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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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