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1 /* | |
2 ** The author disclaims copyright to this source code. | |
3 ** | |
4 ************************************************************************* | |
5 ** Implementation of the "simple" full-text-search tokenizer. | |
6 */ | |
7 | |
8 #include <assert.h> | |
9 #if !defined(__APPLE__) | |
10 #include <malloc.h> | |
11 #else | |
12 #include <stdlib.h> | |
13 #endif | |
14 #include <stdio.h> | |
15 #include <string.h> | |
16 #include <ctype.h> | |
17 | |
18 #include "tokenizer.h" | |
19 | |
20 /* Duplicate a string; the caller must free() the returned string. | |
21 * (We don't use strdup() since it's not part of the standard C library and | |
22 * may not be available everywhere.) */ | |
23 /* TODO(shess) Copied from fulltext.c, consider util.c for such | |
24 ** things. */ | |
25 static char *string_dup(const char *s){ | |
26 char *str = malloc(strlen(s) + 1); | |
27 strcpy(str, s); | |
28 return str; | |
29 } | |
30 | |
31 typedef struct simple_tokenizer { | |
32 sqlite3_tokenizer base; | |
33 const char *zDelim; /* token delimiters */ | |
34 } simple_tokenizer; | |
35 | |
36 typedef struct simple_tokenizer_cursor { | |
37 sqlite3_tokenizer_cursor base; | |
38 const char *pInput; /* input we are tokenizing */ | |
39 int nBytes; /* size of the input */ | |
40 const char *pCurrent; /* current position in pInput */ | |
41 int iToken; /* index of next token to be returned */ | |
42 char *zToken; /* storage for current token */ | |
43 int nTokenBytes; /* actual size of current token */ | |
44 int nTokenAllocated; /* space allocated to zToken buffer */ | |
45 } simple_tokenizer_cursor; | |
46 | |
47 static sqlite3_tokenizer_module simpleTokenizerModule;/* forward declaration */ | |
48 | |
49 static int simpleCreate( | |
50 int argc, const char **argv, | |
51 sqlite3_tokenizer **ppTokenizer | |
52 ){ | |
53 simple_tokenizer *t; | |
54 | |
55 t = (simple_tokenizer *) malloc(sizeof(simple_tokenizer)); | |
56 /* TODO(shess) Delimiters need to remain the same from run to run, | |
57 ** else we need to reindex. One solution would be a meta-table to | |
58 ** track such information in the database, then we'd only want this | |
59 ** information on the initial create. | |
60 */ | |
61 if( argc>1 ){ | |
62 t->zDelim = string_dup(argv[1]); | |
63 } else { | |
64 /* Build a string excluding alphanumeric ASCII characters */ | |
65 char zDelim[0x80]; /* nul-terminated, so nul not a member */ | |
66 int i, j; | |
67 for(i=1, j=0; i<0x80; i++){ | |
68 if( !isalnum(i) ){ | |
69 zDelim[j++] = i; | |
70 } | |
71 } | |
72 zDelim[j++] = '\0'; | |
73 assert( j<=sizeof(zDelim) ); | |
74 t->zDelim = string_dup(zDelim); | |
75 } | |
76 | |
77 *ppTokenizer = &t->base; | |
78 return SQLITE_OK; | |
79 } | |
80 | |
81 static int simpleDestroy(sqlite3_tokenizer *pTokenizer){ | |
82 simple_tokenizer *t = (simple_tokenizer *) pTokenizer; | |
83 | |
84 free((void *) t->zDelim); | |
85 free(t); | |
86 | |
87 return SQLITE_OK; | |
88 } | |
89 | |
90 static int simpleOpen( | |
91 sqlite3_tokenizer *pTokenizer, | |
92 const char *pInput, int nBytes, | |
93 sqlite3_tokenizer_cursor **ppCursor | |
94 ){ | |
95 simple_tokenizer_cursor *c; | |
96 | |
97 c = (simple_tokenizer_cursor *) malloc(sizeof(simple_tokenizer_cursor)); | |
98 c->pInput = pInput; | |
99 c->nBytes = nBytes<0 ? (int) strlen(pInput) : nBytes; | |
100 c->pCurrent = c->pInput; /* start tokenizing at the beginning */ | |
101 c->iToken = 0; | |
102 c->zToken = NULL; /* no space allocated, yet. */ | |
103 c->nTokenBytes = 0; | |
104 c->nTokenAllocated = 0; | |
105 | |
106 *ppCursor = &c->base; | |
107 return SQLITE_OK; | |
108 } | |
109 | |
110 static int simpleClose(sqlite3_tokenizer_cursor *pCursor){ | |
111 simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; | |
112 | |
113 if( NULL!=c->zToken ){ | |
114 free(c->zToken); | |
115 } | |
116 free(c); | |
117 | |
118 return SQLITE_OK; | |
119 } | |
120 | |
121 static int simpleNext( | |
122 sqlite3_tokenizer_cursor *pCursor, | |
123 const char **ppToken, int *pnBytes, | |
124 int *piStartOffset, int *piEndOffset, int *piPosition | |
125 ){ | |
126 simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; | |
127 simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer; | |
128 int ii; | |
129 | |
130 while( c->pCurrent-c->pInput<c->nBytes ){ | |
131 int n = (int) strcspn(c->pCurrent, t->zDelim); | |
132 if( n>0 ){ | |
133 if( n+1>c->nTokenAllocated ){ | |
134 c->zToken = realloc(c->zToken, n+1); | |
135 } | |
136 for(ii=0; ii<n; ii++){ | |
137 /* TODO(shess) This needs expansion to handle UTF-8 | |
138 ** case-insensitivity. | |
139 */ | |
140 char ch = c->pCurrent[ii]; | |
141 c->zToken[ii] = (unsigned char)ch<0x80 ? tolower(ch) : ch; | |
142 } | |
143 c->zToken[n] = '\0'; | |
144 *ppToken = c->zToken; | |
145 *pnBytes = n; | |
146 *piStartOffset = (int) (c->pCurrent-c->pInput); | |
147 *piEndOffset = *piStartOffset+n; | |
148 *piPosition = c->iToken++; | |
149 c->pCurrent += n + 1; | |
150 | |
151 return SQLITE_OK; | |
152 } | |
153 c->pCurrent += n + 1; | |
154 /* TODO(shess) could strspn() to skip delimiters en masse. Needs | |
155 ** to happen in two places, though, which is annoying. | |
156 */ | |
157 } | |
158 return SQLITE_DONE; | |
159 } | |
160 | |
161 static sqlite3_tokenizer_module simpleTokenizerModule = { | |
162 0, | |
163 simpleCreate, | |
164 simpleDestroy, | |
165 simpleOpen, | |
166 simpleClose, | |
167 simpleNext, | |
168 }; | |
169 | |
170 void get_simple_tokenizer_module( | |
171 sqlite3_tokenizer_module **ppModule | |
172 ){ | |
173 *ppModule = &simpleTokenizerModule; | |
174 } | |
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