自学教程：C++ sqlite3HashFind函数代码示例

/*** This function is called to drop a trigger from the database schema. **** This may be called directly from the parser and therefore identifies** the trigger by name.  The sqlite3DropTriggerPtr() routine does the** same job as this routine except it takes a pointer to the trigger** instead of the trigger name.**/void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){  Trigger *pTrigger = 0;  int i;  const char *zDb;  const char *zName;  int nName;  sqlite3 *db = pParse->db;  if( db->mallocFailed ) goto drop_trigger_cleanup;  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){    goto drop_trigger_cleanup;  }  assert( pName->nSrc==1 );  zDb = pName->a[0].zDatabase;  zName = pName->a[0].zName;  nName = strlen(zName);  for(i=OMIT_TEMPDB; i<db->nDb; i++){    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */    if( zDb && sqlite3StrICmp(db->aDb[j].zName, zDb) ) continue;    pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName, nName);    if( pTrigger ) break;  }  if( !pTrigger ){    if( !noErr ){      sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);    }    goto drop_trigger_cleanup;  }  sqlite3DropTriggerPtr(pParse, pTrigger);drop_trigger_cleanup:  sqlite3SrcListDelete(pName);}

/*** This function is invoked by the vdbe to call the xCreate method** of the virtual table named zTab in database iDb. **** If an error occurs, *pzErr is set to point an an English language** description of the error and an SQLITE_XXX error code is returned.** In this case the caller must call sqlite3DbFree(db, ) on *pzErr.*/int sqlite3VtabCallCreate(sqlite3 *db, int iDb, const char *zTab, char **pzErr){  int rc = SQLITE_OK;  Table *pTab;  Module *pMod;  const char *zMod;  pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zName);  assert( pTab && (pTab->tabFlags & TF_Virtual)!=0 && !pTab->pVTable );  /* Locate the required virtual table module */  zMod = pTab->azModuleArg[0];  pMod = (Module*)sqlite3HashFind(&db->aModule, zMod, sqlite3Strlen30(zMod));  /* If the module has been registered and includes a Create method,   ** invoke it now. If the module has not been registered, return an   ** error. Otherwise, do nothing.  */  if( !pMod ){    *pzErr = sqlite3MPrintf(db, "no such module: %s", zMod);    rc = SQLITE_ERROR;  }else{    rc = vtabCallConstructor(db, pTab, pMod, pMod->pModule->xCreate, pzErr);  }  /* Justification of ALWAYS():  The xConstructor method is required to  ** create a valid sqlite3_vtab if it returns SQLITE_OK. */  if( rc==SQLITE_OK && ALWAYS(sqlite3GetVTable(db, pTab)) ){    rc = growVTrans(db);    if( rc==SQLITE_OK ){      addToVTrans(db, sqlite3GetVTable(db, pTab));    }  }  return rc;}

/*** This function is invoked by the parser to call the xConnect() method** of the virtual table pTab. If an error occurs, an error code is returned ** and an error left in pParse.**** This call is a no-op if table pTab is not a virtual table.*/int sqlite3VtabCallConnect(Parse *pParse, Table *pTab){  sqlite3 *db = pParse->db;  const char *zMod;  Module *pMod;  int rc;  assert( pTab );  if( (pTab->tabFlags & TF_Virtual)==0 || sqlite3GetVTable(db, pTab) ){    return SQLITE_OK;  }  /* Locate the required virtual table module */  zMod = pTab->azModuleArg[0];  pMod = (Module*)sqlite3HashFind(&db->aModule, zMod, sqlite3Strlen30(zMod));  if( !pMod ){    const char *zModule = pTab->azModuleArg[0];    sqlite3ErrorMsg(pParse, "no such module: %s", zModule);    rc = SQLITE_ERROR;  }else{    char *zErr = 0;    rc = vtabCallConstructor(db, pTab, pMod, pMod->pModule->xConnect, &zErr);    if( rc!=SQLITE_OK ){      sqlite3ErrorMsg(pParse, "%s", zErr);    }    sqlite3DbFree(db, zErr);  }  return rc;}

/*** Locate and return an entry from the db.aCollSeq hash table. If the entry** specified by zName and nName is not found and parameter 'create' is** true, then create a new entry. Otherwise return NULL.**** Each pointer stored in the sqlite3.aCollSeq hash table contains an** array of three CollSeq structures. The first is the collation sequence** prefferred for UTF-8, the second UTF-16le, and the third UTF-16be.**** Stored immediately after the three collation sequences is a copy of** the collation sequence name. A pointer to this string is stored in** each collation sequence structure.*/static CollSeq *findCollSeqEntry(    sqlite3 *db,    const char *zName,    int nName,    int create) {    CollSeq *pColl;    if( nName<0 ) nName = strlen(zName);    pColl = sqlite3HashFind(&db->aCollSeq, zName, nName);    if( 0==pColl && create ) {        pColl = sqliteMalloc( 3*sizeof(*pColl) + nName + 1 );        if( pColl ) {            CollSeq *pDel = 0;            pColl[0].zName = (char*)&pColl[3];            pColl[0].enc = SQLITE_UTF8;            pColl[1].zName = (char*)&pColl[3];            pColl[1].enc = SQLITE_UTF16LE;            pColl[2].zName = (char*)&pColl[3];            pColl[2].enc = SQLITE_UTF16BE;            memcpy(pColl[0].zName, zName, nName);            pColl[0].zName[nName] = 0;            pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, nName, pColl);            /* If a malloc() failure occured in sqlite3HashInsert(), it will            ** return the pColl pointer to be deleted (because it wasn't added            ** to the hash table).            */            assert( !pDel || (sqlite3_malloc_failed && pDel==pColl) );            sqliteFree(pDel);        }    }    return pColl;}

static int exist_callback(void *pArg, int argc, char **argv, char **columnNames){	extension_cache *cache;	char key[ARRAY_SIZE];	int pri;	time_t now;	int needs_add=0;	switch_config *config=NULL;	int timeout=0;	char *context;	if (pArg) {		config = pArg;		timeout = config->timeout;	}	if (!timeout)		timeout = default_timeout;	context = argv[5] ? argv[5] : argv[0];	if (!strcmp(context,"_any_")) {		ast_verbose(VERBOSE_PREFIX_2 "SQLiteSwitch: magic extension: %s not cached/n",argv[1]);		return 0;	}	snprintf(key, ARRAY_SIZE, "%s.%s", argv[1], context);	time(&now);	pri = atoi(argv[2]);	cache = (extension_cache *) sqlite3HashFind(&extens,key,strlen(key));	if (! cache) {		cache = malloc(sizeof(extension_cache));		needs_add = 1;	}	if (needs_add || cache->expires < now) {		memset(cache,0,sizeof(extension_cache));		strncpy(cache->context,argv[0],sizeof(cache->context));		strncpy(cache->exten,argv[1],sizeof(cache->exten));	}	cache->expires = now + timeout;	if (config && ! config->seeheads) {		ast_verbose(VERBOSE_PREFIX_2 "SQLiteSwitch: extension %[email
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