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-rw-r--r--e-util/e-trie.c344
1 files changed, 344 insertions, 0 deletions
diff --git a/e-util/e-trie.c b/e-util/e-trie.c
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+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
+/*
+ * Authors: Jeffrey Stedfast <fejj@ximian.com>
+ *
+ * Copyright 2002 Ximian, Inc. (www.ximian.com)
+ *
+ * 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 of the License, 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., 59 Temple Street #330, Boston, MA 02111-1307, USA.
+ *
+ */
+
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <string.h>
+
+#include "e-trie.h"
+#include "e-memory.h"
+
+#define d(x)
+
+struct _trie_state {
+ struct _trie_state *next;
+ struct _trie_state *fail;
+ struct _trie_match *match;
+ unsigned int final;
+ int id;
+};
+
+struct _trie_match {
+ struct _trie_match *next;
+ struct _trie_state *state;
+ gunichar c;
+};
+
+struct _ETrie {
+ struct _trie_state root;
+ GPtrArray *fail_states;
+ gboolean icase;
+
+ E_Memchunk *match_chunks;
+ E_Memchunk *state_chunks;
+};
+
+
+static __inline__ gunichar
+trie_utf8_getc (const unsigned char **in, size_t inlen)
+{
+ register const unsigned char *inptr = *in;
+ const unsigned char *inend = inptr + inlen;
+ register unsigned char c, r;
+ register gunichar u, m;
+
+ if (inlen == 0)
+ return 0;
+
+again:
+ r = *inptr++;
+loop:
+ if (r < 0x80) {
+ *in = inptr;
+ u = r;
+ } else if (r < 0xfe) { /* valid start char? */
+ u = r;
+ m = 0x7f80; /* used to mask out the length bits */
+ do {
+ if (inptr >= inend)
+ return 0;
+
+ c = *inptr++;
+ if ((c & 0xc0) != 0x80) {
+ r = c;
+ goto loop;
+ }
+
+ u = (u << 6) | (c & 0x3f);
+ r <<= 1;
+ m <<= 5;
+ } while (r & 0x40);
+
+ *in = inptr;
+
+ u &= ~m;
+ } else {
+ goto again;
+ }
+
+ return u;
+}
+
+
+ETrie *
+e_trie_new (gboolean icase)
+{
+ ETrie *trie;
+
+ trie = g_new (ETrie, 1);
+ trie->root.next = NULL;
+ trie->root.fail = NULL;
+ trie->root.match = NULL;
+ trie->root.final = 0;
+
+ trie->fail_states = g_ptr_array_sized_new (8);
+ trie->icase = icase;
+
+ trie->match_chunks = e_memchunk_new (8, sizeof (struct _trie_match));
+ trie->state_chunks = e_memchunk_new (8, sizeof (struct _trie_state));
+
+ return trie;
+}
+
+void
+e_trie_free (ETrie *trie)
+{
+ e_memchunk_destroy (trie->match_chunks);
+ e_memchunk_destroy (trie->state_chunks);
+ g_free (trie);
+}
+
+
+
+static struct _trie_match *
+g (struct _trie_state *s, gunichar c)
+{
+ struct _trie_match *m = s->match;
+
+ while (m && m->c != c)
+ m = m->next;
+
+ return m;
+}
+
+static struct _trie_state *
+trie_insert (ETrie *trie, int depth, struct _trie_state *q, gunichar c)
+{
+ struct _trie_match *m;
+
+ m = e_memchunk_alloc (trie->match_chunks);
+ m->next = q->match;
+ m->c = c;
+
+ q->match = m;
+ q = m->state = e_memchunk_alloc (trie->state_chunks);
+ q->match = NULL;
+ q->fail = &trie->root;
+ q->final = 0;
+ q->id = -1;
+
+ if (trie->fail_states->len < depth + 1) {
+ unsigned int size = trie->fail_states->len;
+
+ size = MAX (size + 64, depth + 1);
+ g_ptr_array_set_size (trie->fail_states, size);
+ }
+
+ q->next = trie->fail_states->pdata[depth];
+ trie->fail_states->pdata[depth] = q;
+
+ return q;
+}
+
+
+#if 1
+static void
+dump_trie (struct _trie_state *s, int depth)
+{
+ char *p = g_alloca ((depth * 2) + 1);
+ struct _trie_match *m;
+
+ memset (p, ' ', depth * 2);
+ p[depth * 2] = '\0';
+
+ fprintf (stderr, "%s[state] %p: final=%d; pattern-id=%d; fail=%p\n",
+ p, s, s->final, s->id, s->fail);
+ m = s->match;
+ while (m) {
+ fprintf (stderr, " %s'%c' -> %p\n", p, m->c, m->state);
+ if (m->state)
+ dump_trie (m->state, depth + 1);
+
+ m = m->next;
+ }
+}
+#endif
+
+
+/*
+ * final = empty set
+ * FOR p = 1 TO #pat
+ * q = root
+ * FOR j = 1 TO m[p]
+ * IF g(q, pat[p][j]) == null
+ * insert(q, pat[p][j])
+ * ENDIF
+ * q = g(q, pat[p][j])
+ * ENDFOR
+ * final = union(final, q)
+ * ENDFOR
+*/
+
+void
+e_trie_add (ETrie *trie, const char *pattern)
+{
+ const unsigned char *inptr = (const unsigned char *) pattern;
+ struct _trie_state *q, *q1, *r;
+ struct _trie_match *m, *n;
+ int i, depth = 0;
+ gunichar c;
+
+ /* Step 1: add the pattern to the trie */
+
+ q = &trie->root;
+
+ while ((c = trie_utf8_getc (&inptr, -1))) {
+ if (trie->icase)
+ c = g_unichar_tolower (c);
+
+ m = g (q, c);
+ if (m == NULL) {
+ q = trie_insert (trie, depth, q, c);
+ } else {
+ q = m->state;
+ }
+
+ depth++;
+ }
+
+ q->final = depth;
+ q->id = pattern_id;
+
+ /* Step 2: compute failure graph */
+
+ for (i = 0; i < trie->fail_states->len; i++) {
+ q = trie->fail_states->pdata[i];
+ while (q) {
+ m = q->match;
+ while (m) {
+ c = m->c;
+ q1 = m->state;
+ r = q->fail;
+ while (r && (n = g (r, c)) == NULL)
+ r = r->fail;
+
+ if (r != NULL) {
+ q1->fail = n->state;
+ if (q1->fail->final > q1->final)
+ q1->final = q1->fail->final;
+ } else {
+ if ((n = g (&trie->root, c)))
+ q1->fail = n->state;
+ else
+ q1->fail = &trie->root;
+ }
+
+ m = m->next;
+ }
+
+ q = q->next;
+ }
+ }
+
+ d(fprintf (stderr, "\nafter adding pattern '%s' to trie %p:\n", pattern, trie));
+ d(dump_trie (&trie->root, 0));
+}
+
+/*
+ * Aho-Corasick
+ *
+ * q = root
+ * FOR i = 1 TO n
+ * WHILE q != fail AND g(q, text[i]) == fail
+ * q = h(q)
+ * ENDWHILE
+ * IF q == fail
+ * q = root
+ * ELSE
+ * q = g(q, text[i])
+ * ENDIF
+ * IF isElement(q, final)
+ * RETURN TRUE
+ * ENDIF
+ * ENDFOR
+ * RETURN FALSE
+ */
+
+const char *
+e_trie_search (ETrie *trie, const char *buffer, size_t buflen, const char **pattern)
+{
+ const unsigned char *inptr, *inend, *prev, *pat;
+ register size_t inlen = buflen;
+ struct _trie_state *q;
+ struct _trie_match *m;
+ gunichar c, u;
+
+ inptr = (const unsigned char *) buffer;
+ inend = inptr + buflen;
+
+ q = &trie->root;
+ pat = prev = inptr;
+ while ((c = trie_utf8_getc (&inptr, inlen))) {
+ inlen = (inend - inptr);
+
+ if (trie->icase)
+ c = g_unichar_tolower (c);
+
+ while (q != NULL && (m = g (q, c)) == NULL)
+ q = q->fail;
+
+ if (q == &trie->root)
+ pat = prev;
+
+ if (q == NULL) {
+ q = &trie->root;
+ pat = inptr;
+ } else if (m != NULL) {
+ q = m->state;
+
+ if (q->final) {
+ if (matched_id)
+ *matched_id = q->id;
+
+ return (const char *) pat;
+ }
+ }
+
+ prev = inptr;
+ }
+
+ return NULL;
+}
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