--- /dev/null
+/* kwset.c - search for any of a set of keywords.
+ Copyright 1989, 1998, 2000, 2005 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
+ 02110-1301, USA. */
+
+/* Written August 1989 by Mike Haertel.
+ The author may be reached (Email) at the address mike@ai.mit.edu,
+ or (US mail) as Mike Haertel c/o Free Software Foundation. */
+
+/* The algorithm implemented by these routines bears a startling resemblence
+ to one discovered by Beate Commentz-Walter, although it is not identical.
+ See "A String Matching Algorithm Fast on the Average," Technical Report,
+ IBM-Germany, Scientific Center Heidelberg, Tiergartenstrasse 15, D-6900
+ Heidelberg, Germany. See also Aho, A.V., and M. Corasick, "Efficient
+ String Matching: An Aid to Bibliographic Search," CACM June 1975,
+ Vol. 18, No. 6, which describes the failure function used below. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include <sys/types.h>
+#include "system.h"
+#include "kwset.h"
+#include "obstack.h"
+
+#ifdef GREP
+extern char *xmalloc();
+# undef malloc
+# define malloc xmalloc
+#endif
+
+#define NCHAR (UCHAR_MAX + 1)
+#define obstack_chunk_alloc malloc
+#define obstack_chunk_free free
+
+#define U(c) ((unsigned char) (c))
+
+/* Balanced tree of edges and labels leaving a given trie node. */
+struct tree
+{
+ struct tree *llink; /* Left link; MUST be first field. */
+ struct tree *rlink; /* Right link (to larger labels). */
+ struct trie *trie; /* Trie node pointed to by this edge. */
+ unsigned char label; /* Label on this edge. */
+ char balance; /* Difference in depths of subtrees. */
+};
+
+/* Node of a trie representing a set of reversed keywords. */
+struct trie
+{
+ unsigned int accepting; /* Word index of accepted word, or zero. */
+ struct tree *links; /* Tree of edges leaving this node. */
+ struct trie *parent; /* Parent of this node. */
+ struct trie *next; /* List of all trie nodes in level order. */
+ struct trie *fail; /* Aho-Corasick failure function. */
+ int depth; /* Depth of this node from the root. */
+ int shift; /* Shift function for search failures. */
+ int maxshift; /* Max shift of self and descendents. */
+};
+
+/* Structure returned opaquely to the caller, containing everything. */
+struct kwset
+{
+ struct obstack obstack; /* Obstack for node allocation. */
+ int words; /* Number of words in the trie. */
+ struct trie *trie; /* The trie itself. */
+ int mind; /* Minimum depth of an accepting node. */
+ int maxd; /* Maximum depth of any node. */
+ unsigned char delta[NCHAR]; /* Delta table for rapid search. */
+ struct trie *next[NCHAR]; /* Table of children of the root. */
+ char *target; /* Target string if there's only one. */
+ int mind2; /* Used in Boyer-Moore search for one string. */
+ char const *trans; /* Character translation table. */
+};
+
+/* Allocate and initialize a keyword set object, returning an opaque
+ pointer to it. Return NULL if memory is not available. */
+kwset_t
+kwsalloc (char const *trans)
+{
+ struct kwset *kwset;
+
+ kwset = (struct kwset *) malloc(sizeof (struct kwset));
+ if (!kwset)
+ return NULL;
+
+ obstack_init(&kwset->obstack);
+ kwset->words = 0;
+ kwset->trie
+ = (struct trie *) obstack_alloc(&kwset->obstack, sizeof (struct trie));
+ if (!kwset->trie)
+ {
+ kwsfree((kwset_t) kwset);
+ return NULL;
+ }
+ kwset->trie->accepting = 0;
+ kwset->trie->links = NULL;
+ kwset->trie->parent = NULL;
+ kwset->trie->next = NULL;
+ kwset->trie->fail = NULL;
+ kwset->trie->depth = 0;
+ kwset->trie->shift = 0;
+ kwset->mind = INT_MAX;
+ kwset->maxd = -1;
+ kwset->target = NULL;
+ kwset->trans = trans;
+
+ return (kwset_t) kwset;
+}
+
+/* This upper bound is valid for CHAR_BIT >= 4 and
+ exact for CHAR_BIT in { 4..11, 13, 15, 17, 19 }. */
+#define DEPTH_SIZE (CHAR_BIT + CHAR_BIT/2)
+
+/* Add the given string to the contents of the keyword set. Return NULL
+ for success, an error message otherwise. */
+const char *
+kwsincr (kwset_t kws, char const *text, size_t len)
+{
+ struct kwset *kwset;
+ register struct trie *trie;
+ register unsigned char label;
+ register struct tree *link;
+ register int depth;
+ struct tree *links[DEPTH_SIZE];
+ enum { L, R } dirs[DEPTH_SIZE];
+ struct tree *t, *r, *l, *rl, *lr;
+
+ kwset = (struct kwset *) kws;
+ trie = kwset->trie;
+ text += len;
+
+ /* Descend the trie (built of reversed keywords) character-by-character,
+ installing new nodes when necessary. */
+ while (len--)
+ {
+ label = kwset->trans ? kwset->trans[U(*--text)] : *--text;
+
+ /* Descend the tree of outgoing links for this trie node,
+ looking for the current character and keeping track
+ of the path followed. */
+ link = trie->links;
+ links[0] = (struct tree *) &trie->links;
+ dirs[0] = L;
+ depth = 1;
+
+ while (link && label != link->label)
+ {
+ links[depth] = link;
+ if (label < link->label)
+ dirs[depth++] = L, link = link->llink;
+ else
+ dirs[depth++] = R, link = link->rlink;
+ }
+
+ /* The current character doesn't have an outgoing link at
+ this trie node, so build a new trie node and install
+ a link in the current trie node's tree. */
+ if (!link)
+ {
+ link = (struct tree *) obstack_alloc(&kwset->obstack,
+ sizeof (struct tree));
+ if (!link)
+ return _("memory exhausted");
+ link->llink = NULL;
+ link->rlink = NULL;
+ link->trie = (struct trie *) obstack_alloc(&kwset->obstack,
+ sizeof (struct trie));
+ if (!link->trie)
+ {
+ obstack_free(&kwset->obstack, link);
+ return _("memory exhausted");
+ }
+ link->trie->accepting = 0;
+ link->trie->links = NULL;
+ link->trie->parent = trie;
+ link->trie->next = NULL;
+ link->trie->fail = NULL;
+ link->trie->depth = trie->depth + 1;
+ link->trie->shift = 0;
+ link->label = label;
+ link->balance = 0;
+
+ /* Install the new tree node in its parent. */
+ if (dirs[--depth] == L)
+ links[depth]->llink = link;
+ else
+ links[depth]->rlink = link;
+
+ /* Back up the tree fixing the balance flags. */
+ while (depth && !links[depth]->balance)
+ {
+ if (dirs[depth] == L)
+ --links[depth]->balance;
+ else
+ ++links[depth]->balance;
+ --depth;
+ }
+
+ /* Rebalance the tree by pointer rotations if necessary. */
+ if (depth && ((dirs[depth] == L && --links[depth]->balance)
+ || (dirs[depth] == R && ++links[depth]->balance)))
+ {
+ switch (links[depth]->balance)
+ {
+ case (char) -2:
+ switch (dirs[depth + 1])
+ {
+ case L:
+ r = links[depth], t = r->llink, rl = t->rlink;
+ t->rlink = r, r->llink = rl;
+ t->balance = r->balance = 0;
+ break;
+ case R:
+ r = links[depth], l = r->llink, t = l->rlink;
+ rl = t->rlink, lr = t->llink;
+ t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
+ l->balance = t->balance != 1 ? 0 : -1;
+ r->balance = t->balance != (char) -1 ? 0 : 1;
+ t->balance = 0;
+ break;
+ default:
+ abort ();
+ }
+ break;
+ case 2:
+ switch (dirs[depth + 1])
+ {
+ case R:
+ l = links[depth], t = l->rlink, lr = t->llink;
+ t->llink = l, l->rlink = lr;
+ t->balance = l->balance = 0;
+ break;
+ case L:
+ l = links[depth], r = l->rlink, t = r->llink;
+ lr = t->llink, rl = t->rlink;
+ t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
+ l->balance = t->balance != 1 ? 0 : -1;
+ r->balance = t->balance != (char) -1 ? 0 : 1;
+ t->balance = 0;
+ break;
+ default:
+ abort ();
+ }
+ break;
+ default:
+ abort ();
+ }
+
+ if (dirs[depth - 1] == L)
+ links[depth - 1]->llink = t;
+ else
+ links[depth - 1]->rlink = t;
+ }
+ }
+
+ trie = link->trie;
+ }
+
+ /* Mark the node we finally reached as accepting, encoding the
+ index number of this word in the keyword set so far. */
+ if (!trie->accepting)
+ trie->accepting = 1 + 2 * kwset->words;
+ ++kwset->words;
+
+ /* Keep track of the longest and shortest string of the keyword set. */
+ if (trie->depth < kwset->mind)
+ kwset->mind = trie->depth;
+ if (trie->depth > kwset->maxd)
+ kwset->maxd = trie->depth;
+
+ return NULL;
+}
+
+/* Enqueue the trie nodes referenced from the given tree in the
+ given queue. */
+static void
+enqueue (struct tree *tree, struct trie **last)
+{
+ if (!tree)
+ return;
+ enqueue(tree->llink, last);
+ enqueue(tree->rlink, last);
+ (*last) = (*last)->next = tree->trie;
+}
+
+/* Compute the Aho-Corasick failure function for the trie nodes referenced
+ from the given tree, given the failure function for their parent as
+ well as a last resort failure node. */
+static void
+treefails (register struct tree const *tree, struct trie const *fail,
+ struct trie *recourse)
+{
+ register struct tree *link;
+
+ if (!tree)
+ return;
+
+ treefails(tree->llink, fail, recourse);
+ treefails(tree->rlink, fail, recourse);
+
+ /* Find, in the chain of fails going back to the root, the first
+ node that has a descendent on the current label. */
+ while (fail)
+ {
+ link = fail->links;
+ while (link && tree->label != link->label)
+ if (tree->label < link->label)
+ link = link->llink;
+ else
+ link = link->rlink;
+ if (link)
+ {
+ tree->trie->fail = link->trie;
+ return;
+ }
+ fail = fail->fail;
+ }
+
+ tree->trie->fail = recourse;
+}
+
+/* Set delta entries for the links of the given tree such that
+ the preexisting delta value is larger than the current depth. */
+static void
+treedelta (register struct tree const *tree,
+ register unsigned int depth,
+ unsigned char delta[])
+{
+ if (!tree)
+ return;
+ treedelta(tree->llink, depth, delta);
+ treedelta(tree->rlink, depth, delta);
+ if (depth < delta[tree->label])
+ delta[tree->label] = depth;
+}
+
+/* Return true if A has every label in B. */
+static int
+hasevery (register struct tree const *a, register struct tree const *b)
+{
+ if (!b)
+ return 1;
+ if (!hasevery(a, b->llink))
+ return 0;
+ if (!hasevery(a, b->rlink))
+ return 0;
+ while (a && b->label != a->label)
+ if (b->label < a->label)
+ a = a->llink;
+ else
+ a = a->rlink;
+ return !!a;
+}
+
+/* Compute a vector, indexed by character code, of the trie nodes
+ referenced from the given tree. */
+static void
+treenext (struct tree const *tree, struct trie *next[])
+{
+ if (!tree)
+ return;
+ treenext(tree->llink, next);
+ treenext(tree->rlink, next);
+ next[tree->label] = tree->trie;
+}
+
+/* Compute the shift for each trie node, as well as the delta
+ table and next cache for the given keyword set. */
+const char *
+kwsprep (kwset_t kws)
+{
+ register struct kwset *kwset;
+ register int i;
+ register struct trie *curr;
+ register char const *trans;
+ unsigned char delta[NCHAR];
+
+ kwset = (struct kwset *) kws;
+
+ /* Initial values for the delta table; will be changed later. The
+ delta entry for a given character is the smallest depth of any
+ node at which an outgoing edge is labeled by that character. */
+ memset(delta, kwset->mind < UCHAR_MAX ? kwset->mind : UCHAR_MAX, NCHAR);
+
+ /* Check if we can use the simple boyer-moore algorithm, instead
+ of the hairy commentz-walter algorithm. */
+ if (kwset->words == 1 && kwset->trans == NULL)
+ {
+ char c;
+
+ /* Looking for just one string. Extract it from the trie. */
+ kwset->target = obstack_alloc(&kwset->obstack, kwset->mind);
+ if (!kwset->target)
+ return _("memory exhausted");
+ for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i)
+ {
+ kwset->target[i] = curr->links->label;
+ curr = curr->links->trie;
+ }
+ /* Build the Boyer Moore delta. Boy that's easy compared to CW. */
+ for (i = 0; i < kwset->mind; ++i)
+ delta[U(kwset->target[i])] = kwset->mind - (i + 1);
+ /* Find the minimal delta2 shift that we might make after
+ a backwards match has failed. */
+ c = kwset->target[kwset->mind - 1];
+ for (i = kwset->mind - 2; i >= 0; --i)
+ if (kwset->target[i] == c)
+ break;
+ kwset->mind2 = kwset->mind - (i + 1);
+ }
+ else
+ {
+ register struct trie *fail;
+ struct trie *last, *next[NCHAR];
+
+ /* Traverse the nodes of the trie in level order, simultaneously
+ computing the delta table, failure function, and shift function. */
+ for (curr = last = kwset->trie; curr; curr = curr->next)
+ {
+ /* Enqueue the immediate descendents in the level order queue. */
+ enqueue(curr->links, &last);
+
+ curr->shift = kwset->mind;
+ curr->maxshift = kwset->mind;
+
+ /* Update the delta table for the descendents of this node. */
+ treedelta(curr->links, curr->depth, delta);
+
+ /* Compute the failure function for the decendents of this node. */
+ treefails(curr->links, curr->fail, kwset->trie);
+
+ /* Update the shifts at each node in the current node's chain
+ of fails back to the root. */
+ for (fail = curr->fail; fail; fail = fail->fail)
+ {
+ /* If the current node has some outgoing edge that the fail
+ doesn't, then the shift at the fail should be no larger
+ than the difference of their depths. */
+ if (!hasevery(fail->links, curr->links))
+ if (curr->depth - fail->depth < fail->shift)
+ fail->shift = curr->depth - fail->depth;
+
+ /* If the current node is accepting then the shift at the
+ fail and its descendents should be no larger than the
+ difference of their depths. */
+ if (curr->accepting && fail->maxshift > curr->depth - fail->depth)
+ fail->maxshift = curr->depth - fail->depth;
+ }
+ }
+
+ /* Traverse the trie in level order again, fixing up all nodes whose
+ shift exceeds their inherited maxshift. */
+ for (curr = kwset->trie->next; curr; curr = curr->next)
+ {
+ if (curr->maxshift > curr->parent->maxshift)
+ curr->maxshift = curr->parent->maxshift;
+ if (curr->shift > curr->maxshift)
+ curr->shift = curr->maxshift;
+ }
+
+ /* Create a vector, indexed by character code, of the outgoing links
+ from the root node. */
+ for (i = 0; i < NCHAR; ++i)
+ next[i] = NULL;
+ treenext(kwset->trie->links, next);
+
+ if ((trans = kwset->trans) != NULL)
+ for (i = 0; i < NCHAR; ++i)
+ kwset->next[i] = next[U(trans[i])];
+ else
+ memcpy(kwset->next, next, NCHAR * sizeof(struct trie *));
+ }
+
+ /* Fix things up for any translation table. */
+ if ((trans = kwset->trans) != NULL)
+ for (i = 0; i < NCHAR; ++i)
+ kwset->delta[i] = delta[U(trans[i])];
+ else
+ memcpy(kwset->delta, delta, NCHAR);
+
+ return NULL;
+}
+
+/* Fast boyer-moore search. */
+static size_t
+bmexec (kwset_t kws, char const *text, size_t size)
+{
+ struct kwset const *kwset;
+ register unsigned char const *d1;
+ register char const *ep, *sp, *tp;
+ register int d, gc, i, len, md2;
+
+ kwset = (struct kwset const *) kws;
+ len = kwset->mind;
+
+ if (len == 0)
+ return 0;
+ if (len > size)
+ return -1;
+ if (len == 1)
+ {
+ tp = memchr (text, kwset->target[0], size);
+ return tp ? tp - text : -1;
+ }
+
+ d1 = kwset->delta;
+ sp = kwset->target + len;
+ gc = U(sp[-2]);
+ md2 = kwset->mind2;
+ tp = text + len;
+
+ /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */
+ if (size > 12 * len)
+ /* 11 is not a bug, the initial offset happens only once. */
+ for (ep = text + size - 11 * len;;)
+ {
+ while (tp <= ep)
+ {
+ d = d1[U(tp[-1])], tp += d;
+ d = d1[U(tp[-1])], tp += d;
+ if (d == 0)
+ goto found;
+ d = d1[U(tp[-1])], tp += d;
+ d = d1[U(tp[-1])], tp += d;
+ d = d1[U(tp[-1])], tp += d;
+ if (d == 0)
+ goto found;
+ d = d1[U(tp[-1])], tp += d;
+ d = d1[U(tp[-1])], tp += d;
+ d = d1[U(tp[-1])], tp += d;
+ if (d == 0)
+ goto found;
+ d = d1[U(tp[-1])], tp += d;
+ d = d1[U(tp[-1])], tp += d;
+ }
+ break;
+ found:
+ if (U(tp[-2]) == gc)
+ {
+ for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i)
+ ;
+ if (i > len)
+ return tp - len - text;
+ }
+ tp += md2;
+ }
+
+ /* Now we have only a few characters left to search. We
+ carefully avoid ever producing an out-of-bounds pointer. */
+ ep = text + size;
+ d = d1[U(tp[-1])];
+ while (d <= ep - tp)
+ {
+ d = d1[U((tp += d)[-1])];
+ if (d != 0)
+ continue;
+ if (U(tp[-2]) == gc)
+ {
+ for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i)
+ ;
+ if (i > len)
+ return tp - len - text;
+ }
+ d = md2;
+ }
+
+ return -1;
+}
+
+/* Hairy multiple string search. */
+static size_t
+cwexec (kwset_t kws, char const *text, size_t len, struct kwsmatch *kwsmatch)
+{
+ struct kwset const *kwset;
+ struct trie * const *next;
+ struct trie const *trie;
+ struct trie const *accept;
+ char const *beg, *lim, *mch, *lmch;
+ register unsigned char c;
+ register unsigned char const *delta;
+ register int d;
+ register char const *end, *qlim;
+ register struct tree const *tree;
+ register char const *trans;
+
+#ifdef lint
+ accept = NULL;
+#endif
+
+ /* Initialize register copies and look for easy ways out. */
+ kwset = (struct kwset *) kws;
+ if (len < kwset->mind)
+ return -1;
+ next = kwset->next;
+ delta = kwset->delta;
+ trans = kwset->trans;
+ lim = text + len;
+ end = text;
+ if ((d = kwset->mind) != 0)
+ mch = NULL;
+ else
+ {
+ mch = text, accept = kwset->trie;
+ goto match;
+ }
+
+ if (len >= 4 * kwset->mind)
+ qlim = lim - 4 * kwset->mind;
+ else
+ qlim = NULL;
+
+ while (lim - end >= d)
+ {
+ if (qlim && end <= qlim)
+ {
+ end += d - 1;
+ while ((d = delta[c = *end]) && end < qlim)
+ {
+ end += d;
+ end += delta[U(*end)];
+ end += delta[U(*end)];
+ }
+ ++end;
+ }
+ else
+ d = delta[c = (end += d)[-1]];
+ if (d)
+ continue;
+ beg = end - 1;
+ trie = next[c];
+ if (trie->accepting)
+ {
+ mch = beg;
+ accept = trie;
+ }
+ d = trie->shift;
+ while (beg > text)
+ {
+ c = trans ? trans[U(*--beg)] : *--beg;
+ tree = trie->links;
+ while (tree && c != tree->label)
+ if (c < tree->label)
+ tree = tree->llink;
+ else
+ tree = tree->rlink;
+ if (tree)
+ {
+ trie = tree->trie;
+ if (trie->accepting)
+ {
+ mch = beg;
+ accept = trie;
+ }
+ }
+ else
+ break;
+ d = trie->shift;
+ }
+ if (mch)
+ goto match;
+ }
+ return -1;
+
+ match:
+ /* Given a known match, find the longest possible match anchored
+ at or before its starting point. This is nearly a verbatim
+ copy of the preceding main search loops. */
+ if (lim - mch > kwset->maxd)
+ lim = mch + kwset->maxd;
+ lmch = 0;
+ d = 1;
+ while (lim - end >= d)
+ {
+ if ((d = delta[c = (end += d)[-1]]) != 0)
+ continue;
+ beg = end - 1;
+ if (!(trie = next[c]))
+ {
+ d = 1;
+ continue;
+ }
+ if (trie->accepting && beg <= mch)
+ {
+ lmch = beg;
+ accept = trie;
+ }
+ d = trie->shift;
+ while (beg > text)
+ {
+ c = trans ? trans[U(*--beg)] : *--beg;
+ tree = trie->links;
+ while (tree && c != tree->label)
+ if (c < tree->label)
+ tree = tree->llink;
+ else
+ tree = tree->rlink;
+ if (tree)
+ {
+ trie = tree->trie;
+ if (trie->accepting && beg <= mch)
+ {
+ lmch = beg;
+ accept = trie;
+ }
+ }
+ else
+ break;
+ d = trie->shift;
+ }
+ if (lmch)
+ {
+ mch = lmch;
+ goto match;
+ }
+ if (!d)
+ d = 1;
+ }
+
+ if (kwsmatch)
+ {
+ kwsmatch->index = accept->accepting / 2;
+ kwsmatch->offset[0] = mch - text;
+ kwsmatch->size[0] = accept->depth;
+ }
+ return mch - text;
+}
+
+/* Search through the given text for a match of any member of the
+ given keyword set. Return a pointer to the first character of
+ the matching substring, or NULL if no match is found. If FOUNDLEN
+ is non-NULL store in the referenced location the length of the
+ matching substring. Similarly, if FOUNDIDX is non-NULL, store
+ in the referenced location the index number of the particular
+ keyword matched. */
+size_t
+kwsexec (kwset_t kws, char const *text, size_t size,
+ struct kwsmatch *kwsmatch)
+{
+ struct kwset const *kwset = (struct kwset *) kws;
+ if (kwset->words == 1 && kwset->trans == NULL)
+ {
+ size_t ret = bmexec (kws, text, size);
+ if (kwsmatch != NULL && ret != (size_t) -1)
+ {
+ kwsmatch->index = 0;
+ kwsmatch->offset[0] = ret;
+ kwsmatch->size[0] = kwset->mind;
+ }
+ return ret;
+ }
+ else
+ return cwexec(kws, text, size, kwsmatch);
+}
+
+/* Free the components of the given keyword set. */
+void
+kwsfree (kwset_t kws)
+{
+ struct kwset *kwset;
+
+ kwset = (struct kwset *) kws;
+ obstack_free(&kwset->obstack, NULL);
+ free(kws);
+}
projects / git.git / commitdiff