git

1
/*
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 * This file has been copied from commit e7ac713d^ in the GNU grep git
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 * repository. A few small changes have been made to adapt the code to
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 * Git.
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 */
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/* kwset.c - search for any of a set of keywords.
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   Copyright 1989, 1998, 2000, 2005 Free Software Foundation, Inc.
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10
   This program is free software; you can redistribute it and/or modify
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   it under the terms of the GNU General Public License as published by
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   the Free Software Foundation; either version 2, or (at your option)
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   any later version.
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   This program is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   GNU General Public License for more details.
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   You should have received a copy of the GNU General Public License
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   along with this program; if not, see <https://www.gnu.org/licenses/>. */
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/* Written August 1989 by Mike Haertel.
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   The author may be reached (Email) at the address mike@ai.mit.edu,
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   or (US mail) as Mike Haertel c/o Free Software Foundation. */
26

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/* The algorithm implemented by these routines bears a startling resemblance
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   to one discovered by Beate Commentz-Walter, although it is not identical.
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   See "A String Matching Algorithm Fast on the Average," Technical Report,
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   IBM-Germany, Scientific Center Heidelberg, Tiergartenstrasse 15, D-6900
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   Heidelberg, Germany.  See also Aho, A.V., and M. Corasick, "Efficient
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   String Matching:  An Aid to Bibliographic Search," CACM June 1975,
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   Vol. 18, No. 6, which describes the failure function used below. */
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#include "git-compat-util.h"
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37
#include "kwset.h"
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#include "compat/obstack.h"
39

40
#define NCHAR (UCHAR_MAX + 1)
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/* adapter for `xmalloc()`, which takes `size_t`, not `long` */
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static void *obstack_chunk_alloc(long size)
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{
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	if (size < 0)
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		BUG("Cannot allocate a negative amount: %ld", size);
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	return xmalloc(size);
47
}
48
#define obstack_chunk_free free
49

50
#define U(c) ((unsigned char) (c))
51

52
/* For case-insensitive kwset */
53
const unsigned char tolower_trans_tbl[256] = {
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	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
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	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
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	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
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	 ' ',  '!',  '"',  '#',  '$',  '%',  '&', 0x27,
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	 '(',  ')',  '*',  '+',  ',',  '-',  '.',  '/',
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	 '0',  '1',  '2',  '3',  '4',  '5',  '6',  '7',
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	 '8',  '9',  ':',  ';',  '<',  '=',  '>',  '?',
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	 '@',  'a',  'b',  'c',  'd',  'e',  'f',  'g',
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	 'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o',
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	 'p',  'q',  'r',  's',  't',  'u',  'v',  'w',
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	 'x',  'y',  'z',  '[', 0x5c,  ']',  '^',  '_',
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	 '`',  'a',  'b',  'c',  'd',  'e',  'f',  'g',
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	 'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o',
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	 'p',  'q',  'r',  's',  't',  'u',  'v',  'w',
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	 'x',  'y',  'z',  '{',  '|',  '}',  '~', 0x7f,
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	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
71
	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
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	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
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	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
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	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
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	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
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	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
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	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
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	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
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	0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
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	0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
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	0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
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	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
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	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
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	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
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	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
86
};
87

88
/* Balanced tree of edges and labels leaving a given trie node. */
89
struct tree
90
{
91
  struct tree *llink;		/* Left link; MUST be first field. */
92
  struct tree *rlink;		/* Right link (to larger labels). */
93
  struct trie *trie;		/* Trie node pointed to by this edge. */
94
  unsigned char label;		/* Label on this edge. */
95
  char balance;			/* Difference in depths of subtrees. */
96
};
97

98
/* Node of a trie representing a set of reversed keywords. */
99
struct trie
100
{
101
  unsigned int accepting;	/* Word index of accepted word, or zero. */
102
  struct tree *links;		/* Tree of edges leaving this node. */
103
  struct trie *parent;		/* Parent of this node. */
104
  struct trie *next;		/* List of all trie nodes in level order. */
105
  struct trie *fail;		/* Aho-Corasick failure function. */
106
  int depth;			/* Depth of this node from the root. */
107
  int shift;			/* Shift function for search failures. */
108
  int maxshift;			/* Max shift of self and descendants. */
109
};
110

111
/* Structure returned opaquely to the caller, containing everything. */
112
struct kwset
113
{
114
  struct obstack obstack;	/* Obstack for node allocation. */
115
  int words;			/* Number of words in the trie. */
116
  struct trie *trie;		/* The trie itself. */
117
  int mind;			/* Minimum depth of an accepting node. */
118
  int maxd;			/* Maximum depth of any node. */
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  unsigned char delta[NCHAR];	/* Delta table for rapid search. */
120
  struct trie *next[NCHAR];	/* Table of children of the root. */
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  char *target;			/* Target string if there's only one. */
122
  int mind2;			/* Used in Boyer-Moore search for one string. */
123
  unsigned char const *trans;  /* Character translation table. */
124
};
125

126
/* Allocate and initialize a keyword set object, returning an opaque
127
   pointer to it.  Return NULL if memory is not available. */
128
kwset_t
129
kwsalloc (unsigned char const *trans)
130
{
131
  struct kwset *kwset;
132

133
  kwset = (struct kwset *) xmalloc(sizeof (struct kwset));
134

135
  obstack_init(&kwset->obstack);
136
  kwset->words = 0;
137
  kwset->trie
138
    = (struct trie *) obstack_alloc(&kwset->obstack, sizeof (struct trie));
139
  if (!kwset->trie)
140
    {
141
      kwsfree((kwset_t) kwset);
142
      return NULL;
143
    }
144
  kwset->trie->accepting = 0;
145
  kwset->trie->links = NULL;
146
  kwset->trie->parent = NULL;
147
  kwset->trie->next = NULL;
148
  kwset->trie->fail = NULL;
149
  kwset->trie->depth = 0;
150
  kwset->trie->shift = 0;
151
  kwset->mind = INT_MAX;
152
  kwset->maxd = -1;
153
  kwset->target = NULL;
154
  kwset->trans = trans;
155

156
  return (kwset_t) kwset;
157
}
158

159
/* This upper bound is valid for CHAR_BIT >= 4 and
160
   exact for CHAR_BIT in { 4..11, 13, 15, 17, 19 }. */
161
#define DEPTH_SIZE (CHAR_BIT + CHAR_BIT/2)
162

163
/* Add the given string to the contents of the keyword set.  Return NULL
164
   for success, an error message otherwise. */
165
const char *
166
kwsincr (kwset_t kws, char const *text, size_t len)
167
{
168
  struct kwset *kwset;
169
  register struct trie *trie;
170
  register unsigned char label;
171
  register struct tree *link;
172
  register int depth;
173
  struct tree *links[DEPTH_SIZE];
174
  enum { L, R } dirs[DEPTH_SIZE];
175
  struct tree *t, *r, *l, *rl, *lr;
176

177
  kwset = (struct kwset *) kws;
178
  trie = kwset->trie;
179
  text += len;
180

181
  /* Descend the trie (built of reversed keywords) character-by-character,
182
     installing new nodes when necessary. */
183
  while (len--)
184
    {
185
      label = kwset->trans ? kwset->trans[U(*--text)] : *--text;
186

187
      /* Descend the tree of outgoing links for this trie node,
188
	 looking for the current character and keeping track
189
	 of the path followed. */
190
      link = trie->links;
191
      links[0] = (struct tree *) &trie->links;
192
      dirs[0] = L;
193
      depth = 1;
194

195
      while (link && label != link->label)
196
	{
197
	  links[depth] = link;
198
	  if (label < link->label)
199
	    dirs[depth++] = L, link = link->llink;
200
	  else
201
	    dirs[depth++] = R, link = link->rlink;
202
	}
203

204
      /* The current character doesn't have an outgoing link at
205
	 this trie node, so build a new trie node and install
206
	 a link in the current trie node's tree. */
207
      if (!link)
208
	{
209
	  link = (struct tree *) obstack_alloc(&kwset->obstack,
210
					       sizeof (struct tree));
211
	  if (!link)
212
	    return "memory exhausted";
213
	  link->llink = NULL;
214
	  link->rlink = NULL;
215
	  link->trie = (struct trie *) obstack_alloc(&kwset->obstack,
216
						     sizeof (struct trie));
217
	  if (!link->trie)
218
	    {
219
	      obstack_free(&kwset->obstack, link);
220
	      return "memory exhausted";
221
	    }
222
	  link->trie->accepting = 0;
223
	  link->trie->links = NULL;
224
	  link->trie->parent = trie;
225
	  link->trie->next = NULL;
226
	  link->trie->fail = NULL;
227
	  link->trie->depth = trie->depth + 1;
228
	  link->trie->shift = 0;
229
	  link->label = label;
230
	  link->balance = 0;
231

232
	  /* Install the new tree node in its parent. */
233
	  if (dirs[--depth] == L)
234
	    links[depth]->llink = link;
235
	  else
236
	    links[depth]->rlink = link;
237

238
	  /* Back up the tree fixing the balance flags. */
239
	  while (depth && !links[depth]->balance)
240
	    {
241
	      if (dirs[depth] == L)
242
		--links[depth]->balance;
243
	      else
244
		++links[depth]->balance;
245
	      --depth;
246
	    }
247

248
	  /* Rebalance the tree by pointer rotations if necessary. */
249
	  if (depth && ((dirs[depth] == L && --links[depth]->balance)
250
			|| (dirs[depth] == R && ++links[depth]->balance)))
251
	    {
252
	      switch (links[depth]->balance)
253
		{
254
		case (char) -2:
255
		  switch (dirs[depth + 1])
256
		    {
257
		    case L:
258
		      r = links[depth], t = r->llink, rl = t->rlink;
259
		      t->rlink = r, r->llink = rl;
260
		      t->balance = r->balance = 0;
261
		      break;
262
		    case R:
263
		      r = links[depth], l = r->llink, t = l->rlink;
264
		      rl = t->rlink, lr = t->llink;
265
		      t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
266
		      l->balance = t->balance != 1 ? 0 : -1;
267
		      r->balance = t->balance != (char) -1 ? 0 : 1;
268
		      t->balance = 0;
269
		      break;
270
		    default:
271
		      abort ();
272
		    }
273
		  break;
274
		case 2:
275
		  switch (dirs[depth + 1])
276
		    {
277
		    case R:
278
		      l = links[depth], t = l->rlink, lr = t->llink;
279
		      t->llink = l, l->rlink = lr;
280
		      t->balance = l->balance = 0;
281
		      break;
282
		    case L:
283
		      l = links[depth], r = l->rlink, t = r->llink;
284
		      lr = t->llink, rl = t->rlink;
285
		      t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
286
		      l->balance = t->balance != 1 ? 0 : -1;
287
		      r->balance = t->balance != (char) -1 ? 0 : 1;
288
		      t->balance = 0;
289
		      break;
290
		    default:
291
		      abort ();
292
		    }
293
		  break;
294
		default:
295
		  abort ();
296
		}
297

298
	      if (dirs[depth - 1] == L)
299
		links[depth - 1]->llink = t;
300
	      else
301
		links[depth - 1]->rlink = t;
302
	    }
303
	}
304

305
      trie = link->trie;
306
    }
307

308
  /* Mark the node we finally reached as accepting, encoding the
309
     index number of this word in the keyword set so far. */
310
  if (!trie->accepting)
311
    trie->accepting = 1 + 2 * kwset->words;
312
  ++kwset->words;
313

314
  /* Keep track of the longest and shortest string of the keyword set. */
315
  if (trie->depth < kwset->mind)
316
    kwset->mind = trie->depth;
317
  if (trie->depth > kwset->maxd)
318
    kwset->maxd = trie->depth;
319

320
  return NULL;
321
}
322

323
/* Enqueue the trie nodes referenced from the given tree in the
324
   given queue. */
325
static void
326
enqueue (struct tree *tree, struct trie **last)
327
{
328
  if (!tree)
329
    return;
330
  enqueue(tree->llink, last);
331
  enqueue(tree->rlink, last);
332
  (*last) = (*last)->next = tree->trie;
333
}
334

335
/* Compute the Aho-Corasick failure function for the trie nodes referenced
336
   from the given tree, given the failure function for their parent as
337
   well as a last resort failure node. */
338
static void
339
treefails (register struct tree const *tree, struct trie const *fail,
340
	   struct trie *recourse)
341
{
342
  register struct tree *link;
343

344
  if (!tree)
345
    return;
346

347
  treefails(tree->llink, fail, recourse);
348
  treefails(tree->rlink, fail, recourse);
349

350
  /* Find, in the chain of fails going back to the root, the first
351
     node that has a descendant on the current label. */
352
  while (fail)
353
    {
354
      link = fail->links;
355
      while (link && tree->label != link->label)
356
	if (tree->label < link->label)
357
	  link = link->llink;
358
	else
359
	  link = link->rlink;
360
      if (link)
361
	{
362
	  tree->trie->fail = link->trie;
363
	  return;
364
	}
365
      fail = fail->fail;
366
    }
367

368
  tree->trie->fail = recourse;
369
}
370

371
/* Set delta entries for the links of the given tree such that
372
   the preexisting delta value is larger than the current depth. */
373
static void
374
treedelta (register struct tree const *tree,
375
	   register unsigned int depth,
376
	   unsigned char delta[])
377
{
378
  if (!tree)
379
    return;
380
  treedelta(tree->llink, depth, delta);
381
  treedelta(tree->rlink, depth, delta);
382
  if (depth < delta[tree->label])
383
    delta[tree->label] = depth;
384
}
385

386
/* Return true if A has every label in B. */
387
static int
388
hasevery (register struct tree const *a, register struct tree const *b)
389
{
390
  if (!b)
391
    return 1;
392
  if (!hasevery(a, b->llink))
393
    return 0;
394
  if (!hasevery(a, b->rlink))
395
    return 0;
396
  while (a && b->label != a->label)
397
    if (b->label < a->label)
398
      a = a->llink;
399
    else
400
      a = a->rlink;
401
  return !!a;
402
}
403

404
/* Compute a vector, indexed by character code, of the trie nodes
405
   referenced from the given tree. */
406
static void
407
treenext (struct tree const *tree, struct trie *next[])
408
{
409
  if (!tree)
410
    return;
411
  treenext(tree->llink, next);
412
  treenext(tree->rlink, next);
413
  next[tree->label] = tree->trie;
414
}
415

416
/* Compute the shift for each trie node, as well as the delta
417
   table and next cache for the given keyword set. */
418
const char *
419
kwsprep (kwset_t kws)
420
{
421
  register struct kwset *kwset;
422
  register int i;
423
  register struct trie *curr;
424
  register unsigned char const *trans;
425
  unsigned char delta[NCHAR];
426

427
  kwset = (struct kwset *) kws;
428

429
  /* Initial values for the delta table; will be changed later.  The
430
     delta entry for a given character is the smallest depth of any
431
     node at which an outgoing edge is labeled by that character. */
432
  memset(delta, kwset->mind < UCHAR_MAX ? kwset->mind : UCHAR_MAX, NCHAR);
433

434
  /* Check if we can use the simple boyer-moore algorithm, instead
435
     of the hairy commentz-walter algorithm. */
436
  if (kwset->words == 1 && kwset->trans == NULL)
437
    {
438
      char c;
439

440
      /* Looking for just one string.  Extract it from the trie. */
441
      kwset->target = obstack_alloc(&kwset->obstack, kwset->mind);
442
      if (!kwset->target)
443
	return "memory exhausted";
444
      for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i)
445
	{
446
	  kwset->target[i] = curr->links->label;
447
	  curr = curr->links->trie;
448
	}
449
      /* Build the Boyer Moore delta.  Boy that's easy compared to CW. */
450
      for (i = 0; i < kwset->mind; ++i)
451
	delta[U(kwset->target[i])] = kwset->mind - (i + 1);
452
      /* Find the minimal delta2 shift that we might make after
453
	 a backwards match has failed. */
454
      c = kwset->target[kwset->mind - 1];
455
      for (i = kwset->mind - 2; i >= 0; --i)
456
	if (kwset->target[i] == c)
457
	  break;
458
      kwset->mind2 = kwset->mind - (i + 1);
459
    }
460
  else
461
    {
462
      register struct trie *fail;
463
      struct trie *last, *next[NCHAR];
464

465
      /* Traverse the nodes of the trie in level order, simultaneously
466
	 computing the delta table, failure function, and shift function. */
467
      for (curr = last = kwset->trie; curr; curr = curr->next)
468
	{
469
	  /* Enqueue the immediate descendants in the level order queue. */
470
	  enqueue(curr->links, &last);
471

472
	  curr->shift = kwset->mind;
473
	  curr->maxshift = kwset->mind;
474

475
	  /* Update the delta table for the descendants of this node. */
476
	  treedelta(curr->links, curr->depth, delta);
477

478
	  /* Compute the failure function for the descendants of this node. */
479
	  treefails(curr->links, curr->fail, kwset->trie);
480

481
	  /* Update the shifts at each node in the current node's chain
482
	     of fails back to the root. */
483
	  for (fail = curr->fail; fail; fail = fail->fail)
484
	    {
485
	      /* If the current node has some outgoing edge that the fail
486
		 doesn't, then the shift at the fail should be no larger
487
		 than the difference of their depths. */
488
	      if (!hasevery(fail->links, curr->links))
489
		if (curr->depth - fail->depth < fail->shift)
490
		  fail->shift = curr->depth - fail->depth;
491

492
	      /* If the current node is accepting then the shift at the
493
		 fail and its descendants should be no larger than the
494
		 difference of their depths. */
495
	      if (curr->accepting && fail->maxshift > curr->depth - fail->depth)
496
		fail->maxshift = curr->depth - fail->depth;
497
	    }
498
	}
499

500
      /* Traverse the trie in level order again, fixing up all nodes whose
501
	 shift exceeds their inherited maxshift. */
502
      for (curr = kwset->trie->next; curr; curr = curr->next)
503
	{
504
	  if (curr->maxshift > curr->parent->maxshift)
505
	    curr->maxshift = curr->parent->maxshift;
506
	  if (curr->shift > curr->maxshift)
507
	    curr->shift = curr->maxshift;
508
	}
509

510
      /* Create a vector, indexed by character code, of the outgoing links
511
	 from the root node. */
512
      for (i = 0; i < NCHAR; ++i)
513
	next[i] = NULL;
514
      treenext(kwset->trie->links, next);
515

516
      if ((trans = kwset->trans))
517
	for (i = 0; i < NCHAR; ++i)
518
	  kwset->next[i] = next[U(trans[i])];
519
      else
520
	COPY_ARRAY(kwset->next, next, NCHAR);
521
    }
522

523
  /* Fix things up for any translation table. */
524
  if ((trans = kwset->trans))
525
    for (i = 0; i < NCHAR; ++i)
526
      kwset->delta[i] = delta[U(trans[i])];
527
  else
528
    memcpy(kwset->delta, delta, NCHAR);
529

530
  return NULL;
531
}
532

533
/* Fast boyer-moore search. */
534
static size_t
535
bmexec (kwset_t kws, char const *text, size_t size)
536
{
537
  struct kwset const *kwset;
538
  register unsigned char const *d1;
539
  register char const *ep, *sp, *tp;
540
  register int d, gc, i, len, md2;
541

542
  kwset = (struct kwset const *) kws;
543
  len = kwset->mind;
544

545
  if (len == 0)
546
    return 0;
547
  if (len > size)
548
    return -1;
549
  if (len == 1)
550
    {
551
      tp = memchr (text, kwset->target[0], size);
552
      return tp ? tp - text : -1;
553
    }
554

555
  d1 = kwset->delta;
556
  sp = kwset->target + len;
557
  gc = U(sp[-2]);
558
  md2 = kwset->mind2;
559
  tp = text + len;
560

561
  /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */
562
  if (size > 12 * len)
563
    /* 11 is not a bug, the initial offset happens only once. */
564
    for (ep = text + size - 11 * len;;)
565
      {
566
	while (tp <= ep)
567
	  {
568
	    d = d1[U(tp[-1])], tp += d;
569
	    d = d1[U(tp[-1])], tp += d;
570
	    if (d == 0)
571
	      goto found;
572
	    d = d1[U(tp[-1])], tp += d;
573
	    d = d1[U(tp[-1])], tp += d;
574
	    d = d1[U(tp[-1])], tp += d;
575
	    if (d == 0)
576
	      goto found;
577
	    d = d1[U(tp[-1])], tp += d;
578
	    d = d1[U(tp[-1])], tp += d;
579
	    d = d1[U(tp[-1])], tp += d;
580
	    if (d == 0)
581
	      goto found;
582
	    d = d1[U(tp[-1])], tp += d;
583
	    d = d1[U(tp[-1])], tp += d;
584
	  }
585
	break;
586
      found:
587
	if (U(tp[-2]) == gc)
588
	  {
589
	    for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i)
590
	      ;
591
	    if (i > len)
592
	      return tp - len - text;
593
	  }
594
	tp += md2;
595
      }
596

597
  /* Now we have only a few characters left to search.  We
598
     carefully avoid ever producing an out-of-bounds pointer. */
599
  ep = text + size;
600
  d = d1[U(tp[-1])];
601
  while (d <= ep - tp)
602
    {
603
      d = d1[U((tp += d)[-1])];
604
      if (d != 0)
605
	continue;
606
      if (U(tp[-2]) == gc)
607
	{
608
	  for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i)
609
	    ;
610
	  if (i > len)
611
	    return tp - len - text;
612
	}
613
      d = md2;
614
    }
615

616
  return -1;
617
}
618

619
/* Hairy multiple string search. */
620
static size_t
621
cwexec (kwset_t kws, char const *text, size_t len, struct kwsmatch *kwsmatch)
622
{
623
  struct kwset const *kwset;
624
  struct trie * const *next;
625
  struct trie const *trie;
626
  struct trie const *accept;
627
  char const *beg, *lim, *mch, *lmch;
628
  register unsigned char c;
629
  register unsigned char const *delta;
630
  register int d;
631
  register char const *end, *qlim;
632
  register struct tree const *tree;
633
  register unsigned char const *trans;
634

635
  accept = NULL;
636

637
  /* Initialize register copies and look for easy ways out. */
638
  kwset = (struct kwset *) kws;
639
  if (len < kwset->mind)
640
    return -1;
641
  next = kwset->next;
642
  delta = kwset->delta;
643
  trans = kwset->trans;
644
  lim = text + len;
645
  end = text;
646
  if ((d = kwset->mind) != 0)
647
    mch = NULL;
648
  else
649
    {
650
      mch = text, accept = kwset->trie;
651
      goto match;
652
    }
653

654
  if (len >= 4 * kwset->mind)
655
    qlim = lim - 4 * kwset->mind;
656
  else
657
    qlim = NULL;
658

659
  while (lim - end >= d)
660
    {
661
      if (qlim && end <= qlim)
662
	{
663
	  end += d - 1;
664
	  while ((d = delta[c = *end]) && end < qlim)
665
	    {
666
	      end += d;
667
	      end += delta[U(*end)];
668
	      end += delta[U(*end)];
669
	    }
670
	  ++end;
671
	}
672
      else
673
	d = delta[c = (end += d)[-1]];
674
      if (d)
675
	continue;
676
      beg = end - 1;
677
      trie = next[c];
678
      if (trie->accepting)
679
	{
680
	  mch = beg;
681
	  accept = trie;
682
	}
683
      d = trie->shift;
684
      while (beg > text)
685
	{
686
	  c = trans ? trans[U(*--beg)] : *--beg;
687
	  tree = trie->links;
688
	  while (tree && c != tree->label)
689
	    if (c < tree->label)
690
	      tree = tree->llink;
691
	    else
692
	      tree = tree->rlink;
693
	  if (tree)
694
	    {
695
	      trie = tree->trie;
696
	      if (trie->accepting)
697
		{
698
		  mch = beg;
699
		  accept = trie;
700
		}
701
	    }
702
	  else
703
	    break;
704
	  d = trie->shift;
705
	}
706
      if (mch)
707
	goto match;
708
    }
709
  return -1;
710

711
 match:
712
  /* Given a known match, find the longest possible match anchored
713
     at or before its starting point.  This is nearly a verbatim
714
     copy of the preceding main search loops. */
715
  if (lim - mch > kwset->maxd)
716
    lim = mch + kwset->maxd;
717
  lmch = NULL;
718
  d = 1;
719
  while (lim - end >= d)
720
    {
721
      if ((d = delta[c = (end += d)[-1]]) != 0)
722
	continue;
723
      beg = end - 1;
724
      if (!(trie = next[c]))
725
	{
726
	  d = 1;
727
	  continue;
728
	}
729
      if (trie->accepting && beg <= mch)
730
	{
731
	  lmch = beg;
732
	  accept = trie;
733
	}
734
      d = trie->shift;
735
      while (beg > text)
736
	{
737
	  c = trans ? trans[U(*--beg)] : *--beg;
738
	  tree = trie->links;
739
	  while (tree && c != tree->label)
740
	    if (c < tree->label)
741
	      tree = tree->llink;
742
	    else
743
	      tree = tree->rlink;
744
	  if (tree)
745
	    {
746
	      trie = tree->trie;
747
	      if (trie->accepting && beg <= mch)
748
		{
749
		  lmch = beg;
750
		  accept = trie;
751
		}
752
	    }
753
	  else
754
	    break;
755
	  d = trie->shift;
756
	}
757
      if (lmch)
758
	{
759
	  mch = lmch;
760
	  goto match;
761
	}
762
      if (!d)
763
	d = 1;
764
    }
765

766
  if (kwsmatch)
767
    {
768
      kwsmatch->index = accept->accepting / 2;
769
      kwsmatch->offset[0] = mch - text;
770
      kwsmatch->size[0] = accept->depth;
771
    }
772
  return mch - text;
773
}
774

775
/* Search through the given text for a match of any member of the
776
   given keyword set.  Return a pointer to the first character of
777
   the matching substring, or NULL if no match is found.  If FOUNDLEN
778
   is non-NULL store in the referenced location the length of the
779
   matching substring.  Similarly, if FOUNDIDX is non-NULL, store
780
   in the referenced location the index number of the particular
781
   keyword matched. */
782
size_t
783
kwsexec (kwset_t kws, char const *text, size_t size,
784
	 struct kwsmatch *kwsmatch)
785
{
786
  struct kwset const *kwset = (struct kwset *) kws;
787
  if (kwset->words == 1 && kwset->trans == NULL)
788
    {
789
      size_t ret = bmexec (kws, text, size);
790
      if (kwsmatch != NULL && ret != (size_t) -1)
791
	{
792
	  kwsmatch->index = 0;
793
	  kwsmatch->offset[0] = ret;
794
	  kwsmatch->size[0] = kwset->mind;
795
	}
796
      return ret;
797
    }
798
  else
799
    return cwexec(kws, text, size, kwsmatch);
800
}
801

802
/* Free the components of the given keyword set. */
803
void
804
kwsfree (kwset_t kws)
805
{
806
  struct kwset *kwset;
807

808
  kwset = (struct kwset *) kws;
809
  obstack_free(&kwset->obstack, NULL);
810
  free(kws);
811
}
812