1 /*
2 ** 2013 Apr 22
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 the "fts3tokenize" virtual table module.
14 ** An fts3tokenize virtual table is created as follows:
15 **
16 ** CREATE VIRTUAL TABLE <tbl> USING fts3tokenize(
17 ** <tokenizer-name>, <arg-1>, ...
18 ** );
19 **
20 ** The table created has the following schema:
21 **
22 ** CREATE TABLE <tbl>(input, token, start, end, position)
23 **
24 ** When queried, the query must include a WHERE clause of type:
25 **
26 ** input = <string>
27 **
28 ** The virtual table module tokenizes this <string>, using the FTS3
29 ** tokenizer specified by the arguments to the CREATE VIRTUAL TABLE
30 ** statement and returns one row for each token in the result. With
31 ** fields set as follows:
32 **
33 ** input: Always set to a copy of <string>
34 ** token: A token from the input.
35 ** start: Byte offset of the token within the input <string>.
36 ** end: Byte offset of the byte immediately following the end of the
37 ** token within the input string.
38 ** pos: Token offset of token within input.
39 **
40 */
41 #include "fts3Int.h"
42 #if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
43
44 #include <string.h>
45 #include <assert.h>
46
47 typedef struct Fts3tokTable Fts3tokTable;
48 typedef struct Fts3tokCursor Fts3tokCursor;
49
50 /*
51 ** Virtual table structure.
52 */
53 struct Fts3tokTable {
54 sqlite3_vtab base; /* Base class used by SQLite core */
55 const sqlite3_tokenizer_module *pMod;
56 sqlite3_tokenizer *pTok;
57 };
58
59 /*
60 ** Virtual table cursor structure.
61 */
62 struct Fts3tokCursor {
63 sqlite3_vtab_cursor base; /* Base class used by SQLite core */
64 char *zInput; /* Input string */
65 sqlite3_tokenizer_cursor *pCsr; /* Cursor to iterate through zInput */
66 int iRowid; /* Current 'rowid' value */
67 const char *zToken; /* Current 'token' value */
68 int nToken; /* Size of zToken in bytes */
69 int iStart; /* Current 'start' value */
70 int iEnd; /* Current 'end' value */
71 int iPos; /* Current 'pos' value */
72 };
73
74 /*
75 ** Query FTS for the tokenizer implementation named zName.
76 */
fts3tokQueryTokenizer(Fts3Hash * pHash,const char * zName,const sqlite3_tokenizer_module ** pp,char ** pzErr)77 static int fts3tokQueryTokenizer(
78 Fts3Hash *pHash,
79 const char *zName,
80 const sqlite3_tokenizer_module **pp,
81 char **pzErr
82 ){
83 sqlite3_tokenizer_module *p;
84 int nName = (int)strlen(zName);
85
86 p = (sqlite3_tokenizer_module *)sqlite3Fts3HashFind(pHash, zName, nName+1);
87 if( !p ){
88 sqlite3Fts3ErrMsg(pzErr, "unknown tokenizer: %s", zName);
89 return SQLITE_ERROR;
90 }
91
92 *pp = p;
93 return SQLITE_OK;
94 }
95
96 /*
97 ** The second argument, argv[], is an array of pointers to nul-terminated
98 ** strings. This function makes a copy of the array and strings into a
99 ** single block of memory. It then dequotes any of the strings that appear
100 ** to be quoted.
101 **
102 ** If successful, output parameter *pazDequote is set to point at the
103 ** array of dequoted strings and SQLITE_OK is returned. The caller is
104 ** responsible for eventually calling sqlite3_free() to free the array
105 ** in this case. Or, if an error occurs, an SQLite error code is returned.
106 ** The final value of *pazDequote is undefined in this case.
107 */
fts3tokDequoteArray(int argc,const char * const * argv,char *** pazDequote)108 static int fts3tokDequoteArray(
109 int argc, /* Number of elements in argv[] */
110 const char * const *argv, /* Input array */
111 char ***pazDequote /* Output array */
112 ){
113 int rc = SQLITE_OK; /* Return code */
114 if( argc==0 ){
115 *pazDequote = 0;
116 }else{
117 int i;
118 int nByte = 0;
119 char **azDequote;
120
121 for(i=0; i<argc; i++){
122 nByte += (int)(strlen(argv[i]) + 1);
123 }
124
125 *pazDequote = azDequote = sqlite3_malloc64(sizeof(char *)*argc + nByte);
126 if( azDequote==0 ){
127 rc = SQLITE_NOMEM;
128 }else{
129 char *pSpace = (char *)&azDequote[argc];
130 for(i=0; i<argc; i++){
131 int n = (int)strlen(argv[i]);
132 azDequote[i] = pSpace;
133 memcpy(pSpace, argv[i], n+1);
134 sqlite3Fts3Dequote(pSpace);
135 pSpace += (n+1);
136 }
137 }
138 }
139
140 return rc;
141 }
142
143 /*
144 ** Schema of the tokenizer table.
145 */
146 #define FTS3_TOK_SCHEMA "CREATE TABLE x(input, token, start, end, position)"
147
148 /*
149 ** This function does all the work for both the xConnect and xCreate methods.
150 ** These tables have no persistent representation of their own, so xConnect
151 ** and xCreate are identical operations.
152 **
153 ** argv[0]: module name
154 ** argv[1]: database name
155 ** argv[2]: table name
156 ** argv[3]: first argument (tokenizer name)
157 */
fts3tokConnectMethod(sqlite3 * db,void * pHash,int argc,const char * const * argv,sqlite3_vtab ** ppVtab,char ** pzErr)158 static int fts3tokConnectMethod(
159 sqlite3 *db, /* Database connection */
160 void *pHash, /* Hash table of tokenizers */
161 int argc, /* Number of elements in argv array */
162 const char * const *argv, /* xCreate/xConnect argument array */
163 sqlite3_vtab **ppVtab, /* OUT: New sqlite3_vtab object */
164 char **pzErr /* OUT: sqlite3_malloc'd error message */
165 ){
166 Fts3tokTable *pTab = 0;
167 const sqlite3_tokenizer_module *pMod = 0;
168 sqlite3_tokenizer *pTok = 0;
169 int rc;
170 char **azDequote = 0;
171 int nDequote;
172
173 rc = sqlite3_declare_vtab(db, FTS3_TOK_SCHEMA);
174 if( rc!=SQLITE_OK ) return rc;
175
176 nDequote = argc-3;
177 rc = fts3tokDequoteArray(nDequote, &argv[3], &azDequote);
178
179 if( rc==SQLITE_OK ){
180 const char *zModule;
181 if( nDequote<1 ){
182 zModule = "simple";
183 }else{
184 zModule = azDequote[0];
185 }
186 rc = fts3tokQueryTokenizer((Fts3Hash*)pHash, zModule, &pMod, pzErr);
187 }
188
189 assert( (rc==SQLITE_OK)==(pMod!=0) );
190 if( rc==SQLITE_OK ){
191 const char * const *azArg = 0;
192 if( nDequote>1 ) azArg = (const char * const *)&azDequote[1];
193 rc = pMod->xCreate((nDequote>1 ? nDequote-1 : 0), azArg, &pTok);
194 }
195
196 if( rc==SQLITE_OK ){
197 pTab = (Fts3tokTable *)sqlite3_malloc(sizeof(Fts3tokTable));
198 if( pTab==0 ){
199 rc = SQLITE_NOMEM;
200 }
201 }
202
203 if( rc==SQLITE_OK ){
204 memset(pTab, 0, sizeof(Fts3tokTable));
205 pTab->pMod = pMod;
206 pTab->pTok = pTok;
207 *ppVtab = &pTab->base;
208 }else{
209 if( pTok ){
210 pMod->xDestroy(pTok);
211 }
212 }
213
214 sqlite3_free(azDequote);
215 return rc;
216 }
217
218 /*
219 ** This function does the work for both the xDisconnect and xDestroy methods.
220 ** These tables have no persistent representation of their own, so xDisconnect
221 ** and xDestroy are identical operations.
222 */
fts3tokDisconnectMethod(sqlite3_vtab * pVtab)223 static int fts3tokDisconnectMethod(sqlite3_vtab *pVtab){
224 Fts3tokTable *pTab = (Fts3tokTable *)pVtab;
225
226 pTab->pMod->xDestroy(pTab->pTok);
227 sqlite3_free(pTab);
228 return SQLITE_OK;
229 }
230
231 /*
232 ** xBestIndex - Analyze a WHERE and ORDER BY clause.
233 */
fts3tokBestIndexMethod(sqlite3_vtab * pVTab,sqlite3_index_info * pInfo)234 static int fts3tokBestIndexMethod(
235 sqlite3_vtab *pVTab,
236 sqlite3_index_info *pInfo
237 ){
238 int i;
239 UNUSED_PARAMETER(pVTab);
240
241 for(i=0; i<pInfo->nConstraint; i++){
242 if( pInfo->aConstraint[i].usable
243 && pInfo->aConstraint[i].iColumn==0
244 && pInfo->aConstraint[i].op==SQLITE_INDEX_CONSTRAINT_EQ
245 ){
246 pInfo->idxNum = 1;
247 pInfo->aConstraintUsage[i].argvIndex = 1;
248 pInfo->aConstraintUsage[i].omit = 1;
249 pInfo->estimatedCost = 1;
250 return SQLITE_OK;
251 }
252 }
253
254 pInfo->idxNum = 0;
255 assert( pInfo->estimatedCost>1000000.0 );
256
257 return SQLITE_OK;
258 }
259
260 /*
261 ** xOpen - Open a cursor.
262 */
fts3tokOpenMethod(sqlite3_vtab * pVTab,sqlite3_vtab_cursor ** ppCsr)263 static int fts3tokOpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
264 Fts3tokCursor *pCsr;
265 UNUSED_PARAMETER(pVTab);
266
267 pCsr = (Fts3tokCursor *)sqlite3_malloc(sizeof(Fts3tokCursor));
268 if( pCsr==0 ){
269 return SQLITE_NOMEM;
270 }
271 memset(pCsr, 0, sizeof(Fts3tokCursor));
272
273 *ppCsr = (sqlite3_vtab_cursor *)pCsr;
274 return SQLITE_OK;
275 }
276
277 /*
278 ** Reset the tokenizer cursor passed as the only argument. As if it had
279 ** just been returned by fts3tokOpenMethod().
280 */
fts3tokResetCursor(Fts3tokCursor * pCsr)281 static void fts3tokResetCursor(Fts3tokCursor *pCsr){
282 if( pCsr->pCsr ){
283 Fts3tokTable *pTab = (Fts3tokTable *)(pCsr->base.pVtab);
284 pTab->pMod->xClose(pCsr->pCsr);
285 pCsr->pCsr = 0;
286 }
287 sqlite3_free(pCsr->zInput);
288 pCsr->zInput = 0;
289 pCsr->zToken = 0;
290 pCsr->nToken = 0;
291 pCsr->iStart = 0;
292 pCsr->iEnd = 0;
293 pCsr->iPos = 0;
294 pCsr->iRowid = 0;
295 }
296
297 /*
298 ** xClose - Close a cursor.
299 */
fts3tokCloseMethod(sqlite3_vtab_cursor * pCursor)300 static int fts3tokCloseMethod(sqlite3_vtab_cursor *pCursor){
301 Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
302
303 fts3tokResetCursor(pCsr);
304 sqlite3_free(pCsr);
305 return SQLITE_OK;
306 }
307
308 /*
309 ** xNext - Advance the cursor to the next row, if any.
310 */
fts3tokNextMethod(sqlite3_vtab_cursor * pCursor)311 static int fts3tokNextMethod(sqlite3_vtab_cursor *pCursor){
312 Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
313 Fts3tokTable *pTab = (Fts3tokTable *)(pCursor->pVtab);
314 int rc; /* Return code */
315
316 pCsr->iRowid++;
317 rc = pTab->pMod->xNext(pCsr->pCsr,
318 &pCsr->zToken, &pCsr->nToken,
319 &pCsr->iStart, &pCsr->iEnd, &pCsr->iPos
320 );
321
322 if( rc!=SQLITE_OK ){
323 fts3tokResetCursor(pCsr);
324 if( rc==SQLITE_DONE ) rc = SQLITE_OK;
325 }
326
327 return rc;
328 }
329
330 /*
331 ** xFilter - Initialize a cursor to point at the start of its data.
332 */
fts3tokFilterMethod(sqlite3_vtab_cursor * pCursor,int idxNum,const char * idxStr,int nVal,sqlite3_value ** apVal)333 static int fts3tokFilterMethod(
334 sqlite3_vtab_cursor *pCursor, /* The cursor used for this query */
335 int idxNum, /* Strategy index */
336 const char *idxStr, /* Unused */
337 int nVal, /* Number of elements in apVal */
338 sqlite3_value **apVal /* Arguments for the indexing scheme */
339 ){
340 int rc = SQLITE_ERROR;
341 Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
342 Fts3tokTable *pTab = (Fts3tokTable *)(pCursor->pVtab);
343 UNUSED_PARAMETER(idxStr);
344 UNUSED_PARAMETER(nVal);
345
346 fts3tokResetCursor(pCsr);
347 if( idxNum==1 ){
348 const char *zByte = (const char *)sqlite3_value_text(apVal[0]);
349 int nByte = sqlite3_value_bytes(apVal[0]);
350 pCsr->zInput = sqlite3_malloc64(nByte+1);
351 if( pCsr->zInput==0 ){
352 rc = SQLITE_NOMEM;
353 }else{
354 if( nByte>0 ) memcpy(pCsr->zInput, zByte, nByte);
355 pCsr->zInput[nByte] = 0;
356 rc = pTab->pMod->xOpen(pTab->pTok, pCsr->zInput, nByte, &pCsr->pCsr);
357 if( rc==SQLITE_OK ){
358 pCsr->pCsr->pTokenizer = pTab->pTok;
359 }
360 }
361 }
362
363 if( rc!=SQLITE_OK ) return rc;
364 return fts3tokNextMethod(pCursor);
365 }
366
367 /*
368 ** xEof - Return true if the cursor is at EOF, or false otherwise.
369 */
fts3tokEofMethod(sqlite3_vtab_cursor * pCursor)370 static int fts3tokEofMethod(sqlite3_vtab_cursor *pCursor){
371 Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
372 return (pCsr->zToken==0);
373 }
374
375 /*
376 ** xColumn - Return a column value.
377 */
fts3tokColumnMethod(sqlite3_vtab_cursor * pCursor,sqlite3_context * pCtx,int iCol)378 static int fts3tokColumnMethod(
379 sqlite3_vtab_cursor *pCursor, /* Cursor to retrieve value from */
380 sqlite3_context *pCtx, /* Context for sqlite3_result_xxx() calls */
381 int iCol /* Index of column to read value from */
382 ){
383 Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
384
385 /* CREATE TABLE x(input, token, start, end, position) */
386 switch( iCol ){
387 case 0:
388 sqlite3_result_text(pCtx, pCsr->zInput, -1, SQLITE_TRANSIENT);
389 break;
390 case 1:
391 sqlite3_result_text(pCtx, pCsr->zToken, pCsr->nToken, SQLITE_TRANSIENT);
392 break;
393 case 2:
394 sqlite3_result_int(pCtx, pCsr->iStart);
395 break;
396 case 3:
397 sqlite3_result_int(pCtx, pCsr->iEnd);
398 break;
399 default:
400 assert( iCol==4 );
401 sqlite3_result_int(pCtx, pCsr->iPos);
402 break;
403 }
404 return SQLITE_OK;
405 }
406
407 /*
408 ** xRowid - Return the current rowid for the cursor.
409 */
fts3tokRowidMethod(sqlite3_vtab_cursor * pCursor,sqlite_int64 * pRowid)410 static int fts3tokRowidMethod(
411 sqlite3_vtab_cursor *pCursor, /* Cursor to retrieve value from */
412 sqlite_int64 *pRowid /* OUT: Rowid value */
413 ){
414 Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
415 *pRowid = (sqlite3_int64)pCsr->iRowid;
416 return SQLITE_OK;
417 }
418
419 /*
420 ** Register the fts3tok module with database connection db. Return SQLITE_OK
421 ** if successful or an error code if sqlite3_create_module() fails.
422 */
sqlite3Fts3InitTok(sqlite3 * db,Fts3Hash * pHash,void (* xDestroy)(void *))423 int sqlite3Fts3InitTok(sqlite3 *db, Fts3Hash *pHash, void(*xDestroy)(void*)){
424 static const sqlite3_module fts3tok_module = {
425 0, /* iVersion */
426 fts3tokConnectMethod, /* xCreate */
427 fts3tokConnectMethod, /* xConnect */
428 fts3tokBestIndexMethod, /* xBestIndex */
429 fts3tokDisconnectMethod, /* xDisconnect */
430 fts3tokDisconnectMethod, /* xDestroy */
431 fts3tokOpenMethod, /* xOpen */
432 fts3tokCloseMethod, /* xClose */
433 fts3tokFilterMethod, /* xFilter */
434 fts3tokNextMethod, /* xNext */
435 fts3tokEofMethod, /* xEof */
436 fts3tokColumnMethod, /* xColumn */
437 fts3tokRowidMethod, /* xRowid */
438 0, /* xUpdate */
439 0, /* xBegin */
440 0, /* xSync */
441 0, /* xCommit */
442 0, /* xRollback */
443 0, /* xFindFunction */
444 0, /* xRename */
445 0, /* xSavepoint */
446 0, /* xRelease */
447 0, /* xRollbackTo */
448 0 /* xShadowName */
449 };
450 int rc; /* Return code */
451
452 rc = sqlite3_create_module_v2(
453 db, "fts3tokenize", &fts3tok_module, (void*)pHash, xDestroy
454 );
455 return rc;
456 }
457
458 #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
459