153451Speter/* kwset.c - search for any of a set of keywords. 2126435Sache Copyright 1989, 1998, 2000 Free Software Foundation, Inc. 353451Speter 453451Speter This program is free software; you can redistribute it and/or modify 553451Speter it under the terms of the GNU General Public License as published by 653474Sobrien the Free Software Foundation; either version 2, or (at your option) 753451Speter any later version. 853451Speter 953451Speter This program is distributed in the hope that it will be useful, 1053451Speter but WITHOUT ANY WARRANTY; without even the implied warranty of 1153451Speter MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 1253451Speter GNU General Public License for more details. 1353451Speter 1453451Speter You should have received a copy of the GNU General Public License 1553451Speter along with this program; if not, write to the Free Software 1653474Sobrien Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 1753474Sobrien 02111-1307, USA. */ 1853451Speter 19126435Sache/* $FreeBSD$ */ 20126435Sache 2153474Sobrien/* Written August 1989 by Mike Haertel. 2253451Speter The author may be reached (Email) at the address mike@ai.mit.edu, 2353451Speter or (US mail) as Mike Haertel c/o Free Software Foundation. */ 2453451Speter 2553451Speter/* The algorithm implemented by these routines bears a startling resemblence 2653451Speter to one discovered by Beate Commentz-Walter, although it is not identical. 2753451Speter See "A String Matching Algorithm Fast on the Average," Technical Report, 2853451Speter IBM-Germany, Scientific Center Heidelberg, Tiergartenstrasse 15, D-6900 2953451Speter Heidelberg, Germany. See also Aho, A.V., and M. Corasick, "Efficient 3053451Speter String Matching: An Aid to Bibliographic Search," CACM June 1975, 3153451Speter Vol. 18, No. 6, which describes the failure function used below. */ 3253451Speter 3353474Sobrien#ifdef HAVE_CONFIG_H 3453474Sobrien# include <config.h> 3553474Sobrien#endif 3653451Speter#include <sys/types.h> 3753474Sobrien#include "system.h" 3853474Sobrien#include "kwset.h" 3953474Sobrien#include "obstack.h" 4053451Speter 4153451Speter#ifdef GREP 4253451Speterextern char *xmalloc(); 4353474Sobrien# undef malloc 4453474Sobrien# define malloc xmalloc 4553451Speter#endif 4653451Speter 4753451Speter#define NCHAR (UCHAR_MAX + 1) 4853451Speter#define obstack_chunk_alloc malloc 4953451Speter#define obstack_chunk_free free 5053451Speter 5153451Speter/* Balanced tree of edges and labels leaving a given trie node. */ 5253451Speterstruct tree 5353451Speter{ 5453451Speter struct tree *llink; /* Left link; MUST be first field. */ 5553451Speter struct tree *rlink; /* Right link (to larger labels). */ 5653451Speter struct trie *trie; /* Trie node pointed to by this edge. */ 5753451Speter unsigned char label; /* Label on this edge. */ 5853451Speter char balance; /* Difference in depths of subtrees. */ 5953451Speter}; 6053451Speter 6153451Speter/* Node of a trie representing a set of reversed keywords. */ 6253451Speterstruct trie 6353451Speter{ 6453451Speter unsigned int accepting; /* Word index of accepted word, or zero. */ 6553451Speter struct tree *links; /* Tree of edges leaving this node. */ 6653451Speter struct trie *parent; /* Parent of this node. */ 6753451Speter struct trie *next; /* List of all trie nodes in level order. */ 6853451Speter struct trie *fail; /* Aho-Corasick failure function. */ 6953451Speter int depth; /* Depth of this node from the root. */ 7053451Speter int shift; /* Shift function for search failures. */ 7153451Speter int maxshift; /* Max shift of self and descendents. */ 7253451Speter}; 7353451Speter 7453451Speter/* Structure returned opaquely to the caller, containing everything. */ 7553451Speterstruct kwset 7653451Speter{ 7753451Speter struct obstack obstack; /* Obstack for node allocation. */ 7853451Speter int words; /* Number of words in the trie. */ 7953451Speter struct trie *trie; /* The trie itself. */ 8053451Speter int mind; /* Minimum depth of an accepting node. */ 8153451Speter int maxd; /* Maximum depth of any node. */ 8253451Speter unsigned char delta[NCHAR]; /* Delta table for rapid search. */ 8353451Speter struct trie *next[NCHAR]; /* Table of children of the root. */ 8453451Speter char *target; /* Target string if there's only one. */ 8553451Speter int mind2; /* Used in Boyer-Moore search for one string. */ 86131557Stjr char const *trans; /* Character translation table. */ 8753451Speter}; 8853451Speter 8953451Speter/* Allocate and initialize a keyword set object, returning an opaque 9053451Speter pointer to it. Return NULL if memory is not available. */ 9153451Speterkwset_t 92131557Stjrkwsalloc (char const *trans) 9353451Speter{ 9453451Speter struct kwset *kwset; 9553451Speter 9653451Speter kwset = (struct kwset *) malloc(sizeof (struct kwset)); 9753451Speter if (!kwset) 9853451Speter return 0; 9953451Speter 10053451Speter obstack_init(&kwset->obstack); 10153451Speter kwset->words = 0; 10253451Speter kwset->trie 10353451Speter = (struct trie *) obstack_alloc(&kwset->obstack, sizeof (struct trie)); 10453451Speter if (!kwset->trie) 10553451Speter { 10653451Speter kwsfree((kwset_t) kwset); 10753451Speter return 0; 10853451Speter } 10953451Speter kwset->trie->accepting = 0; 11053451Speter kwset->trie->links = 0; 11153451Speter kwset->trie->parent = 0; 11253451Speter kwset->trie->next = 0; 11353451Speter kwset->trie->fail = 0; 11453451Speter kwset->trie->depth = 0; 11553451Speter kwset->trie->shift = 0; 11653451Speter kwset->mind = INT_MAX; 11753451Speter kwset->maxd = -1; 11853451Speter kwset->target = 0; 11953451Speter kwset->trans = trans; 12053451Speter 12153451Speter return (kwset_t) kwset; 12253451Speter} 12353451Speter 12453451Speter/* Add the given string to the contents of the keyword set. Return NULL 12553451Speter for success, an error message otherwise. */ 12653451Speterchar * 127131557Stjrkwsincr (kwset_t kws, char const *text, size_t len) 12853451Speter{ 12953451Speter struct kwset *kwset; 13053451Speter register struct trie *trie; 13153451Speter register unsigned char label; 13253451Speter register struct tree *link; 13353451Speter register int depth; 13453451Speter struct tree *links[12]; 13553451Speter enum { L, R } dirs[12]; 13653451Speter struct tree *t, *r, *l, *rl, *lr; 13753451Speter 13853451Speter kwset = (struct kwset *) kws; 13953451Speter trie = kwset->trie; 14053451Speter text += len; 14153451Speter 14253451Speter /* Descend the trie (built of reversed keywords) character-by-character, 14353451Speter installing new nodes when necessary. */ 14453451Speter while (len--) 14553451Speter { 14653451Speter label = kwset->trans ? kwset->trans[(unsigned char) *--text] : *--text; 14753451Speter 14853451Speter /* Descend the tree of outgoing links for this trie node, 14953451Speter looking for the current character and keeping track 15053451Speter of the path followed. */ 15153451Speter link = trie->links; 15253451Speter links[0] = (struct tree *) &trie->links; 15353451Speter dirs[0] = L; 15453451Speter depth = 1; 15553451Speter 15653451Speter while (link && label != link->label) 15753451Speter { 15853451Speter links[depth] = link; 15953451Speter if (label < link->label) 16053451Speter dirs[depth++] = L, link = link->llink; 16153451Speter else 16253451Speter dirs[depth++] = R, link = link->rlink; 16353451Speter } 16453451Speter 16553451Speter /* The current character doesn't have an outgoing link at 16653451Speter this trie node, so build a new trie node and install 16753451Speter a link in the current trie node's tree. */ 16853451Speter if (!link) 16953451Speter { 17053451Speter link = (struct tree *) obstack_alloc(&kwset->obstack, 17153451Speter sizeof (struct tree)); 17253451Speter if (!link) 17353474Sobrien return _("memory exhausted"); 17453451Speter link->llink = 0; 17553451Speter link->rlink = 0; 17653451Speter link->trie = (struct trie *) obstack_alloc(&kwset->obstack, 17753451Speter sizeof (struct trie)); 17853451Speter if (!link->trie) 17953474Sobrien return _("memory exhausted"); 18053451Speter link->trie->accepting = 0; 18153451Speter link->trie->links = 0; 18253451Speter link->trie->parent = trie; 18353451Speter link->trie->next = 0; 18453451Speter link->trie->fail = 0; 18553451Speter link->trie->depth = trie->depth + 1; 18653451Speter link->trie->shift = 0; 18753451Speter link->label = label; 18853451Speter link->balance = 0; 18953451Speter 19053451Speter /* Install the new tree node in its parent. */ 19153451Speter if (dirs[--depth] == L) 19253451Speter links[depth]->llink = link; 19353451Speter else 19453451Speter links[depth]->rlink = link; 19553451Speter 19653451Speter /* Back up the tree fixing the balance flags. */ 19753451Speter while (depth && !links[depth]->balance) 19853451Speter { 19953451Speter if (dirs[depth] == L) 20053451Speter --links[depth]->balance; 20153451Speter else 20253451Speter ++links[depth]->balance; 20353451Speter --depth; 20453451Speter } 20553451Speter 20653451Speter /* Rebalance the tree by pointer rotations if necessary. */ 20753451Speter if (depth && ((dirs[depth] == L && --links[depth]->balance) 20853451Speter || (dirs[depth] == R && ++links[depth]->balance))) 20953451Speter { 21053451Speter switch (links[depth]->balance) 21153451Speter { 21253451Speter case (char) -2: 21353451Speter switch (dirs[depth + 1]) 21453451Speter { 21553451Speter case L: 21653451Speter r = links[depth], t = r->llink, rl = t->rlink; 21753451Speter t->rlink = r, r->llink = rl; 21853451Speter t->balance = r->balance = 0; 21953451Speter break; 22053451Speter case R: 22153451Speter r = links[depth], l = r->llink, t = l->rlink; 22253451Speter rl = t->rlink, lr = t->llink; 22353451Speter t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl; 22453451Speter l->balance = t->balance != 1 ? 0 : -1; 22553451Speter r->balance = t->balance != (char) -1 ? 0 : 1; 22653451Speter t->balance = 0; 22753451Speter break; 22853474Sobrien default: 22953474Sobrien abort (); 23053451Speter } 23153451Speter break; 23253451Speter case 2: 23353451Speter switch (dirs[depth + 1]) 23453451Speter { 23553451Speter case R: 23653451Speter l = links[depth], t = l->rlink, lr = t->llink; 23753451Speter t->llink = l, l->rlink = lr; 23853451Speter t->balance = l->balance = 0; 23953451Speter break; 24053451Speter case L: 24153451Speter l = links[depth], r = l->rlink, t = r->llink; 24253451Speter lr = t->llink, rl = t->rlink; 24353451Speter t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl; 24453451Speter l->balance = t->balance != 1 ? 0 : -1; 24553451Speter r->balance = t->balance != (char) -1 ? 0 : 1; 24653451Speter t->balance = 0; 24753451Speter break; 24853474Sobrien default: 24953474Sobrien abort (); 25053451Speter } 25153451Speter break; 25253474Sobrien default: 25353474Sobrien abort (); 25453451Speter } 25553451Speter 25653451Speter if (dirs[depth - 1] == L) 25753451Speter links[depth - 1]->llink = t; 25853451Speter else 25953451Speter links[depth - 1]->rlink = t; 26053451Speter } 26153451Speter } 26253451Speter 26353451Speter trie = link->trie; 26453451Speter } 26553451Speter 26653451Speter /* Mark the node we finally reached as accepting, encoding the 26753451Speter index number of this word in the keyword set so far. */ 26853451Speter if (!trie->accepting) 26953451Speter trie->accepting = 1 + 2 * kwset->words; 27053451Speter ++kwset->words; 27153451Speter 27253451Speter /* Keep track of the longest and shortest string of the keyword set. */ 27353451Speter if (trie->depth < kwset->mind) 27453451Speter kwset->mind = trie->depth; 27553451Speter if (trie->depth > kwset->maxd) 27653451Speter kwset->maxd = trie->depth; 27753451Speter 27853451Speter return 0; 27953451Speter} 28053451Speter 28153451Speter/* Enqueue the trie nodes referenced from the given tree in the 28253451Speter given queue. */ 28353451Speterstatic void 28456918Sruenqueue (struct tree *tree, struct trie **last) 28553451Speter{ 28653451Speter if (!tree) 28753451Speter return; 28853451Speter enqueue(tree->llink, last); 28953451Speter enqueue(tree->rlink, last); 29053451Speter (*last) = (*last)->next = tree->trie; 29153451Speter} 29253451Speter 29353451Speter/* Compute the Aho-Corasick failure function for the trie nodes referenced 29453451Speter from the given tree, given the failure function for their parent as 29553451Speter well as a last resort failure node. */ 29653451Speterstatic void 297131557Stjrtreefails (register struct tree const *tree, struct trie const *fail, 298131557Stjr struct trie *recourse) 29953451Speter{ 30053451Speter register struct tree *link; 30153451Speter 30253451Speter if (!tree) 30353451Speter return; 30453451Speter 30553451Speter treefails(tree->llink, fail, recourse); 30653451Speter treefails(tree->rlink, fail, recourse); 30753451Speter 30853451Speter /* Find, in the chain of fails going back to the root, the first 30953451Speter node that has a descendent on the current label. */ 31053451Speter while (fail) 31153451Speter { 31253451Speter link = fail->links; 31353451Speter while (link && tree->label != link->label) 31453451Speter if (tree->label < link->label) 31553451Speter link = link->llink; 31653451Speter else 31753451Speter link = link->rlink; 31853451Speter if (link) 31953451Speter { 32053451Speter tree->trie->fail = link->trie; 32153451Speter return; 32253451Speter } 32353451Speter fail = fail->fail; 32453451Speter } 32553451Speter 32653451Speter tree->trie->fail = recourse; 32753451Speter} 32853451Speter 32953451Speter/* Set delta entries for the links of the given tree such that 33053451Speter the preexisting delta value is larger than the current depth. */ 33153451Speterstatic void 332131557Stjrtreedelta (register struct tree const *tree, 33356918Sru register unsigned int depth, 33456918Sru unsigned char delta[]) 33553451Speter{ 33653451Speter if (!tree) 33753451Speter return; 33853451Speter treedelta(tree->llink, depth, delta); 33953451Speter treedelta(tree->rlink, depth, delta); 34053451Speter if (depth < delta[tree->label]) 34153451Speter delta[tree->label] = depth; 34253451Speter} 34353451Speter 34453451Speter/* Return true if A has every label in B. */ 34553451Speterstatic int 346131557Stjrhasevery (register struct tree const *a, register struct tree const *b) 34753451Speter{ 34853451Speter if (!b) 34953451Speter return 1; 35053451Speter if (!hasevery(a, b->llink)) 35153451Speter return 0; 35253451Speter if (!hasevery(a, b->rlink)) 35353451Speter return 0; 35453451Speter while (a && b->label != a->label) 35553451Speter if (b->label < a->label) 35653451Speter a = a->llink; 35753451Speter else 35853451Speter a = a->rlink; 35953451Speter return !!a; 36053451Speter} 36153451Speter 36253451Speter/* Compute a vector, indexed by character code, of the trie nodes 36353451Speter referenced from the given tree. */ 36453451Speterstatic void 365131557Stjrtreenext (struct tree const *tree, struct trie *next[]) 36653451Speter{ 36753451Speter if (!tree) 36853451Speter return; 36953451Speter treenext(tree->llink, next); 37053451Speter treenext(tree->rlink, next); 37153451Speter next[tree->label] = tree->trie; 37253451Speter} 37353451Speter 37453451Speter/* Compute the shift for each trie node, as well as the delta 37553451Speter table and next cache for the given keyword set. */ 37653451Speterchar * 37756918Srukwsprep (kwset_t kws) 37853451Speter{ 37953451Speter register struct kwset *kwset; 38053451Speter register int i; 38153451Speter register struct trie *curr, *fail; 382131557Stjr register char const *trans; 38353451Speter unsigned char delta[NCHAR]; 38453451Speter struct trie *last, *next[NCHAR]; 38553451Speter 38653451Speter kwset = (struct kwset *) kws; 38753451Speter 38853451Speter /* Initial values for the delta table; will be changed later. The 38953451Speter delta entry for a given character is the smallest depth of any 39053451Speter node at which an outgoing edge is labeled by that character. */ 39153451Speter if (kwset->mind < 256) 39253451Speter for (i = 0; i < NCHAR; ++i) 39353451Speter delta[i] = kwset->mind; 39453451Speter else 39553451Speter for (i = 0; i < NCHAR; ++i) 39653451Speter delta[i] = 255; 39753451Speter 39853451Speter /* Check if we can use the simple boyer-moore algorithm, instead 39953451Speter of the hairy commentz-walter algorithm. */ 40053451Speter if (kwset->words == 1 && kwset->trans == 0) 40153451Speter { 40253451Speter /* Looking for just one string. Extract it from the trie. */ 40353451Speter kwset->target = obstack_alloc(&kwset->obstack, kwset->mind); 40453451Speter for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i) 40553451Speter { 40653451Speter kwset->target[i] = curr->links->label; 40753451Speter curr = curr->links->trie; 40853451Speter } 40953451Speter /* Build the Boyer Moore delta. Boy that's easy compared to CW. */ 41053451Speter for (i = 0; i < kwset->mind; ++i) 41153451Speter delta[(unsigned char) kwset->target[i]] = kwset->mind - (i + 1); 41253451Speter kwset->mind2 = kwset->mind; 41353451Speter /* Find the minimal delta2 shift that we might make after 41453451Speter a backwards match has failed. */ 41553451Speter for (i = 0; i < kwset->mind - 1; ++i) 41653451Speter if (kwset->target[i] == kwset->target[kwset->mind - 1]) 41753451Speter kwset->mind2 = kwset->mind - (i + 1); 41853451Speter } 41953451Speter else 42053451Speter { 42153451Speter /* Traverse the nodes of the trie in level order, simultaneously 42253451Speter computing the delta table, failure function, and shift function. */ 42353451Speter for (curr = last = kwset->trie; curr; curr = curr->next) 42453451Speter { 42553451Speter /* Enqueue the immediate descendents in the level order queue. */ 42653451Speter enqueue(curr->links, &last); 42753451Speter 42853451Speter curr->shift = kwset->mind; 42953451Speter curr->maxshift = kwset->mind; 43053451Speter 43153451Speter /* Update the delta table for the descendents of this node. */ 43253451Speter treedelta(curr->links, curr->depth, delta); 43353451Speter 43453451Speter /* Compute the failure function for the decendents of this node. */ 43553451Speter treefails(curr->links, curr->fail, kwset->trie); 43653451Speter 43753451Speter /* Update the shifts at each node in the current node's chain 43853451Speter of fails back to the root. */ 43953451Speter for (fail = curr->fail; fail; fail = fail->fail) 44053451Speter { 44153451Speter /* If the current node has some outgoing edge that the fail 44253451Speter doesn't, then the shift at the fail should be no larger 44353451Speter than the difference of their depths. */ 44453451Speter if (!hasevery(fail->links, curr->links)) 44553451Speter if (curr->depth - fail->depth < fail->shift) 44653451Speter fail->shift = curr->depth - fail->depth; 44753451Speter 44853451Speter /* If the current node is accepting then the shift at the 44953451Speter fail and its descendents should be no larger than the 45053451Speter difference of their depths. */ 45153451Speter if (curr->accepting && fail->maxshift > curr->depth - fail->depth) 45253451Speter fail->maxshift = curr->depth - fail->depth; 45353451Speter } 45453451Speter } 45553451Speter 45653451Speter /* Traverse the trie in level order again, fixing up all nodes whose 45753451Speter shift exceeds their inherited maxshift. */ 45853451Speter for (curr = kwset->trie->next; curr; curr = curr->next) 45953451Speter { 46053451Speter if (curr->maxshift > curr->parent->maxshift) 46153451Speter curr->maxshift = curr->parent->maxshift; 46253451Speter if (curr->shift > curr->maxshift) 46353451Speter curr->shift = curr->maxshift; 46453451Speter } 46553451Speter 46653451Speter /* Create a vector, indexed by character code, of the outgoing links 46753451Speter from the root node. */ 46853451Speter for (i = 0; i < NCHAR; ++i) 46953451Speter next[i] = 0; 47053451Speter treenext(kwset->trie->links, next); 47153451Speter 47253451Speter if ((trans = kwset->trans) != 0) 47353451Speter for (i = 0; i < NCHAR; ++i) 47453451Speter kwset->next[i] = next[(unsigned char) trans[i]]; 47553451Speter else 47653451Speter for (i = 0; i < NCHAR; ++i) 47753451Speter kwset->next[i] = next[i]; 47853451Speter } 47953451Speter 48053451Speter /* Fix things up for any translation table. */ 48153451Speter if ((trans = kwset->trans) != 0) 48253451Speter for (i = 0; i < NCHAR; ++i) 48353451Speter kwset->delta[i] = delta[(unsigned char) trans[i]]; 48453451Speter else 48553451Speter for (i = 0; i < NCHAR; ++i) 48653451Speter kwset->delta[i] = delta[i]; 48753451Speter 48853451Speter return 0; 48953451Speter} 49053451Speter 49153451Speter#define U(C) ((unsigned char) (C)) 49253451Speter 49353451Speter/* Fast boyer-moore search. */ 494131557Stjrstatic size_t 495131557Stjrbmexec (kwset_t kws, char const *text, size_t size) 49653451Speter{ 497131557Stjr struct kwset const *kwset; 498131557Stjr register unsigned char const *d1; 499131557Stjr register char const *ep, *sp, *tp; 50053451Speter register int d, gc, i, len, md2; 50153451Speter 502131557Stjr kwset = (struct kwset const *) kws; 50353451Speter len = kwset->mind; 50453451Speter 50553451Speter if (len == 0) 506131557Stjr return 0; 50753451Speter if (len > size) 508131557Stjr return -1; 50953451Speter if (len == 1) 510131557Stjr { 511131557Stjr tp = memchr (text, kwset->target[0], size); 512131557Stjr return tp ? tp - text : -1; 513131557Stjr } 51453451Speter 51553451Speter d1 = kwset->delta; 51653451Speter sp = kwset->target + len; 51753451Speter gc = U(sp[-2]); 51853451Speter md2 = kwset->mind2; 51953451Speter tp = text + len; 52053451Speter 52153451Speter /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */ 52253451Speter if (size > 12 * len) 52353451Speter /* 11 is not a bug, the initial offset happens only once. */ 52453451Speter for (ep = text + size - 11 * len;;) 52553451Speter { 52653451Speter while (tp <= ep) 52753451Speter { 52853451Speter d = d1[U(tp[-1])], tp += d; 52953451Speter d = d1[U(tp[-1])], tp += d; 53053451Speter if (d == 0) 53153451Speter goto found; 53253451Speter d = d1[U(tp[-1])], tp += d; 53353451Speter d = d1[U(tp[-1])], tp += d; 53453451Speter d = d1[U(tp[-1])], tp += d; 53553451Speter if (d == 0) 53653451Speter goto found; 53753451Speter d = d1[U(tp[-1])], tp += d; 53853451Speter d = d1[U(tp[-1])], tp += d; 53953451Speter d = d1[U(tp[-1])], tp += d; 54053451Speter if (d == 0) 54153451Speter goto found; 54253451Speter d = d1[U(tp[-1])], tp += d; 54353451Speter d = d1[U(tp[-1])], tp += d; 54453451Speter } 54553451Speter break; 54653451Speter found: 54753451Speter if (U(tp[-2]) == gc) 54853451Speter { 54953451Speter for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i) 55053451Speter ; 55153451Speter if (i > len) 552131557Stjr return tp - len - text; 55353451Speter } 55453451Speter tp += md2; 55553451Speter } 55653451Speter 55753451Speter /* Now we have only a few characters left to search. We 55853451Speter carefully avoid ever producing an out-of-bounds pointer. */ 55953451Speter ep = text + size; 56053451Speter d = d1[U(tp[-1])]; 56153451Speter while (d <= ep - tp) 56253451Speter { 56353451Speter d = d1[U((tp += d)[-1])]; 56453451Speter if (d != 0) 56553451Speter continue; 56653451Speter if (U(tp[-2]) == gc) 56753451Speter { 56853451Speter for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i) 56953451Speter ; 57053451Speter if (i > len) 571131557Stjr return tp - len - text; 57253451Speter } 57353451Speter d = md2; 57453451Speter } 57553451Speter 576131557Stjr return -1; 57753451Speter} 57853451Speter 57953451Speter/* Hairy multiple string search. */ 580131557Stjrstatic size_t 581131557Stjrcwexec (kwset_t kws, char const *text, size_t len, struct kwsmatch *kwsmatch) 58253451Speter{ 583131557Stjr struct kwset const *kwset; 584131557Stjr struct trie * const *next; 585131557Stjr struct trie const *trie; 586131557Stjr struct trie const *accept; 587131557Stjr char const *beg, *lim, *mch, *lmch; 588131557Stjr register unsigned char c; 589131557Stjr register unsigned char const *delta; 59053451Speter register int d; 591131557Stjr register char const *end, *qlim; 592131557Stjr register struct tree const *tree; 593131557Stjr register char const *trans; 59453451Speter 59553474Sobrien#ifdef lint 59653474Sobrien accept = NULL; 59753474Sobrien#endif 59853474Sobrien 59953451Speter /* Initialize register copies and look for easy ways out. */ 60053451Speter kwset = (struct kwset *) kws; 60153451Speter if (len < kwset->mind) 602131557Stjr return -1; 60353451Speter next = kwset->next; 60453451Speter delta = kwset->delta; 60553451Speter trans = kwset->trans; 60653451Speter lim = text + len; 60753451Speter end = text; 60853451Speter if ((d = kwset->mind) != 0) 60953451Speter mch = 0; 61053451Speter else 61153451Speter { 61253451Speter mch = text, accept = kwset->trie; 61353451Speter goto match; 61453451Speter } 61553451Speter 61653451Speter if (len >= 4 * kwset->mind) 61753451Speter qlim = lim - 4 * kwset->mind; 61853451Speter else 61953451Speter qlim = 0; 62053451Speter 62153451Speter while (lim - end >= d) 62253451Speter { 62353451Speter if (qlim && end <= qlim) 62453451Speter { 62553451Speter end += d - 1; 62653451Speter while ((d = delta[c = *end]) && end < qlim) 62753451Speter { 62853451Speter end += d; 62953451Speter end += delta[(unsigned char) *end]; 63053451Speter end += delta[(unsigned char) *end]; 63153451Speter } 63253451Speter ++end; 63353451Speter } 63453451Speter else 63553451Speter d = delta[c = (end += d)[-1]]; 63653451Speter if (d) 63753451Speter continue; 63853451Speter beg = end - 1; 63953451Speter trie = next[c]; 64053451Speter if (trie->accepting) 64153451Speter { 64253451Speter mch = beg; 64353451Speter accept = trie; 64453451Speter } 64553451Speter d = trie->shift; 64653451Speter while (beg > text) 64753451Speter { 64853451Speter c = trans ? trans[(unsigned char) *--beg] : *--beg; 64953451Speter tree = trie->links; 65053451Speter while (tree && c != tree->label) 65153451Speter if (c < tree->label) 65253451Speter tree = tree->llink; 65353451Speter else 65453451Speter tree = tree->rlink; 65553451Speter if (tree) 65653451Speter { 65753451Speter trie = tree->trie; 65853451Speter if (trie->accepting) 65953451Speter { 66053451Speter mch = beg; 66153451Speter accept = trie; 66253451Speter } 66353451Speter } 66453451Speter else 66553451Speter break; 66653451Speter d = trie->shift; 66753451Speter } 66853451Speter if (mch) 66953451Speter goto match; 67053451Speter } 671131557Stjr return -1; 67253451Speter 67353451Speter match: 67453451Speter /* Given a known match, find the longest possible match anchored 67553451Speter at or before its starting point. This is nearly a verbatim 67653451Speter copy of the preceding main search loops. */ 67753451Speter if (lim - mch > kwset->maxd) 67853451Speter lim = mch + kwset->maxd; 67953451Speter lmch = 0; 68053451Speter d = 1; 68153451Speter while (lim - end >= d) 68253451Speter { 68353451Speter if ((d = delta[c = (end += d)[-1]]) != 0) 68453451Speter continue; 68553451Speter beg = end - 1; 68653451Speter if (!(trie = next[c])) 68753451Speter { 68853451Speter d = 1; 68953451Speter continue; 69053451Speter } 69153451Speter if (trie->accepting && beg <= mch) 69253451Speter { 69353451Speter lmch = beg; 69453451Speter accept = trie; 69553451Speter } 69653451Speter d = trie->shift; 69753451Speter while (beg > text) 69853451Speter { 69953451Speter c = trans ? trans[(unsigned char) *--beg] : *--beg; 70053451Speter tree = trie->links; 70153451Speter while (tree && c != tree->label) 70253451Speter if (c < tree->label) 70353451Speter tree = tree->llink; 70453451Speter else 70553451Speter tree = tree->rlink; 70653451Speter if (tree) 70753451Speter { 70853451Speter trie = tree->trie; 70953451Speter if (trie->accepting && beg <= mch) 71053451Speter { 71153451Speter lmch = beg; 71253451Speter accept = trie; 71353451Speter } 71453451Speter } 71553451Speter else 71653451Speter break; 71753451Speter d = trie->shift; 71853451Speter } 71953451Speter if (lmch) 72053451Speter { 72153451Speter mch = lmch; 72253451Speter goto match; 72353451Speter } 72453451Speter if (!d) 72553451Speter d = 1; 72653451Speter } 72753451Speter 72853451Speter if (kwsmatch) 72953451Speter { 73053451Speter kwsmatch->index = accept->accepting / 2; 731131557Stjr kwsmatch->offset[0] = mch - text; 73253451Speter kwsmatch->size[0] = accept->depth; 73353451Speter } 734131557Stjr return mch - text; 73553451Speter} 73653451Speter 73753451Speter/* Search through the given text for a match of any member of the 73853451Speter given keyword set. Return a pointer to the first character of 73953451Speter the matching substring, or NULL if no match is found. If FOUNDLEN 74053451Speter is non-NULL store in the referenced location the length of the 74153451Speter matching substring. Similarly, if FOUNDIDX is non-NULL, store 74253451Speter in the referenced location the index number of the particular 74353451Speter keyword matched. */ 744131557Stjrsize_t 745131557Stjrkwsexec (kwset_t kws, char const *text, size_t size, 746131557Stjr struct kwsmatch *kwsmatch) 74753451Speter{ 748131557Stjr struct kwset const *kwset = (struct kwset *) kws; 74953451Speter if (kwset->words == 1 && kwset->trans == 0) 75053451Speter { 751131557Stjr size_t ret = bmexec (kws, text, size); 752131557Stjr if (kwsmatch != 0 && ret != (size_t) -1) 75353451Speter { 75453451Speter kwsmatch->index = 0; 755131557Stjr kwsmatch->offset[0] = ret; 75653451Speter kwsmatch->size[0] = kwset->mind; 75753451Speter } 75853451Speter return ret; 75953451Speter } 76053451Speter else 76153451Speter return cwexec(kws, text, size, kwsmatch); 76253451Speter} 76353451Speter 76453451Speter/* Free the components of the given keyword set. */ 76553451Spetervoid 76656918Srukwsfree (kwset_t kws) 76753451Speter{ 76853451Speter struct kwset *kwset; 76953451Speter 77053451Speter kwset = (struct kwset *) kws; 77153451Speter obstack_free(&kwset->obstack, 0); 77253451Speter free(kws); 77353451Speter} 774