/*
** Insert a new FuncDef into a FuncDefHash hash table.
*/
void sqlite3FuncDefInsert(
FuncDefHash *pHash, /* The hash table into which to insert */
FuncDef *pDef /* The function definition to insert */
){
FuncDef *pOther;
int nName = sqlite3Strlen30(pDef->zName);
u8 c1 = (u8)pDef->zName[0];
int h = (sqlite3UpperToLower[c1] + nName) % ArraySize(pHash->a);
pOther = functionSearch(pHash, h, pDef->zName, nName);
if( pOther ){
pDef->pNext = pOther->pNext;
pOther->pNext = pDef;
}else{
pDef->pNext = 0;
pDef->pHash = pHash->a[h];
pHash->a[h] = pDef;
}
}
/*
** Insert a new FuncDef into a FuncDefHash hash table.
*/
void sqlite3InsertBuiltinFuncs(
FuncDef *aDef, /* List of global functions to be inserted */
int nDef /* Length of the apDef[] list */
){
int i;
for(i=0; i<nDef; i++){
FuncDef *pOther;
const char *zName = aDef[i].zName;
int nName = sqlite3Strlen30(zName);
int h = (zName[0] + nName) % SQLITE_FUNC_HASH_SZ;
assert( zName[0]>='a' && zName[0]<='z' );
pOther = functionSearch(h, zName);
if( pOther ){
assert( pOther!=&aDef[i] && pOther->pNext!=&aDef[i] );
aDef[i].pNext = pOther->pNext;
pOther->pNext = &aDef[i];
}else{
aDef[i].pNext = 0;
aDef[i].u.pHash = sqlite3BuiltinFunctions.a[h];
sqlite3BuiltinFunctions.a[h] = &aDef[i];
}
}
}
/*
** Locate a user function given a name, a number of arguments and a flag
** indicating whether the function prefers UTF-16 over UTF-8. Return a
** pointer to the FuncDef structure that defines that function, or return
** NULL if the function does not exist.
**
** If the createFlag argument is true, then a new (blank) FuncDef
** structure is created and liked into the "db" structure if a
** no matching function previously existed.
**
** If nArg is -2, then the first valid function found is returned. A
** function is valid if xSFunc is non-zero. The nArg==(-2)
** case is used to see if zName is a valid function name for some number
** of arguments. If nArg is -2, then createFlag must be 0.
**
** If createFlag is false, then a function with the required name and
** number of arguments may be returned even if the eTextRep flag does not
** match that requested.
*/
FuncDef *sqlite3FindFunction(
sqlite3 *db, /* An open database */
const char *zName, /* Name of the function. zero-terminated */
int nArg, /* Number of arguments. -1 means any number */
u8 enc, /* Preferred text encoding */
u8 createFlag /* Create new entry if true and does not otherwise exist */
){
FuncDef *p; /* Iterator variable */
FuncDef *pBest = 0; /* Best match found so far */
int bestScore = 0; /* Score of best match */
int h; /* Hash value */
int nName; /* Length of the name */
assert( nArg>=(-2) );
assert( nArg>=(-1) || createFlag==0 );
nName = sqlite3Strlen30(zName);
/* First search for a match amongst the application-defined functions.
*/
p = (FuncDef*)sqlite3HashFind(&db->aFunc, zName);
while( p ){
int score = matchQuality(p, nArg, enc);
if( score>bestScore ){
pBest = p;
bestScore = score;
}
p = p->pNext;
}
/* If no match is found, search the built-in functions.
**
** If the DBFLAG_PreferBuiltin flag is set, then search the built-in
** functions even if a prior app-defined function was found. And give
** priority to built-in functions.
**
** Except, if createFlag is true, that means that we are trying to
** install a new function. Whatever FuncDef structure is returned it will
** have fields overwritten with new information appropriate for the
** new function. But the FuncDefs for built-in functions are read-only.
** So we must not search for built-ins when creating a new function.
*/
if( !createFlag && (pBest==0 || (db->mDbFlags & DBFLAG_PreferBuiltin)!=0) ){
bestScore = 0;
h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % SQLITE_FUNC_HASH_SZ;
p = functionSearch(h, zName);
while( p ){
int score = matchQuality(p, nArg, enc);
if( score>bestScore ){
pBest = p;
bestScore = score;
}
p = p->pNext;
}
}
/* If the createFlag parameter is true and the search did not reveal an
** exact match for the name, number of arguments and encoding, then add a
** new entry to the hash table and return it.
*/
if( createFlag && bestScore<FUNC_PERFECT_MATCH &&
(pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){
FuncDef *pOther;
pBest->zName = (const char*)&pBest[1];
pBest->nArg = (u16)nArg;
pBest->funcFlags = enc;
memcpy((char*)&pBest[1], zName, nName+1);
pOther = (FuncDef*)sqlite3HashInsert(&db->aFunc, pBest->zName, pBest);
if( pOther==pBest ){
sqlite3DbFree(db, pBest);
sqlite3OomFault(db);
return 0;
}else{
pBest->pNext = pOther;
}
}
if( pBest && (pBest->xSFunc || createFlag) ){
return pBest;
}
return 0;
}
/*
** Locate a user function given a name, a number of arguments and a flag
** indicating whether the function prefers UTF-16 over UTF-8. Return a
** pointer to the FuncDef structure that defines that function, or return
** NULL if the function does not exist.
**
** If the createFlag argument is true, then a new (blank) FuncDef
** structure is created and liked into the "db" structure if a
** no matching function previously existed. When createFlag is true
** and the nArg parameter is -1, then only a function that accepts
** any number of arguments will be returned.
**
** If createFlag is false and nArg is -1, then the first valid
** function found is returned. A function is valid if either xFunc
** or xStep is non-zero.
**
** If createFlag is false, then a function with the required name and
** number of arguments may be returned even if the eTextRep flag does not
** match that requested.
*/
FuncDef *sqlite3FindFunction(
sqlite3 *db, /* An open database */
const char *zName, /* Name of the function. Not null-terminated */
int nName, /* Number of characters in the name */
int nArg, /* Number of arguments. -1 means any number */
u8 enc, /* Preferred text encoding */
int createFlag /* Create new entry if true and does not otherwise exist */
){
FuncDef *p; /* Iterator variable */
FuncDef *pBest = 0; /* Best match found so far */
int bestScore = 0; /* Score of best match */
int h; /* Hash value */
assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
if( nArg<-1 ) nArg = -1;
h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % ArraySize(db->aFunc.a);
/* First search for a match amongst the application-defined functions.
*/
p = functionSearch(&db->aFunc, h, zName, nName);
while( p ){
int score = matchQuality(p, nArg, enc);
if( score>bestScore ){
pBest = p;
bestScore = score;
}
p = p->pNext;
}
/* If no match is found, search the built-in functions.
**
** Except, if createFlag is true, that means that we are trying to
** install a new function. Whatever FuncDef structure is returned will
** have fields overwritten with new information appropriate for the
** new function. But the FuncDefs for built-in functions are read-only.
** So we must not search for built-ins when creating a new function.
*/
if( !createFlag && !pBest ){
FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions);
p = functionSearch(pHash, h, zName, nName);
while( p ){
int score = matchQuality(p, nArg, enc);
if( score>bestScore ){
pBest = p;
bestScore = score;
}
p = p->pNext;
}
}
/* If the createFlag parameter is true and the search did not reveal an
** exact match for the name, number of arguments and encoding, then add a
** new entry to the hash table and return it.
*/
if( createFlag && (bestScore<6 || pBest->nArg!=nArg) &&
(pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){
pBest->zName = (char *)&pBest[1];
pBest->nArg = (u16)nArg;
pBest->iPrefEnc = enc;
memcpy(pBest->zName, zName, nName);
pBest->zName[nName] = 0;
sqlite3FuncDefInsert(&db->aFunc, pBest);
}
if( pBest && (pBest->xStep || pBest->xFunc || createFlag) ){
return pBest;
}
return 0;
}
