It seems that we have a mess here.
How would we overload/replace the "like" function with things like this done
internally by sqlite without public documentaion ?
Also I do not see a setting of SQLITE_DETERMINISTIC isn't like deterministic
?
Cheers !
/*
** Set the LIKEOPT flag on the 2-argument function with the given name.
*/
static void setLikeOptFlag(sqlite3 *db, const char *zName, u8 flagVal){
? FuncDef *pDef;
? pDef = sqlite3FindFunction(db, zName, 2, SQLITE_UTF8, 0);
? if( ALWAYS(pDef) ){
??? pDef->funcFlags |= flagVal;
? }
}
/*
** Register the built-in LIKE and GLOB functions.? The caseSensitive
** parameter determines whether or not the LIKE operator is case
** sensitive.? GLOB is always case sensitive.
*/
void sqlite3RegisterLikeFunctions(sqlite3 *db, int caseSensitive){
? struct compareInfo *pInfo;
? if( caseSensitive ){
??? pInfo = (struct compareInfo*)&likeInfoAlt;
? }else{
??? pInfo = (struct compareInfo*)&likeInfoNorm;
? }
? sqlite3CreateFunc(db, "like", 2, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0);
? sqlite3CreateFunc(db, "like", 3, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0);
? sqlite3CreateFunc(db, "glob", 2, SQLITE_UTF8,
????? (struct compareInfo*)&globInfo, likeFunc, 0, 0, 0);
? setLikeOptFlag(db, "glob", SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE);
? setLikeOptFlag(db, "like",
????? caseSensitive ? (SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE) :
SQLITE_FUNC_LIKE);
}
/*
** pExpr points to an expression which implements a function.? If
** it is appropriate to apply the LIKE optimization to that function
** then set aWc[0] through aWc[2] to the wildcard characters and
** return TRUE.? If the function is not a LIKE-style function then
** return FALSE.
**
** *pIsNocase is set to true if uppercase and lowercase are equivalent for
** the function (default for LIKE).? If the function makes the distinction
** between uppercase and lowercase (as does GLOB) then *pIsNocase is set to
** false.
*/
int sqlite3IsLikeFunction(sqlite3 *db, Expr *pExpr, int *pIsNocase, char
*aWc){
? FuncDef *pDef;
? if( pExpr->op!=TK_FUNCTION
?? || !pExpr->x.pList
?? || pExpr->x.pList->nExpr!=2
? ){
??? return 0;
? }
? assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
? pDef = sqlite3FindFunction(db, pExpr->u.zToken, 2, SQLITE_UTF8, 0);
? if( NEVER(pDef==0) || (pDef->funcFlags & SQLITE_FUNC_LIKE)==0 ){
??? return 0;
? }
? /* The memcpy() statement assumes that the wildcard characters are
? ** the first three statements in the compareInfo structure.? The
? ** asserts() that follow verify that assumption
? */
? memcpy(aWc, pDef->pUserData, 3);
? assert( (char*)&likeInfoAlt == (char*)&likeInfoAlt.matchAll );
? assert( &((char*)&likeInfoAlt)[1] == (char*)&likeInfoAlt.matchOne );
? assert( &((char*)&likeInfoAlt)[2] == (char*)&likeInfoAlt.matchSet );
? *pIsNocase = (pDef->funcFlags & SQLITE_FUNC_CASE)==0;
? return 1;
}
?
