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Overview
Comment:Better comment to describe the confusing operand reversal for infix functions. (CVS 3325)
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SHA1: 30dfb9bf2131370fe57e000495f5c292d392a010
User & Date: drh 2006-07-08 18:41:37.000
Context
2006-07-10
21:15
Back out the changes of ticket #1687 since they broken the ActiveTcl build. (CVS 3326) (check-in: b10d4220dc user: drh tags: trunk)
2006-07-08
18:41
Better comment to describe the confusing operand reversal for infix functions. (CVS 3325) (check-in: 30dfb9bf21 user: drh tags: trunk)
18:35
For infix functions (LIKE, GLOB, REGEXP, and MATCH) treat the left operand as the first argument for the purposes of virtual table function overloading, even though the left operand is really the the second argument. (CVS 3324) (check-in: 6e98373ca1 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/expr.c.
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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** 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 $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**








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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.265 2006/07/08 18:41:37 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**
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      CollSeq *pColl = 0;
      zId = (char*)pExpr->token.z;
      nId = pExpr->token.n;
      pDef = sqlite3FindFunction(pParse->db, zId, nId, nExpr, enc, 0);
      assert( pDef!=0 );
      nExpr = sqlite3ExprCodeExprList(pParse, pList);
#ifndef SQLITE_OMIT_VIRTUALTABLE
      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
      for(i=0; i<nExpr && i<32; i++){
        if( sqlite3ExprIsConstant(pList->a[i].pExpr) ){
          constMask |= (1<<i);
        }








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      CollSeq *pColl = 0;
      zId = (char*)pExpr->token.z;
      nId = pExpr->token.n;
      pDef = sqlite3FindFunction(pParse->db, zId, nId, nExpr, enc, 0);
      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) ){
        pDef = sqlite3VtabOverloadFunction(pDef, nExpr, pList->a[1].pExpr);
      }else if( nExpr>0 ){


        pDef = sqlite3VtabOverloadFunction(pDef, nExpr, pList->a[0].pExpr);
      }
#endif
      for(i=0; i<nExpr && i<32; i++){
        if( sqlite3ExprIsConstant(pList->a[i].pExpr) ){
          constMask |= (1<<i);
        }
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