1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
|
/* Copyright (C) 2005 MySQL AB
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; version 2 of the License.
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 Place, Suite 330, Boston, MA 02111-1307 USA */
/*
Implementation of trie and Aho-Corasick automaton.
Supports only charsets that can be compared byte-wise.
TODO:
Add character frequencies. Can increase lookup speed
up to 30%.
Implement character-wise comparision.
*/
#include "mysys_priv.h"
#include <m_string.h>
#include <my_trie.h>
#include <my_base.h>
/*
SYNOPSIS
TRIE *trie_init (TRIE *trie, CHARSET_INFO *charset);
DESCRIPTION
Allocates or initializes a `TRIE' object. If `trie' is a `NULL'
pointer, the function allocates, initializes, and returns a new
object. Otherwise, the object is initialized and the address of
the object is returned. If `trie_init()' allocates a new object,
it will be freed when `trie_free()' is called.
RETURN VALUE
An initialized `TRIE*' object. `NULL' if there was insufficient
memory to allocate a new object.
*/
TRIE *trie_init (TRIE *trie, CHARSET_INFO *charset)
{
MEM_ROOT mem_root;
assert(charset);
init_alloc_root(&mem_root,
(sizeof(TRIE_NODE) * 128) + ALLOC_ROOT_MIN_BLOCK_SIZE,
sizeof(TRIE_NODE) * 128);
if (! trie)
{
if (! (trie= (TRIE *)alloc_root(&mem_root, sizeof(TRIE))))
{
free_root(&mem_root, MYF(0));
return(NULL);
}
}
memcpy(&trie->mem_root, &mem_root, sizeof(MEM_ROOT));
trie->root.leaf= 0;
trie->root.c= 0;
trie->root.next= NULL;
trie->root.links= NULL;
trie->root.fail= NULL;
trie->charset= charset;
trie->nnodes= 0;
trie->nwords= 0;
return(trie);
}
/*
SYNOPSIS
void trie_free (TRIE *trie);
trie - valid pointer to `TRIE'
DESCRIPTION
Frees the memory allocated for a `trie'.
RETURN VALUE
None.
*/
void trie_free (TRIE *trie)
{
MEM_ROOT mem_root;
assert(trie);
memcpy(&mem_root, &trie->mem_root, sizeof(MEM_ROOT));
free_root(&mem_root, MYF(0));
return;
}
/*
SYNOPSIS
bool trie_insert (TRIE *trie, const uchar *key, uint keylen);
trie - valid pointer to `TRIE'
key - valid pointer to key to insert
keylen - non-0 key length
DESCRIPTION
Inserts new key into trie.
RETURN VALUE
Upon successful completion, `trie_insert' returns `false'. Otherwise
`true' is returned.
NOTES
If this function fails you must assume `trie' is broken.
However it can be freed with trie_free().
*/
bool trie_insert (TRIE *trie, const uchar *key, uint keylen)
{
TRIE_NODE *node;
TRIE_NODE *next;
uchar p;
uint k;
assert(trie && key && keylen);
node= &trie->root;
trie->root.fail= NULL;
for (k= 0; k < keylen; k++)
{
p= key[k];
for (next= node->links; next; next= next->next)
if (next->c == p)
break;
if (! next)
{
TRIE_NODE *tmp= (TRIE_NODE *)alloc_root(&trie->mem_root,
sizeof(TRIE_NODE));
if (! tmp)
return(true);
tmp->leaf= 0;
tmp->c= p;
tmp->links= tmp->fail= tmp->next= NULL;
trie->nnodes++;
if (! node->links)
{
node->links= tmp;
}
else
{
for (next= node->links; next->next; next= next->next) /* no-op */;
next->next= tmp;
}
node= tmp;
}
else
{
node= next;
}
}
node->leaf= keylen;
trie->nwords++;
return(false);
}
/*
SYNOPSIS
bool trie_prepare (TRIE *trie);
trie - valid pointer to `TRIE'
DESCRIPTION
Constructs Aho-Corasick automaton.
RETURN VALUE
Upon successful completion, `trie_prepare' returns `false'. Otherwise
`true' is returned.
*/
bool ac_trie_prepare (TRIE *trie)
{
TRIE_NODE **tmp_nodes;
TRIE_NODE *node;
uint32 fnode= 0;
uint32 lnode= 0;
assert(trie);
tmp_nodes= (TRIE_NODE **)my_malloc(trie->nnodes * sizeof(TRIE_NODE *), MYF(0));
if (! tmp_nodes)
return(true);
trie->root.fail= &trie->root;
for (node= trie->root.links; node; node= node->next)
{
node->fail= &trie->root;
tmp_nodes[lnode++]= node;
}
while (fnode < lnode)
{
TRIE_NODE *current= (TRIE_NODE *)tmp_nodes[fnode++];
for (node= current->links; node; node= node->next)
{
TRIE_NODE *fail= current->fail;
tmp_nodes[lnode++]= node;
while (! (node->fail= trie_goto(&trie->root, fail, node->c)))
fail= fail->fail;
}
}
my_free((uchar*)tmp_nodes, MYF(0));
return(false);
}
/*
SYNOPSIS
void ac_trie_init (TRIE *trie, AC_TRIE_STATE *state);
trie - valid pointer to `TRIE'
state - value pointer to `AC_TRIE_STATE'
DESCRIPTION
Initializes `AC_TRIE_STATE' object.
*/
void ac_trie_init (TRIE *trie, AC_TRIE_STATE *state)
{
assert(trie && state);
state->trie= trie;
state->node= &trie->root;
return;
}
|