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[chromium-blink-merge.git] / third_party / sqlite / sqlite-src-3080704 / src / callback.c
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1 /*
2 ** 2005 May 23
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.
11 *************************************************************************
13 ** This file contains functions used to access the internal hash tables
14 ** of user defined functions and collation sequences.
17 #include "sqliteInt.h"
20 ** Invoke the 'collation needed' callback to request a collation sequence
21 ** in the encoding enc of name zName, length nName.
23 static void callCollNeeded(sqlite3 *db, int enc, const char *zName){
24 assert( !db->xCollNeeded || !db->xCollNeeded16 );
25 if( db->xCollNeeded ){
26 char *zExternal = sqlite3DbStrDup(db, zName);
27 if( !zExternal ) return;
28 db->xCollNeeded(db->pCollNeededArg, db, enc, zExternal);
29 sqlite3DbFree(db, zExternal);
31 #ifndef SQLITE_OMIT_UTF16
32 if( db->xCollNeeded16 ){
33 char const *zExternal;
34 sqlite3_value *pTmp = sqlite3ValueNew(db);
35 sqlite3ValueSetStr(pTmp, -1, zName, SQLITE_UTF8, SQLITE_STATIC);
36 zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);
37 if( zExternal ){
38 db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal);
40 sqlite3ValueFree(pTmp);
42 #endif
46 ** This routine is called if the collation factory fails to deliver a
47 ** collation function in the best encoding but there may be other versions
48 ** of this collation function (for other text encodings) available. Use one
49 ** of these instead if they exist. Avoid a UTF-8 <-> UTF-16 conversion if
50 ** possible.
52 static int synthCollSeq(sqlite3 *db, CollSeq *pColl){
53 CollSeq *pColl2;
54 char *z = pColl->zName;
55 int i;
56 static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 };
57 for(i=0; i<3; i++){
58 pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, 0);
59 if( pColl2->xCmp!=0 ){
60 memcpy(pColl, pColl2, sizeof(CollSeq));
61 pColl->xDel = 0; /* Do not copy the destructor */
62 return SQLITE_OK;
65 return SQLITE_ERROR;
69 ** This function is responsible for invoking the collation factory callback
70 ** or substituting a collation sequence of a different encoding when the
71 ** requested collation sequence is not available in the desired encoding.
72 **
73 ** If it is not NULL, then pColl must point to the database native encoding
74 ** collation sequence with name zName, length nName.
76 ** The return value is either the collation sequence to be used in database
77 ** db for collation type name zName, length nName, or NULL, if no collation
78 ** sequence can be found. If no collation is found, leave an error message.
80 ** See also: sqlite3LocateCollSeq(), sqlite3FindCollSeq()
82 CollSeq *sqlite3GetCollSeq(
83 Parse *pParse, /* Parsing context */
84 u8 enc, /* The desired encoding for the collating sequence */
85 CollSeq *pColl, /* Collating sequence with native encoding, or NULL */
86 const char *zName /* Collating sequence name */
88 CollSeq *p;
89 sqlite3 *db = pParse->db;
91 p = pColl;
92 if( !p ){
93 p = sqlite3FindCollSeq(db, enc, zName, 0);
95 if( !p || !p->xCmp ){
96 /* No collation sequence of this type for this encoding is registered.
97 ** Call the collation factory to see if it can supply us with one.
99 callCollNeeded(db, enc, zName);
100 p = sqlite3FindCollSeq(db, enc, zName, 0);
102 if( p && !p->xCmp && synthCollSeq(db, p) ){
103 p = 0;
105 assert( !p || p->xCmp );
106 if( p==0 ){
107 sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);
109 return p;
113 ** This routine is called on a collation sequence before it is used to
114 ** check that it is defined. An undefined collation sequence exists when
115 ** a database is loaded that contains references to collation sequences
116 ** that have not been defined by sqlite3_create_collation() etc.
118 ** If required, this routine calls the 'collation needed' callback to
119 ** request a definition of the collating sequence. If this doesn't work,
120 ** an equivalent collating sequence that uses a text encoding different
121 ** from the main database is substituted, if one is available.
123 int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){
124 if( pColl ){
125 const char *zName = pColl->zName;
126 sqlite3 *db = pParse->db;
127 CollSeq *p = sqlite3GetCollSeq(pParse, ENC(db), pColl, zName);
128 if( !p ){
129 return SQLITE_ERROR;
131 assert( p==pColl );
133 return SQLITE_OK;
139 ** Locate and return an entry from the db.aCollSeq hash table. If the entry
140 ** specified by zName and nName is not found and parameter 'create' is
141 ** true, then create a new entry. Otherwise return NULL.
143 ** Each pointer stored in the sqlite3.aCollSeq hash table contains an
144 ** array of three CollSeq structures. The first is the collation sequence
145 ** preferred for UTF-8, the second UTF-16le, and the third UTF-16be.
147 ** Stored immediately after the three collation sequences is a copy of
148 ** the collation sequence name. A pointer to this string is stored in
149 ** each collation sequence structure.
151 static CollSeq *findCollSeqEntry(
152 sqlite3 *db, /* Database connection */
153 const char *zName, /* Name of the collating sequence */
154 int create /* Create a new entry if true */
156 CollSeq *pColl;
157 pColl = sqlite3HashFind(&db->aCollSeq, zName);
159 if( 0==pColl && create ){
160 int nName = sqlite3Strlen30(zName);
161 pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1);
162 if( pColl ){
163 CollSeq *pDel = 0;
164 pColl[0].zName = (char*)&pColl[3];
165 pColl[0].enc = SQLITE_UTF8;
166 pColl[1].zName = (char*)&pColl[3];
167 pColl[1].enc = SQLITE_UTF16LE;
168 pColl[2].zName = (char*)&pColl[3];
169 pColl[2].enc = SQLITE_UTF16BE;
170 memcpy(pColl[0].zName, zName, nName);
171 pColl[0].zName[nName] = 0;
172 pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, pColl);
174 /* If a malloc() failure occurred in sqlite3HashInsert(), it will
175 ** return the pColl pointer to be deleted (because it wasn't added
176 ** to the hash table).
178 assert( pDel==0 || pDel==pColl );
179 if( pDel!=0 ){
180 db->mallocFailed = 1;
181 sqlite3DbFree(db, pDel);
182 pColl = 0;
186 return pColl;
190 ** Parameter zName points to a UTF-8 encoded string nName bytes long.
191 ** Return the CollSeq* pointer for the collation sequence named zName
192 ** for the encoding 'enc' from the database 'db'.
194 ** If the entry specified is not found and 'create' is true, then create a
195 ** new entry. Otherwise return NULL.
197 ** A separate function sqlite3LocateCollSeq() is a wrapper around
198 ** this routine. sqlite3LocateCollSeq() invokes the collation factory
199 ** if necessary and generates an error message if the collating sequence
200 ** cannot be found.
202 ** See also: sqlite3LocateCollSeq(), sqlite3GetCollSeq()
204 CollSeq *sqlite3FindCollSeq(
205 sqlite3 *db,
206 u8 enc,
207 const char *zName,
208 int create
210 CollSeq *pColl;
211 if( zName ){
212 pColl = findCollSeqEntry(db, zName, create);
213 }else{
214 pColl = db->pDfltColl;
216 assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
217 assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );
218 if( pColl ) pColl += enc-1;
219 return pColl;
222 /* During the search for the best function definition, this procedure
223 ** is called to test how well the function passed as the first argument
224 ** matches the request for a function with nArg arguments in a system
225 ** that uses encoding enc. The value returned indicates how well the
226 ** request is matched. A higher value indicates a better match.
228 ** If nArg is -1 that means to only return a match (non-zero) if p->nArg
229 ** is also -1. In other words, we are searching for a function that
230 ** takes a variable number of arguments.
232 ** If nArg is -2 that means that we are searching for any function
233 ** regardless of the number of arguments it uses, so return a positive
234 ** match score for any
236 ** The returned value is always between 0 and 6, as follows:
238 ** 0: Not a match.
239 ** 1: UTF8/16 conversion required and function takes any number of arguments.
240 ** 2: UTF16 byte order change required and function takes any number of args.
241 ** 3: encoding matches and function takes any number of arguments
242 ** 4: UTF8/16 conversion required - argument count matches exactly
243 ** 5: UTF16 byte order conversion required - argument count matches exactly
244 ** 6: Perfect match: encoding and argument count match exactly.
246 ** If nArg==(-2) then any function with a non-null xStep or xFunc is
247 ** a perfect match and any function with both xStep and xFunc NULL is
248 ** a non-match.
250 #define FUNC_PERFECT_MATCH 6 /* The score for a perfect match */
251 static int matchQuality(
252 FuncDef *p, /* The function we are evaluating for match quality */
253 int nArg, /* Desired number of arguments. (-1)==any */
254 u8 enc /* Desired text encoding */
256 int match;
258 /* nArg of -2 is a special case */
259 if( nArg==(-2) ) return (p->xFunc==0 && p->xStep==0) ? 0 : FUNC_PERFECT_MATCH;
261 /* Wrong number of arguments means "no match" */
262 if( p->nArg!=nArg && p->nArg>=0 ) return 0;
264 /* Give a better score to a function with a specific number of arguments
265 ** than to function that accepts any number of arguments. */
266 if( p->nArg==nArg ){
267 match = 4;
268 }else{
269 match = 1;
272 /* Bonus points if the text encoding matches */
273 if( enc==(p->funcFlags & SQLITE_FUNC_ENCMASK) ){
274 match += 2; /* Exact encoding match */
275 }else if( (enc & p->funcFlags & 2)!=0 ){
276 match += 1; /* Both are UTF16, but with different byte orders */
279 return match;
283 ** Search a FuncDefHash for a function with the given name. Return
284 ** a pointer to the matching FuncDef if found, or 0 if there is no match.
286 static FuncDef *functionSearch(
287 FuncDefHash *pHash, /* Hash table to search */
288 int h, /* Hash of the name */
289 const char *zFunc, /* Name of function */
290 int nFunc /* Number of bytes in zFunc */
292 FuncDef *p;
293 for(p=pHash->a[h]; p; p=p->pHash){
294 if( sqlite3StrNICmp(p->zName, zFunc, nFunc)==0 && p->zName[nFunc]==0 ){
295 return p;
298 return 0;
302 ** Insert a new FuncDef into a FuncDefHash hash table.
304 void sqlite3FuncDefInsert(
305 FuncDefHash *pHash, /* The hash table into which to insert */
306 FuncDef *pDef /* The function definition to insert */
308 FuncDef *pOther;
309 int nName = sqlite3Strlen30(pDef->zName);
310 u8 c1 = (u8)pDef->zName[0];
311 int h = (sqlite3UpperToLower[c1] + nName) % ArraySize(pHash->a);
312 pOther = functionSearch(pHash, h, pDef->zName, nName);
313 if( pOther ){
314 assert( pOther!=pDef && pOther->pNext!=pDef );
315 pDef->pNext = pOther->pNext;
316 pOther->pNext = pDef;
317 }else{
318 pDef->pNext = 0;
319 pDef->pHash = pHash->a[h];
320 pHash->a[h] = pDef;
327 ** Locate a user function given a name, a number of arguments and a flag
328 ** indicating whether the function prefers UTF-16 over UTF-8. Return a
329 ** pointer to the FuncDef structure that defines that function, or return
330 ** NULL if the function does not exist.
332 ** If the createFlag argument is true, then a new (blank) FuncDef
333 ** structure is created and liked into the "db" structure if a
334 ** no matching function previously existed.
336 ** If nArg is -2, then the first valid function found is returned. A
337 ** function is valid if either xFunc or xStep is non-zero. The nArg==(-2)
338 ** case is used to see if zName is a valid function name for some number
339 ** of arguments. If nArg is -2, then createFlag must be 0.
341 ** If createFlag is false, then a function with the required name and
342 ** number of arguments may be returned even if the eTextRep flag does not
343 ** match that requested.
345 FuncDef *sqlite3FindFunction(
346 sqlite3 *db, /* An open database */
347 const char *zName, /* Name of the function. Not null-terminated */
348 int nName, /* Number of characters in the name */
349 int nArg, /* Number of arguments. -1 means any number */
350 u8 enc, /* Preferred text encoding */
351 u8 createFlag /* Create new entry if true and does not otherwise exist */
353 FuncDef *p; /* Iterator variable */
354 FuncDef *pBest = 0; /* Best match found so far */
355 int bestScore = 0; /* Score of best match */
356 int h; /* Hash value */
358 assert( nArg>=(-2) );
359 assert( nArg>=(-1) || createFlag==0 );
360 h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % ArraySize(db->aFunc.a);
362 /* First search for a match amongst the application-defined functions.
364 p = functionSearch(&db->aFunc, h, zName, nName);
365 while( p ){
366 int score = matchQuality(p, nArg, enc);
367 if( score>bestScore ){
368 pBest = p;
369 bestScore = score;
371 p = p->pNext;
374 /* If no match is found, search the built-in functions.
376 ** If the SQLITE_PreferBuiltin flag is set, then search the built-in
377 ** functions even if a prior app-defined function was found. And give
378 ** priority to built-in functions.
380 ** Except, if createFlag is true, that means that we are trying to
381 ** install a new function. Whatever FuncDef structure is returned it will
382 ** have fields overwritten with new information appropriate for the
383 ** new function. But the FuncDefs for built-in functions are read-only.
384 ** So we must not search for built-ins when creating a new function.
386 if( !createFlag && (pBest==0 || (db->flags & SQLITE_PreferBuiltin)!=0) ){
387 FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions);
388 bestScore = 0;
389 p = functionSearch(pHash, h, zName, nName);
390 while( p ){
391 int score = matchQuality(p, nArg, enc);
392 if( score>bestScore ){
393 pBest = p;
394 bestScore = score;
396 p = p->pNext;
400 /* If the createFlag parameter is true and the search did not reveal an
401 ** exact match for the name, number of arguments and encoding, then add a
402 ** new entry to the hash table and return it.
404 if( createFlag && bestScore<FUNC_PERFECT_MATCH &&
405 (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){
406 pBest->zName = (char *)&pBest[1];
407 pBest->nArg = (u16)nArg;
408 pBest->funcFlags = enc;
409 memcpy(pBest->zName, zName, nName);
410 pBest->zName[nName] = 0;
411 sqlite3FuncDefInsert(&db->aFunc, pBest);
414 if( pBest && (pBest->xStep || pBest->xFunc || createFlag) ){
415 return pBest;
417 return 0;
421 ** Free all resources held by the schema structure. The void* argument points
422 ** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the
423 ** pointer itself, it just cleans up subsidiary resources (i.e. the contents
424 ** of the schema hash tables).
426 ** The Schema.cache_size variable is not cleared.
428 void sqlite3SchemaClear(void *p){
429 Hash temp1;
430 Hash temp2;
431 HashElem *pElem;
432 Schema *pSchema = (Schema *)p;
434 temp1 = pSchema->tblHash;
435 temp2 = pSchema->trigHash;
436 sqlite3HashInit(&pSchema->trigHash);
437 sqlite3HashClear(&pSchema->idxHash);
438 for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){
439 sqlite3DeleteTrigger(0, (Trigger*)sqliteHashData(pElem));
441 sqlite3HashClear(&temp2);
442 sqlite3HashInit(&pSchema->tblHash);
443 for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
444 Table *pTab = sqliteHashData(pElem);
445 sqlite3DeleteTable(0, pTab);
447 sqlite3HashClear(&temp1);
448 sqlite3HashClear(&pSchema->fkeyHash);
449 pSchema->pSeqTab = 0;
450 if( pSchema->schemaFlags & DB_SchemaLoaded ){
451 pSchema->iGeneration++;
452 pSchema->schemaFlags &= ~DB_SchemaLoaded;
457 ** Find and return the schema associated with a BTree. Create
458 ** a new one if necessary.
460 Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){
461 Schema * p;
462 if( pBt ){
463 p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear);
464 }else{
465 p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema));
467 if( !p ){
468 db->mallocFailed = 1;
469 }else if ( 0==p->file_format ){
470 sqlite3HashInit(&p->tblHash);
471 sqlite3HashInit(&p->idxHash);
472 sqlite3HashInit(&p->trigHash);
473 sqlite3HashInit(&p->fkeyHash);
474 p->enc = SQLITE_UTF8;
476 return p;