = t->rlink;
 245                      t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
 246                      l->balance = t->balance != 1 ? 0 : -1;
 247                      r->balance = t->balance != (char) -1 ? 0 : 1;
 248                      t->balance = 0;
 249                      break;
 250                    default:
 251                      abort ();
 252                    }
 253                  break;
 254                default:
 255                  abort ();
 256                }
 257
 258              if (dirs[depth - 1] == L)
 259                links[depth - 1]->llink = t;
 260              else
 261                links[depth - 1]->rlink = t;
 262            }
 263        }
 264
 265      trie = link->trie;
 266    }
 267
 268  /* Mark the node we finally reached as accepting, encoding the
 269     index number of this word in the keyword set so far. */
 270  if (!trie->accepting)
 271    trie->accepting = 1 + 2 * kwset->words;
 272  ++kwset->words;
 273
 274  /* Keep track of the longest and shortest string of the keyword set. */
 275  if (trie->depth < kwset->mind)
 276    kwset->mind = trie->depth;
 277  if (trie->depth > kwset->maxd)
 278    kwset->maxd = trie->depth;
 279
 280  return NULL;
 281}
 282
 283/* Enqueue the trie nodes referenced from the given tree in the
 284   given queue. */
 285static void
 286enqueue (struct tree *tree, struct trie **last)
 287{
 288  if (!tree)
 289    return;
 290  enqueue(tree->llink, last);
 291  enqueue(tree->rlink, last);
 292  (*last) = (*last)->next = tree->trie;
 293}
 294
 295/* Compute the Aho-Corasick failure function for the trie nodes referenced
 296   from the given tree, given the failure function for their parent as
 297   well as a last resort failure node. */
 298static void
 299treefails (register struct tree const *tree, struct trie const *fail,
 300           struct trie *recourse)
 301{
 302  register struct tree *link;
 303
 304  if (!tree)
 305    return;
 306
 307  treefails(tree->llink, fail, recourse);
 308  treefails(tree->rlink, fail, recourse);
 309
 310  /* Find, in the chain of fails going back to the root, the first
 311     node that has a descendant on the current label. */
 312  while (fail)
 313    {
 314      link = fail->links;
 315      while (link && tree->label != link->label)
 316        if (tree->label < link->label)
 317          link = link->llink;
 318        else
 319          link = link->rlink;
 320      if (link)
 321        {
 322          tree->trie->fail = link->trie;
 323          return;
 324        }
 325      fail = fail->fail;
 326    }
 327
 328  tree->trie->fail = recourse;
 329}
 330
 331/* Set delta entries for the links of the given tree such that
 332   the preexisting delta value is larger than the current depth. */
 333static void
 334treedelta (register struct tree const *tree,
 335           register unsigned int depth,
 336           unsigned char delta[])
 337{
 338  if (!tree)
 339    return;
 340  treedelta(tree->llink, depth, delta);
 341  treedelta(tree->rlink, depth, delta);
 342  if (depth < delta[tree->label])
 343    delta[tree->label] = depth;
 344}
 345
 346/* Return true if A has every label in B. */
 347static int
 348hasevery (register struct tree const *a, register struct tree const *b)
 349{
 350  if (!b)
 351    return 1;
 352  if (!hasevery(a, b->llink))
 353    return 0;
 354  if (!hasevery(a, b->rlink))
 355    return 0;
 356  while (a && b->label != a->label)
 357    if (b->label < a->label)
 358      a = a->llink;
 359    else
 360      a = a->rlink;
 361  return !!a;
 362}
 363
 364/* Compute a vector, indexed by character code, of the trie nodes
 365   referenced from the given tree. */
 366static void
 367treenext (struct tree const *tree, struct trie *next[])
 368{
 369  if (!tree)
 370    return;
 371  treenext(tree->llink, next);
 372  treenext(tree->rlink, next);
 373  next[tree->label] = tree->trie;
 374}
 375
 376/* Compute the shift for each trie node, as well as the delta
 377   table and next cache for the given keyword set. */
 378const char *
 379kwsprep (kwset_t kws)
 380{
 381  register struct kwset *kwset;
 382  register int i;
 383  register struct trie *curr;
 384  register char const *trans;
 385  unsigned char delta[NCHAR];
 386
 387  kwset = (struct kwset *) kws;
 388
 389  /* Initial values for the delta table; will be changed later.  The
 390     delta entry for a given character is the smallest depth of any
 391     node at which an outgoing edge is labeled by that character. */
 392  memset(delta, kwset->mind < UCHAR_MAX ? kwset->mind : UCHAR_MAX, NCHAR);
 393
 394  /* Check if we can use the simple boyer-moore algorithm, instead
 395     of the hairy commentz-walter algorithm. */
 396  if (kwset->words == 1 && kwset->trans == NULL)
 397    {
 398      char c;
 399
 400      /* Looking for just one string.  Extract it from the trie. */
 401      kwset->target = obstack_alloc(&kwset->obstack, kwset->mind);
 402      if (!kwset->target)
 403        return "memory exhausted";
 404      for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i)
 405        {
 406          kwset->target[i] = curr->links->label;
 407          curr = curr->links->trie;
 408        }
 409      /* Build the Boyer Moore delta.  Boy that's easy compared to CW. */
 410      for (i = 0; i < kwset->mind; ++i)
 411        delta[U(kwset->target[i])] = kwset->mind - (i + 1);
 412      /* Find the minimal delta2 shift that we might make after
 413         a backwards match has failed. */
 414      c = kwset->target[kwset->mind - 1];
 415      for (i = kwset->mind - 2; i >= 0; --i)
 416        if (kwset->target[i] == c)
 417          break;
 418      kwset->mind2 = kwset->mind - (i + 1);
 419    }
 420  else
 421    {
 422      register struct trie *fail;
 423      struct trie *last, *next[NCHAR];
 424
 425      /* Traverse the nodes of the trie in level order, simultaneously
 426         computing the delta table, failure function, and shift function. */
 427      for (curr = last = kwset->trie; curr; curr = curr->next)
 428        {
 429          /* Enqueue the immediate descendants in the level order queue. */
 430          enqueue(curr->links, &last);
 431
 432          curr->shift = kwset->mind;
 433          curr->maxshift = kwset->mind;
 434
 435          /* Update the delta table for the descendants of this node. */
 436          treedelta(curr->links, curr->depth, delta);
 437
 438          /* Compute the failure function for the descendants of this node. */
 439          treefails(curr->links, curr->fail, kwset->trie);
 440
 441          /* Update the shifts at each node in the current node's chain
 442             of fails back to the root. */
 443          for (fail = curr->fail; fail; fail = fail->fail)
 444            {
 445              /* If the current node has some outgoing edge that the fail
 446                 doesn't, then the shift at the fail should be no larger
 447                 than the difference of their depths. */
 448              if (!hasevery(fail->links, curr->links))
 449                if (curr->depth - fail->depth < fail->shift)
 450                  fail->shift = curr->depth - fail->depth;
 451
 452              /* If the current node is accepting then the shift at the
 453                 fail and its descendants should be no larger than the
 454                 difference of their depths. */
 455              if (curr->accepting && fail->maxshift > curr->depth - fail->depth)
 456                fail->maxshift = curr->depth - fail->depth;
 457            }
 458        }
 459
 460      /* Traverse the trie in level order again, fixing up all nodes whose
 461         shift exceeds their inherited maxshift. */
 462      for (curr = kwset->trie->next; curr; curr = curr->next)
 463        {
 464          if (curr->maxshift > curr->parent->maxshift)
 465            curr->maxshift = curr->parent->maxshift;
 466          if (curr->shift > curr->maxshift)
 467            curr->shift = curr->maxshift;
 468        }
 469
 470      /* Create a vector, indexed by character code, of the outgoing links
 471         from the root node. */
 472      for (i = 0; i < NCHAR; ++i)
 473        next[i] = NULL;
 474      treenext(kwset->trie->links, next);
 475
 476      if ((trans = kwset->trans) != NULL)
 477        for (i = 0; i < NCHAR; ++i)
 478          kwset->next[i] = next[U(trans[i])];
 479      else
 480        memcpy(kwset->next, next, NCHAR * sizeof(struct trie *));
 481    }
 482
 483  /* Fix things up for any translation table. */
 484  if ((trans = kwset->trans) != NULL)
 485    for (i = 0; i < NCHAR; ++i)
 486      kwset->delta[i] = delta[U(trans[i])];
 487  else
 488    memcpy(kwset->delta, delta, NCHAR);
 489
 490  return NULL;
 491}
 492
 493/* Fast boyer-moore search. */
 494static size_t
 495bmexec (kwset_t kws, char const *text, size_t size)
 496{
 497  struct kwset const *kwset;
 498  register unsigned char const *d1;
 499  register char const *ep, *sp, *tp;
 500  register int d, gc, i, len, md2;
 501
 502  kwset = (struct kwset const *) kws;
 503  len = kwset->mind;
 504
 505  if (len == 0)
 506    return 0;
 507  if (len > size)
 508    return -1;
 509  if (len == 1)
 510    {
 511      tp = memchr (text, kwset->target[0], size);
 512      return tp ? tp - text : -1;
 513    }
 514
 515  d1 = kwset->delta;
 516  sp = kwset->target + len;
 517  gc = U(sp[-2]);
 518  md2 = kwset->mind2;
 519  tp = text + len;
 520
 521  /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */
 522  if (size > 12 * len)
 523    /* 11 is not a bug, the initial offset happens only once. */
 524    for (ep = text + size - 11 * len;;)
 525      {
 526        while (tp <= ep)
 527          {
 528            d = d1[U(tp[-1])], tp += d;
 529            d = d1[U(tp[-1])], tp += d;
 530            if (d == 0)
 531              goto found;
 532            d = d1[U(tp[-1])], tp += d;
 533            d = d1[U(tp[-1])], tp += d;
 534            d = d1[U(tp[-1])], tp += d;
 535            if (d == 0)
 536              goto found;
 537            d = d1[U(tp[-1])], tp += d;
 538            d = d1[U(tp[-1])], tp += d;
 539            d = d1[U(tp[-1])], tp += d;
 540            if (d == 0)
 541              goto found;
 542            d = d1[U(tp[-1])], tp += d;
 543            d = d1[U(tp[-1])], tp += d;
 544          }
 545        break;
 546      found:
 547        if (U(tp[-2]) == gc)
 548          {
 549            for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i)
 550              ;
 551            if (i > len)
 552              return tp - len - text;
 553          }
 554        tp += md2;
 555      }
 556
 557  /* Now we have only a few characters left to search.  We
 558     carefully avoid ever producing an out-of-bounds pointer. */
 559  ep = text + size;
 560  d = d1[U(tp[-1])];
 561  while (d <= ep - tp)
 562    {
 563      d = d1[U((tp += d)[-1])];
 564      if (d != 0)
 565        continue;
 566      if (U(tp[-2]) == gc)
 567        {
 568          for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i)
 569            ;
 570          if (i > len)
 571            return tp - len - text;
 572        }
 573      d = md2;
 574    }
 575
 576  return -1;
 577}
 578
 579/* Hairy multiple string search. */
 580static size_t
 581cwexec (kwset_t kws, char const *text, size_t len, struct kwsmatch *kwsmatch)
 582{
 583  struct kwset const *kwset;
 584  struct trie * const *next;
 585  struct trie const *trie;
 586  struct trie const *accept;
 587  char const *beg, *lim, *mch, *lmch;
 588  register unsigned char c;
 589  register unsigned char const *delta;
 590  register int d;
 591  register char const *end, *qlim;
 592  register struct tree const *tree;
 593  register char const *trans;
 594
 595  accept = NULL;
 596
 597  /* Initialize register copies and look for easy ways out. */
 598  kwset = (struct kwset *) kws;
 599  if (len < kwset->mind)
 600    return -1;
 601  next = kwset->next;
 602  delta = kwset->delta;
 603  trans = kwset->trans;
 604  lim = text + len;
 605  end = text;
 606  if ((d = kwset->mind) != 0)
 607    mch = NULL;
 608  else
 609    {
 610      mch = text, accept = kwset->trie;
 611      goto match;
 612    }
 613
 614  if (len >= 4 * kwset->mind)
 615    qlim = lim - 4 * kwset->mind;
 616  else
 617    qlim = NULL;
 618
 619  while (lim - end >= d)
 620    {
 621      if (qlim && end <= qlim)
 622        {
 623          end += d - 1;
 624          while ((d = delta[c = *end]) && end < qlim)
 625            {
 626              end += d;
 627              end += delta[U(*end)];
 628              end += delta[U(*end)];
 629            }
 630          ++end;
 631        }
 632      else
 633        d = delta[c = (end += d)[-1]];
 634      if (d)
 635        continue;
 636      beg = end - 1;
 637      trie = next[c];
 638      if (trie->accepting)
 639        {
 640          mch = beg;
 641          accept = trie;
 642        }
 643      d = trie->shift;
 644      while (beg > text)
 645        {
 646          c = trans ? trans[U(*--beg)] : *--beg;
 647          tree = trie->links;
 648          while (tree && c != tree->label)
 649            if (c < tree->label)
 650              tree = tree->llink;
 651            else
 652              tree = tree->rlink;
 653          if (tree)
 654            {
 655              trie = tree->trie;
 656              if (trie->accepting)
 657                {
 658                  mch = beg;
 659                  accept = trie;
 660                }
 661            }
 662          else
 663            break;
 664          d = trie->shift;
 665        }
 666      if (mch)
 667        goto match;
 668    }
 669  return -1;
 670
 671 match:
 672  /* Given a known match, find the longest possible match anchored
 673     at or before its starting point.  This is nearly a verbatim
 674     copy of the preceding main search loops. */
 675  if (lim - mch > kwset->maxd)
 676    lim = mch + kwset->maxd;
 677  lmch = NULL;
 678  d = 1;
 679  while (lim - end >= d)
 680    {
 681      if ((d = delta[c = (end += d)[-1]]) != 0)
 682        continue;
 683      beg = end - 1;
 684      if (!(trie = next[c]))
 685        {
 686          d = 1;
 687          continue;
 688        }
 689      if (trie->accepting && beg <= mch)
 690        {
 691          lmch = beg;
 692          accept = trie;
 693        }
 694      d = trie->shift;
 695      while (beg > text)
 696        {
 697          c = trans ? trans[U(*--beg)] : *--beg;
 698          tree = trie->links;
 699          while (tree && c != tree->label)
 700            if (c < tree->label)
 701              tree = tree->llink;
 702            else
 703              tree = tree->rlink;
 704          if (tree)
 705            {
 706              trie = tree->trie;
 707              if (trie->accepting && beg <= mch)
 708                {
 709                  lmch = beg;
 710                  accept = trie;
 711                }
 712            }
 713          else
 714            break;
 715          d = trie->shift;
 716        }
 717      if (lmch)
 718        {
 719          mch = lmch;
 720          goto match;
 721        }
 722      if (!d)
 723        d = 1;
 724    }
 725
 726  if (kwsmatch)
 727    {
 728      kwsmatch->index = accept->accepting / 2;
 729      kwsmatch->offset[0] = mch - text;
 730      kwsmatch->size[0] = accept->depth;
 731    }
 732  return mch - text;
 733}
 734
 735/* Search through the given text for a match of any member of the
 736   given keyword set.  Return a pointer to the first character of
 737   the matching substring, or NULL if no match is found.  If FOUNDLEN
 738   is non-NULL store in the referenced location the length of the
 739   matching substring.  Similarly, if FOUNDIDX is non-NULL, store
 740   in the referenced location the index number of the particular
 741   keyword matched. */
 742size_t
 743kwsexec (kwset_t kws, char const *text, size_t size,
 744         struct kwsmatch *kwsmatch)
 745{
 746  struct kwset const *kwset = (struct kwset *) kws;
 747  if (kwset->words == 1 && kwset->trans == NULL)
 748    {
 749      size_t ret = bmexec (kws, text, size);
 750      if (kwsmatch != NULL && ret != (size_t) -1)
 751        {
 752          kwsmatch->index = 0;
 753          kwsmatch->offset[0] = ret;
 754          kwsmatch->size[0] = kwset->mind;
 755        }
 756      return ret;
 757    }
 758  else
 759    return cwexec(kws, text, size, kwsmatch);
 760}
 761
 762/* Free the components of the given keyword set. */
 763void
 764kwsfree (kwset_t kws)
 765{
 766  struct kwset *kwset;
 767
 768  kwset = (struct kwset *) kws;
 769  obstack_free(&kwset->obstack, NULL);
 770  free(kws);
 771}