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Add new routines to simplify dealing with collating sequences in expressions:

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sqlite3ExprNNCollSeq() and sqlite3ExprCollSeqMatch().

FossilOrigin-Name: 490e488ea963fe725b16212822c8608f2b6abce688931b611446bc2cbfe6b87c
This commit is contained in:
drh
2017-09-28 01:58:23 +00:00
parent db8e68b4cd
commit 70efa84da7
7 changed files with 55 additions and 35 deletions
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35
src/expr.c
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@@ -124,6 +124,11 @@ Expr *sqlite3ExprSkipCollate(Expr *pExpr){
** Return the collation sequence for the expression pExpr. If
** there is no defined collating sequence, return NULL.
**
** See also: sqlite3ExprNNCollSeq()
**
** The sqlite3ExprNNCollSeq() works the same exact that it returns the
** default collation if pExpr has no defined collation.
**
** The collating sequence might be determined by a COLLATE operator
** or by the presence of a column with a defined collating sequence.
** COLLATE operators take first precedence. Left operands take
@@ -188,6 +193,32 @@ CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){
return pColl;
}
/*
** Return the collation sequence for the expression pExpr. If
** there is no defined collating sequence, return a pointer to the
** defautl collation sequence.
**
** See also: sqlite3ExprCollSeq()
**
** The sqlite3ExprCollSeq() routine works the same except that it
** returns NULL if there is no defined collation.
*/
CollSeq *sqlite3ExprNNCollSeq(Parse *pParse, Expr *pExpr){
CollSeq *p = sqlite3ExprCollSeq(pParse, pExpr);
if( p==0 ) p = pParse->db->pDfltColl;
assert( p!=0 );
return p;
}
/*
** Return TRUE if the two expressions have equivalent collating sequences.
*/
int sqlite3ExprCollSeqMatch(Parse *pParse, Expr *pE1, Expr *pE2){
CollSeq *pColl1 = sqlite3ExprNNCollSeq(pParse, pE1);
CollSeq *pColl2 = sqlite3ExprNNCollSeq(pParse, pE2);
return sqlite3StrICmp(pColl1->zName, pColl2->zName)==0;
}
/*
** pExpr is an operand of a comparison operator. aff2 is the
** type affinity of the other operand. This routine returns the
@@ -1843,8 +1874,8 @@ static int exprNodeIsConstantOrGroupBy(Walker *pWalker, Expr *pExpr){
for(i=0; i<pGroupBy->nExpr; i++){
Expr *p = pGroupBy->a[i].pExpr;
if( sqlite3ExprCompare(0, pExpr, p, -1)<2 ){
CollSeq *pColl = sqlite3ExprCollSeq(pWalker->pParse, p);
if( pColl==0 || sqlite3_stricmp("BINARY", pColl->zName)==0 ){
CollSeq *pColl = sqlite3ExprNNCollSeq(pWalker->pParse, p);
if( sqlite3_stricmp("BINARY", pColl->zName)==0 ){
return WRC_Prune;
}
}