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| 1 /* | |
| 2 ** 2013-03-14 | |
| 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 ** This file contains code for a demonstration virtual table that finds | |
| 14 ** "approximate matches" - strings from a finite set that are nearly the | |
| 15 ** same as a single input string. The virtual table is called "amatch". | |
| 16 ** | |
| 17 ** A amatch virtual table is created like this: | |
| 18 ** | |
| 19 ** CREATE VIRTUAL TABLE f USING approximate_match( | |
| 20 ** vocabulary_table=<tablename>, -- V | |
| 21 ** vocabulary_word=<columnname>, -- W | |
| 22 ** vocabulary_language=<columnname>, -- L | |
| 23 ** edit_distances=<edit-cost-table> | |
| 24 ** ); | |
| 25 ** | |
| 26 ** When it is created, the new amatch table must be supplied with the | |
| 27 ** the name of a table V and columns V.W and V.L such that | |
| 28 ** | |
| 29 ** SELECT W FROM V WHERE L=$language | |
| 30 ** | |
| 31 ** returns the allowed vocabulary for the match. If the "vocabulary_language" | |
| 32 ** or L columnname is left unspecified or is an empty string, then no | |
| 33 ** filtering of the vocabulary by language is performed. | |
| 34 ** | |
| 35 ** For efficiency, it is essential that the vocabulary table be indexed: | |
| 36 ** | |
| 37 ** CREATE vocab_index ON V(W) | |
| 38 ** | |
| 39 ** A separate edit-cost-table provides scoring information that defines | |
| 40 ** what it means for one string to be "close" to another. | |
| 41 ** | |
| 42 ** The edit-cost-table must contain exactly four columns (more precisely, | |
| 43 ** the statement "SELECT * FROM <edit-cost-table>" must return records | |
| 44 ** that consist of four columns). It does not matter what the columns are | |
| 45 ** named. | |
| 46 ** | |
| 47 ** Each row in the edit-cost-table represents a single character | |
| 48 ** transformation going from user input to the vocabulary. The leftmost | |
| 49 ** column of the row (column 0) contains an integer identifier of the | |
| 50 ** language to which the transformation rule belongs (see "MULTIPLE LANGUAGES" | |
| 51 ** below). The second column of the row (column 1) contains the input | |
| 52 ** character or characters - the characters of user input. The third | |
| 53 ** column contains characters as they appear in the vocabulary table. | |
| 54 ** And the fourth column contains the integer cost of making the | |
| 55 ** transformation. For example: | |
| 56 ** | |
| 57 ** CREATE TABLE f_data(iLang, cFrom, cTo, Cost); | |
| 58 ** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, '', 'a', 100); | |
| 59 ** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, 'b', '', 87); | |
| 60 ** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, 'o', 'oe', 38); | |
| 61 ** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, 'oe', 'o', 40); | |
| 62 ** | |
| 63 ** The first row inserted into the edit-cost-table by the SQL script | |
| 64 ** above indicates that the cost of having an extra 'a' in the vocabulary | |
| 65 ** table that is missing in the user input 100. (All costs are integers. | |
| 66 ** Overall cost must not exceed 16777216.) The second INSERT statement | |
| 67 ** creates a rule saying that the cost of having a single letter 'b' in | |
| 68 ** user input which is missing in the vocabulary table is 87. The third | |
| 69 ** INSERT statement mean that the cost of matching an 'o' in user input | |
| 70 ** against an 'oe' in the vocabulary table is 38. And so forth. | |
| 71 ** | |
| 72 ** The following rules are special: | |
| 73 ** | |
| 74 ** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, '?', '', 97); | |
| 75 ** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, '', '?', 98); | |
| 76 ** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, '?', '?', 99); | |
| 77 ** | |
| 78 ** The '?' to '' rule is the cost of having any single character in the input | |
| 79 ** that is not found in the vocabular. The '' to '?' rule is the cost of | |
| 80 ** having a character in the vocabulary table that is missing from input. | |
| 81 ** And the '?' to '?' rule is the cost of doing an arbitrary character | |
| 82 ** substitution. These three generic rules apply across all languages. | |
| 83 ** In other words, the iLang field is ignored for the generic substitution | |
| 84 ** rules. If more than one cost is given for a generic substitution rule, | |
| 85 ** then the lowest cost is used. | |
| 86 ** | |
| 87 ** Once it has been created, the amatch virtual table can be queried | |
| 88 ** as follows: | |
| 89 ** | |
| 90 ** SELECT word, distance FROM f | |
| 91 ** WHERE word MATCH 'abcdefg' | |
| 92 ** AND distance<200; | |
| 93 ** | |
| 94 ** This query outputs the strings contained in the T(F) field that | |
| 95 ** are close to "abcdefg" and in order of increasing distance. No string | |
| 96 ** is output more than once. If there are multiple ways to transform the | |
| 97 ** target string ("abcdefg") into a string in the vocabulary table then | |
| 98 ** the lowest cost transform is the one that is returned. In this example, | |
| 99 ** the search is limited to strings with a total distance of less than 200. | |
| 100 ** | |
| 101 ** For efficiency, it is important to put tight bounds on the distance. | |
| 102 ** The time and memory space needed to perform this query is exponential | |
| 103 ** in the maximum distance. A good rule of thumb is to limit the distance | |
| 104 ** to no more than 1.5 or 2 times the maximum cost of any rule in the | |
| 105 ** edit-cost-table. | |
| 106 ** | |
| 107 ** The amatch is a read-only table. Any attempt to DELETE, INSERT, or | |
| 108 ** UPDATE on a amatch table will throw an error. | |
| 109 ** | |
| 110 ** It is important to put some kind of a limit on the amatch output. This | |
| 111 ** can be either in the form of a LIMIT clause at the end of the query, | |
| 112 ** or better, a "distance<NNN" constraint where NNN is some number. The | |
| 113 ** running time and memory requirement is exponential in the value of NNN | |
| 114 ** so you want to make sure that NNN is not too big. A value of NNN that | |
| 115 ** is about twice the average transformation cost seems to give good results. | |
| 116 ** | |
| 117 ** The amatch table can be useful for tasks such as spelling correction. | |
| 118 ** Suppose all allowed words are in table vocabulary(w). Then one would create | |
| 119 ** an amatch virtual table like this: | |
| 120 ** | |
| 121 ** CREATE VIRTUAL TABLE ex1 USING amatch( | |
| 122 ** vocabtable=vocabulary, | |
| 123 ** vocabcolumn=w, | |
| 124 ** edit_distances=ec1 | |
| 125 ** ); | |
| 126 ** | |
| 127 ** Then given an input word $word, look up close spellings this way: | |
| 128 ** | |
| 129 ** SELECT word, distance FROM ex1 | |
| 130 ** WHERE word MATCH $word AND distance<200; | |
| 131 ** | |
| 132 ** MULTIPLE LANGUAGES | |
| 133 ** | |
| 134 ** Normally, the "iLang" value associated with all character transformations | |
| 135 ** in the edit-cost-table is zero. However, if required, the amatch | |
| 136 ** virtual table allows multiple languages to be defined. Each query uses | |
| 137 ** only a single iLang value. This allows, for example, a single | |
| 138 ** amatch table to support multiple languages. | |
| 139 ** | |
| 140 ** By default, only the rules with iLang=0 are used. To specify an | |
| 141 ** alternative language, a "language = ?" expression must be added to the | |
| 142 ** WHERE clause of a SELECT, where ? is the integer identifier of the desired | |
| 143 ** language. For example: | |
| 144 ** | |
| 145 ** SELECT word, distance FROM ex1 | |
| 146 ** WHERE word MATCH $word | |
| 147 ** AND distance<=200 | |
| 148 ** AND language=1 -- Specify use language 1 instead of 0 | |
| 149 ** | |
| 150 ** If no "language = ?" constraint is specified in the WHERE clause, language | |
| 151 ** 0 is used. | |
| 152 ** | |
| 153 ** LIMITS | |
| 154 ** | |
| 155 ** The maximum language number is 2147483647. The maximum length of either | |
| 156 ** of the strings in the second or third column of the amatch data table | |
| 157 ** is 50 bytes. The maximum cost on a rule is 1000. | |
| 158 */ | |
| 159 #include "sqlite3ext.h" | |
| 160 SQLITE_EXTENSION_INIT1 | |
| 161 #include <stdlib.h> | |
| 162 #include <string.h> | |
| 163 #include <assert.h> | |
| 164 #include <stdio.h> | |
| 165 #include <ctype.h> | |
| 166 | |
| 167 #ifndef SQLITE_OMIT_VIRTUALTABLE | |
| 168 | |
| 169 /* | |
| 170 ** Forward declaration of objects used by this implementation | |
| 171 */ | |
| 172 typedef struct amatch_vtab amatch_vtab; | |
| 173 typedef struct amatch_cursor amatch_cursor; | |
| 174 typedef struct amatch_rule amatch_rule; | |
| 175 typedef struct amatch_word amatch_word; | |
| 176 typedef struct amatch_avl amatch_avl; | |
| 177 | |
| 178 | |
| 179 /***************************************************************************** | |
| 180 ** AVL Tree implementation | |
| 181 */ | |
| 182 /* | |
| 183 ** Objects that want to be members of the AVL tree should embedded an | |
| 184 ** instance of this structure. | |
| 185 */ | |
| 186 struct amatch_avl { | |
| 187 amatch_word *pWord; /* Points to the object being stored in the tree */ | |
| 188 char *zKey; /* Key. zero-terminated string. Must be unique */ | |
| 189 amatch_avl *pBefore; /* Other elements less than zKey */ | |
| 190 amatch_avl *pAfter; /* Other elements greater than zKey */ | |
| 191 amatch_avl *pUp; /* Parent element */ | |
| 192 short int height; /* Height of this node. Leaf==1 */ | |
| 193 short int imbalance; /* Height difference between pBefore and pAfter */ | |
| 194 }; | |
| 195 | |
| 196 /* Recompute the amatch_avl.height and amatch_avl.imbalance fields for p. | |
| 197 ** Assume that the children of p have correct heights. | |
| 198 */ | |
| 199 static void amatchAvlRecomputeHeight(amatch_avl *p){ | |
| 200 short int hBefore = p->pBefore ? p->pBefore->height : 0; | |
| 201 short int hAfter = p->pAfter ? p->pAfter->height : 0; | |
| 202 p->imbalance = hBefore - hAfter; /* -: pAfter higher. +: pBefore higher */ | |
| 203 p->height = (hBefore>hAfter ? hBefore : hAfter)+1; | |
| 204 } | |
| 205 | |
| 206 /* | |
| 207 ** P B | |
| 208 ** / \ / \ | |
| 209 ** B Z ==> X P | |
| 210 ** / \ / \ | |
| 211 ** X Y Y Z | |
| 212 ** | |
| 213 */ | |
| 214 static amatch_avl *amatchAvlRotateBefore(amatch_avl *pP){ | |
| 215 amatch_avl *pB = pP->pBefore; | |
| 216 amatch_avl *pY = pB->pAfter; | |
| 217 pB->pUp = pP->pUp; | |
| 218 pB->pAfter = pP; | |
| 219 pP->pUp = pB; | |
| 220 pP->pBefore = pY; | |
| 221 if( pY ) pY->pUp = pP; | |
| 222 amatchAvlRecomputeHeight(pP); | |
| 223 amatchAvlRecomputeHeight(pB); | |
| 224 return pB; | |
| 225 } | |
| 226 | |
| 227 /* | |
| 228 ** P A | |
| 229 ** / \ / \ | |
| 230 ** X A ==> P Z | |
| 231 ** / \ / \ | |
| 232 ** Y Z X Y | |
| 233 ** | |
| 234 */ | |
| 235 static amatch_avl *amatchAvlRotateAfter(amatch_avl *pP){ | |
| 236 amatch_avl *pA = pP->pAfter; | |
| 237 amatch_avl *pY = pA->pBefore; | |
| 238 pA->pUp = pP->pUp; | |
| 239 pA->pBefore = pP; | |
| 240 pP->pUp = pA; | |
| 241 pP->pAfter = pY; | |
| 242 if( pY ) pY->pUp = pP; | |
| 243 amatchAvlRecomputeHeight(pP); | |
| 244 amatchAvlRecomputeHeight(pA); | |
| 245 return pA; | |
| 246 } | |
| 247 | |
| 248 /* | |
| 249 ** Return a pointer to the pBefore or pAfter pointer in the parent | |
| 250 ** of p that points to p. Or if p is the root node, return pp. | |
| 251 */ | |
| 252 static amatch_avl **amatchAvlFromPtr(amatch_avl *p, amatch_avl **pp){ | |
| 253 amatch_avl *pUp = p->pUp; | |
| 254 if( pUp==0 ) return pp; | |
| 255 if( pUp->pAfter==p ) return &pUp->pAfter; | |
| 256 return &pUp->pBefore; | |
| 257 } | |
| 258 | |
| 259 /* | |
| 260 ** Rebalance all nodes starting with p and working up to the root. | |
| 261 ** Return the new root. | |
| 262 */ | |
| 263 static amatch_avl *amatchAvlBalance(amatch_avl *p){ | |
| 264 amatch_avl *pTop = p; | |
| 265 amatch_avl **pp; | |
| 266 while( p ){ | |
| 267 amatchAvlRecomputeHeight(p); | |
| 268 if( p->imbalance>=2 ){ | |
| 269 amatch_avl *pB = p->pBefore; | |
| 270 if( pB->imbalance<0 ) p->pBefore = amatchAvlRotateAfter(pB); | |
| 271 pp = amatchAvlFromPtr(p,&p); | |
| 272 p = *pp = amatchAvlRotateBefore(p); | |
| 273 }else if( p->imbalance<=(-2) ){ | |
| 274 amatch_avl *pA = p->pAfter; | |
| 275 if( pA->imbalance>0 ) p->pAfter = amatchAvlRotateBefore(pA); | |
| 276 pp = amatchAvlFromPtr(p,&p); | |
| 277 p = *pp = amatchAvlRotateAfter(p); | |
| 278 } | |
| 279 pTop = p; | |
| 280 p = p->pUp; | |
| 281 } | |
| 282 return pTop; | |
| 283 } | |
| 284 | |
| 285 /* Search the tree rooted at p for an entry with zKey. Return a pointer | |
| 286 ** to the entry or return NULL. | |
| 287 */ | |
| 288 static amatch_avl *amatchAvlSearch(amatch_avl *p, const char *zKey){ | |
| 289 int c; | |
| 290 while( p && (c = strcmp(zKey, p->zKey))!=0 ){ | |
| 291 p = (c<0) ? p->pBefore : p->pAfter; | |
| 292 } | |
| 293 return p; | |
| 294 } | |
| 295 | |
| 296 /* Find the first node (the one with the smallest key). | |
| 297 */ | |
| 298 static amatch_avl *amatchAvlFirst(amatch_avl *p){ | |
| 299 if( p ) while( p->pBefore ) p = p->pBefore; | |
| 300 return p; | |
| 301 } | |
| 302 | |
| 303 #if 0 /* NOT USED */ | |
| 304 /* Return the node with the next larger key after p. | |
| 305 */ | |
| 306 static amatch_avl *amatchAvlNext(amatch_avl *p){ | |
| 307 amatch_avl *pPrev = 0; | |
| 308 while( p && p->pAfter==pPrev ){ | |
| 309 pPrev = p; | |
| 310 p = p->pUp; | |
| 311 } | |
| 312 if( p && pPrev==0 ){ | |
| 313 p = amatchAvlFirst(p->pAfter); | |
| 314 } | |
| 315 return p; | |
| 316 } | |
| 317 #endif | |
| 318 | |
| 319 #if 0 /* NOT USED */ | |
| 320 /* Verify AVL tree integrity | |
| 321 */ | |
| 322 static int amatchAvlIntegrity(amatch_avl *pHead){ | |
| 323 amatch_avl *p; | |
| 324 if( pHead==0 ) return 1; | |
| 325 if( (p = pHead->pBefore)!=0 ){ | |
| 326 assert( p->pUp==pHead ); | |
| 327 assert( amatchAvlIntegrity(p) ); | |
| 328 assert( strcmp(p->zKey, pHead->zKey)<0 ); | |
| 329 while( p->pAfter ) p = p->pAfter; | |
| 330 assert( strcmp(p->zKey, pHead->zKey)<0 ); | |
| 331 } | |
| 332 if( (p = pHead->pAfter)!=0 ){ | |
| 333 assert( p->pUp==pHead ); | |
| 334 assert( amatchAvlIntegrity(p) ); | |
| 335 assert( strcmp(p->zKey, pHead->zKey)>0 ); | |
| 336 p = amatchAvlFirst(p); | |
| 337 assert( strcmp(p->zKey, pHead->zKey)>0 ); | |
| 338 } | |
| 339 return 1; | |
| 340 } | |
| 341 static int amatchAvlIntegrity2(amatch_avl *pHead){ | |
| 342 amatch_avl *p, *pNext; | |
| 343 for(p=amatchAvlFirst(pHead); p; p=pNext){ | |
| 344 pNext = amatchAvlNext(p); | |
| 345 if( pNext==0 ) break; | |
| 346 assert( strcmp(p->zKey, pNext->zKey)<0 ); | |
| 347 } | |
| 348 return 1; | |
| 349 } | |
| 350 #endif | |
| 351 | |
| 352 /* Insert a new node pNew. Return NULL on success. If the key is not | |
| 353 ** unique, then do not perform the insert but instead leave pNew unchanged | |
| 354 ** and return a pointer to an existing node with the same key. | |
| 355 */ | |
| 356 static amatch_avl *amatchAvlInsert(amatch_avl **ppHead, amatch_avl *pNew){ | |
| 357 int c; | |
| 358 amatch_avl *p = *ppHead; | |
| 359 if( p==0 ){ | |
| 360 p = pNew; | |
| 361 pNew->pUp = 0; | |
| 362 }else{ | |
| 363 while( p ){ | |
| 364 c = strcmp(pNew->zKey, p->zKey); | |
| 365 if( c<0 ){ | |
| 366 if( p->pBefore ){ | |
| 367 p = p->pBefore; | |
| 368 }else{ | |
| 369 p->pBefore = pNew; | |
| 370 pNew->pUp = p; | |
| 371 break; | |
| 372 } | |
| 373 }else if( c>0 ){ | |
| 374 if( p->pAfter ){ | |
| 375 p = p->pAfter; | |
| 376 }else{ | |
| 377 p->pAfter = pNew; | |
| 378 pNew->pUp = p; | |
| 379 break; | |
| 380 } | |
| 381 }else{ | |
| 382 return p; | |
| 383 } | |
| 384 } | |
| 385 } | |
| 386 pNew->pBefore = 0; | |
| 387 pNew->pAfter = 0; | |
| 388 pNew->height = 1; | |
| 389 pNew->imbalance = 0; | |
| 390 *ppHead = amatchAvlBalance(p); | |
| 391 /* assert( amatchAvlIntegrity(*ppHead) ); */ | |
| 392 /* assert( amatchAvlIntegrity2(*ppHead) ); */ | |
| 393 return 0; | |
| 394 } | |
| 395 | |
| 396 /* Remove node pOld from the tree. pOld must be an element of the tree or | |
| 397 ** the AVL tree will become corrupt. | |
| 398 */ | |
| 399 static void amatchAvlRemove(amatch_avl **ppHead, amatch_avl *pOld){ | |
| 400 amatch_avl **ppParent; | |
| 401 amatch_avl *pBalance; | |
| 402 /* assert( amatchAvlSearch(*ppHead, pOld->zKey)==pOld ); */ | |
| 403 ppParent = amatchAvlFromPtr(pOld, ppHead); | |
| 404 if( pOld->pBefore==0 && pOld->pAfter==0 ){ | |
| 405 *ppParent = 0; | |
| 406 pBalance = pOld->pUp; | |
| 407 }else if( pOld->pBefore && pOld->pAfter ){ | |
| 408 amatch_avl *pX, *pY; | |
| 409 pX = amatchAvlFirst(pOld->pAfter); | |
| 410 *amatchAvlFromPtr(pX, 0) = pX->pAfter; | |
| 411 if( pX->pAfter ) pX->pAfter->pUp = pX->pUp; | |
| 412 pBalance = pX->pUp; | |
| 413 pX->pAfter = pOld->pAfter; | |
| 414 if( pX->pAfter ){ | |
| 415 pX->pAfter->pUp = pX; | |
| 416 }else{ | |
| 417 assert( pBalance==pOld ); | |
| 418 pBalance = pX; | |
| 419 } | |
| 420 pX->pBefore = pY = pOld->pBefore; | |
| 421 if( pY ) pY->pUp = pX; | |
| 422 pX->pUp = pOld->pUp; | |
| 423 *ppParent = pX; | |
| 424 }else if( pOld->pBefore==0 ){ | |
| 425 *ppParent = pBalance = pOld->pAfter; | |
| 426 pBalance->pUp = pOld->pUp; | |
| 427 }else if( pOld->pAfter==0 ){ | |
| 428 *ppParent = pBalance = pOld->pBefore; | |
| 429 pBalance->pUp = pOld->pUp; | |
| 430 } | |
| 431 *ppHead = amatchAvlBalance(pBalance); | |
| 432 pOld->pUp = 0; | |
| 433 pOld->pBefore = 0; | |
| 434 pOld->pAfter = 0; | |
| 435 /* assert( amatchAvlIntegrity(*ppHead) ); */ | |
| 436 /* assert( amatchAvlIntegrity2(*ppHead) ); */ | |
| 437 } | |
| 438 /* | |
| 439 ** End of the AVL Tree implementation | |
| 440 ******************************************************************************/ | |
| 441 | |
| 442 | |
| 443 /* | |
| 444 ** Various types. | |
| 445 ** | |
| 446 ** amatch_cost is the "cost" of an edit operation. | |
| 447 ** | |
| 448 ** amatch_len is the length of a matching string. | |
| 449 ** | |
| 450 ** amatch_langid is an ruleset identifier. | |
| 451 */ | |
| 452 typedef int amatch_cost; | |
| 453 typedef signed char amatch_len; | |
| 454 typedef int amatch_langid; | |
| 455 | |
| 456 /* | |
| 457 ** Limits | |
| 458 */ | |
| 459 #define AMATCH_MX_LENGTH 50 /* Maximum length of a rule string */ | |
| 460 #define AMATCH_MX_LANGID 2147483647 /* Maximum rule ID */ | |
| 461 #define AMATCH_MX_COST 1000 /* Maximum single-rule cost */ | |
| 462 | |
| 463 /* | |
| 464 ** A match or partial match | |
| 465 */ | |
| 466 struct amatch_word { | |
| 467 amatch_word *pNext; /* Next on a list of all amatch_words */ | |
| 468 amatch_avl sCost; /* Linkage of this node into the cost tree */ | |
| 469 amatch_avl sWord; /* Linkage of this node into the word tree */ | |
| 470 amatch_cost rCost; /* Cost of the match so far */ | |
| 471 int iSeq; /* Sequence number */ | |
| 472 char zCost[10]; /* Cost key (text rendering of rCost) */ | |
| 473 short int nMatch; /* Input characters matched */ | |
| 474 char zWord[4]; /* Text of the word. Extra space appended as needed */ | |
| 475 }; | |
| 476 | |
| 477 /* | |
| 478 ** Each transformation rule is stored as an instance of this object. | |
| 479 ** All rules are kept on a linked list sorted by rCost. | |
| 480 */ | |
| 481 struct amatch_rule { | |
| 482 amatch_rule *pNext; /* Next rule in order of increasing rCost */ | |
| 483 char *zFrom; /* Transform from (a string from user input) */ | |
| 484 amatch_cost rCost; /* Cost of this transformation */ | |
| 485 amatch_langid iLang; /* The langauge to which this rule belongs */ | |
| 486 amatch_len nFrom, nTo; /* Length of the zFrom and zTo strings */ | |
| 487 char zTo[4]; /* Tranform to V.W value (extra space appended) */ | |
| 488 }; | |
| 489 | |
| 490 /* | |
| 491 ** A amatch virtual-table object | |
| 492 */ | |
| 493 struct amatch_vtab { | |
| 494 sqlite3_vtab base; /* Base class - must be first */ | |
| 495 char *zClassName; /* Name of this class. Default: "amatch" */ | |
| 496 char *zDb; /* Name of database. (ex: "main") */ | |
| 497 char *zSelf; /* Name of this virtual table */ | |
| 498 char *zCostTab; /* Name of edit-cost-table */ | |
| 499 char *zVocabTab; /* Name of vocabulary table */ | |
| 500 char *zVocabWord; /* Name of vocabulary table word column */ | |
| 501 char *zVocabLang; /* Name of vocabulary table language column */ | |
| 502 amatch_rule *pRule; /* All active rules in this amatch */ | |
| 503 amatch_cost rIns; /* Generic insertion cost '' -> ? */ | |
| 504 amatch_cost rDel; /* Generic deletion cost ? -> '' */ | |
| 505 amatch_cost rSub; /* Generic substitution cost ? -> ? */ | |
| 506 sqlite3 *db; /* The database connection */ | |
| 507 sqlite3_stmt *pVCheck; /* Query to check zVocabTab */ | |
| 508 int nCursor; /* Number of active cursors */ | |
| 509 }; | |
| 510 | |
| 511 /* A amatch cursor object */ | |
| 512 struct amatch_cursor { | |
| 513 sqlite3_vtab_cursor base; /* Base class - must be first */ | |
| 514 sqlite3_int64 iRowid; /* The rowid of the current word */ | |
| 515 amatch_langid iLang; /* Use this language ID */ | |
| 516 amatch_cost rLimit; /* Maximum cost of any term */ | |
| 517 int nBuf; /* Space allocated for zBuf */ | |
| 518 int oomErr; /* True following an OOM error */ | |
| 519 int nWord; /* Number of amatch_word objects */ | |
| 520 char *zBuf; /* Temp-use buffer space */ | |
| 521 char *zInput; /* Input word to match against */ | |
| 522 amatch_vtab *pVtab; /* The virtual table this cursor belongs to */ | |
| 523 amatch_word *pAllWords; /* List of all amatch_word objects */ | |
| 524 amatch_word *pCurrent; /* Most recent solution */ | |
| 525 amatch_avl *pCost; /* amatch_word objects keyed by iCost */ | |
| 526 amatch_avl *pWord; /* amatch_word objects keyed by zWord */ | |
| 527 }; | |
| 528 | |
| 529 /* | |
| 530 ** The two input rule lists are both sorted in order of increasing | |
| 531 ** cost. Merge them together into a single list, sorted by cost, and | |
| 532 ** return a pointer to the head of that list. | |
| 533 */ | |
| 534 static amatch_rule *amatchMergeRules(amatch_rule *pA, amatch_rule *pB){ | |
| 535 amatch_rule head; | |
| 536 amatch_rule *pTail; | |
| 537 | |
| 538 pTail = &head; | |
| 539 while( pA && pB ){ | |
| 540 if( pA->rCost<=pB->rCost ){ | |
| 541 pTail->pNext = pA; | |
| 542 pTail = pA; | |
| 543 pA = pA->pNext; | |
| 544 }else{ | |
| 545 pTail->pNext = pB; | |
| 546 pTail = pB; | |
| 547 pB = pB->pNext; | |
| 548 } | |
| 549 } | |
| 550 if( pA==0 ){ | |
| 551 pTail->pNext = pB; | |
| 552 }else{ | |
| 553 pTail->pNext = pA; | |
| 554 } | |
| 555 return head.pNext; | |
| 556 } | |
| 557 | |
| 558 /* | |
| 559 ** Statement pStmt currently points to a row in the amatch data table. This | |
| 560 ** function allocates and populates a amatch_rule structure according to | |
| 561 ** the content of the row. | |
| 562 ** | |
| 563 ** If successful, *ppRule is set to point to the new object and SQLITE_OK | |
| 564 ** is returned. Otherwise, *ppRule is zeroed, *pzErr may be set to point | |
| 565 ** to an error message and an SQLite error code returned. | |
| 566 */ | |
| 567 static int amatchLoadOneRule( | |
| 568 amatch_vtab *p, /* Fuzzer virtual table handle */ | |
| 569 sqlite3_stmt *pStmt, /* Base rule on statements current row */ | |
| 570 amatch_rule **ppRule, /* OUT: New rule object */ | |
| 571 char **pzErr /* OUT: Error message */ | |
| 572 ){ | |
| 573 sqlite3_int64 iLang = sqlite3_column_int64(pStmt, 0); | |
| 574 const char *zFrom = (const char *)sqlite3_column_text(pStmt, 1); | |
| 575 const char *zTo = (const char *)sqlite3_column_text(pStmt, 2); | |
| 576 amatch_cost rCost = sqlite3_column_int(pStmt, 3); | |
| 577 | |
| 578 int rc = SQLITE_OK; /* Return code */ | |
| 579 int nFrom; /* Size of string zFrom, in bytes */ | |
| 580 int nTo; /* Size of string zTo, in bytes */ | |
| 581 amatch_rule *pRule = 0; /* New rule object to return */ | |
| 582 | |
| 583 if( zFrom==0 ) zFrom = ""; | |
| 584 if( zTo==0 ) zTo = ""; | |
| 585 nFrom = (int)strlen(zFrom); | |
| 586 nTo = (int)strlen(zTo); | |
| 587 | |
| 588 /* Silently ignore null transformations */ | |
| 589 if( strcmp(zFrom, zTo)==0 ){ | |
| 590 if( zFrom[0]=='?' && zFrom[1]==0 ){ | |
| 591 if( p->rSub==0 || p->rSub>rCost ) p->rSub = rCost; | |
| 592 } | |
| 593 *ppRule = 0; | |
| 594 return SQLITE_OK; | |
| 595 } | |
| 596 | |
| 597 if( rCost<=0 || rCost>AMATCH_MX_COST ){ | |
| 598 *pzErr = sqlite3_mprintf("%s: cost must be between 1 and %d", | |
| 599 p->zClassName, AMATCH_MX_COST | |
| 600 ); | |
| 601 rc = SQLITE_ERROR; | |
| 602 }else | |
| 603 if( nFrom>AMATCH_MX_LENGTH || nTo>AMATCH_MX_LENGTH ){ | |
| 604 *pzErr = sqlite3_mprintf("%s: maximum string length is %d", | |
| 605 p->zClassName, AMATCH_MX_LENGTH | |
| 606 ); | |
| 607 rc = SQLITE_ERROR; | |
| 608 }else | |
| 609 if( iLang<0 || iLang>AMATCH_MX_LANGID ){ | |
| 610 *pzErr = sqlite3_mprintf("%s: iLang must be between 0 and %d", | |
| 611 p->zClassName, AMATCH_MX_LANGID | |
| 612 ); | |
| 613 rc = SQLITE_ERROR; | |
| 614 }else | |
| 615 if( strcmp(zFrom,"")==0 && strcmp(zTo,"?")==0 ){ | |
| 616 if( p->rIns==0 || p->rIns>rCost ) p->rIns = rCost; | |
| 617 }else | |
| 618 if( strcmp(zFrom,"?")==0 && strcmp(zTo,"")==0 ){ | |
| 619 if( p->rDel==0 || p->rDel>rCost ) p->rDel = rCost; | |
| 620 }else | |
| 621 { | |
| 622 pRule = sqlite3_malloc( sizeof(*pRule) + nFrom + nTo ); | |
| 623 if( pRule==0 ){ | |
| 624 rc = SQLITE_NOMEM; | |
| 625 }else{ | |
| 626 memset(pRule, 0, sizeof(*pRule)); | |
| 627 pRule->zFrom = &pRule->zTo[nTo+1]; | |
| 628 pRule->nFrom = nFrom; | |
| 629 memcpy(pRule->zFrom, zFrom, nFrom+1); | |
| 630 memcpy(pRule->zTo, zTo, nTo+1); | |
| 631 pRule->nTo = nTo; | |
| 632 pRule->rCost = rCost; | |
| 633 pRule->iLang = (int)iLang; | |
| 634 } | |
| 635 } | |
| 636 | |
| 637 *ppRule = pRule; | |
| 638 return rc; | |
| 639 } | |
| 640 | |
| 641 /* | |
| 642 ** Free all the content in the edit-cost-table | |
| 643 */ | |
| 644 static void amatchFreeRules(amatch_vtab *p){ | |
| 645 while( p->pRule ){ | |
| 646 amatch_rule *pRule = p->pRule; | |
| 647 p->pRule = pRule->pNext; | |
| 648 sqlite3_free(pRule); | |
| 649 } | |
| 650 p->pRule = 0; | |
| 651 } | |
| 652 | |
| 653 /* | |
| 654 ** Load the content of the amatch data table into memory. | |
| 655 */ | |
| 656 static int amatchLoadRules( | |
| 657 sqlite3 *db, /* Database handle */ | |
| 658 amatch_vtab *p, /* Virtual amatch table to configure */ | |
| 659 char **pzErr /* OUT: Error message */ | |
| 660 ){ | |
| 661 int rc = SQLITE_OK; /* Return code */ | |
| 662 char *zSql; /* SELECT used to read from rules table */ | |
| 663 amatch_rule *pHead = 0; | |
| 664 | |
| 665 zSql = sqlite3_mprintf("SELECT * FROM %Q.%Q", p->zDb, p->zCostTab); | |
| 666 if( zSql==0 ){ | |
| 667 rc = SQLITE_NOMEM; | |
| 668 }else{ | |
| 669 int rc2; /* finalize() return code */ | |
| 670 sqlite3_stmt *pStmt = 0; | |
| 671 rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0); | |
| 672 if( rc!=SQLITE_OK ){ | |
| 673 *pzErr = sqlite3_mprintf("%s: %s", p->zClassName, sqlite3_errmsg(db)); | |
| 674 }else if( sqlite3_column_count(pStmt)!=4 ){ | |
| 675 *pzErr = sqlite3_mprintf("%s: %s has %d columns, expected 4", | |
| 676 p->zClassName, p->zCostTab, sqlite3_column_count(pStmt) | |
| 677 ); | |
| 678 rc = SQLITE_ERROR; | |
| 679 }else{ | |
| 680 while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){ | |
| 681 amatch_rule *pRule = 0; | |
| 682 rc = amatchLoadOneRule(p, pStmt, &pRule, pzErr); | |
| 683 if( pRule ){ | |
| 684 pRule->pNext = pHead; | |
| 685 pHead = pRule; | |
| 686 } | |
| 687 } | |
| 688 } | |
| 689 rc2 = sqlite3_finalize(pStmt); | |
| 690 if( rc==SQLITE_OK ) rc = rc2; | |
| 691 } | |
| 692 sqlite3_free(zSql); | |
| 693 | |
| 694 /* All rules are now in a singly linked list starting at pHead. This | |
| 695 ** block sorts them by cost and then sets amatch_vtab.pRule to point to | |
| 696 ** point to the head of the sorted list. | |
| 697 */ | |
| 698 if( rc==SQLITE_OK ){ | |
| 699 unsigned int i; | |
| 700 amatch_rule *pX; | |
| 701 amatch_rule *a[15]; | |
| 702 for(i=0; i<sizeof(a)/sizeof(a[0]); i++) a[i] = 0; | |
| 703 while( (pX = pHead)!=0 ){ | |
| 704 pHead = pX->pNext; | |
| 705 pX->pNext = 0; | |
| 706 for(i=0; a[i] && i<sizeof(a)/sizeof(a[0])-1; i++){ | |
| 707 pX = amatchMergeRules(a[i], pX); | |
| 708 a[i] = 0; | |
| 709 } | |
| 710 a[i] = amatchMergeRules(a[i], pX); | |
| 711 } | |
| 712 for(pX=a[0], i=1; i<sizeof(a)/sizeof(a[0]); i++){ | |
| 713 pX = amatchMergeRules(a[i], pX); | |
| 714 } | |
| 715 p->pRule = amatchMergeRules(p->pRule, pX); | |
| 716 }else{ | |
| 717 /* An error has occurred. Setting p->pRule to point to the head of the | |
| 718 ** allocated list ensures that the list will be cleaned up in this case. | |
| 719 */ | |
| 720 assert( p->pRule==0 ); | |
| 721 p->pRule = pHead; | |
| 722 } | |
| 723 | |
| 724 return rc; | |
| 725 } | |
| 726 | |
| 727 /* | |
| 728 ** This function converts an SQL quoted string into an unquoted string | |
| 729 ** and returns a pointer to a buffer allocated using sqlite3_malloc() | |
| 730 ** containing the result. The caller should eventually free this buffer | |
| 731 ** using sqlite3_free. | |
| 732 ** | |
| 733 ** Examples: | |
| 734 ** | |
| 735 ** "abc" becomes abc | |
| 736 ** 'xyz' becomes xyz | |
| 737 ** [pqr] becomes pqr | |
| 738 ** `mno` becomes mno | |
| 739 */ | |
| 740 static char *amatchDequote(const char *zIn){ | |
| 741 int nIn; /* Size of input string, in bytes */ | |
| 742 char *zOut; /* Output (dequoted) string */ | |
| 743 | |
| 744 nIn = (int)strlen(zIn); | |
| 745 zOut = sqlite3_malloc(nIn+1); | |
| 746 if( zOut ){ | |
| 747 char q = zIn[0]; /* Quote character (if any ) */ | |
| 748 | |
| 749 if( q!='[' && q!= '\'' && q!='"' && q!='`' ){ | |
| 750 memcpy(zOut, zIn, nIn+1); | |
| 751 }else{ | |
| 752 int iOut = 0; /* Index of next byte to write to output */ | |
| 753 int iIn; /* Index of next byte to read from input */ | |
| 754 | |
| 755 if( q=='[' ) q = ']'; | |
| 756 for(iIn=1; iIn<nIn; iIn++){ | |
| 757 if( zIn[iIn]==q ) iIn++; | |
| 758 zOut[iOut++] = zIn[iIn]; | |
| 759 } | |
| 760 } | |
| 761 assert( (int)strlen(zOut)<=nIn ); | |
| 762 } | |
| 763 return zOut; | |
| 764 } | |
| 765 | |
| 766 /* | |
| 767 ** Deallocate the pVCheck prepared statement. | |
| 768 */ | |
| 769 static void amatchVCheckClear(amatch_vtab *p){ | |
| 770 if( p->pVCheck ){ | |
| 771 sqlite3_finalize(p->pVCheck); | |
| 772 p->pVCheck = 0; | |
| 773 } | |
| 774 } | |
| 775 | |
| 776 /* | |
| 777 ** Deallocate an amatch_vtab object | |
| 778 */ | |
| 779 static void amatchFree(amatch_vtab *p){ | |
| 780 if( p ){ | |
| 781 amatchFreeRules(p); | |
| 782 amatchVCheckClear(p); | |
| 783 sqlite3_free(p->zClassName); | |
| 784 sqlite3_free(p->zDb); | |
| 785 sqlite3_free(p->zCostTab); | |
| 786 sqlite3_free(p->zVocabTab); | |
| 787 sqlite3_free(p->zVocabWord); | |
| 788 sqlite3_free(p->zVocabLang); | |
| 789 sqlite3_free(p->zSelf); | |
| 790 memset(p, 0, sizeof(*p)); | |
| 791 sqlite3_free(p); | |
| 792 } | |
| 793 } | |
| 794 | |
| 795 /* | |
| 796 ** xDisconnect/xDestroy method for the amatch module. | |
| 797 */ | |
| 798 static int amatchDisconnect(sqlite3_vtab *pVtab){ | |
| 799 amatch_vtab *p = (amatch_vtab*)pVtab; | |
| 800 assert( p->nCursor==0 ); | |
| 801 amatchFree(p); | |
| 802 return SQLITE_OK; | |
| 803 } | |
| 804 | |
| 805 /* | |
| 806 ** Check to see if the argument is of the form: | |
| 807 ** | |
| 808 ** KEY = VALUE | |
| 809 ** | |
| 810 ** If it is, return a pointer to the first character of VALUE. | |
| 811 ** If not, return NULL. Spaces around the = are ignored. | |
| 812 */ | |
| 813 static const char *amatchValueOfKey(const char *zKey, const char *zStr){ | |
| 814 int nKey = (int)strlen(zKey); | |
| 815 int nStr = (int)strlen(zStr); | |
| 816 int i; | |
| 817 if( nStr<nKey+1 ) return 0; | |
| 818 if( memcmp(zStr, zKey, nKey)!=0 ) return 0; | |
| 819 for(i=nKey; isspace(zStr[i]); i++){} | |
| 820 if( zStr[i]!='=' ) return 0; | |
| 821 i++; | |
| 822 while( isspace(zStr[i]) ){ i++; } | |
| 823 return zStr+i; | |
| 824 } | |
| 825 | |
| 826 /* | |
| 827 ** xConnect/xCreate method for the amatch module. Arguments are: | |
| 828 ** | |
| 829 ** argv[0] -> module name ("approximate_match") | |
| 830 ** argv[1] -> database name | |
| 831 ** argv[2] -> table name | |
| 832 ** argv[3...] -> arguments | |
| 833 */ | |
| 834 static int amatchConnect( | |
| 835 sqlite3 *db, | |
| 836 void *pAux, | |
| 837 int argc, const char *const*argv, | |
| 838 sqlite3_vtab **ppVtab, | |
| 839 char **pzErr | |
| 840 ){ | |
| 841 int rc = SQLITE_OK; /* Return code */ | |
| 842 amatch_vtab *pNew = 0; /* New virtual table */ | |
| 843 const char *zModule = argv[0]; | |
| 844 const char *zDb = argv[1]; | |
| 845 const char *zVal; | |
| 846 int i; | |
| 847 | |
| 848 (void)pAux; | |
| 849 *ppVtab = 0; | |
| 850 pNew = sqlite3_malloc( sizeof(*pNew) ); | |
| 851 if( pNew==0 ) return SQLITE_NOMEM; | |
| 852 rc = SQLITE_NOMEM; | |
| 853 memset(pNew, 0, sizeof(*pNew)); | |
| 854 pNew->db = db; | |
| 855 pNew->zClassName = sqlite3_mprintf("%s", zModule); | |
| 856 if( pNew->zClassName==0 ) goto amatchConnectError; | |
| 857 pNew->zDb = sqlite3_mprintf("%s", zDb); | |
| 858 if( pNew->zDb==0 ) goto amatchConnectError; | |
| 859 pNew->zSelf = sqlite3_mprintf("%s", argv[2]); | |
| 860 if( pNew->zSelf==0 ) goto amatchConnectError; | |
| 861 for(i=3; i<argc; i++){ | |
| 862 zVal = amatchValueOfKey("vocabulary_table", argv[i]); | |
| 863 if( zVal ){ | |
| 864 sqlite3_free(pNew->zVocabTab); | |
| 865 pNew->zVocabTab = amatchDequote(zVal); | |
| 866 if( pNew->zVocabTab==0 ) goto amatchConnectError; | |
| 867 continue; | |
| 868 } | |
| 869 zVal = amatchValueOfKey("vocabulary_word", argv[i]); | |
| 870 if( zVal ){ | |
| 871 sqlite3_free(pNew->zVocabWord); | |
| 872 pNew->zVocabWord = amatchDequote(zVal); | |
| 873 if( pNew->zVocabWord==0 ) goto amatchConnectError; | |
| 874 continue; | |
| 875 } | |
| 876 zVal = amatchValueOfKey("vocabulary_language", argv[i]); | |
| 877 if( zVal ){ | |
| 878 sqlite3_free(pNew->zVocabLang); | |
| 879 pNew->zVocabLang = amatchDequote(zVal); | |
| 880 if( pNew->zVocabLang==0 ) goto amatchConnectError; | |
| 881 continue; | |
| 882 } | |
| 883 zVal = amatchValueOfKey("edit_distances", argv[i]); | |
| 884 if( zVal ){ | |
| 885 sqlite3_free(pNew->zCostTab); | |
| 886 pNew->zCostTab = amatchDequote(zVal); | |
| 887 if( pNew->zCostTab==0 ) goto amatchConnectError; | |
| 888 continue; | |
| 889 } | |
| 890 *pzErr = sqlite3_mprintf("unrecognized argument: [%s]\n", argv[i]); | |
| 891 amatchFree(pNew); | |
| 892 *ppVtab = 0; | |
| 893 return SQLITE_ERROR; | |
| 894 } | |
| 895 rc = SQLITE_OK; | |
| 896 if( pNew->zCostTab==0 ){ | |
| 897 *pzErr = sqlite3_mprintf("no edit_distances table specified"); | |
| 898 rc = SQLITE_ERROR; | |
| 899 }else{ | |
| 900 rc = amatchLoadRules(db, pNew, pzErr); | |
| 901 } | |
| 902 if( rc==SQLITE_OK ){ | |
| 903 rc = sqlite3_declare_vtab(db, | |
| 904 "CREATE TABLE x(word,distance,language," | |
| 905 "command HIDDEN,nword HIDDEN)" | |
| 906 ); | |
| 907 #define AMATCH_COL_WORD 0 | |
| 908 #define AMATCH_COL_DISTANCE 1 | |
| 909 #define AMATCH_COL_LANGUAGE 2 | |
| 910 #define AMATCH_COL_COMMAND 3 | |
| 911 #define AMATCH_COL_NWORD 4 | |
| 912 } | |
| 913 if( rc!=SQLITE_OK ){ | |
| 914 amatchFree(pNew); | |
| 915 } | |
| 916 *ppVtab = &pNew->base; | |
| 917 return rc; | |
| 918 | |
| 919 amatchConnectError: | |
| 920 amatchFree(pNew); | |
| 921 return rc; | |
| 922 } | |
| 923 | |
| 924 /* | |
| 925 ** Open a new amatch cursor. | |
| 926 */ | |
| 927 static int amatchOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){ | |
| 928 amatch_vtab *p = (amatch_vtab*)pVTab; | |
| 929 amatch_cursor *pCur; | |
| 930 pCur = sqlite3_malloc( sizeof(*pCur) ); | |
| 931 if( pCur==0 ) return SQLITE_NOMEM; | |
| 932 memset(pCur, 0, sizeof(*pCur)); | |
| 933 pCur->pVtab = p; | |
| 934 *ppCursor = &pCur->base; | |
| 935 p->nCursor++; | |
| 936 return SQLITE_OK; | |
| 937 } | |
| 938 | |
| 939 /* | |
| 940 ** Free up all the memory allocated by a cursor. Set it rLimit to 0 | |
| 941 ** to indicate that it is at EOF. | |
| 942 */ | |
| 943 static void amatchClearCursor(amatch_cursor *pCur){ | |
| 944 amatch_word *pWord, *pNextWord; | |
| 945 for(pWord=pCur->pAllWords; pWord; pWord=pNextWord){ | |
| 946 pNextWord = pWord->pNext; | |
| 947 sqlite3_free(pWord); | |
| 948 } | |
| 949 pCur->pAllWords = 0; | |
| 950 sqlite3_free(pCur->zInput); | |
| 951 pCur->zInput = 0; | |
| 952 sqlite3_free(pCur->zBuf); | |
| 953 pCur->zBuf = 0; | |
| 954 pCur->nBuf = 0; | |
| 955 pCur->pCost = 0; | |
| 956 pCur->pWord = 0; | |
| 957 pCur->pCurrent = 0; | |
| 958 pCur->rLimit = 1000000; | |
| 959 pCur->iLang = 0; | |
| 960 pCur->nWord = 0; | |
| 961 } | |
| 962 | |
| 963 /* | |
| 964 ** Close a amatch cursor. | |
| 965 */ | |
| 966 static int amatchClose(sqlite3_vtab_cursor *cur){ | |
| 967 amatch_cursor *pCur = (amatch_cursor *)cur; | |
| 968 amatchClearCursor(pCur); | |
| 969 pCur->pVtab->nCursor--; | |
| 970 sqlite3_free(pCur); | |
| 971 return SQLITE_OK; | |
| 972 } | |
| 973 | |
| 974 /* | |
| 975 ** Render a 24-bit unsigned integer as a 4-byte base-64 number. | |
| 976 */ | |
| 977 static void amatchEncodeInt(int x, char *z){ | |
| 978 static const char a[] = | |
| 979 "0123456789" | |
| 980 "ABCDEFGHIJ" | |
| 981 "KLMNOPQRST" | |
| 982 "UVWXYZ^abc" | |
| 983 "defghijklm" | |
| 984 "nopqrstuvw" | |
| 985 "xyz~"; | |
| 986 z[0] = a[(x>>18)&0x3f]; | |
| 987 z[1] = a[(x>>12)&0x3f]; | |
| 988 z[2] = a[(x>>6)&0x3f]; | |
| 989 z[3] = a[x&0x3f]; | |
| 990 } | |
| 991 | |
| 992 /* | |
| 993 ** Write the zCost[] field for a amatch_word object | |
| 994 */ | |
| 995 static void amatchWriteCost(amatch_word *pWord){ | |
| 996 amatchEncodeInt(pWord->rCost, pWord->zCost); | |
| 997 amatchEncodeInt(pWord->iSeq, pWord->zCost+4); | |
| 998 pWord->zCost[8] = 0; | |
| 999 } | |
| 1000 | |
| 1001 /* | |
| 1002 ** Add a new amatch_word object to the queue. | |
| 1003 ** | |
| 1004 ** If a prior amatch_word object with the same zWord, and nMatch | |
| 1005 ** already exists, update its rCost (if the new rCost is less) but | |
| 1006 ** otherwise leave it unchanged. Do not add a duplicate. | |
| 1007 ** | |
| 1008 ** Do nothing if the cost exceeds threshold. | |
| 1009 */ | |
| 1010 static void amatchAddWord( | |
| 1011 amatch_cursor *pCur, | |
| 1012 amatch_cost rCost, | |
| 1013 int nMatch, | |
| 1014 const char *zWordBase, | |
| 1015 const char *zWordTail | |
| 1016 ){ | |
| 1017 amatch_word *pWord; | |
| 1018 amatch_avl *pNode; | |
| 1019 amatch_avl *pOther; | |
| 1020 int nBase, nTail; | |
| 1021 char zBuf[4]; | |
| 1022 | |
| 1023 if( rCost>pCur->rLimit ){ | |
| 1024 return; | |
| 1025 } | |
| 1026 nBase = (int)strlen(zWordBase); | |
| 1027 nTail = (int)strlen(zWordTail); | |
| 1028 if( nBase+nTail+3>pCur->nBuf ){ | |
| 1029 pCur->nBuf = nBase+nTail+100; | |
| 1030 pCur->zBuf = sqlite3_realloc(pCur->zBuf, pCur->nBuf); | |
| 1031 if( pCur->zBuf==0 ){ | |
| 1032 pCur->nBuf = 0; | |
| 1033 return; | |
| 1034 } | |
| 1035 } | |
| 1036 amatchEncodeInt(nMatch, zBuf); | |
| 1037 memcpy(pCur->zBuf, zBuf+2, 2); | |
| 1038 memcpy(pCur->zBuf+2, zWordBase, nBase); | |
| 1039 memcpy(pCur->zBuf+2+nBase, zWordTail, nTail+1); | |
| 1040 pNode = amatchAvlSearch(pCur->pWord, pCur->zBuf); | |
| 1041 if( pNode ){ | |
| 1042 pWord = pNode->pWord; | |
| 1043 if( pWord->rCost>rCost ){ | |
| 1044 #ifdef AMATCH_TRACE_1 | |
| 1045 printf("UPDATE [%s][%.*s^%s] %d (\"%s\" \"%s\")\n", | |
| 1046 pWord->zWord+2, pWord->nMatch, pCur->zInput, pCur->zInput, | |
| 1047 pWord->rCost, pWord->zWord, pWord->zCost); | |
| 1048 #endif | |
| 1049 amatchAvlRemove(&pCur->pCost, &pWord->sCost); | |
| 1050 pWord->rCost = rCost; | |
| 1051 amatchWriteCost(pWord); | |
| 1052 #ifdef AMATCH_TRACE_1 | |
| 1053 printf(" ---> %d (\"%s\" \"%s\")\n", | |
| 1054 pWord->rCost, pWord->zWord, pWord->zCost); | |
| 1055 #endif | |
| 1056 pOther = amatchAvlInsert(&pCur->pCost, &pWord->sCost); | |
| 1057 assert( pOther==0 ); (void)pOther; | |
| 1058 } | |
| 1059 return; | |
| 1060 } | |
| 1061 pWord = sqlite3_malloc( sizeof(*pWord) + nBase + nTail - 1 ); | |
| 1062 if( pWord==0 ) return; | |
| 1063 memset(pWord, 0, sizeof(*pWord)); | |
| 1064 pWord->rCost = rCost; | |
| 1065 pWord->iSeq = pCur->nWord++; | |
| 1066 amatchWriteCost(pWord); | |
| 1067 pWord->nMatch = nMatch; | |
| 1068 pWord->pNext = pCur->pAllWords; | |
| 1069 pCur->pAllWords = pWord; | |
| 1070 pWord->sCost.zKey = pWord->zCost; | |
| 1071 pWord->sCost.pWord = pWord; | |
| 1072 pOther = amatchAvlInsert(&pCur->pCost, &pWord->sCost); | |
| 1073 assert( pOther==0 ); (void)pOther; | |
| 1074 pWord->sWord.zKey = pWord->zWord; | |
| 1075 pWord->sWord.pWord = pWord; | |
| 1076 strcpy(pWord->zWord, pCur->zBuf); | |
| 1077 pOther = amatchAvlInsert(&pCur->pWord, &pWord->sWord); | |
| 1078 assert( pOther==0 ); (void)pOther; | |
| 1079 #ifdef AMATCH_TRACE_1 | |
| 1080 printf("INSERT [%s][%.*s^%s] %d (\"%s\" \"%s\")\n", pWord->zWord+2, | |
| 1081 pWord->nMatch, pCur->zInput, pCur->zInput+pWord->nMatch, rCost, | |
| 1082 pWord->zWord, pWord->zCost); | |
| 1083 #endif | |
| 1084 } | |
| 1085 | |
| 1086 /* | |
| 1087 ** Advance a cursor to its next row of output | |
| 1088 */ | |
| 1089 static int amatchNext(sqlite3_vtab_cursor *cur){ | |
| 1090 amatch_cursor *pCur = (amatch_cursor*)cur; | |
| 1091 amatch_word *pWord = 0; | |
| 1092 amatch_avl *pNode; | |
| 1093 int isMatch = 0; | |
| 1094 amatch_vtab *p = pCur->pVtab; | |
| 1095 int nWord; | |
| 1096 int rc; | |
| 1097 int i; | |
| 1098 const char *zW; | |
| 1099 amatch_rule *pRule; | |
| 1100 char *zBuf = 0; | |
| 1101 char nBuf = 0; | |
| 1102 char zNext[8]; | |
| 1103 char zNextIn[8]; | |
| 1104 int nNextIn; | |
| 1105 | |
| 1106 if( p->pVCheck==0 ){ | |
| 1107 char *zSql; | |
| 1108 if( p->zVocabLang && p->zVocabLang[0] ){ | |
| 1109 zSql = sqlite3_mprintf( | |
| 1110 "SELECT \"%w\" FROM \"%w\"", | |
| 1111 " WHERE \"%w\">=?1 AND \"%w\"=?2" | |
| 1112 " ORDER BY 1", | |
| 1113 p->zVocabWord, p->zVocabTab, | |
| 1114 p->zVocabWord, p->zVocabLang | |
| 1115 ); | |
| 1116 }else{ | |
| 1117 zSql = sqlite3_mprintf( | |
| 1118 "SELECT \"%w\" FROM \"%w\"" | |
| 1119 " WHERE \"%w\">=?1" | |
| 1120 " ORDER BY 1", | |
| 1121 p->zVocabWord, p->zVocabTab, | |
| 1122 p->zVocabWord | |
| 1123 ); | |
| 1124 } | |
| 1125 rc = sqlite3_prepare_v2(p->db, zSql, -1, &p->pVCheck, 0); | |
| 1126 sqlite3_free(zSql); | |
| 1127 if( rc ) return rc; | |
| 1128 } | |
| 1129 sqlite3_bind_int(p->pVCheck, 2, pCur->iLang); | |
| 1130 | |
| 1131 do{ | |
| 1132 pNode = amatchAvlFirst(pCur->pCost); | |
| 1133 if( pNode==0 ){ | |
| 1134 pWord = 0; | |
| 1135 break; | |
| 1136 } | |
| 1137 pWord = pNode->pWord; | |
| 1138 amatchAvlRemove(&pCur->pCost, &pWord->sCost); | |
| 1139 | |
| 1140 #ifdef AMATCH_TRACE_1 | |
| 1141 printf("PROCESS [%s][%.*s^%s] %d (\"%s\" \"%s\")\n", | |
| 1142 pWord->zWord+2, pWord->nMatch, pCur->zInput, pCur->zInput+pWord->nMatch, | |
| 1143 pWord->rCost, pWord->zWord, pWord->zCost); | |
| 1144 #endif | |
| 1145 nWord = (int)strlen(pWord->zWord+2); | |
| 1146 if( nWord+20>nBuf ){ | |
| 1147 nBuf = nWord+100; | |
| 1148 zBuf = sqlite3_realloc(zBuf, nBuf); | |
| 1149 if( zBuf==0 ) return SQLITE_NOMEM; | |
| 1150 } | |
| 1151 strcpy(zBuf, pWord->zWord+2); | |
| 1152 zNext[0] = 0; | |
| 1153 zNextIn[0] = pCur->zInput[pWord->nMatch]; | |
| 1154 if( zNextIn[0] ){ | |
| 1155 for(i=1; i<=4 && (pCur->zInput[pWord->nMatch+i]&0xc0)==0x80; i++){ | |
| 1156 zNextIn[i] = pCur->zInput[pWord->nMatch+i]; | |
| 1157 } | |
| 1158 zNextIn[i] = 0; | |
| 1159 nNextIn = i; | |
| 1160 }else{ | |
| 1161 nNextIn = 0; | |
| 1162 } | |
| 1163 | |
| 1164 if( zNextIn[0] && zNextIn[0]!='*' ){ | |
| 1165 sqlite3_reset(p->pVCheck); | |
| 1166 strcat(zBuf, zNextIn); | |
| 1167 sqlite3_bind_text(p->pVCheck, 1, zBuf, nWord+nNextIn, SQLITE_STATIC); | |
| 1168 rc = sqlite3_step(p->pVCheck); | |
| 1169 if( rc==SQLITE_ROW ){ | |
| 1170 zW = (const char*)sqlite3_column_text(p->pVCheck, 0); | |
| 1171 if( strncmp(zBuf, zW, nWord+nNextIn)==0 ){ | |
| 1172 amatchAddWord(pCur, pWord->rCost, pWord->nMatch+nNextIn, zBuf, ""); | |
| 1173 } | |
| 1174 } | |
| 1175 zBuf[nWord] = 0; | |
| 1176 } | |
| 1177 | |
| 1178 while( 1 ){ | |
| 1179 strcpy(zBuf+nWord, zNext); | |
| 1180 sqlite3_reset(p->pVCheck); | |
| 1181 sqlite3_bind_text(p->pVCheck, 1, zBuf, -1, SQLITE_TRANSIENT); | |
| 1182 rc = sqlite3_step(p->pVCheck); | |
| 1183 if( rc!=SQLITE_ROW ) break; | |
| 1184 zW = (const char*)sqlite3_column_text(p->pVCheck, 0); | |
| 1185 strcpy(zBuf+nWord, zNext); | |
| 1186 if( strncmp(zW, zBuf, nWord)!=0 ) break; | |
| 1187 if( (zNextIn[0]=='*' && zNextIn[1]==0) | |
| 1188 || (zNextIn[0]==0 && zW[nWord]==0) | |
| 1189 ){ | |
| 1190 isMatch = 1; | |
| 1191 zNextIn[0] = 0; | |
| 1192 nNextIn = 0; | |
| 1193 break; | |
| 1194 } | |
| 1195 zNext[0] = zW[nWord]; | |
| 1196 for(i=1; i<=4 && (zW[nWord+i]&0xc0)==0x80; i++){ | |
| 1197 zNext[i] = zW[nWord+i]; | |
| 1198 } | |
| 1199 zNext[i] = 0; | |
| 1200 zBuf[nWord] = 0; | |
| 1201 if( p->rIns>0 ){ | |
| 1202 amatchAddWord(pCur, pWord->rCost+p->rIns, pWord->nMatch, | |
| 1203 zBuf, zNext); | |
| 1204 } | |
| 1205 if( p->rSub>0 ){ | |
| 1206 amatchAddWord(pCur, pWord->rCost+p->rSub, pWord->nMatch+nNextIn, | |
| 1207 zBuf, zNext); | |
| 1208 } | |
| 1209 if( p->rIns<0 && p->rSub<0 ) break; | |
| 1210 zNext[i-1]++; /* FIX ME */ | |
| 1211 } | |
| 1212 sqlite3_reset(p->pVCheck); | |
| 1213 | |
| 1214 if( p->rDel>0 ){ | |
| 1215 zBuf[nWord] = 0; | |
| 1216 amatchAddWord(pCur, pWord->rCost+p->rDel, pWord->nMatch+nNextIn, | |
| 1217 zBuf, ""); | |
| 1218 } | |
| 1219 | |
| 1220 for(pRule=p->pRule; pRule; pRule=pRule->pNext){ | |
| 1221 if( pRule->iLang!=pCur->iLang ) continue; | |
| 1222 if( strncmp(pRule->zFrom, pCur->zInput+pWord->nMatch, pRule->nFrom)==0 ){ | |
| 1223 amatchAddWord(pCur, pWord->rCost+pRule->rCost, | |
| 1224 pWord->nMatch+pRule->nFrom, pWord->zWord+2, pRule->zTo); | |
| 1225 } | |
| 1226 } | |
| 1227 }while( !isMatch ); | |
| 1228 pCur->pCurrent = pWord; | |
| 1229 sqlite3_free(zBuf); | |
| 1230 return SQLITE_OK; | |
| 1231 } | |
| 1232 | |
| 1233 /* | |
| 1234 ** Called to "rewind" a cursor back to the beginning so that | |
| 1235 ** it starts its output over again. Always called at least once | |
| 1236 ** prior to any amatchColumn, amatchRowid, or amatchEof call. | |
| 1237 */ | |
| 1238 static int amatchFilter( | |
| 1239 sqlite3_vtab_cursor *pVtabCursor, | |
| 1240 int idxNum, const char *idxStr, | |
| 1241 int argc, sqlite3_value **argv | |
| 1242 ){ | |
| 1243 amatch_cursor *pCur = (amatch_cursor *)pVtabCursor; | |
| 1244 const char *zWord = "*"; | |
| 1245 int idx; | |
| 1246 | |
| 1247 amatchClearCursor(pCur); | |
| 1248 idx = 0; | |
| 1249 if( idxNum & 1 ){ | |
| 1250 zWord = (const char*)sqlite3_value_text(argv[0]); | |
| 1251 idx++; | |
| 1252 } | |
| 1253 if( idxNum & 2 ){ | |
| 1254 pCur->rLimit = (amatch_cost)sqlite3_value_int(argv[idx]); | |
| 1255 idx++; | |
| 1256 } | |
| 1257 if( idxNum & 4 ){ | |
| 1258 pCur->iLang = (amatch_cost)sqlite3_value_int(argv[idx]); | |
| 1259 idx++; | |
| 1260 } | |
| 1261 pCur->zInput = sqlite3_mprintf("%s", zWord); | |
| 1262 if( pCur->zInput==0 ) return SQLITE_NOMEM; | |
| 1263 amatchAddWord(pCur, 0, 0, "", ""); | |
| 1264 amatchNext(pVtabCursor); | |
| 1265 | |
| 1266 return SQLITE_OK; | |
| 1267 } | |
| 1268 | |
| 1269 /* | |
| 1270 ** Only the word and distance columns have values. All other columns | |
| 1271 ** return NULL | |
| 1272 */ | |
| 1273 static int amatchColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){ | |
| 1274 amatch_cursor *pCur = (amatch_cursor*)cur; | |
| 1275 switch( i ){ | |
| 1276 case AMATCH_COL_WORD: { | |
| 1277 sqlite3_result_text(ctx, pCur->pCurrent->zWord+2, -1, SQLITE_STATIC); | |
| 1278 break; | |
| 1279 } | |
| 1280 case AMATCH_COL_DISTANCE: { | |
| 1281 sqlite3_result_int(ctx, pCur->pCurrent->rCost); | |
| 1282 break; | |
| 1283 } | |
| 1284 case AMATCH_COL_LANGUAGE: { | |
| 1285 sqlite3_result_int(ctx, pCur->iLang); | |
| 1286 break; | |
| 1287 } | |
| 1288 case AMATCH_COL_NWORD: { | |
| 1289 sqlite3_result_int(ctx, pCur->nWord); | |
| 1290 break; | |
| 1291 } | |
| 1292 default: { | |
| 1293 sqlite3_result_null(ctx); | |
| 1294 break; | |
| 1295 } | |
| 1296 } | |
| 1297 return SQLITE_OK; | |
| 1298 } | |
| 1299 | |
| 1300 /* | |
| 1301 ** The rowid. | |
| 1302 */ | |
| 1303 static int amatchRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){ | |
| 1304 amatch_cursor *pCur = (amatch_cursor*)cur; | |
| 1305 *pRowid = pCur->iRowid; | |
| 1306 return SQLITE_OK; | |
| 1307 } | |
| 1308 | |
| 1309 /* | |
| 1310 ** EOF indicator | |
| 1311 */ | |
| 1312 static int amatchEof(sqlite3_vtab_cursor *cur){ | |
| 1313 amatch_cursor *pCur = (amatch_cursor*)cur; | |
| 1314 return pCur->pCurrent==0; | |
| 1315 } | |
| 1316 | |
| 1317 /* | |
| 1318 ** Search for terms of these forms: | |
| 1319 ** | |
| 1320 ** (A) word MATCH $str | |
| 1321 ** (B1) distance < $value | |
| 1322 ** (B2) distance <= $value | |
| 1323 ** (C) language == $language | |
| 1324 ** | |
| 1325 ** The distance< and distance<= are both treated as distance<=. | |
| 1326 ** The query plan number is a bit vector: | |
| 1327 ** | |
| 1328 ** bit 1: Term of the form (A) found | |
| 1329 ** bit 2: Term like (B1) or (B2) found | |
| 1330 ** bit 3: Term like (C) found | |
| 1331 ** | |
| 1332 ** If bit-1 is set, $str is always in filter.argv[0]. If bit-2 is set | |
| 1333 ** then $value is in filter.argv[0] if bit-1 is clear and is in | |
| 1334 ** filter.argv[1] if bit-1 is set. If bit-3 is set, then $ruleid is | |
| 1335 ** in filter.argv[0] if bit-1 and bit-2 are both zero, is in | |
| 1336 ** filter.argv[1] if exactly one of bit-1 and bit-2 are set, and is in | |
| 1337 ** filter.argv[2] if both bit-1 and bit-2 are set. | |
| 1338 */ | |
| 1339 static int amatchBestIndex( | |
| 1340 sqlite3_vtab *tab, | |
| 1341 sqlite3_index_info *pIdxInfo | |
| 1342 ){ | |
| 1343 int iPlan = 0; | |
| 1344 int iDistTerm = -1; | |
| 1345 int iLangTerm = -1; | |
| 1346 int i; | |
| 1347 const struct sqlite3_index_constraint *pConstraint; | |
| 1348 | |
| 1349 (void)tab; | |
| 1350 pConstraint = pIdxInfo->aConstraint; | |
| 1351 for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){ | |
| 1352 if( pConstraint->usable==0 ) continue; | |
| 1353 if( (iPlan & 1)==0 | |
| 1354 && pConstraint->iColumn==0 | |
| 1355 && pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH | |
| 1356 ){ | |
| 1357 iPlan |= 1; | |
| 1358 pIdxInfo->aConstraintUsage[i].argvIndex = 1; | |
| 1359 pIdxInfo->aConstraintUsage[i].omit = 1; | |
| 1360 } | |
| 1361 if( (iPlan & 2)==0 | |
| 1362 && pConstraint->iColumn==1 | |
| 1363 && (pConstraint->op==SQLITE_INDEX_CONSTRAINT_LT | |
| 1364 || pConstraint->op==SQLITE_INDEX_CONSTRAINT_LE) | |
| 1365 ){ | |
| 1366 iPlan |= 2; | |
| 1367 iDistTerm = i; | |
| 1368 } | |
| 1369 if( (iPlan & 4)==0 | |
| 1370 && pConstraint->iColumn==2 | |
| 1371 && pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ | |
| 1372 ){ | |
| 1373 iPlan |= 4; | |
| 1374 pIdxInfo->aConstraintUsage[i].omit = 1; | |
| 1375 iLangTerm = i; | |
| 1376 } | |
| 1377 } | |
| 1378 if( iPlan & 2 ){ | |
| 1379 pIdxInfo->aConstraintUsage[iDistTerm].argvIndex = 1+((iPlan&1)!=0); | |
| 1380 } | |
| 1381 if( iPlan & 4 ){ | |
| 1382 int idx = 1; | |
| 1383 if( iPlan & 1 ) idx++; | |
| 1384 if( iPlan & 2 ) idx++; | |
| 1385 pIdxInfo->aConstraintUsage[iLangTerm].argvIndex = idx; | |
| 1386 } | |
| 1387 pIdxInfo->idxNum = iPlan; | |
| 1388 if( pIdxInfo->nOrderBy==1 | |
| 1389 && pIdxInfo->aOrderBy[0].iColumn==1 | |
| 1390 && pIdxInfo->aOrderBy[0].desc==0 | |
| 1391 ){ | |
| 1392 pIdxInfo->orderByConsumed = 1; | |
| 1393 } | |
| 1394 pIdxInfo->estimatedCost = (double)10000; | |
| 1395 | |
| 1396 return SQLITE_OK; | |
| 1397 } | |
| 1398 | |
| 1399 /* | |
| 1400 ** The xUpdate() method. | |
| 1401 ** | |
| 1402 ** This implementation disallows DELETE and UPDATE. The only thing | |
| 1403 ** allowed is INSERT into the "command" column. | |
| 1404 */ | |
| 1405 static int amatchUpdate( | |
| 1406 sqlite3_vtab *pVTab, | |
| 1407 int argc, | |
| 1408 sqlite3_value **argv, | |
| 1409 sqlite_int64 *pRowid | |
| 1410 ){ | |
| 1411 amatch_vtab *p = (amatch_vtab*)pVTab; | |
| 1412 const unsigned char *zCmd; | |
| 1413 (void)pRowid; | |
| 1414 if( argc==1 ){ | |
| 1415 pVTab->zErrMsg = sqlite3_mprintf("DELETE from %s is not allowed", | |
| 1416 p->zSelf); | |
| 1417 return SQLITE_ERROR; | |
| 1418 } | |
| 1419 if( sqlite3_value_type(argv[0])!=SQLITE_NULL ){ | |
| 1420 pVTab->zErrMsg = sqlite3_mprintf("UPDATE of %s is not allowed", | |
| 1421 p->zSelf); | |
| 1422 return SQLITE_ERROR; | |
| 1423 } | |
| 1424 if( sqlite3_value_type(argv[2+AMATCH_COL_WORD])!=SQLITE_NULL | |
| 1425 || sqlite3_value_type(argv[2+AMATCH_COL_DISTANCE])!=SQLITE_NULL | |
| 1426 || sqlite3_value_type(argv[2+AMATCH_COL_LANGUAGE])!=SQLITE_NULL | |
| 1427 ){ | |
| 1428 pVTab->zErrMsg = sqlite3_mprintf( | |
| 1429 "INSERT INTO %s allowed for column [command] only", p->zSelf); | |
| 1430 return SQLITE_ERROR; | |
| 1431 } | |
| 1432 zCmd = sqlite3_value_text(argv[2+AMATCH_COL_COMMAND]); | |
| 1433 if( zCmd==0 ) return SQLITE_OK; | |
| 1434 | |
| 1435 return SQLITE_OK; | |
| 1436 } | |
| 1437 | |
| 1438 /* | |
| 1439 ** A virtual table module that implements the "approximate_match". | |
| 1440 */ | |
| 1441 static sqlite3_module amatchModule = { | |
| 1442 0, /* iVersion */ | |
| 1443 amatchConnect, /* xCreate */ | |
| 1444 amatchConnect, /* xConnect */ | |
| 1445 amatchBestIndex, /* xBestIndex */ | |
| 1446 amatchDisconnect, /* xDisconnect */ | |
| 1447 amatchDisconnect, /* xDestroy */ | |
| 1448 amatchOpen, /* xOpen - open a cursor */ | |
| 1449 amatchClose, /* xClose - close a cursor */ | |
| 1450 amatchFilter, /* xFilter - configure scan constraints */ | |
| 1451 amatchNext, /* xNext - advance a cursor */ | |
| 1452 amatchEof, /* xEof - check for end of scan */ | |
| 1453 amatchColumn, /* xColumn - read data */ | |
| 1454 amatchRowid, /* xRowid - read data */ | |
| 1455 amatchUpdate, /* xUpdate */ | |
| 1456 0, /* xBegin */ | |
| 1457 0, /* xSync */ | |
| 1458 0, /* xCommit */ | |
| 1459 0, /* xRollback */ | |
| 1460 0, /* xFindMethod */ | |
| 1461 0, /* xRename */ | |
| 1462 0, /* xSavepoint */ | |
| 1463 0, /* xRelease */ | |
| 1464 0 /* xRollbackTo */ | |
| 1465 }; | |
| 1466 | |
| 1467 #endif /* SQLITE_OMIT_VIRTUALTABLE */ | |
| 1468 | |
| 1469 /* | |
| 1470 ** Register the amatch virtual table | |
| 1471 */ | |
| 1472 #ifdef _WIN32 | |
| 1473 __declspec(dllexport) | |
| 1474 #endif | |
| 1475 int sqlite3_amatch_init( | |
| 1476 sqlite3 *db, | |
| 1477 char **pzErrMsg, | |
| 1478 const sqlite3_api_routines *pApi | |
| 1479 ){ | |
| 1480 int rc = SQLITE_OK; | |
| 1481 SQLITE_EXTENSION_INIT2(pApi); | |
| 1482 (void)pzErrMsg; /* Not used */ | |
| 1483 #ifndef SQLITE_OMIT_VIRTUALTABLE | |
| 1484 rc = sqlite3_create_module(db, "approximate_match", &amatchModule, 0); | |
| 1485 #endif /* SQLITE_OMIT_VIRTUALTABLE */ | |
| 1486 return rc; | |
| 1487 } | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 2363173002:
[sqlite] Remove obsolete reference version 3.8.7.4. (Closed)
