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| 1 /* |
| 2 ** 2006 Oct 10 |
| 3 ** |
| 4 ** The author disclaims copyright to this source code. In place of |
| 5 ** a legal notice, here is a blessing: |
| 6 ** |
| 7 ** May you do good and not evil. |
| 8 ** May you find forgiveness for yourself and forgive others. |
| 9 ** May you share freely, never taking more than you give. |
| 10 ** |
| 11 ****************************************************************************** |
| 12 ** |
| 13 ** Implementation of the "simple" full-text-search tokenizer. |
| 14 */ |
| 15 |
| 16 /* |
| 17 ** The code in this file is only compiled if: |
| 18 ** |
| 19 ** * The FTS2 module is being built as an extension |
| 20 ** (in which case SQLITE_CORE is not defined), or |
| 21 ** |
| 22 ** * The FTS2 module is being built into the core of |
| 23 ** SQLite (in which case SQLITE_ENABLE_FTS2 is defined). |
| 24 */ |
| 25 #if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS2) |
| 26 |
| 27 |
| 28 #include <assert.h> |
| 29 #include <stdlib.h> |
| 30 #include <stdio.h> |
| 31 #include <string.h> |
| 32 |
| 33 #include "fts2_tokenizer.h" |
| 34 |
| 35 typedef struct simple_tokenizer { |
| 36 sqlite3_tokenizer base; |
| 37 char delim[128]; /* flag ASCII delimiters */ |
| 38 } simple_tokenizer; |
| 39 |
| 40 typedef struct simple_tokenizer_cursor { |
| 41 sqlite3_tokenizer_cursor base; |
| 42 const char *pInput; /* input we are tokenizing */ |
| 43 int nBytes; /* size of the input */ |
| 44 int iOffset; /* current position in pInput */ |
| 45 int iToken; /* index of next token to be returned */ |
| 46 char *pToken; /* storage for current token */ |
| 47 int nTokenAllocated; /* space allocated to zToken buffer */ |
| 48 } simple_tokenizer_cursor; |
| 49 |
| 50 |
| 51 /* Forward declaration */ |
| 52 static const sqlite3_tokenizer_module simpleTokenizerModule; |
| 53 |
| 54 static int simpleDelim(simple_tokenizer *t, unsigned char c){ |
| 55 return c<0x80 && t->delim[c]; |
| 56 } |
| 57 |
| 58 /* |
| 59 ** Create a new tokenizer instance. |
| 60 */ |
| 61 static int simpleCreate( |
| 62 int argc, const char * const *argv, |
| 63 sqlite3_tokenizer **ppTokenizer |
| 64 ){ |
| 65 simple_tokenizer *t; |
| 66 |
| 67 t = (simple_tokenizer *) sqlite3_malloc(sizeof(*t)); |
| 68 if( t==NULL ) return SQLITE_NOMEM; |
| 69 memset(t, 0, sizeof(*t)); |
| 70 |
| 71 /* TODO(shess) Delimiters need to remain the same from run to run, |
| 72 ** else we need to reindex. One solution would be a meta-table to |
| 73 ** track such information in the database, then we'd only want this |
| 74 ** information on the initial create. |
| 75 */ |
| 76 if( argc>1 ){ |
| 77 int i, n = strlen(argv[1]); |
| 78 for(i=0; i<n; i++){ |
| 79 unsigned char ch = argv[1][i]; |
| 80 /* We explicitly don't support UTF-8 delimiters for now. */ |
| 81 if( ch>=0x80 ){ |
| 82 sqlite3_free(t); |
| 83 return SQLITE_ERROR; |
| 84 } |
| 85 t->delim[ch] = 1; |
| 86 } |
| 87 } else { |
| 88 /* Mark non-alphanumeric ASCII characters as delimiters */ |
| 89 int i; |
| 90 for(i=1; i<0x80; i++){ |
| 91 t->delim[i] = !((i>='0' && i<='9') || (i>='A' && i<='Z') || |
| 92 (i>='a' && i<='z')); |
| 93 } |
| 94 } |
| 95 |
| 96 *ppTokenizer = &t->base; |
| 97 return SQLITE_OK; |
| 98 } |
| 99 |
| 100 /* |
| 101 ** Destroy a tokenizer |
| 102 */ |
| 103 static int simpleDestroy(sqlite3_tokenizer *pTokenizer){ |
| 104 sqlite3_free(pTokenizer); |
| 105 return SQLITE_OK; |
| 106 } |
| 107 |
| 108 /* |
| 109 ** Prepare to begin tokenizing a particular string. The input |
| 110 ** string to be tokenized is pInput[0..nBytes-1]. A cursor |
| 111 ** used to incrementally tokenize this string is returned in |
| 112 ** *ppCursor. |
| 113 */ |
| 114 static int simpleOpen( |
| 115 sqlite3_tokenizer *pTokenizer, /* The tokenizer */ |
| 116 const char *pInput, int nBytes, /* String to be tokenized */ |
| 117 sqlite3_tokenizer_cursor **ppCursor /* OUT: Tokenization cursor */ |
| 118 ){ |
| 119 simple_tokenizer_cursor *c; |
| 120 |
| 121 c = (simple_tokenizer_cursor *) sqlite3_malloc(sizeof(*c)); |
| 122 if( c==NULL ) return SQLITE_NOMEM; |
| 123 |
| 124 c->pInput = pInput; |
| 125 if( pInput==0 ){ |
| 126 c->nBytes = 0; |
| 127 }else if( nBytes<0 ){ |
| 128 c->nBytes = (int)strlen(pInput); |
| 129 }else{ |
| 130 c->nBytes = nBytes; |
| 131 } |
| 132 c->iOffset = 0; /* start tokenizing at the beginning */ |
| 133 c->iToken = 0; |
| 134 c->pToken = NULL; /* no space allocated, yet. */ |
| 135 c->nTokenAllocated = 0; |
| 136 |
| 137 *ppCursor = &c->base; |
| 138 return SQLITE_OK; |
| 139 } |
| 140 |
| 141 /* |
| 142 ** Close a tokenization cursor previously opened by a call to |
| 143 ** simpleOpen() above. |
| 144 */ |
| 145 static int simpleClose(sqlite3_tokenizer_cursor *pCursor){ |
| 146 simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; |
| 147 sqlite3_free(c->pToken); |
| 148 sqlite3_free(c); |
| 149 return SQLITE_OK; |
| 150 } |
| 151 |
| 152 /* |
| 153 ** Extract the next token from a tokenization cursor. The cursor must |
| 154 ** have been opened by a prior call to simpleOpen(). |
| 155 */ |
| 156 static int simpleNext( |
| 157 sqlite3_tokenizer_cursor *pCursor, /* Cursor returned by simpleOpen */ |
| 158 const char **ppToken, /* OUT: *ppToken is the token text */ |
| 159 int *pnBytes, /* OUT: Number of bytes in token */ |
| 160 int *piStartOffset, /* OUT: Starting offset of token */ |
| 161 int *piEndOffset, /* OUT: Ending offset of token */ |
| 162 int *piPosition /* OUT: Position integer of token */ |
| 163 ){ |
| 164 simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; |
| 165 simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer; |
| 166 unsigned char *p = (unsigned char *)c->pInput; |
| 167 |
| 168 while( c->iOffset<c->nBytes ){ |
| 169 int iStartOffset; |
| 170 |
| 171 /* Scan past delimiter characters */ |
| 172 while( c->iOffset<c->nBytes && simpleDelim(t, p[c->iOffset]) ){ |
| 173 c->iOffset++; |
| 174 } |
| 175 |
| 176 /* Count non-delimiter characters. */ |
| 177 iStartOffset = c->iOffset; |
| 178 while( c->iOffset<c->nBytes && !simpleDelim(t, p[c->iOffset]) ){ |
| 179 c->iOffset++; |
| 180 } |
| 181 |
| 182 if( c->iOffset>iStartOffset ){ |
| 183 int i, n = c->iOffset-iStartOffset; |
| 184 if( n>c->nTokenAllocated ){ |
| 185 c->nTokenAllocated = n+20; |
| 186 c->pToken = sqlite3_realloc(c->pToken, c->nTokenAllocated); |
| 187 if( c->pToken==NULL ) return SQLITE_NOMEM; |
| 188 } |
| 189 for(i=0; i<n; i++){ |
| 190 /* TODO(shess) This needs expansion to handle UTF-8 |
| 191 ** case-insensitivity. |
| 192 */ |
| 193 unsigned char ch = p[iStartOffset+i]; |
| 194 c->pToken[i] = (ch>='A' && ch<='Z') ? (ch - 'A' + 'a') : ch; |
| 195 } |
| 196 *ppToken = c->pToken; |
| 197 *pnBytes = n; |
| 198 *piStartOffset = iStartOffset; |
| 199 *piEndOffset = c->iOffset; |
| 200 *piPosition = c->iToken++; |
| 201 |
| 202 return SQLITE_OK; |
| 203 } |
| 204 } |
| 205 return SQLITE_DONE; |
| 206 } |
| 207 |
| 208 /* |
| 209 ** The set of routines that implement the simple tokenizer |
| 210 */ |
| 211 static const sqlite3_tokenizer_module simpleTokenizerModule = { |
| 212 0, |
| 213 simpleCreate, |
| 214 simpleDestroy, |
| 215 simpleOpen, |
| 216 simpleClose, |
| 217 simpleNext, |
| 218 }; |
| 219 |
| 220 /* |
| 221 ** Allocate a new simple tokenizer. Return a pointer to the new |
| 222 ** tokenizer in *ppModule |
| 223 */ |
| 224 void sqlite3Fts2SimpleTokenizerModule( |
| 225 sqlite3_tokenizer_module const**ppModule |
| 226 ){ |
| 227 *ppModule = &simpleTokenizerModule; |
| 228 } |
| 229 |
| 230 #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS2) */ |
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