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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 FTS3 module is being built as an extension |
| 20 ** (in which case SQLITE_CORE is not defined), or |
| 21 ** |
| 22 ** * The FTS3 module is being built into the core of |
| 23 ** SQLite (in which case SQLITE_ENABLE_FTS3 is defined). |
| 24 */ |
| 25 #if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) |
| 26 |
| 27 #include "fts3Int.h" |
| 28 |
| 29 #include <assert.h> |
| 30 #include <stdlib.h> |
| 31 #include <stdio.h> |
| 32 #include <string.h> |
| 33 |
| 34 #include "fts3_tokenizer.h" |
| 35 |
| 36 typedef struct simple_tokenizer { |
| 37 sqlite3_tokenizer base; |
| 38 char delim[128]; /* flag ASCII delimiters */ |
| 39 } simple_tokenizer; |
| 40 |
| 41 typedef struct simple_tokenizer_cursor { |
| 42 sqlite3_tokenizer_cursor base; |
| 43 const char *pInput; /* input we are tokenizing */ |
| 44 int nBytes; /* size of the input */ |
| 45 int iOffset; /* current position in pInput */ |
| 46 int iToken; /* index of next token to be returned */ |
| 47 char *pToken; /* storage for current token */ |
| 48 int nTokenAllocated; /* space allocated to zToken buffer */ |
| 49 } simple_tokenizer_cursor; |
| 50 |
| 51 |
| 52 static int simpleDelim(simple_tokenizer *t, unsigned char c){ |
| 53 return c<0x80 && t->delim[c]; |
| 54 } |
| 55 static int fts3_isalnum(int x){ |
| 56 return (x>='0' && x<='9') || (x>='A' && x<='Z') || (x>='a' && x<='z'); |
| 57 } |
| 58 |
| 59 /* |
| 60 ** Create a new tokenizer instance. |
| 61 */ |
| 62 static int simpleCreate( |
| 63 int argc, const char * const *argv, |
| 64 sqlite3_tokenizer **ppTokenizer |
| 65 ){ |
| 66 simple_tokenizer *t; |
| 67 |
| 68 t = (simple_tokenizer *) sqlite3_malloc(sizeof(*t)); |
| 69 if( t==NULL ) return SQLITE_NOMEM; |
| 70 memset(t, 0, sizeof(*t)); |
| 71 |
| 72 /* TODO(shess) Delimiters need to remain the same from run to run, |
| 73 ** else we need to reindex. One solution would be a meta-table to |
| 74 ** track such information in the database, then we'd only want this |
| 75 ** information on the initial create. |
| 76 */ |
| 77 if( argc>1 ){ |
| 78 int i, n = (int)strlen(argv[1]); |
| 79 for(i=0; i<n; i++){ |
| 80 unsigned char ch = argv[1][i]; |
| 81 /* We explicitly don't support UTF-8 delimiters for now. */ |
| 82 if( ch>=0x80 ){ |
| 83 sqlite3_free(t); |
| 84 return SQLITE_ERROR; |
| 85 } |
| 86 t->delim[ch] = 1; |
| 87 } |
| 88 } else { |
| 89 /* Mark non-alphanumeric ASCII characters as delimiters */ |
| 90 int i; |
| 91 for(i=1; i<0x80; i++){ |
| 92 t->delim[i] = !fts3_isalnum(i) ? -1 : 0; |
| 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 UNUSED_PARAMETER(pTokenizer); |
| 122 |
| 123 c = (simple_tokenizer_cursor *) sqlite3_malloc(sizeof(*c)); |
| 124 if( c==NULL ) return SQLITE_NOMEM; |
| 125 |
| 126 c->pInput = pInput; |
| 127 if( pInput==0 ){ |
| 128 c->nBytes = 0; |
| 129 }else if( nBytes<0 ){ |
| 130 c->nBytes = (int)strlen(pInput); |
| 131 }else{ |
| 132 c->nBytes = nBytes; |
| 133 } |
| 134 c->iOffset = 0; /* start tokenizing at the beginning */ |
| 135 c->iToken = 0; |
| 136 c->pToken = NULL; /* no space allocated, yet. */ |
| 137 c->nTokenAllocated = 0; |
| 138 |
| 139 *ppCursor = &c->base; |
| 140 return SQLITE_OK; |
| 141 } |
| 142 |
| 143 /* |
| 144 ** Close a tokenization cursor previously opened by a call to |
| 145 ** simpleOpen() above. |
| 146 */ |
| 147 static int simpleClose(sqlite3_tokenizer_cursor *pCursor){ |
| 148 simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; |
| 149 sqlite3_free(c->pToken); |
| 150 sqlite3_free(c); |
| 151 return SQLITE_OK; |
| 152 } |
| 153 |
| 154 /* |
| 155 ** Extract the next token from a tokenization cursor. The cursor must |
| 156 ** have been opened by a prior call to simpleOpen(). |
| 157 */ |
| 158 static int simpleNext( |
| 159 sqlite3_tokenizer_cursor *pCursor, /* Cursor returned by simpleOpen */ |
| 160 const char **ppToken, /* OUT: *ppToken is the token text */ |
| 161 int *pnBytes, /* OUT: Number of bytes in token */ |
| 162 int *piStartOffset, /* OUT: Starting offset of token */ |
| 163 int *piEndOffset, /* OUT: Ending offset of token */ |
| 164 int *piPosition /* OUT: Position integer of token */ |
| 165 ){ |
| 166 simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; |
| 167 simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer; |
| 168 unsigned char *p = (unsigned char *)c->pInput; |
| 169 |
| 170 while( c->iOffset<c->nBytes ){ |
| 171 int iStartOffset; |
| 172 |
| 173 /* Scan past delimiter characters */ |
| 174 while( c->iOffset<c->nBytes && simpleDelim(t, p[c->iOffset]) ){ |
| 175 c->iOffset++; |
| 176 } |
| 177 |
| 178 /* Count non-delimiter characters. */ |
| 179 iStartOffset = c->iOffset; |
| 180 while( c->iOffset<c->nBytes && !simpleDelim(t, p[c->iOffset]) ){ |
| 181 c->iOffset++; |
| 182 } |
| 183 |
| 184 if( c->iOffset>iStartOffset ){ |
| 185 int i, n = c->iOffset-iStartOffset; |
| 186 if( n>c->nTokenAllocated ){ |
| 187 char *pNew; |
| 188 c->nTokenAllocated = n+20; |
| 189 pNew = sqlite3_realloc(c->pToken, c->nTokenAllocated); |
| 190 if( !pNew ) return SQLITE_NOMEM; |
| 191 c->pToken = pNew; |
| 192 } |
| 193 for(i=0; i<n; i++){ |
| 194 /* TODO(shess) This needs expansion to handle UTF-8 |
| 195 ** case-insensitivity. |
| 196 */ |
| 197 unsigned char ch = p[iStartOffset+i]; |
| 198 c->pToken[i] = (char)((ch>='A' && ch<='Z') ? ch-'A'+'a' : ch); |
| 199 } |
| 200 *ppToken = c->pToken; |
| 201 *pnBytes = n; |
| 202 *piStartOffset = iStartOffset; |
| 203 *piEndOffset = c->iOffset; |
| 204 *piPosition = c->iToken++; |
| 205 |
| 206 return SQLITE_OK; |
| 207 } |
| 208 } |
| 209 return SQLITE_DONE; |
| 210 } |
| 211 |
| 212 /* |
| 213 ** The set of routines that implement the simple tokenizer |
| 214 */ |
| 215 static const sqlite3_tokenizer_module simpleTokenizerModule = { |
| 216 0, |
| 217 simpleCreate, |
| 218 simpleDestroy, |
| 219 simpleOpen, |
| 220 simpleClose, |
| 221 simpleNext, |
| 222 }; |
| 223 |
| 224 /* |
| 225 ** Allocate a new simple tokenizer. Return a pointer to the new |
| 226 ** tokenizer in *ppModule |
| 227 */ |
| 228 void sqlite3Fts3SimpleTokenizerModule( |
| 229 sqlite3_tokenizer_module const**ppModule |
| 230 ){ |
| 231 *ppModule = &simpleTokenizerModule; |
| 232 } |
| 233 |
| 234 #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */ |
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