Better comment to describe the confusing operand reversal for infix
functions. (CVS 3325)
FossilOrigin-Name: 30dfb9bf2131370fe57e000495f5c292d392a010
diff --git a/src/expr.c b/src/expr.c
index 1f8346a..5ba7cde 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -12,7 +12,7 @@
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
-** $Id: expr.c,v 1.264 2006/07/08 18:35:00 drh Exp $
+** $Id: expr.c,v 1.265 2006/07/08 18:41:37 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -1675,16 +1675,21 @@
assert( pDef!=0 );
nExpr = sqlite3ExprCodeExprList(pParse, pList);
#ifndef SQLITE_OMIT_VIRTUALTABLE
+ /* Possibly overload the function if the first argument is
+ ** a virtual table column.
+ **
+ ** For infix functions (LIKE, GLOB, REGEXP, and MATCH) use the
+ ** second argument, not the first, as the argument to test to
+ ** see if it is a column in a virtual table. This is done because
+ ** the left operand of infix functions (the operand we want to
+ ** control overloading) ends up as the second argument to the
+ ** function. The expression "A glob B" is equivalent to
+ ** "glob(B,A). We want to use the A in "A glob B" to test
+ ** for function overloading. But we use the B term in "glob(B,A)".
+ */
if( nExpr>=2 && (pExpr->flags & EP_InfixFunc) ){
- /* For infix functions GLOB, LIKE, REGEXP, and MATCH, check
- ** the second argument to the function which is operand to
- ** left of the function name. Users normally consider the
- ** left operand to be the first argument, even though it is
- ** really the second argument to the underlying function. */
pDef = sqlite3VtabOverloadFunction(pDef, nExpr, pList->a[1].pExpr);
}else if( nExpr>0 ){
- /* For normal functions, go by the first argument - the first
- ** argument after the "(" that follows the function name */
pDef = sqlite3VtabOverloadFunction(pDef, nExpr, pList->a[0].pExpr);
}
#endif