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 1.266 2006/07/11 13:15:08 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

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

    assert( pToken->dyn==0 );
    pNew->span = pNew->token = *pToken;
  }else if( pLeft && pRight ){
    sqlite3ExprSpan(pNew, &pLeft->span, &pRight->span);
  }
  return pNew;
}

/*
** Works like sqlite3Expr() but frees its pLeft and pRight arguments
** if it fails due to a malloc problem.
*/
Expr *sqlite3ExprOrFree(int op, Expr *pLeft, Expr *pRight, const Token *pToken){
  Expr *pNew = sqlite3Expr(op, pLeft, pRight, pToken);
  if( pNew==0 ){
    sqlite3ExprDelete(pLeft);
    sqlite3ExprDelete(pRight);
  }
  return pNew;
}

/*
** When doing a nested parse, you can include terms in an expression
** that look like this:   #0 #1 #2 ...  These terms refer to elements
** on the stack.  "#0" means the top of the stack.
** "#1" means the next down on the stack.  And so forth.
**

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.319 2006/07/11 13:15:08 drh Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.

    zAlias1 = pTab1->zName;
  }
  pE1b = sqlite3CreateIdExpr(zAlias1);
  if( zAlias2==0 ){
    zAlias2 = pTab2->zName;
  }
  pE2b = sqlite3CreateIdExpr(zAlias2);
  pE1c = sqlite3ExprOrFree(TK_DOT, pE1b, pE1a, 0);
  pE2c = sqlite3ExprOrFree(TK_DOT, pE2b, pE2a, 0);
  pE = sqlite3ExprOrFree(TK_EQ, pE1c, pE2c, 0);
  if( pE ){
    ExprSetProperty(pE, EP_FromJoin);
    pE->iRightJoinTable = iRightJoinTable;
  }
  pE = sqlite3ExprAnd(*ppExpr, pE);
  if( pE ){
    *ppExpr = pE;
  }
}

/*
** Set the EP_FromJoin property on all terms of the given expression.
** And set the Expr.iRightJoinTable to iTable for every term in the
** expression.
**

  ** key column, no index is necessary so set pIdx to NULL.  If no
  ** usable index is found, return 0.
  */
  if( iCol<0 ){
    pIdx = 0;
  }else{
    CollSeq *pColl = sqlite3ExprCollSeq(pParse, pExpr);
    if( pColl==0 ) return 0;
    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
      assert( pIdx->nColumn>=1 );
      if( pIdx->aiColumn[0]==iCol && 
          0==sqlite3StrICmp(pIdx->azColl[0], pColl->zName) ){
        break;
      }
    }

/*
** 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 1.520 2006/07/11 13:15:08 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Extra interface definitions for those who need them
*/

void sqlite3ErrorClear(Parse*);
void sqlite3Dequote(char*);
void sqlite3DequoteExpr(Expr*);
int sqlite3KeywordCode(const unsigned char*, int);
int sqlite3RunParser(Parse*, const char*, char **);
void sqlite3FinishCoding(Parse*);
Expr *sqlite3Expr(int, Expr*, Expr*, const Token*);
Expr *sqlite3ExprOrFree(int, Expr*, Expr*, const Token*);
Expr *sqlite3RegisterExpr(Parse*,Token*);
Expr *sqlite3ExprAnd(Expr*, Expr*);
void sqlite3ExprSpan(Expr*,Token*,Token*);
Expr *sqlite3ExprFunction(ExprList*, Token*);
void sqlite3ExprAssignVarNumber(Parse*, Expr*);
void sqlite3ExprDelete(Expr*);
ExprList *sqlite3ExprListAppend(ExprList*,Expr*,Token*);