**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.
**
** $Id: where.c,v 1.89 2004/02/22 20:05:02 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.
................................................................................
** are being used, so we assign a single bit in a 32-bit word to track
** that cursor.  Then a 32-bit integer is able to show the set of all
** cursors being used.
*/
typedef struct ExprMaskSet ExprMaskSet;
struct ExprMaskSet {
  int n;          /* Number of assigned cursor values */
  int ix[32];     /* Cursor assigned to each bit */
};

/*
** Determine the number of elements in an array.
*/
#define ARRAYSIZE(X)  (sizeof(X)/sizeof(X[0]))

................................................................................
** sets their opcodes to TK_COLUMN and their Expr.iTable fields to
** the VDBE cursor number of the table.
*/
static int exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){
  unsigned int mask = 0;
  if( p==0 ) return 0;
  if( p->op==TK_COLUMN ){
    return getMask(pMaskSet, p->iTable);


  }
  if( p->pRight ){
    mask = exprTableUsage(pMaskSet, p->pRight);
  }
  if( p->pLeft ){
    mask |= exprTableUsage(pMaskSet, p->pLeft);
  }

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.
**
** $Id: where.c,v 1.89.2.1 2004/07/19 02:24:03 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.
................................................................................
** are being used, so we assign a single bit in a 32-bit word to track
** that cursor.  Then a 32-bit integer is able to show the set of all
** cursors being used.
*/
typedef struct ExprMaskSet ExprMaskSet;
struct ExprMaskSet {
  int n;          /* Number of assigned cursor values */
  int ix[31];     /* Cursor assigned to each bit */
};

/*
** Determine the number of elements in an array.
*/
#define ARRAYSIZE(X)  (sizeof(X)/sizeof(X[0]))

................................................................................
** sets their opcodes to TK_COLUMN and their Expr.iTable fields to
** the VDBE cursor number of the table.
*/
static int exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){
  unsigned int mask = 0;
  if( p==0 ) return 0;
  if( p->op==TK_COLUMN ){
    mask = getMask(pMaskSet, p->iTable);
    if( mask==0 ) mask = -1;
    return mask;
  }
  if( p->pRight ){
    mask = exprTableUsage(pMaskSet, p->pRight);
  }
  if( p->pLeft ){
    mask |= exprTableUsage(pMaskSet, p->pLeft);
  }