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| 1 /* | |
| 2 ** 2006 September 30 | |
| 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 ** Implementation of the full-text-search tokenizer that implements | |
| 13 ** a Porter stemmer. | |
| 14 */ | |
| 15 | |
| 16 /* | |
| 17 ** The code in this file is only compiled if: | |
| 18 ** | |
| 19 ** * The FTS1 module is being built as an extension | |
| 20 ** (in which case SQLITE_CORE is not defined), or | |
| 21 ** | |
| 22 ** * The FTS1 module is being built into the core of | |
| 23 ** SQLite (in which case SQLITE_ENABLE_FTS1 is defined). | |
| 24 */ | |
| 25 #if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) | |
| 26 | |
| 27 | |
| 28 #include <assert.h> | |
| 29 #include <stdlib.h> | |
| 30 #include <stdio.h> | |
| 31 #include <string.h> | |
| 32 #include <ctype.h> | |
| 33 | |
| 34 #include "fts1_tokenizer.h" | |
| 35 | |
| 36 /* | |
| 37 ** Class derived from sqlite3_tokenizer | |
| 38 */ | |
| 39 typedef struct porter_tokenizer { | |
| 40 sqlite3_tokenizer base; /* Base class */ | |
| 41 } porter_tokenizer; | |
| 42 | |
| 43 /* | |
| 44 ** Class derived from sqlit3_tokenizer_cursor | |
| 45 */ | |
| 46 typedef struct porter_tokenizer_cursor { | |
| 47 sqlite3_tokenizer_cursor base; | |
| 48 const char *zInput; /* input we are tokenizing */ | |
| 49 int nInput; /* size of the input */ | |
| 50 int iOffset; /* current position in zInput */ | |
| 51 int iToken; /* index of next token to be returned */ | |
| 52 char *zToken; /* storage for current token */ | |
| 53 int nAllocated; /* space allocated to zToken buffer */ | |
| 54 } porter_tokenizer_cursor; | |
| 55 | |
| 56 | |
| 57 /* Forward declaration */ | |
| 58 static const sqlite3_tokenizer_module porterTokenizerModule; | |
| 59 | |
| 60 | |
| 61 /* | |
| 62 ** Create a new tokenizer instance. | |
| 63 */ | |
| 64 static int porterCreate( | |
| 65 int argc, const char * const *argv, | |
| 66 sqlite3_tokenizer **ppTokenizer | |
| 67 ){ | |
| 68 porter_tokenizer *t; | |
| 69 t = (porter_tokenizer *) calloc(sizeof(*t), 1); | |
| 70 if( t==NULL ) return SQLITE_NOMEM; | |
| 71 | |
| 72 *ppTokenizer = &t->base; | |
| 73 return SQLITE_OK; | |
| 74 } | |
| 75 | |
| 76 /* | |
| 77 ** Destroy a tokenizer | |
| 78 */ | |
| 79 static int porterDestroy(sqlite3_tokenizer *pTokenizer){ | |
| 80 free(pTokenizer); | |
| 81 return SQLITE_OK; | |
| 82 } | |
| 83 | |
| 84 /* | |
| 85 ** Prepare to begin tokenizing a particular string. The input | |
| 86 ** string to be tokenized is zInput[0..nInput-1]. A cursor | |
| 87 ** used to incrementally tokenize this string is returned in | |
| 88 ** *ppCursor. | |
| 89 */ | |
| 90 static int porterOpen( | |
| 91 sqlite3_tokenizer *pTokenizer, /* The tokenizer */ | |
| 92 const char *zInput, int nInput, /* String to be tokenized */ | |
| 93 sqlite3_tokenizer_cursor **ppCursor /* OUT: Tokenization cursor */ | |
| 94 ){ | |
| 95 porter_tokenizer_cursor *c; | |
| 96 | |
| 97 c = (porter_tokenizer_cursor *) malloc(sizeof(*c)); | |
| 98 if( c==NULL ) return SQLITE_NOMEM; | |
| 99 | |
| 100 c->zInput = zInput; | |
| 101 if( zInput==0 ){ | |
| 102 c->nInput = 0; | |
| 103 }else if( nInput<0 ){ | |
| 104 c->nInput = (int)strlen(zInput); | |
| 105 }else{ | |
| 106 c->nInput = nInput; | |
| 107 } | |
| 108 c->iOffset = 0; /* start tokenizing at the beginning */ | |
| 109 c->iToken = 0; | |
| 110 c->zToken = NULL; /* no space allocated, yet. */ | |
| 111 c->nAllocated = 0; | |
| 112 | |
| 113 *ppCursor = &c->base; | |
| 114 return SQLITE_OK; | |
| 115 } | |
| 116 | |
| 117 /* | |
| 118 ** Close a tokenization cursor previously opened by a call to | |
| 119 ** porterOpen() above. | |
| 120 */ | |
| 121 static int porterClose(sqlite3_tokenizer_cursor *pCursor){ | |
| 122 porter_tokenizer_cursor *c = (porter_tokenizer_cursor *) pCursor; | |
| 123 free(c->zToken); | |
| 124 free(c); | |
| 125 return SQLITE_OK; | |
| 126 } | |
| 127 /* | |
| 128 ** Vowel or consonant | |
| 129 */ | |
| 130 static const char cType[] = { | |
| 131 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, | |
| 132 1, 1, 1, 2, 1 | |
| 133 }; | |
| 134 | |
| 135 /* | |
| 136 ** isConsonant() and isVowel() determine if their first character in | |
| 137 ** the string they point to is a consonant or a vowel, according | |
| 138 ** to Porter ruls. | |
| 139 ** | |
| 140 ** A consonate is any letter other than 'a', 'e', 'i', 'o', or 'u'. | |
| 141 ** 'Y' is a consonant unless it follows another consonant, | |
| 142 ** in which case it is a vowel. | |
| 143 ** | |
| 144 ** In these routine, the letters are in reverse order. So the 'y' rule | |
| 145 ** is that 'y' is a consonant unless it is followed by another | |
| 146 ** consonent. | |
| 147 */ | |
| 148 static int isVowel(const char*); | |
| 149 static int isConsonant(const char *z){ | |
| 150 int j; | |
| 151 char x = *z; | |
| 152 if( x==0 ) return 0; | |
| 153 assert( x>='a' && x<='z' ); | |
| 154 j = cType[x-'a']; | |
| 155 if( j<2 ) return j; | |
| 156 return z[1]==0 || isVowel(z + 1); | |
| 157 } | |
| 158 static int isVowel(const char *z){ | |
| 159 int j; | |
| 160 char x = *z; | |
| 161 if( x==0 ) return 0; | |
| 162 assert( x>='a' && x<='z' ); | |
| 163 j = cType[x-'a']; | |
| 164 if( j<2 ) return 1-j; | |
| 165 return isConsonant(z + 1); | |
| 166 } | |
| 167 | |
| 168 /* | |
| 169 ** Let any sequence of one or more vowels be represented by V and let | |
| 170 ** C be sequence of one or more consonants. Then every word can be | |
| 171 ** represented as: | |
| 172 ** | |
| 173 ** [C] (VC){m} [V] | |
| 174 ** | |
| 175 ** In prose: A word is an optional consonant followed by zero or | |
| 176 ** vowel-consonant pairs followed by an optional vowel. "m" is the | |
| 177 ** number of vowel consonant pairs. This routine computes the value | |
| 178 ** of m for the first i bytes of a word. | |
| 179 ** | |
| 180 ** Return true if the m-value for z is 1 or more. In other words, | |
| 181 ** return true if z contains at least one vowel that is followed | |
| 182 ** by a consonant. | |
| 183 ** | |
| 184 ** In this routine z[] is in reverse order. So we are really looking | |
| 185 ** for an instance of of a consonant followed by a vowel. | |
| 186 */ | |
| 187 static int m_gt_0(const char *z){ | |
| 188 while( isVowel(z) ){ z++; } | |
| 189 if( *z==0 ) return 0; | |
| 190 while( isConsonant(z) ){ z++; } | |
| 191 return *z!=0; | |
| 192 } | |
| 193 | |
| 194 /* Like mgt0 above except we are looking for a value of m which is | |
| 195 ** exactly 1 | |
| 196 */ | |
| 197 static int m_eq_1(const char *z){ | |
| 198 while( isVowel(z) ){ z++; } | |
| 199 if( *z==0 ) return 0; | |
| 200 while( isConsonant(z) ){ z++; } | |
| 201 if( *z==0 ) return 0; | |
| 202 while( isVowel(z) ){ z++; } | |
| 203 if( *z==0 ) return 1; | |
| 204 while( isConsonant(z) ){ z++; } | |
| 205 return *z==0; | |
| 206 } | |
| 207 | |
| 208 /* Like mgt0 above except we are looking for a value of m>1 instead | |
| 209 ** or m>0 | |
| 210 */ | |
| 211 static int m_gt_1(const char *z){ | |
| 212 while( isVowel(z) ){ z++; } | |
| 213 if( *z==0 ) return 0; | |
| 214 while( isConsonant(z) ){ z++; } | |
| 215 if( *z==0 ) return 0; | |
| 216 while( isVowel(z) ){ z++; } | |
| 217 if( *z==0 ) return 0; | |
| 218 while( isConsonant(z) ){ z++; } | |
| 219 return *z!=0; | |
| 220 } | |
| 221 | |
| 222 /* | |
| 223 ** Return TRUE if there is a vowel anywhere within z[0..n-1] | |
| 224 */ | |
| 225 static int hasVowel(const char *z){ | |
| 226 while( isConsonant(z) ){ z++; } | |
| 227 return *z!=0; | |
| 228 } | |
| 229 | |
| 230 /* | |
| 231 ** Return TRUE if the word ends in a double consonant. | |
| 232 ** | |
| 233 ** The text is reversed here. So we are really looking at | |
| 234 ** the first two characters of z[]. | |
| 235 */ | |
| 236 static int doubleConsonant(const char *z){ | |
| 237 return isConsonant(z) && z[0]==z[1] && isConsonant(z+1); | |
| 238 } | |
| 239 | |
| 240 /* | |
| 241 ** Return TRUE if the word ends with three letters which | |
| 242 ** are consonant-vowel-consonent and where the final consonant | |
| 243 ** is not 'w', 'x', or 'y'. | |
| 244 ** | |
| 245 ** The word is reversed here. So we are really checking the | |
| 246 ** first three letters and the first one cannot be in [wxy]. | |
| 247 */ | |
| 248 static int star_oh(const char *z){ | |
| 249 return | |
| 250 z[0]!=0 && isConsonant(z) && | |
| 251 z[0]!='w' && z[0]!='x' && z[0]!='y' && | |
| 252 z[1]!=0 && isVowel(z+1) && | |
| 253 z[2]!=0 && isConsonant(z+2); | |
| 254 } | |
| 255 | |
| 256 /* | |
| 257 ** If the word ends with zFrom and xCond() is true for the stem | |
| 258 ** of the word that preceeds the zFrom ending, then change the | |
| 259 ** ending to zTo. | |
| 260 ** | |
| 261 ** The input word *pz and zFrom are both in reverse order. zTo | |
| 262 ** is in normal order. | |
| 263 ** | |
| 264 ** Return TRUE if zFrom matches. Return FALSE if zFrom does not | |
| 265 ** match. Not that TRUE is returned even if xCond() fails and | |
| 266 ** no substitution occurs. | |
| 267 */ | |
| 268 static int stem( | |
| 269 char **pz, /* The word being stemmed (Reversed) */ | |
| 270 const char *zFrom, /* If the ending matches this... (Reversed) */ | |
| 271 const char *zTo, /* ... change the ending to this (not reversed) */ | |
| 272 int (*xCond)(const char*) /* Condition that must be true */ | |
| 273 ){ | |
| 274 char *z = *pz; | |
| 275 while( *zFrom && *zFrom==*z ){ z++; zFrom++; } | |
| 276 if( *zFrom!=0 ) return 0; | |
| 277 if( xCond && !xCond(z) ) return 1; | |
| 278 while( *zTo ){ | |
| 279 *(--z) = *(zTo++); | |
| 280 } | |
| 281 *pz = z; | |
| 282 return 1; | |
| 283 } | |
| 284 | |
| 285 /* | |
| 286 ** This is the fallback stemmer used when the porter stemmer is | |
| 287 ** inappropriate. The input word is copied into the output with | |
| 288 ** US-ASCII case folding. If the input word is too long (more | |
| 289 ** than 20 bytes if it contains no digits or more than 6 bytes if | |
| 290 ** it contains digits) then word is truncated to 20 or 6 bytes | |
| 291 ** by taking 10 or 3 bytes from the beginning and end. | |
| 292 */ | |
| 293 static void copy_stemmer(const char *zIn, int nIn, char *zOut, int *pnOut){ | |
| 294 int i, mx, j; | |
| 295 int hasDigit = 0; | |
| 296 for(i=0; i<nIn; i++){ | |
| 297 int c = zIn[i]; | |
| 298 if( c>='A' && c<='Z' ){ | |
| 299 zOut[i] = c - 'A' + 'a'; | |
| 300 }else{ | |
| 301 if( c>='0' && c<='9' ) hasDigit = 1; | |
| 302 zOut[i] = c; | |
| 303 } | |
| 304 } | |
| 305 mx = hasDigit ? 3 : 10; | |
| 306 if( nIn>mx*2 ){ | |
| 307 for(j=mx, i=nIn-mx; i<nIn; i++, j++){ | |
| 308 zOut[j] = zOut[i]; | |
| 309 } | |
| 310 i = j; | |
| 311 } | |
| 312 zOut[i] = 0; | |
| 313 *pnOut = i; | |
| 314 } | |
| 315 | |
| 316 | |
| 317 /* | |
| 318 ** Stem the input word zIn[0..nIn-1]. Store the output in zOut. | |
| 319 ** zOut is at least big enough to hold nIn bytes. Write the actual | |
| 320 ** size of the output word (exclusive of the '\0' terminator) into *pnOut. | |
| 321 ** | |
| 322 ** Any upper-case characters in the US-ASCII character set ([A-Z]) | |
| 323 ** are converted to lower case. Upper-case UTF characters are | |
| 324 ** unchanged. | |
| 325 ** | |
| 326 ** Words that are longer than about 20 bytes are stemmed by retaining | |
| 327 ** a few bytes from the beginning and the end of the word. If the | |
| 328 ** word contains digits, 3 bytes are taken from the beginning and | |
| 329 ** 3 bytes from the end. For long words without digits, 10 bytes | |
| 330 ** are taken from each end. US-ASCII case folding still applies. | |
| 331 ** | |
| 332 ** If the input word contains not digits but does characters not | |
| 333 ** in [a-zA-Z] then no stemming is attempted and this routine just | |
| 334 ** copies the input into the input into the output with US-ASCII | |
| 335 ** case folding. | |
| 336 ** | |
| 337 ** Stemming never increases the length of the word. So there is | |
| 338 ** no chance of overflowing the zOut buffer. | |
| 339 */ | |
| 340 static void porter_stemmer(const char *zIn, int nIn, char *zOut, int *pnOut){ | |
| 341 int i, j, c; | |
| 342 char zReverse[28]; | |
| 343 char *z, *z2; | |
| 344 if( nIn<3 || nIn>=sizeof(zReverse)-7 ){ | |
| 345 /* The word is too big or too small for the porter stemmer. | |
| 346 ** Fallback to the copy stemmer */ | |
| 347 copy_stemmer(zIn, nIn, zOut, pnOut); | |
| 348 return; | |
| 349 } | |
| 350 for(i=0, j=sizeof(zReverse)-6; i<nIn; i++, j--){ | |
| 351 c = zIn[i]; | |
| 352 if( c>='A' && c<='Z' ){ | |
| 353 zReverse[j] = c + 'a' - 'A'; | |
| 354 }else if( c>='a' && c<='z' ){ | |
| 355 zReverse[j] = c; | |
| 356 }else{ | |
| 357 /* The use of a character not in [a-zA-Z] means that we fallback | |
| 358 ** to the copy stemmer */ | |
| 359 copy_stemmer(zIn, nIn, zOut, pnOut); | |
| 360 return; | |
| 361 } | |
| 362 } | |
| 363 memset(&zReverse[sizeof(zReverse)-5], 0, 5); | |
| 364 z = &zReverse[j+1]; | |
| 365 | |
| 366 | |
| 367 /* Step 1a */ | |
| 368 if( z[0]=='s' ){ | |
| 369 if( | |
| 370 !stem(&z, "sess", "ss", 0) && | |
| 371 !stem(&z, "sei", "i", 0) && | |
| 372 !stem(&z, "ss", "ss", 0) | |
| 373 ){ | |
| 374 z++; | |
| 375 } | |
| 376 } | |
| 377 | |
| 378 /* Step 1b */ | |
| 379 z2 = z; | |
| 380 if( stem(&z, "dee", "ee", m_gt_0) ){ | |
| 381 /* Do nothing. The work was all in the test */ | |
| 382 }else if( | |
| 383 (stem(&z, "gni", "", hasVowel) || stem(&z, "de", "", hasVowel)) | |
| 384 && z!=z2 | |
| 385 ){ | |
| 386 if( stem(&z, "ta", "ate", 0) || | |
| 387 stem(&z, "lb", "ble", 0) || | |
| 388 stem(&z, "zi", "ize", 0) ){ | |
| 389 /* Do nothing. The work was all in the test */ | |
| 390 }else if( doubleConsonant(z) && (*z!='l' && *z!='s' && *z!='z') ){ | |
| 391 z++; | |
| 392 }else if( m_eq_1(z) && star_oh(z) ){ | |
| 393 *(--z) = 'e'; | |
| 394 } | |
| 395 } | |
| 396 | |
| 397 /* Step 1c */ | |
| 398 if( z[0]=='y' && hasVowel(z+1) ){ | |
| 399 z[0] = 'i'; | |
| 400 } | |
| 401 | |
| 402 /* Step 2 */ | |
| 403 switch( z[1] ){ | |
| 404 case 'a': | |
| 405 stem(&z, "lanoita", "ate", m_gt_0) || | |
| 406 stem(&z, "lanoit", "tion", m_gt_0); | |
| 407 break; | |
| 408 case 'c': | |
| 409 stem(&z, "icne", "ence", m_gt_0) || | |
| 410 stem(&z, "icna", "ance", m_gt_0); | |
| 411 break; | |
| 412 case 'e': | |
| 413 stem(&z, "rezi", "ize", m_gt_0); | |
| 414 break; | |
| 415 case 'g': | |
| 416 stem(&z, "igol", "log", m_gt_0); | |
| 417 break; | |
| 418 case 'l': | |
| 419 stem(&z, "ilb", "ble", m_gt_0) || | |
| 420 stem(&z, "illa", "al", m_gt_0) || | |
| 421 stem(&z, "iltne", "ent", m_gt_0) || | |
| 422 stem(&z, "ile", "e", m_gt_0) || | |
| 423 stem(&z, "ilsuo", "ous", m_gt_0); | |
| 424 break; | |
| 425 case 'o': | |
| 426 stem(&z, "noitazi", "ize", m_gt_0) || | |
| 427 stem(&z, "noita", "ate", m_gt_0) || | |
| 428 stem(&z, "rota", "ate", m_gt_0); | |
| 429 break; | |
| 430 case 's': | |
| 431 stem(&z, "msila", "al", m_gt_0) || | |
| 432 stem(&z, "ssenevi", "ive", m_gt_0) || | |
| 433 stem(&z, "ssenluf", "ful", m_gt_0) || | |
| 434 stem(&z, "ssensuo", "ous", m_gt_0); | |
| 435 break; | |
| 436 case 't': | |
| 437 stem(&z, "itila", "al", m_gt_0) || | |
| 438 stem(&z, "itivi", "ive", m_gt_0) || | |
| 439 stem(&z, "itilib", "ble", m_gt_0); | |
| 440 break; | |
| 441 } | |
| 442 | |
| 443 /* Step 3 */ | |
| 444 switch( z[0] ){ | |
| 445 case 'e': | |
| 446 stem(&z, "etaci", "ic", m_gt_0) || | |
| 447 stem(&z, "evita", "", m_gt_0) || | |
| 448 stem(&z, "ezila", "al", m_gt_0); | |
| 449 break; | |
| 450 case 'i': | |
| 451 stem(&z, "itici", "ic", m_gt_0); | |
| 452 break; | |
| 453 case 'l': | |
| 454 stem(&z, "laci", "ic", m_gt_0) || | |
| 455 stem(&z, "luf", "", m_gt_0); | |
| 456 break; | |
| 457 case 's': | |
| 458 stem(&z, "ssen", "", m_gt_0); | |
| 459 break; | |
| 460 } | |
| 461 | |
| 462 /* Step 4 */ | |
| 463 switch( z[1] ){ | |
| 464 case 'a': | |
| 465 if( z[0]=='l' && m_gt_1(z+2) ){ | |
| 466 z += 2; | |
| 467 } | |
| 468 break; | |
| 469 case 'c': | |
| 470 if( z[0]=='e' && z[2]=='n' && (z[3]=='a' || z[3]=='e') && m_gt_1(z+4) ){ | |
| 471 z += 4; | |
| 472 } | |
| 473 break; | |
| 474 case 'e': | |
| 475 if( z[0]=='r' && m_gt_1(z+2) ){ | |
| 476 z += 2; | |
| 477 } | |
| 478 break; | |
| 479 case 'i': | |
| 480 if( z[0]=='c' && m_gt_1(z+2) ){ | |
| 481 z += 2; | |
| 482 } | |
| 483 break; | |
| 484 case 'l': | |
| 485 if( z[0]=='e' && z[2]=='b' && (z[3]=='a' || z[3]=='i') && m_gt_1(z+4) ){ | |
| 486 z += 4; | |
| 487 } | |
| 488 break; | |
| 489 case 'n': | |
| 490 if( z[0]=='t' ){ | |
| 491 if( z[2]=='a' ){ | |
| 492 if( m_gt_1(z+3) ){ | |
| 493 z += 3; | |
| 494 } | |
| 495 }else if( z[2]=='e' ){ | |
| 496 stem(&z, "tneme", "", m_gt_1) || | |
| 497 stem(&z, "tnem", "", m_gt_1) || | |
| 498 stem(&z, "tne", "", m_gt_1); | |
| 499 } | |
| 500 } | |
| 501 break; | |
| 502 case 'o': | |
| 503 if( z[0]=='u' ){ | |
| 504 if( m_gt_1(z+2) ){ | |
| 505 z += 2; | |
| 506 } | |
| 507 }else if( z[3]=='s' || z[3]=='t' ){ | |
| 508 stem(&z, "noi", "", m_gt_1); | |
| 509 } | |
| 510 break; | |
| 511 case 's': | |
| 512 if( z[0]=='m' && z[2]=='i' && m_gt_1(z+3) ){ | |
| 513 z += 3; | |
| 514 } | |
| 515 break; | |
| 516 case 't': | |
| 517 stem(&z, "eta", "", m_gt_1) || | |
| 518 stem(&z, "iti", "", m_gt_1); | |
| 519 break; | |
| 520 case 'u': | |
| 521 if( z[0]=='s' && z[2]=='o' && m_gt_1(z+3) ){ | |
| 522 z += 3; | |
| 523 } | |
| 524 break; | |
| 525 case 'v': | |
| 526 case 'z': | |
| 527 if( z[0]=='e' && z[2]=='i' && m_gt_1(z+3) ){ | |
| 528 z += 3; | |
| 529 } | |
| 530 break; | |
| 531 } | |
| 532 | |
| 533 /* Step 5a */ | |
| 534 if( z[0]=='e' ){ | |
| 535 if( m_gt_1(z+1) ){ | |
| 536 z++; | |
| 537 }else if( m_eq_1(z+1) && !star_oh(z+1) ){ | |
| 538 z++; | |
| 539 } | |
| 540 } | |
| 541 | |
| 542 /* Step 5b */ | |
| 543 if( m_gt_1(z) && z[0]=='l' && z[1]=='l' ){ | |
| 544 z++; | |
| 545 } | |
| 546 | |
| 547 /* z[] is now the stemmed word in reverse order. Flip it back | |
| 548 ** around into forward order and return. | |
| 549 */ | |
| 550 *pnOut = i = strlen(z); | |
| 551 zOut[i] = 0; | |
| 552 while( *z ){ | |
| 553 zOut[--i] = *(z++); | |
| 554 } | |
| 555 } | |
| 556 | |
| 557 /* | |
| 558 ** Characters that can be part of a token. We assume any character | |
| 559 ** whose value is greater than 0x80 (any UTF character) can be | |
| 560 ** part of a token. In other words, delimiters all must have | |
| 561 ** values of 0x7f or lower. | |
| 562 */ | |
| 563 static const char isIdChar[] = { | |
| 564 /* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */ | |
| 565 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, /* 3x */ | |
| 566 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 4x */ | |
| 567 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, /* 5x */ | |
| 568 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 6x */ | |
| 569 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, /* 7x */ | |
| 570 }; | |
| 571 #define idChar(C) (((ch=C)&0x80)!=0 || (ch>0x2f && isIdChar[ch-0x30])) | |
| 572 #define isDelim(C) (((ch=C)&0x80)==0 && (ch<0x30 || !isIdChar[ch-0x30])) | |
| 573 | |
| 574 /* | |
| 575 ** Extract the next token from a tokenization cursor. The cursor must | |
| 576 ** have been opened by a prior call to porterOpen(). | |
| 577 */ | |
| 578 static int porterNext( | |
| 579 sqlite3_tokenizer_cursor *pCursor, /* Cursor returned by porterOpen */ | |
| 580 const char **pzToken, /* OUT: *pzToken is the token text */ | |
| 581 int *pnBytes, /* OUT: Number of bytes in token */ | |
| 582 int *piStartOffset, /* OUT: Starting offset of token */ | |
| 583 int *piEndOffset, /* OUT: Ending offset of token */ | |
| 584 int *piPosition /* OUT: Position integer of token */ | |
| 585 ){ | |
| 586 porter_tokenizer_cursor *c = (porter_tokenizer_cursor *) pCursor; | |
| 587 const char *z = c->zInput; | |
| 588 | |
| 589 while( c->iOffset<c->nInput ){ | |
| 590 int iStartOffset, ch; | |
| 591 | |
| 592 /* Scan past delimiter characters */ | |
| 593 while( c->iOffset<c->nInput && isDelim(z[c->iOffset]) ){ | |
| 594 c->iOffset++; | |
| 595 } | |
| 596 | |
| 597 /* Count non-delimiter characters. */ | |
| 598 iStartOffset = c->iOffset; | |
| 599 while( c->iOffset<c->nInput && !isDelim(z[c->iOffset]) ){ | |
| 600 c->iOffset++; | |
| 601 } | |
| 602 | |
| 603 if( c->iOffset>iStartOffset ){ | |
| 604 int n = c->iOffset-iStartOffset; | |
| 605 if( n>c->nAllocated ){ | |
| 606 c->nAllocated = n+20; | |
| 607 c->zToken = realloc(c->zToken, c->nAllocated); | |
| 608 if( c->zToken==NULL ) return SQLITE_NOMEM; | |
| 609 } | |
| 610 porter_stemmer(&z[iStartOffset], n, c->zToken, pnBytes); | |
| 611 *pzToken = c->zToken; | |
| 612 *piStartOffset = iStartOffset; | |
| 613 *piEndOffset = c->iOffset; | |
| 614 *piPosition = c->iToken++; | |
| 615 return SQLITE_OK; | |
| 616 } | |
| 617 } | |
| 618 return SQLITE_DONE; | |
| 619 } | |
| 620 | |
| 621 /* | |
| 622 ** The set of routines that implement the porter-stemmer tokenizer | |
| 623 */ | |
| 624 static const sqlite3_tokenizer_module porterTokenizerModule = { | |
| 625 0, | |
| 626 porterCreate, | |
| 627 porterDestroy, | |
| 628 porterOpen, | |
| 629 porterClose, | |
| 630 porterNext, | |
| 631 }; | |
| 632 | |
| 633 /* | |
| 634 ** Allocate a new porter tokenizer. Return a pointer to the new | |
| 635 ** tokenizer in *ppModule | |
| 636 */ | |
| 637 void sqlite3Fts1PorterTokenizerModule( | |
| 638 sqlite3_tokenizer_module const**ppModule | |
| 639 ){ | |
| 640 *ppModule = &porterTokenizerModule; | |
| 641 } | |
| 642 | |
| 643 #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) */ | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 2363173002:
[sqlite] Remove obsolete reference version 3.8.7.4. (Closed)
