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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 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 "sqlite3.h" | |
| 34 #include "sqlite3ext.h" | |
| 35 SQLITE_EXTENSION_INIT3 | |
| 36 #include "fts2_tokenizer.h" | |
| 37 | |
| 38 /* | |
| 39 ** Class derived from sqlite3_tokenizer | |
| 40 */ | |
| 41 typedef struct porter_tokenizer { | |
| 42 sqlite3_tokenizer base; /* Base class */ | |
| 43 } porter_tokenizer; | |
| 44 | |
| 45 /* | |
| 46 ** Class derived from sqlit3_tokenizer_cursor | |
| 47 */ | |
| 48 typedef struct porter_tokenizer_cursor { | |
| 49 sqlite3_tokenizer_cursor base; | |
| 50 const char *zInput; /* input we are tokenizing */ | |
| 51 int nInput; /* size of the input */ | |
| 52 int iOffset; /* current position in zInput */ | |
| 53 int iToken; /* index of next token to be returned */ | |
| 54 char *zToken; /* storage for current token */ | |
| 55 int nAllocated; /* space allocated to zToken buffer */ | |
| 56 } porter_tokenizer_cursor; | |
| 57 | |
| 58 | |
| 59 /* Forward declaration */ | |
| 60 static const sqlite3_tokenizer_module porterTokenizerModule; | |
| 61 | |
| 62 | |
| 63 /* | |
| 64 ** Create a new tokenizer instance. | |
| 65 */ | |
| 66 static int porterCreate( | |
| 67 int argc, const char * const *argv, | |
| 68 sqlite3_tokenizer **ppTokenizer | |
| 69 ){ | |
| 70 porter_tokenizer *t; | |
| 71 t = (porter_tokenizer *) sqlite3_malloc(sizeof(*t)); | |
| 72 if( t==NULL ) return SQLITE_NOMEM; | |
| 73 memset(t, 0, sizeof(*t)); | |
| 74 *ppTokenizer = &t->base; | |
| 75 return SQLITE_OK; | |
| 76 } | |
| 77 | |
| 78 /* | |
| 79 ** Destroy a tokenizer | |
| 80 */ | |
| 81 static int porterDestroy(sqlite3_tokenizer *pTokenizer){ | |
| 82 sqlite3_free(pTokenizer); | |
| 83 return SQLITE_OK; | |
| 84 } | |
| 85 | |
| 86 /* | |
| 87 ** Prepare to begin tokenizing a particular string. The input | |
| 88 ** string to be tokenized is zInput[0..nInput-1]. A cursor | |
| 89 ** used to incrementally tokenize this string is returned in | |
| 90 ** *ppCursor. | |
| 91 */ | |
| 92 static int porterOpen( | |
| 93 sqlite3_tokenizer *pTokenizer, /* The tokenizer */ | |
| 94 const char *zInput, int nInput, /* String to be tokenized */ | |
| 95 sqlite3_tokenizer_cursor **ppCursor /* OUT: Tokenization cursor */ | |
| 96 ){ | |
| 97 porter_tokenizer_cursor *c; | |
| 98 | |
| 99 c = (porter_tokenizer_cursor *) sqlite3_malloc(sizeof(*c)); | |
| 100 if( c==NULL ) return SQLITE_NOMEM; | |
| 101 | |
| 102 c->zInput = zInput; | |
| 103 if( zInput==0 ){ | |
| 104 c->nInput = 0; | |
| 105 }else if( nInput<0 ){ | |
| 106 c->nInput = (int)strlen(zInput); | |
| 107 }else{ | |
| 108 c->nInput = nInput; | |
| 109 } | |
| 110 c->iOffset = 0; /* start tokenizing at the beginning */ | |
| 111 c->iToken = 0; | |
| 112 c->zToken = NULL; /* no space allocated, yet. */ | |
| 113 c->nAllocated = 0; | |
| 114 | |
| 115 *ppCursor = &c->base; | |
| 116 return SQLITE_OK; | |
| 117 } | |
| 118 | |
| 119 /* | |
| 120 ** Close a tokenization cursor previously opened by a call to | |
| 121 ** porterOpen() above. | |
| 122 */ | |
| 123 static int porterClose(sqlite3_tokenizer_cursor *pCursor){ | |
| 124 porter_tokenizer_cursor *c = (porter_tokenizer_cursor *) pCursor; | |
| 125 sqlite3_free(c->zToken); | |
| 126 sqlite3_free(c); | |
| 127 return SQLITE_OK; | |
| 128 } | |
| 129 /* | |
| 130 ** Vowel or consonant | |
| 131 */ | |
| 132 static const char cType[] = { | |
| 133 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, | |
| 134 1, 1, 1, 2, 1 | |
| 135 }; | |
| 136 | |
| 137 /* | |
| 138 ** isConsonant() and isVowel() determine if their first character in | |
| 139 ** the string they point to is a consonant or a vowel, according | |
| 140 ** to Porter ruls. | |
| 141 ** | |
| 142 ** A consonate is any letter other than 'a', 'e', 'i', 'o', or 'u'. | |
| 143 ** 'Y' is a consonant unless it follows another consonant, | |
| 144 ** in which case it is a vowel. | |
| 145 ** | |
| 146 ** In these routine, the letters are in reverse order. So the 'y' rule | |
| 147 ** is that 'y' is a consonant unless it is followed by another | |
| 148 ** consonent. | |
| 149 */ | |
| 150 static int isVowel(const char*); | |
| 151 static int isConsonant(const char *z){ | |
| 152 int j; | |
| 153 char x = *z; | |
| 154 if( x==0 ) return 0; | |
| 155 assert( x>='a' && x<='z' ); | |
| 156 j = cType[x-'a']; | |
| 157 if( j<2 ) return j; | |
| 158 return z[1]==0 || isVowel(z + 1); | |
| 159 } | |
| 160 static int isVowel(const char *z){ | |
| 161 int j; | |
| 162 char x = *z; | |
| 163 if( x==0 ) return 0; | |
| 164 assert( x>='a' && x<='z' ); | |
| 165 j = cType[x-'a']; | |
| 166 if( j<2 ) return 1-j; | |
| 167 return isConsonant(z + 1); | |
| 168 } | |
| 169 | |
| 170 /* | |
| 171 ** Let any sequence of one or more vowels be represented by V and let | |
| 172 ** C be sequence of one or more consonants. Then every word can be | |
| 173 ** represented as: | |
| 174 ** | |
| 175 ** [C] (VC){m} [V] | |
| 176 ** | |
| 177 ** In prose: A word is an optional consonant followed by zero or | |
| 178 ** vowel-consonant pairs followed by an optional vowel. "m" is the | |
| 179 ** number of vowel consonant pairs. This routine computes the value | |
| 180 ** of m for the first i bytes of a word. | |
| 181 ** | |
| 182 ** Return true if the m-value for z is 1 or more. In other words, | |
| 183 ** return true if z contains at least one vowel that is followed | |
| 184 ** by a consonant. | |
| 185 ** | |
| 186 ** In this routine z[] is in reverse order. So we are really looking | |
| 187 ** for an instance of of a consonant followed by a vowel. | |
| 188 */ | |
| 189 static int m_gt_0(const char *z){ | |
| 190 while( isVowel(z) ){ z++; } | |
| 191 if( *z==0 ) return 0; | |
| 192 while( isConsonant(z) ){ z++; } | |
| 193 return *z!=0; | |
| 194 } | |
| 195 | |
| 196 /* Like mgt0 above except we are looking for a value of m which is | |
| 197 ** exactly 1 | |
| 198 */ | |
| 199 static int m_eq_1(const char *z){ | |
| 200 while( isVowel(z) ){ z++; } | |
| 201 if( *z==0 ) return 0; | |
| 202 while( isConsonant(z) ){ z++; } | |
| 203 if( *z==0 ) return 0; | |
| 204 while( isVowel(z) ){ z++; } | |
| 205 if( *z==0 ) return 1; | |
| 206 while( isConsonant(z) ){ z++; } | |
| 207 return *z==0; | |
| 208 } | |
| 209 | |
| 210 /* Like mgt0 above except we are looking for a value of m>1 instead | |
| 211 ** or m>0 | |
| 212 */ | |
| 213 static int m_gt_1(const char *z){ | |
| 214 while( isVowel(z) ){ z++; } | |
| 215 if( *z==0 ) return 0; | |
| 216 while( isConsonant(z) ){ z++; } | |
| 217 if( *z==0 ) return 0; | |
| 218 while( isVowel(z) ){ z++; } | |
| 219 if( *z==0 ) return 0; | |
| 220 while( isConsonant(z) ){ z++; } | |
| 221 return *z!=0; | |
| 222 } | |
| 223 | |
| 224 /* | |
| 225 ** Return TRUE if there is a vowel anywhere within z[0..n-1] | |
| 226 */ | |
| 227 static int hasVowel(const char *z){ | |
| 228 while( isConsonant(z) ){ z++; } | |
| 229 return *z!=0; | |
| 230 } | |
| 231 | |
| 232 /* | |
| 233 ** Return TRUE if the word ends in a double consonant. | |
| 234 ** | |
| 235 ** The text is reversed here. So we are really looking at | |
| 236 ** the first two characters of z[]. | |
| 237 */ | |
| 238 static int doubleConsonant(const char *z){ | |
| 239 return isConsonant(z) && z[0]==z[1] && isConsonant(z+1); | |
| 240 } | |
| 241 | |
| 242 /* | |
| 243 ** Return TRUE if the word ends with three letters which | |
| 244 ** are consonant-vowel-consonent and where the final consonant | |
| 245 ** is not 'w', 'x', or 'y'. | |
| 246 ** | |
| 247 ** The word is reversed here. So we are really checking the | |
| 248 ** first three letters and the first one cannot be in [wxy]. | |
| 249 */ | |
| 250 static int star_oh(const char *z){ | |
| 251 return | |
| 252 z[0]!=0 && isConsonant(z) && | |
| 253 z[0]!='w' && z[0]!='x' && z[0]!='y' && | |
| 254 z[1]!=0 && isVowel(z+1) && | |
| 255 z[2]!=0 && isConsonant(z+2); | |
| 256 } | |
| 257 | |
| 258 /* | |
| 259 ** If the word ends with zFrom and xCond() is true for the stem | |
| 260 ** of the word that preceeds the zFrom ending, then change the | |
| 261 ** ending to zTo. | |
| 262 ** | |
| 263 ** The input word *pz and zFrom are both in reverse order. zTo | |
| 264 ** is in normal order. | |
| 265 ** | |
| 266 ** Return TRUE if zFrom matches. Return FALSE if zFrom does not | |
| 267 ** match. Not that TRUE is returned even if xCond() fails and | |
| 268 ** no substitution occurs. | |
| 269 */ | |
| 270 static int stem( | |
| 271 char **pz, /* The word being stemmed (Reversed) */ | |
| 272 const char *zFrom, /* If the ending matches this... (Reversed) */ | |
| 273 const char *zTo, /* ... change the ending to this (not reversed) */ | |
| 274 int (*xCond)(const char*) /* Condition that must be true */ | |
| 275 ){ | |
| 276 char *z = *pz; | |
| 277 while( *zFrom && *zFrom==*z ){ z++; zFrom++; } | |
| 278 if( *zFrom!=0 ) return 0; | |
| 279 if( xCond && !xCond(z) ) return 1; | |
| 280 while( *zTo ){ | |
| 281 *(--z) = *(zTo++); | |
| 282 } | |
| 283 *pz = z; | |
| 284 return 1; | |
| 285 } | |
| 286 | |
| 287 /* | |
| 288 ** This is the fallback stemmer used when the porter stemmer is | |
| 289 ** inappropriate. The input word is copied into the output with | |
| 290 ** US-ASCII case folding. If the input word is too long (more | |
| 291 ** than 20 bytes if it contains no digits or more than 6 bytes if | |
| 292 ** it contains digits) then word is truncated to 20 or 6 bytes | |
| 293 ** by taking 10 or 3 bytes from the beginning and end. | |
| 294 */ | |
| 295 static void copy_stemmer(const char *zIn, int nIn, char *zOut, int *pnOut){ | |
| 296 int i, mx, j; | |
| 297 int hasDigit = 0; | |
| 298 for(i=0; i<nIn; i++){ | |
| 299 int c = zIn[i]; | |
| 300 if( c>='A' && c<='Z' ){ | |
| 301 zOut[i] = c - 'A' + 'a'; | |
| 302 }else{ | |
| 303 if( c>='0' && c<='9' ) hasDigit = 1; | |
| 304 zOut[i] = c; | |
| 305 } | |
| 306 } | |
| 307 mx = hasDigit ? 3 : 10; | |
| 308 if( nIn>mx*2 ){ | |
| 309 for(j=mx, i=nIn-mx; i<nIn; i++, j++){ | |
| 310 zOut[j] = zOut[i]; | |
| 311 } | |
| 312 i = j; | |
| 313 } | |
| 314 zOut[i] = 0; | |
| 315 *pnOut = i; | |
| 316 } | |
| 317 | |
| 318 | |
| 319 /* | |
| 320 ** Stem the input word zIn[0..nIn-1]. Store the output in zOut. | |
| 321 ** zOut is at least big enough to hold nIn bytes. Write the actual | |
| 322 ** size of the output word (exclusive of the '\0' terminator) into *pnOut. | |
| 323 ** | |
| 324 ** Any upper-case characters in the US-ASCII character set ([A-Z]) | |
| 325 ** are converted to lower case. Upper-case UTF characters are | |
| 326 ** unchanged. | |
| 327 ** | |
| 328 ** Words that are longer than about 20 bytes are stemmed by retaining | |
| 329 ** a few bytes from the beginning and the end of the word. If the | |
| 330 ** word contains digits, 3 bytes are taken from the beginning and | |
| 331 ** 3 bytes from the end. For long words without digits, 10 bytes | |
| 332 ** are taken from each end. US-ASCII case folding still applies. | |
| 333 ** | |
| 334 ** If the input word contains not digits but does characters not | |
| 335 ** in [a-zA-Z] then no stemming is attempted and this routine just | |
| 336 ** copies the input into the input into the output with US-ASCII | |
| 337 ** case folding. | |
| 338 ** | |
| 339 ** Stemming never increases the length of the word. So there is | |
| 340 ** no chance of overflowing the zOut buffer. | |
| 341 */ | |
| 342 static void porter_stemmer(const char *zIn, int nIn, char *zOut, int *pnOut){ | |
| 343 int i, j, c; | |
| 344 char zReverse[28]; | |
| 345 char *z, *z2; | |
| 346 if( nIn<3 || nIn>=sizeof(zReverse)-7 ){ | |
| 347 /* The word is too big or too small for the porter stemmer. | |
| 348 ** Fallback to the copy stemmer */ | |
| 349 copy_stemmer(zIn, nIn, zOut, pnOut); | |
| 350 return; | |
| 351 } | |
| 352 for(i=0, j=sizeof(zReverse)-6; i<nIn; i++, j--){ | |
| 353 c = zIn[i]; | |
| 354 if( c>='A' && c<='Z' ){ | |
| 355 zReverse[j] = c + 'a' - 'A'; | |
| 356 }else if( c>='a' && c<='z' ){ | |
| 357 zReverse[j] = c; | |
| 358 }else{ | |
| 359 /* The use of a character not in [a-zA-Z] means that we fallback | |
| 360 ** to the copy stemmer */ | |
| 361 copy_stemmer(zIn, nIn, zOut, pnOut); | |
| 362 return; | |
| 363 } | |
| 364 } | |
| 365 memset(&zReverse[sizeof(zReverse)-5], 0, 5); | |
| 366 z = &zReverse[j+1]; | |
| 367 | |
| 368 | |
| 369 /* Step 1a */ | |
| 370 if( z[0]=='s' ){ | |
| 371 if( | |
| 372 !stem(&z, "sess", "ss", 0) && | |
| 373 !stem(&z, "sei", "i", 0) && | |
| 374 !stem(&z, "ss", "ss", 0) | |
| 375 ){ | |
| 376 z++; | |
| 377 } | |
| 378 } | |
| 379 | |
| 380 /* Step 1b */ | |
| 381 z2 = z; | |
| 382 if( stem(&z, "dee", "ee", m_gt_0) ){ | |
| 383 /* Do nothing. The work was all in the test */ | |
| 384 }else if( | |
| 385 (stem(&z, "gni", "", hasVowel) || stem(&z, "de", "", hasVowel)) | |
| 386 && z!=z2 | |
| 387 ){ | |
| 388 if( stem(&z, "ta", "ate", 0) || | |
| 389 stem(&z, "lb", "ble", 0) || | |
| 390 stem(&z, "zi", "ize", 0) ){ | |
| 391 /* Do nothing. The work was all in the test */ | |
| 392 }else if( doubleConsonant(z) && (*z!='l' && *z!='s' && *z!='z') ){ | |
| 393 z++; | |
| 394 }else if( m_eq_1(z) && star_oh(z) ){ | |
| 395 *(--z) = 'e'; | |
| 396 } | |
| 397 } | |
| 398 | |
| 399 /* Step 1c */ | |
| 400 if( z[0]=='y' && hasVowel(z+1) ){ | |
| 401 z[0] = 'i'; | |
| 402 } | |
| 403 | |
| 404 /* Step 2 */ | |
| 405 switch( z[1] ){ | |
| 406 case 'a': | |
| 407 stem(&z, "lanoita", "ate", m_gt_0) || | |
| 408 stem(&z, "lanoit", "tion", m_gt_0); | |
| 409 break; | |
| 410 case 'c': | |
| 411 stem(&z, "icne", "ence", m_gt_0) || | |
| 412 stem(&z, "icna", "ance", m_gt_0); | |
| 413 break; | |
| 414 case 'e': | |
| 415 stem(&z, "rezi", "ize", m_gt_0); | |
| 416 break; | |
| 417 case 'g': | |
| 418 stem(&z, "igol", "log", m_gt_0); | |
| 419 break; | |
| 420 case 'l': | |
| 421 stem(&z, "ilb", "ble", m_gt_0) || | |
| 422 stem(&z, "illa", "al", m_gt_0) || | |
| 423 stem(&z, "iltne", "ent", m_gt_0) || | |
| 424 stem(&z, "ile", "e", m_gt_0) || | |
| 425 stem(&z, "ilsuo", "ous", m_gt_0); | |
| 426 break; | |
| 427 case 'o': | |
| 428 stem(&z, "noitazi", "ize", m_gt_0) || | |
| 429 stem(&z, "noita", "ate", m_gt_0) || | |
| 430 stem(&z, "rota", "ate", m_gt_0); | |
| 431 break; | |
| 432 case 's': | |
| 433 stem(&z, "msila", "al", m_gt_0) || | |
| 434 stem(&z, "ssenevi", "ive", m_gt_0) || | |
| 435 stem(&z, "ssenluf", "ful", m_gt_0) || | |
| 436 stem(&z, "ssensuo", "ous", m_gt_0); | |
| 437 break; | |
| 438 case 't': | |
| 439 stem(&z, "itila", "al", m_gt_0) || | |
| 440 stem(&z, "itivi", "ive", m_gt_0) || | |
| 441 stem(&z, "itilib", "ble", m_gt_0); | |
| 442 break; | |
| 443 } | |
| 444 | |
| 445 /* Step 3 */ | |
| 446 switch( z[0] ){ | |
| 447 case 'e': | |
| 448 stem(&z, "etaci", "ic", m_gt_0) || | |
| 449 stem(&z, "evita", "", m_gt_0) || | |
| 450 stem(&z, "ezila", "al", m_gt_0); | |
| 451 break; | |
| 452 case 'i': | |
| 453 stem(&z, "itici", "ic", m_gt_0); | |
| 454 break; | |
| 455 case 'l': | |
| 456 stem(&z, "laci", "ic", m_gt_0) || | |
| 457 stem(&z, "luf", "", m_gt_0); | |
| 458 break; | |
| 459 case 's': | |
| 460 stem(&z, "ssen", "", m_gt_0); | |
| 461 break; | |
| 462 } | |
| 463 | |
| 464 /* Step 4 */ | |
| 465 switch( z[1] ){ | |
| 466 case 'a': | |
| 467 if( z[0]=='l' && m_gt_1(z+2) ){ | |
| 468 z += 2; | |
| 469 } | |
| 470 break; | |
| 471 case 'c': | |
| 472 if( z[0]=='e' && z[2]=='n' && (z[3]=='a' || z[3]=='e') && m_gt_1(z+4) ){ | |
| 473 z += 4; | |
| 474 } | |
| 475 break; | |
| 476 case 'e': | |
| 477 if( z[0]=='r' && m_gt_1(z+2) ){ | |
| 478 z += 2; | |
| 479 } | |
| 480 break; | |
| 481 case 'i': | |
| 482 if( z[0]=='c' && m_gt_1(z+2) ){ | |
| 483 z += 2; | |
| 484 } | |
| 485 break; | |
| 486 case 'l': | |
| 487 if( z[0]=='e' && z[2]=='b' && (z[3]=='a' || z[3]=='i') && m_gt_1(z+4) ){ | |
| 488 z += 4; | |
| 489 } | |
| 490 break; | |
| 491 case 'n': | |
| 492 if( z[0]=='t' ){ | |
| 493 if( z[2]=='a' ){ | |
| 494 if( m_gt_1(z+3) ){ | |
| 495 z += 3; | |
| 496 } | |
| 497 }else if( z[2]=='e' ){ | |
| 498 stem(&z, "tneme", "", m_gt_1) || | |
| 499 stem(&z, "tnem", "", m_gt_1) || | |
| 500 stem(&z, "tne", "", m_gt_1); | |
| 501 } | |
| 502 } | |
| 503 break; | |
| 504 case 'o': | |
| 505 if( z[0]=='u' ){ | |
| 506 if( m_gt_1(z+2) ){ | |
| 507 z += 2; | |
| 508 } | |
| 509 }else if( z[3]=='s' || z[3]=='t' ){ | |
| 510 stem(&z, "noi", "", m_gt_1); | |
| 511 } | |
| 512 break; | |
| 513 case 's': | |
| 514 if( z[0]=='m' && z[2]=='i' && m_gt_1(z+3) ){ | |
| 515 z += 3; | |
| 516 } | |
| 517 break; | |
| 518 case 't': | |
| 519 stem(&z, "eta", "", m_gt_1) || | |
| 520 stem(&z, "iti", "", m_gt_1); | |
| 521 break; | |
| 522 case 'u': | |
| 523 if( z[0]=='s' && z[2]=='o' && m_gt_1(z+3) ){ | |
| 524 z += 3; | |
| 525 } | |
| 526 break; | |
| 527 case 'v': | |
| 528 case 'z': | |
| 529 if( z[0]=='e' && z[2]=='i' && m_gt_1(z+3) ){ | |
| 530 z += 3; | |
| 531 } | |
| 532 break; | |
| 533 } | |
| 534 | |
| 535 /* Step 5a */ | |
| 536 if( z[0]=='e' ){ | |
| 537 if( m_gt_1(z+1) ){ | |
| 538 z++; | |
| 539 }else if( m_eq_1(z+1) && !star_oh(z+1) ){ | |
| 540 z++; | |
| 541 } | |
| 542 } | |
| 543 | |
| 544 /* Step 5b */ | |
| 545 if( m_gt_1(z) && z[0]=='l' && z[1]=='l' ){ | |
| 546 z++; | |
| 547 } | |
| 548 | |
| 549 /* z[] is now the stemmed word in reverse order. Flip it back | |
| 550 ** around into forward order and return. | |
| 551 */ | |
| 552 *pnOut = i = strlen(z); | |
| 553 zOut[i] = 0; | |
| 554 while( *z ){ | |
| 555 zOut[--i] = *(z++); | |
| 556 } | |
| 557 } | |
| 558 | |
| 559 /* | |
| 560 ** Characters that can be part of a token. We assume any character | |
| 561 ** whose value is greater than 0x80 (any UTF character) can be | |
| 562 ** part of a token. In other words, delimiters all must have | |
| 563 ** values of 0x7f or lower. | |
| 564 */ | |
| 565 static const char porterIdChar[] = { | |
| 566 /* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */ | |
| 567 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, /* 3x */ | |
| 568 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 4x */ | |
| 569 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, /* 5x */ | |
| 570 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 6x */ | |
| 571 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, /* 7x */ | |
| 572 }; | |
| 573 #define isDelim(C) (((ch=C)&0x80)==0 && (ch<0x30 || !porterIdChar[ch-0x30])) | |
| 574 | |
| 575 /* | |
| 576 ** Extract the next token from a tokenization cursor. The cursor must | |
| 577 ** have been opened by a prior call to porterOpen(). | |
| 578 */ | |
| 579 static int porterNext( | |
| 580 sqlite3_tokenizer_cursor *pCursor, /* Cursor returned by porterOpen */ | |
| 581 const char **pzToken, /* OUT: *pzToken is the token text */ | |
| 582 int *pnBytes, /* OUT: Number of bytes in token */ | |
| 583 int *piStartOffset, /* OUT: Starting offset of token */ | |
| 584 int *piEndOffset, /* OUT: Ending offset of token */ | |
| 585 int *piPosition /* OUT: Position integer of token */ | |
| 586 ){ | |
| 587 porter_tokenizer_cursor *c = (porter_tokenizer_cursor *) pCursor; | |
| 588 const char *z = c->zInput; | |
| 589 | |
| 590 while( c->iOffset<c->nInput ){ | |
| 591 int iStartOffset, ch; | |
| 592 | |
| 593 /* Scan past delimiter characters */ | |
| 594 while( c->iOffset<c->nInput && isDelim(z[c->iOffset]) ){ | |
| 595 c->iOffset++; | |
| 596 } | |
| 597 | |
| 598 /* Count non-delimiter characters. */ | |
| 599 iStartOffset = c->iOffset; | |
| 600 while( c->iOffset<c->nInput && !isDelim(z[c->iOffset]) ){ | |
| 601 c->iOffset++; | |
| 602 } | |
| 603 | |
| 604 if( c->iOffset>iStartOffset ){ | |
| 605 int n = c->iOffset-iStartOffset; | |
| 606 if( n>c->nAllocated ){ | |
| 607 c->nAllocated = n+20; | |
| 608 c->zToken = sqlite3_realloc(c->zToken, c->nAllocated); | |
| 609 if( c->zToken==NULL ) return SQLITE_NOMEM; | |
| 610 } | |
| 611 porter_stemmer(&z[iStartOffset], n, c->zToken, pnBytes); | |
| 612 *pzToken = c->zToken; | |
| 613 *piStartOffset = iStartOffset; | |
| 614 *piEndOffset = c->iOffset; | |
| 615 *piPosition = c->iToken++; | |
| 616 return SQLITE_OK; | |
| 617 } | |
| 618 } | |
| 619 return SQLITE_DONE; | |
| 620 } | |
| 621 | |
| 622 /* | |
| 623 ** The set of routines that implement the porter-stemmer tokenizer | |
| 624 */ | |
| 625 static const sqlite3_tokenizer_module porterTokenizerModule = { | |
| 626 0, | |
| 627 porterCreate, | |
| 628 porterDestroy, | |
| 629 porterOpen, | |
| 630 porterClose, | |
| 631 porterNext, | |
| 632 }; | |
| 633 | |
| 634 /* | |
| 635 ** Allocate a new porter tokenizer. Return a pointer to the new | |
| 636 ** tokenizer in *ppModule | |
| 637 */ | |
| 638 void sqlite3Fts2PorterTokenizerModule( | |
| 639 sqlite3_tokenizer_module const**ppModule | |
| 640 ){ | |
| 641 *ppModule = &porterTokenizerModule; | |
| 642 } | |
| 643 | |
| 644 #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS2) */ | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 2363173002:
[sqlite] Remove obsolete reference version 3.8.7.4. (Closed)
