kwset.c revision 56918
153451Speter/* kwset.c - search for any of a set of keywords. 253474Sobrien Copyright (C) 1989, 1998 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 1953474Sobrien/* Written August 1989 by Mike Haertel. 2053451Speter The author may be reached (Email) at the address mike@ai.mit.edu, 2153451Speter or (US mail) as Mike Haertel c/o Free Software Foundation. */ 2253451Speter 2353451Speter/* The algorithm implemented by these routines bears a startling resemblence 2453451Speter to one discovered by Beate Commentz-Walter, although it is not identical. 2553451Speter See "A String Matching Algorithm Fast on the Average," Technical Report, 2653451Speter IBM-Germany, Scientific Center Heidelberg, Tiergartenstrasse 15, D-6900 2753451Speter Heidelberg, Germany. See also Aho, A.V., and M. Corasick, "Efficient 2853451Speter String Matching: An Aid to Bibliographic Search," CACM June 1975, 2953451Speter Vol. 18, No. 6, which describes the failure function used below. */ 3053451Speter 3153474Sobrien#ifdef HAVE_CONFIG_H 3253474Sobrien# include <config.h> 3353474Sobrien#endif 3453451Speter#include <sys/types.h> 3553474Sobrien#include "system.h" 3653474Sobrien#include "kwset.h" 3753474Sobrien#include "obstack.h" 3853451Speter 3953451Speter#ifdef GREP 4053451Speterextern char *xmalloc(); 4153474Sobrien# undef malloc 4253474Sobrien# define malloc xmalloc 4353451Speter#endif 4453451Speter 4553451Speter#define NCHAR (UCHAR_MAX + 1) 4653451Speter#define obstack_chunk_alloc malloc 4753451Speter#define obstack_chunk_free free 4853451Speter 4953451Speter/* Balanced tree of edges and labels leaving a given trie node. */ 5053451Speterstruct tree 5153451Speter{ 5253451Speter struct tree *llink; /* Left link; MUST be first field. */ 5353451Speter struct tree *rlink; /* Right link (to larger labels). */ 5453451Speter struct trie *trie; /* Trie node pointed to by this edge. */ 5553451Speter unsigned char label; /* Label on this edge. */ 5653451Speter char balance; /* Difference in depths of subtrees. */ 5753451Speter}; 5853451Speter 5953451Speter/* Node of a trie representing a set of reversed keywords. */ 6053451Speterstruct trie 6153451Speter{ 6253451Speter unsigned int accepting; /* Word index of accepted word, or zero. */ 6353451Speter struct tree *links; /* Tree of edges leaving this node. */ 6453451Speter struct trie *parent; /* Parent of this node. */ 6553451Speter struct trie *next; /* List of all trie nodes in level order. */ 6653451Speter struct trie *fail; /* Aho-Corasick failure function. */ 6753451Speter int depth; /* Depth of this node from the root. */ 6853451Speter int shift; /* Shift function for search failures. */ 6953451Speter int maxshift; /* Max shift of self and descendents. */ 7053451Speter}; 7153451Speter 7253451Speter/* Structure returned opaquely to the caller, containing everything. */ 7353451Speterstruct kwset 7453451Speter{ 7553451Speter struct obstack obstack; /* Obstack for node allocation. */ 7653451Speter int words; /* Number of words in the trie. */ 7753451Speter struct trie *trie; /* The trie itself. */ 7853451Speter int mind; /* Minimum depth of an accepting node. */ 7953451Speter int maxd; /* Maximum depth of any node. */ 8053451Speter unsigned char delta[NCHAR]; /* Delta table for rapid search. */ 8153451Speter struct trie *next[NCHAR]; /* Table of children of the root. */ 8253451Speter char *target; /* Target string if there's only one. */ 8353451Speter int mind2; /* Used in Boyer-Moore search for one string. */ 8453451Speter char *trans; /* Character translation table. */ 8553451Speter}; 8653451Speter 8753474Sobrien/* prototypes */ 8853474Sobrienstatic void enqueue PARAMS((struct tree *, struct trie **)); 8953474Sobrienstatic void treefails PARAMS((register struct tree *, struct trie *, struct trie *)); 9053474Sobrienstatic void treedelta PARAMS((register struct tree *,register unsigned int, unsigned char *)); 9153474Sobrienstatic int hasevery PARAMS((register struct tree *, register struct tree *)); 9253474Sobrienstatic void treenext PARAMS((struct tree *, struct trie **)); 9353474Sobrienstatic char * bmexec PARAMS((kwset_t, char *, size_t)); 9453474Sobrienstatic char * cwexec PARAMS((kwset_t, char *, size_t, struct kwsmatch *)); 9553474Sobrien 9653451Speter/* Allocate and initialize a keyword set object, returning an opaque 9753451Speter pointer to it. Return NULL if memory is not available. */ 9853451Speterkwset_t 9956918Srukwsalloc (char *trans) 10053451Speter{ 10153451Speter struct kwset *kwset; 10253451Speter 10353451Speter kwset = (struct kwset *) malloc(sizeof (struct kwset)); 10453451Speter if (!kwset) 10553451Speter return 0; 10653451Speter 10753451Speter obstack_init(&kwset->obstack); 10853451Speter kwset->words = 0; 10953451Speter kwset->trie 11053451Speter = (struct trie *) obstack_alloc(&kwset->obstack, sizeof (struct trie)); 11153451Speter if (!kwset->trie) 11253451Speter { 11353451Speter kwsfree((kwset_t) kwset); 11453451Speter return 0; 11553451Speter } 11653451Speter kwset->trie->accepting = 0; 11753451Speter kwset->trie->links = 0; 11853451Speter kwset->trie->parent = 0; 11953451Speter kwset->trie->next = 0; 12053451Speter kwset->trie->fail = 0; 12153451Speter kwset->trie->depth = 0; 12253451Speter kwset->trie->shift = 0; 12353451Speter kwset->mind = INT_MAX; 12453451Speter kwset->maxd = -1; 12553451Speter kwset->target = 0; 12653451Speter kwset->trans = trans; 12753451Speter 12853451Speter return (kwset_t) kwset; 12953451Speter} 13053451Speter 13153451Speter/* Add the given string to the contents of the keyword set. Return NULL 13253451Speter for success, an error message otherwise. */ 13353451Speterchar * 13456918Srukwsincr (kwset_t kws, char *text, size_t len) 13553451Speter{ 13653451Speter struct kwset *kwset; 13753451Speter register struct trie *trie; 13853451Speter register unsigned char label; 13953451Speter register struct tree *link; 14053451Speter register int depth; 14153451Speter struct tree *links[12]; 14253451Speter enum { L, R } dirs[12]; 14353451Speter struct tree *t, *r, *l, *rl, *lr; 14453451Speter 14553451Speter kwset = (struct kwset *) kws; 14653451Speter trie = kwset->trie; 14753451Speter text += len; 14853451Speter 14953451Speter /* Descend the trie (built of reversed keywords) character-by-character, 15053451Speter installing new nodes when necessary. */ 15153451Speter while (len--) 15253451Speter { 15353451Speter label = kwset->trans ? kwset->trans[(unsigned char) *--text] : *--text; 15453451Speter 15553451Speter /* Descend the tree of outgoing links for this trie node, 15653451Speter looking for the current character and keeping track 15753451Speter of the path followed. */ 15853451Speter link = trie->links; 15953451Speter links[0] = (struct tree *) &trie->links; 16053451Speter dirs[0] = L; 16153451Speter depth = 1; 16253451Speter 16353451Speter while (link && label != link->label) 16453451Speter { 16553451Speter links[depth] = link; 16653451Speter if (label < link->label) 16753451Speter dirs[depth++] = L, link = link->llink; 16853451Speter else 16953451Speter dirs[depth++] = R, link = link->rlink; 17053451Speter } 17153451Speter 17253451Speter /* The current character doesn't have an outgoing link at 17353451Speter this trie node, so build a new trie node and install 17453451Speter a link in the current trie node's tree. */ 17553451Speter if (!link) 17653451Speter { 17753451Speter link = (struct tree *) obstack_alloc(&kwset->obstack, 17853451Speter sizeof (struct tree)); 17953451Speter if (!link) 18053474Sobrien return _("memory exhausted"); 18153451Speter link->llink = 0; 18253451Speter link->rlink = 0; 18353451Speter link->trie = (struct trie *) obstack_alloc(&kwset->obstack, 18453451Speter sizeof (struct trie)); 18553451Speter if (!link->trie) 18653474Sobrien return _("memory exhausted"); 18753451Speter link->trie->accepting = 0; 18853451Speter link->trie->links = 0; 18953451Speter link->trie->parent = trie; 19053451Speter link->trie->next = 0; 19153451Speter link->trie->fail = 0; 19253451Speter link->trie->depth = trie->depth + 1; 19353451Speter link->trie->shift = 0; 19453451Speter link->label = label; 19553451Speter link->balance = 0; 19653451Speter 19753451Speter /* Install the new tree node in its parent. */ 19853451Speter if (dirs[--depth] == L) 19953451Speter links[depth]->llink = link; 20053451Speter else 20153451Speter links[depth]->rlink = link; 20253451Speter 20353451Speter /* Back up the tree fixing the balance flags. */ 20453451Speter while (depth && !links[depth]->balance) 20553451Speter { 20653451Speter if (dirs[depth] == L) 20753451Speter --links[depth]->balance; 20853451Speter else 20953451Speter ++links[depth]->balance; 21053451Speter --depth; 21153451Speter } 21253451Speter 21353451Speter /* Rebalance the tree by pointer rotations if necessary. */ 21453451Speter if (depth && ((dirs[depth] == L && --links[depth]->balance) 21553451Speter || (dirs[depth] == R && ++links[depth]->balance))) 21653451Speter { 21753451Speter switch (links[depth]->balance) 21853451Speter { 21953451Speter case (char) -2: 22053451Speter switch (dirs[depth + 1]) 22153451Speter { 22253451Speter case L: 22353451Speter r = links[depth], t = r->llink, rl = t->rlink; 22453451Speter t->rlink = r, r->llink = rl; 22553451Speter t->balance = r->balance = 0; 22653451Speter break; 22753451Speter case R: 22853451Speter r = links[depth], l = r->llink, t = l->rlink; 22953451Speter rl = t->rlink, lr = t->llink; 23053451Speter t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl; 23153451Speter l->balance = t->balance != 1 ? 0 : -1; 23253451Speter r->balance = t->balance != (char) -1 ? 0 : 1; 23353451Speter t->balance = 0; 23453451Speter break; 23553474Sobrien default: 23653474Sobrien abort (); 23753451Speter } 23853451Speter break; 23953451Speter case 2: 24053451Speter switch (dirs[depth + 1]) 24153451Speter { 24253451Speter case R: 24353451Speter l = links[depth], t = l->rlink, lr = t->llink; 24453451Speter t->llink = l, l->rlink = lr; 24553451Speter t->balance = l->balance = 0; 24653451Speter break; 24753451Speter case L: 24853451Speter l = links[depth], r = l->rlink, t = r->llink; 24953451Speter lr = t->llink, rl = t->rlink; 25053451Speter t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl; 25153451Speter l->balance = t->balance != 1 ? 0 : -1; 25253451Speter r->balance = t->balance != (char) -1 ? 0 : 1; 25353451Speter t->balance = 0; 25453451Speter break; 25553474Sobrien default: 25653474Sobrien abort (); 25753451Speter } 25853451Speter break; 25953474Sobrien default: 26053474Sobrien abort (); 26153451Speter } 26253451Speter 26353451Speter if (dirs[depth - 1] == L) 26453451Speter links[depth - 1]->llink = t; 26553451Speter else 26653451Speter links[depth - 1]->rlink = t; 26753451Speter } 26853451Speter } 26953451Speter 27053451Speter trie = link->trie; 27153451Speter } 27253451Speter 27353451Speter /* Mark the node we finally reached as accepting, encoding the 27453451Speter index number of this word in the keyword set so far. */ 27553451Speter if (!trie->accepting) 27653451Speter trie->accepting = 1 + 2 * kwset->words; 27753451Speter ++kwset->words; 27853451Speter 27953451Speter /* Keep track of the longest and shortest string of the keyword set. */ 28053451Speter if (trie->depth < kwset->mind) 28153451Speter kwset->mind = trie->depth; 28253451Speter if (trie->depth > kwset->maxd) 28353451Speter kwset->maxd = trie->depth; 28453451Speter 28553451Speter return 0; 28653451Speter} 28753451Speter 28853451Speter/* Enqueue the trie nodes referenced from the given tree in the 28953451Speter given queue. */ 29053451Speterstatic void 29156918Sruenqueue (struct tree *tree, struct trie **last) 29253451Speter{ 29353451Speter if (!tree) 29453451Speter return; 29553451Speter enqueue(tree->llink, last); 29653451Speter enqueue(tree->rlink, last); 29753451Speter (*last) = (*last)->next = tree->trie; 29853451Speter} 29953451Speter 30053451Speter/* Compute the Aho-Corasick failure function for the trie nodes referenced 30153451Speter from the given tree, given the failure function for their parent as 30253451Speter well as a last resort failure node. */ 30353451Speterstatic void 30456918Srutreefails (register struct tree *tree, struct trie *fail, struct trie *recourse) 30553451Speter{ 30653451Speter register struct tree *link; 30753451Speter 30853451Speter if (!tree) 30953451Speter return; 31053451Speter 31153451Speter treefails(tree->llink, fail, recourse); 31253451Speter treefails(tree->rlink, fail, recourse); 31353451Speter 31453451Speter /* Find, in the chain of fails going back to the root, the first 31553451Speter node that has a descendent on the current label. */ 31653451Speter while (fail) 31753451Speter { 31853451Speter link = fail->links; 31953451Speter while (link && tree->label != link->label) 32053451Speter if (tree->label < link->label) 32153451Speter link = link->llink; 32253451Speter else 32353451Speter link = link->rlink; 32453451Speter if (link) 32553451Speter { 32653451Speter tree->trie->fail = link->trie; 32753451Speter return; 32853451Speter } 32953451Speter fail = fail->fail; 33053451Speter } 33153451Speter 33253451Speter tree->trie->fail = recourse; 33353451Speter} 33453451Speter 33553451Speter/* Set delta entries for the links of the given tree such that 33653451Speter the preexisting delta value is larger than the current depth. */ 33753451Speterstatic void 33856918Srutreedelta (register struct tree *tree, 33956918Sru register unsigned int depth, 34056918Sru unsigned char delta[]) 34153451Speter{ 34253451Speter if (!tree) 34353451Speter return; 34453451Speter treedelta(tree->llink, depth, delta); 34553451Speter treedelta(tree->rlink, depth, delta); 34653451Speter if (depth < delta[tree->label]) 34753451Speter delta[tree->label] = depth; 34853451Speter} 34953451Speter 35053451Speter/* Return true if A has every label in B. */ 35153451Speterstatic int 35256918Sruhasevery (register struct tree *a, register struct tree *b) 35353451Speter{ 35453451Speter if (!b) 35553451Speter return 1; 35653451Speter if (!hasevery(a, b->llink)) 35753451Speter return 0; 35853451Speter if (!hasevery(a, b->rlink)) 35953451Speter return 0; 36053451Speter while (a && b->label != a->label) 36153451Speter if (b->label < a->label) 36253451Speter a = a->llink; 36353451Speter else 36453451Speter a = a->rlink; 36553451Speter return !!a; 36653451Speter} 36753451Speter 36853451Speter/* Compute a vector, indexed by character code, of the trie nodes 36953451Speter referenced from the given tree. */ 37053451Speterstatic void 37156918Srutreenext (struct tree *tree, struct trie *next[]) 37253451Speter{ 37353451Speter if (!tree) 37453451Speter return; 37553451Speter treenext(tree->llink, next); 37653451Speter treenext(tree->rlink, next); 37753451Speter next[tree->label] = tree->trie; 37853451Speter} 37953451Speter 38053451Speter/* Compute the shift for each trie node, as well as the delta 38153451Speter table and next cache for the given keyword set. */ 38253451Speterchar * 38356918Srukwsprep (kwset_t kws) 38453451Speter{ 38553451Speter register struct kwset *kwset; 38653451Speter register int i; 38753451Speter register struct trie *curr, *fail; 38853451Speter register char *trans; 38953451Speter unsigned char delta[NCHAR]; 39053451Speter struct trie *last, *next[NCHAR]; 39153451Speter 39253451Speter kwset = (struct kwset *) kws; 39353451Speter 39453451Speter /* Initial values for the delta table; will be changed later. The 39553451Speter delta entry for a given character is the smallest depth of any 39653451Speter node at which an outgoing edge is labeled by that character. */ 39753451Speter if (kwset->mind < 256) 39853451Speter for (i = 0; i < NCHAR; ++i) 39953451Speter delta[i] = kwset->mind; 40053451Speter else 40153451Speter for (i = 0; i < NCHAR; ++i) 40253451Speter delta[i] = 255; 40353451Speter 40453451Speter /* Check if we can use the simple boyer-moore algorithm, instead 40553451Speter of the hairy commentz-walter algorithm. */ 40653451Speter if (kwset->words == 1 && kwset->trans == 0) 40753451Speter { 40853451Speter /* Looking for just one string. Extract it from the trie. */ 40953451Speter kwset->target = obstack_alloc(&kwset->obstack, kwset->mind); 41053451Speter for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i) 41153451Speter { 41253451Speter kwset->target[i] = curr->links->label; 41353451Speter curr = curr->links->trie; 41453451Speter } 41553451Speter /* Build the Boyer Moore delta. Boy that's easy compared to CW. */ 41653451Speter for (i = 0; i < kwset->mind; ++i) 41753451Speter delta[(unsigned char) kwset->target[i]] = kwset->mind - (i + 1); 41853451Speter kwset->mind2 = kwset->mind; 41953451Speter /* Find the minimal delta2 shift that we might make after 42053451Speter a backwards match has failed. */ 42153451Speter for (i = 0; i < kwset->mind - 1; ++i) 42253451Speter if (kwset->target[i] == kwset->target[kwset->mind - 1]) 42353451Speter kwset->mind2 = kwset->mind - (i + 1); 42453451Speter } 42553451Speter else 42653451Speter { 42753451Speter /* Traverse the nodes of the trie in level order, simultaneously 42853451Speter computing the delta table, failure function, and shift function. */ 42953451Speter for (curr = last = kwset->trie; curr; curr = curr->next) 43053451Speter { 43153451Speter /* Enqueue the immediate descendents in the level order queue. */ 43253451Speter enqueue(curr->links, &last); 43353451Speter 43453451Speter curr->shift = kwset->mind; 43553451Speter curr->maxshift = kwset->mind; 43653451Speter 43753451Speter /* Update the delta table for the descendents of this node. */ 43853451Speter treedelta(curr->links, curr->depth, delta); 43953451Speter 44053451Speter /* Compute the failure function for the decendents of this node. */ 44153451Speter treefails(curr->links, curr->fail, kwset->trie); 44253451Speter 44353451Speter /* Update the shifts at each node in the current node's chain 44453451Speter of fails back to the root. */ 44553451Speter for (fail = curr->fail; fail; fail = fail->fail) 44653451Speter { 44753451Speter /* If the current node has some outgoing edge that the fail 44853451Speter doesn't, then the shift at the fail should be no larger 44953451Speter than the difference of their depths. */ 45053451Speter if (!hasevery(fail->links, curr->links)) 45153451Speter if (curr->depth - fail->depth < fail->shift) 45253451Speter fail->shift = curr->depth - fail->depth; 45353451Speter 45453451Speter /* If the current node is accepting then the shift at the 45553451Speter fail and its descendents should be no larger than the 45653451Speter difference of their depths. */ 45753451Speter if (curr->accepting && fail->maxshift > curr->depth - fail->depth) 45853451Speter fail->maxshift = curr->depth - fail->depth; 45953451Speter } 46053451Speter } 46153451Speter 46253451Speter /* Traverse the trie in level order again, fixing up all nodes whose 46353451Speter shift exceeds their inherited maxshift. */ 46453451Speter for (curr = kwset->trie->next; curr; curr = curr->next) 46553451Speter { 46653451Speter if (curr->maxshift > curr->parent->maxshift) 46753451Speter curr->maxshift = curr->parent->maxshift; 46853451Speter if (curr->shift > curr->maxshift) 46953451Speter curr->shift = curr->maxshift; 47053451Speter } 47153451Speter 47253451Speter /* Create a vector, indexed by character code, of the outgoing links 47353451Speter from the root node. */ 47453451Speter for (i = 0; i < NCHAR; ++i) 47553451Speter next[i] = 0; 47653451Speter treenext(kwset->trie->links, next); 47753451Speter 47853451Speter if ((trans = kwset->trans) != 0) 47953451Speter for (i = 0; i < NCHAR; ++i) 48053451Speter kwset->next[i] = next[(unsigned char) trans[i]]; 48153451Speter else 48253451Speter for (i = 0; i < NCHAR; ++i) 48353451Speter kwset->next[i] = next[i]; 48453451Speter } 48553451Speter 48653451Speter /* Fix things up for any translation table. */ 48753451Speter if ((trans = kwset->trans) != 0) 48853451Speter for (i = 0; i < NCHAR; ++i) 48953451Speter kwset->delta[i] = delta[(unsigned char) trans[i]]; 49053451Speter else 49153451Speter for (i = 0; i < NCHAR; ++i) 49253451Speter kwset->delta[i] = delta[i]; 49353451Speter 49453451Speter return 0; 49553451Speter} 49653451Speter 49753451Speter#define U(C) ((unsigned char) (C)) 49853451Speter 49953451Speter/* Fast boyer-moore search. */ 50053451Speterstatic char * 50156918Srubmexec (kwset_t kws, char *text, size_t size) 50253451Speter{ 50353451Speter struct kwset *kwset; 50453451Speter register unsigned char *d1; 50553451Speter register char *ep, *sp, *tp; 50653451Speter register int d, gc, i, len, md2; 50753451Speter 50853451Speter kwset = (struct kwset *) kws; 50953451Speter len = kwset->mind; 51053451Speter 51153451Speter if (len == 0) 51253451Speter return text; 51353451Speter if (len > size) 51453451Speter return 0; 51553451Speter if (len == 1) 51653451Speter return memchr(text, kwset->target[0], size); 51753451Speter 51853451Speter d1 = kwset->delta; 51953451Speter sp = kwset->target + len; 52053451Speter gc = U(sp[-2]); 52153451Speter md2 = kwset->mind2; 52253451Speter tp = text + len; 52353451Speter 52453451Speter /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */ 52553451Speter if (size > 12 * len) 52653451Speter /* 11 is not a bug, the initial offset happens only once. */ 52753451Speter for (ep = text + size - 11 * len;;) 52853451Speter { 52953451Speter while (tp <= ep) 53053451Speter { 53153451Speter d = d1[U(tp[-1])], tp += d; 53253451Speter d = d1[U(tp[-1])], tp += d; 53353451Speter if (d == 0) 53453451Speter goto found; 53553451Speter d = d1[U(tp[-1])], tp += d; 53653451Speter d = d1[U(tp[-1])], tp += d; 53753451Speter d = d1[U(tp[-1])], tp += d; 53853451Speter if (d == 0) 53953451Speter goto found; 54053451Speter d = d1[U(tp[-1])], tp += d; 54153451Speter d = d1[U(tp[-1])], tp += d; 54253451Speter d = d1[U(tp[-1])], tp += d; 54353451Speter if (d == 0) 54453451Speter goto found; 54553451Speter d = d1[U(tp[-1])], tp += d; 54653451Speter d = d1[U(tp[-1])], tp += d; 54753451Speter } 54853451Speter break; 54953451Speter found: 55053451Speter if (U(tp[-2]) == gc) 55153451Speter { 55253451Speter for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i) 55353451Speter ; 55453451Speter if (i > len) 55553451Speter return tp - len; 55653451Speter } 55753451Speter tp += md2; 55853451Speter } 55953451Speter 56053451Speter /* Now we have only a few characters left to search. We 56153451Speter carefully avoid ever producing an out-of-bounds pointer. */ 56253451Speter ep = text + size; 56353451Speter d = d1[U(tp[-1])]; 56453451Speter while (d <= ep - tp) 56553451Speter { 56653451Speter d = d1[U((tp += d)[-1])]; 56753451Speter if (d != 0) 56853451Speter continue; 56953451Speter if (U(tp[-2]) == gc) 57053451Speter { 57153451Speter for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i) 57253451Speter ; 57353451Speter if (i > len) 57453451Speter return tp - len; 57553451Speter } 57653451Speter d = md2; 57753451Speter } 57853451Speter 57953451Speter return 0; 58053451Speter} 58153451Speter 58253451Speter/* Hairy multiple string search. */ 58353451Speterstatic char * 58456918Srucwexec (kwset_t kws, char *text, size_t len, struct kwsmatch *kwsmatch) 58553451Speter{ 58653451Speter struct kwset *kwset; 58753451Speter struct trie **next, *trie, *accept; 58853451Speter char *beg, *lim, *mch, *lmch; 58953451Speter register unsigned char c, *delta; 59053451Speter register int d; 59153451Speter register char *end, *qlim; 59253451Speter register struct tree *tree; 59353451Speter register char *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) 60253451Speter return 0; 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 } 67153451Speter return 0; 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; 73153451Speter kwsmatch->beg[0] = mch; 73253451Speter kwsmatch->size[0] = accept->depth; 73353451Speter } 73453451Speter return mch; 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. */ 74453451Speterchar * 74556918Srukwsexec (kwset_t kws, char *text, size_t size, struct kwsmatch *kwsmatch) 74653451Speter{ 74753451Speter struct kwset *kwset; 74853451Speter char *ret; 74953451Speter 75053451Speter kwset = (struct kwset *) kws; 75153451Speter if (kwset->words == 1 && kwset->trans == 0) 75253451Speter { 75353451Speter ret = bmexec(kws, text, size); 75453451Speter if (kwsmatch != 0 && ret != 0) 75553451Speter { 75653451Speter kwsmatch->index = 0; 75753451Speter kwsmatch->beg[0] = ret; 75853451Speter kwsmatch->size[0] = kwset->mind; 75953451Speter } 76053451Speter return ret; 76153451Speter } 76253451Speter else 76353451Speter return cwexec(kws, text, size, kwsmatch); 76453451Speter} 76553451Speter 76653451Speter/* Free the components of the given keyword set. */ 76753451Spetervoid 76856918Srukwsfree (kwset_t kws) 76953451Speter{ 77053451Speter struct kwset *kwset; 77153451Speter 77253451Speter kwset = (struct kwset *) kws; 77353451Speter obstack_free(&kwset->obstack, 0); 77453451Speter free(kws); 77553451Speter} 776