SQLite

**    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 1.360 2008/04/01 01:42:41 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

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

  sqlite3VdbeAddOp2(pParse->pVdbe, OP_Move, iFrom, iTo);
  for(i=0; i<pParse->nColCache; i++){
    if( pParse->aColCache[i].iReg==iFrom ){
      pParse->aColCache[i].iReg = iTo;
    }
  }
}

/*
** Return true if any register in the range iFrom..iTo (inclusive)
** is used as part of the column cache.
*/
static int usedAsColumnCache(Parse *pParse, int iFrom, int iTo){
  int i;
  for(i=0; i<pParse->nColCache; i++){
    int r = pParse->aColCache[i].iReg;
    if( r>=iFrom && r<=iTo ) return 1;
  }
  return 0;
}

/*
** Theres is a value in register iCurrent.  We ultimately want
** the value to be in register iTarget.  It might be that
** iCurrent and iTarget are the same register.
**
** We are going to modify the value, so we need to make sure it
** is not a cached register.  If iCurrent is a cached register,
** then try to move the value over to iTarget.  If iTarget is a
** cached register, then clear the corresponding cache line.
**
** Return the register that the value ends up in.
*/
int sqlite3ExprWritableRegister(Parse *pParse, int iCurrent, int iTarget){
  assert( pParse->pVdbe!=0 );
  if( !usedAsColumnCache(pParse, iCurrent, iCurrent) ){
    return iCurrent;
  }
  sqlite3VdbeAddOp2(pParse->pVdbe, OP_SCopy, iCurrent, iTarget);
  sqlite3ExprExpireColumnCacheLines(pParse, iTarget, iTarget);
  return iTarget;
}

/*
** Generate code into the current Vdbe to evaluate the given
** expression.  Attempt to store the results in register "target".
** Return the register where results are stored.
**
** With this routine, there is no guaranteed that results will

      break;
    }
    case TK_BITNOT:
    case TK_NOT: {
      assert( TK_BITNOT==OP_BitNot );
      assert( TK_NOT==OP_Not );
      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
      inReg = sqlite3ExprWritableRegister(pParse, inReg, target);
      sqlite3VdbeAddOp1(v, op, inReg);
      break;
    }
    case TK_ISNULL:
    case TK_NOTNULL: {
      int addr;
      assert( TK_ISNULL==OP_IsNull );

      assert(pExpr->pList);
      assert((pExpr->pList->nExpr % 2) == 0);
      assert(pExpr->pList->nExpr > 0);
      pEList = pExpr->pList;
      aListelem = pEList->a;
      nExpr = pEList->nExpr;
      endLabel = sqlite3VdbeMakeLabel(v);

      if( (pX = pExpr->pLeft)!=0 ){
        cacheX = *pX;
        cacheX.iTable = sqlite3ExprCodeTemp(pParse, pX, &regFree1);
        cacheX.op = TK_REGISTER;
        cacheX.iColumn = 0;
        opCompare.op = TK_EQ;
        opCompare.pLeft = &cacheX;
        pTest = &opCompare;
      }
      sqlite3ExprColumnCacheDisable(pParse, 1);
      for(i=0; i<nExpr; i=i+2){
        if( pX ){
          opCompare.pRight = aListelem[i].pExpr;
        }else{
          pTest = aListelem[i].pExpr;
        }
        nextCase = sqlite3VdbeMakeLabel(v);

  if( pList ){
    for(pItem=pList->a, i=0; i<pList->nExpr; i++, pItem++){
      sqlite3ExprAnalyzeAggregates(pNC, pItem->pExpr);
    }
  }
}














/*
** Allocate or deallocate temporary use registers during code generation.
*/
int sqlite3GetTempReg(Parse *pParse){
  int i, r;
  if( pParse->nTempReg==0 ){
    return ++pParse->nMem;

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.684 2008/04/01 01:42:41 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Include the configuration header output by 'configure' if it was run
** (otherwise we get an empty default).

WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, ExprList**, u8);
void sqlite3WhereEnd(WhereInfo*);
int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int);
void sqlite3ExprCodeMove(Parse*, int, int);
void sqlite3ExprClearColumnCache(Parse*, int);
void sqlite3ExprColumnCacheDisable(Parse*, int);
void sqlite3ExprExpireColumnCacheLines(Parse*, int, int);
int sqlite3ExprWritableRegister(Parse*,int,int);
int sqlite3ExprCode(Parse*, Expr*, int);
int sqlite3ExprCodeTemp(Parse*, Expr*, int*);
int sqlite3ExprCodeTarget(Parse*, Expr*, int);
int sqlite3ExprCodeAndCache(Parse*, Expr*, int);
void sqlite3ExprCodeConstants(Parse*, Expr*);
int sqlite3ExprCodeExprList(Parse*, ExprList*, int);
void sqlite3ExprIfTrue(Parse*, Expr*, int, int);

# 2008 April 1
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# Test cases designed to exercise and verify the logic for
# factoring constant expressions out of loops and for
# common subexpression eliminations.
#
# $Id: cse.test,v 1.1 2008/04/01 01:42:41 drh Exp $
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

do_test cse-1.1 {
  execsql {
    CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c, d, e, f);
    INSERT INTO t1 VALUES(1,11,12,13,14,15);
    INSERT INTO t1 VALUES(2,21,22,23,24,25);
  }
  execsql {
    SELECT b, -b, ~b, NOT b, NOT NOT b, b-b, b+b, b*b, b/b, b FROM t1
  }
} {11 -11 -12 0 1 0 22 121 1 11 21 -21 -22 0 1 0 42 441 1 21}
do_test cse-1.2 {
  execsql {
    SELECT b, b%b, b==b, b!=b, b<b, b<=b, b IS NULL, b NOT NULL, b FROM t1
  }
} {11 0 1 0 0 1 0 1 11 21 0 1 0 0 1 0 1 21}
do_test cse-1.3 {
  execsql {
    SELECT b, abs(b), coalesce(b,-b,NOT b,c,NOT c), c, -c FROM t1;
  }
} {11 11 11 12 -12 21 21 21 22 -22}
do_test cse-1.4 {
  execsql {
    SELECT CASE WHEN a==1 THEN b ELSE c END, b, c FROM t1
  }
} {11 11 12 22 21 22}
do_test cse-1.5 {
  execsql {
    SELECT CASE a WHEN 1 THEN b WHEN 2 THEN c ELSE d END, b, c, d FROM t1
  }
} {11 11 12 13 22 21 22 23}
do_test cse-1.6 {
  execsql {
    SELECT CASE b WHEN 11 THEN -b WHEN 21 THEN -c ELSE -d END, b, c, d FROM t1
  }
} {-11 11 12 13 -22 21 22 23}
do_test cse-1.7 {
  execsql {
    SELECT a, -a, ~a, NOT a, NOT NOT a, a-a, a+a, a*a, a/a, a FROM t1
  }
} {1 -1 -2 0 1 0 2 1 1 1 2 -2 -3 0 1 0 4 4 1 2}
do_test cse-1.8 {
  execsql {
    SELECT a, a%a, a==a, a!=a, a<a, a<=a, a IS NULL, a NOT NULL, a FROM t1
  }
} {1 0 1 0 0 1 0 1 1 2 0 1 0 0 1 0 1 2}


finish_test