SQLite

/*
** 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 1.391 2005/07/08 14:14:23 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks

                         ** right side of "<expr> IN (<select>)" */
  Table *pTab;           /* Table for OP_Column expressions. */
};

/*
** The following are the meanings of bits in the Expr.flags field.
*/
#define EP_FromJoin     0x01  /* Originated in ON or USING clause of a join */
#define EP_Agg          0x02  /* Contains one or more aggregate functions */
#define EP_Resolved     0x04  /* IDs have been resolved to COLUMNs */
#define EP_Error        0x08  /* Expression contains one or more errors */
#define EP_Not          0x10  /* Operator preceeded by NOT */
#define EP_VarSelect    0x20  /* pSelect is correlated, not constant */
#define EP_OptOnly      0x40  /* A constraint used by the optimizer only */

/*
** These macros can be used to test, set, or clear bits in the 
** Expr.flags field.
*/
#define ExprHasProperty(E,P)     (((E)->flags&(P))==(P))
#define ExprHasAnyProperty(E,P)  (((E)->flags&(P))!=0)

** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is reponsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
** $Id: where.c,v 1.141 2005/07/08 14:14:23 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.

    }
    loopMask |= getMask(&maskSet, iCur);

    /* Insert code to test every subexpression that can be completely
    ** computed using the current set of tables.
    */
    for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
      Expr *pE = pTerm->p;
      if( pE==0 || ExprHasProperty(pE, EP_OptOnly) ) continue;
      if( (pTerm->prereqAll & loopMask)!=pTerm->prereqAll ) continue;
      if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
        continue;
      }
      sqlite3ExprIfFalse(pParse, pE, cont, 1);
      pTerm->p = 0;
    }
    brk = cont;

    /* For a LEFT OUTER JOIN, generate code that will record the fact that
    ** at least one row of the right table has matched the left table.  
    */
    if( pLevel->iLeftJoin ){
      pLevel->top = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp(v, OP_Integer, 1, 0);
      sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
      VdbeComment((v, "# record LEFT JOIN hit"));
      for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
        Expr *pE = pTerm->p;
        if( pE==0 || ExprHasProperty(pE, EP_OptOnly) ) continue;
        if( (pTerm->prereqAll & loopMask)!=pTerm->prereqAll ) continue;
        sqlite3ExprIfFalse(pParse, pE, cont, 1);
        pTerm->p = 0;
      }
    }
  }
  pWInfo->iContinue = cont;
  freeMaskSet(&maskSet);
  return pWInfo;