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 1.408 2008/12/15 15:27:52 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

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

    /* Consider functions to be constant if all their arguments are constant
    ** and pWalker->u.i==2 */
    case TK_FUNCTION:
      if( pWalker->u.i==2 ) return 0;
      /* Fall through */
    case TK_ID:
    case TK_COLUMN:
    case TK_DOT:
    case TK_AGG_FUNCTION:
    case TK_AGG_COLUMN:
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_SELECT:
    case TK_EXISTS:
      testcase( pExpr->op==TK_SELECT );
      testcase( pExpr->op==TK_EXISTS );
#endif
      testcase( pExpr->op==TK_ID );
      testcase( pExpr->op==TK_COLUMN );
      testcase( pExpr->op==TK_DOT );
      testcase( pExpr->op==TK_AGG_FUNCTION );
      testcase( pExpr->op==TK_AGG_COLUMN );
      pWalker->u.i = 0;
      return WRC_Abort;
    default:
      return WRC_Continue;
  }

int sqlite3IsRowid(const char *z){
  if( sqlite3StrICmp(z, "_ROWID_")==0 ) return 1;
  if( sqlite3StrICmp(z, "ROWID")==0 ) return 1;
  if( sqlite3StrICmp(z, "OID")==0 ) return 1;
  return 0;
}

#ifdef SQLITE_TEST
  int sqlite3_enable_in_opt = 1;
#else
  #define sqlite3_enable_in_opt 1
#endif

/*
** Return true if the IN operator optimization is enabled and
** the SELECT statement p exists and is of the
** simple form:
**
**     SELECT <column> FROM <table>
**
** If this is the case, it may be possible to use an existing table
** or index instead of generating an epheremal table.
*/
#ifndef SQLITE_OMIT_SUBQUERY
static int isCandidateForInOpt(Select *p){
  SrcList *pSrc;
  ExprList *pEList;
  Table *pTab;
  if( !sqlite3_enable_in_opt ) return 0; /* IN optimization must be enabled */
  if( p==0 ) return 0;                   /* right-hand side of IN is SELECT */
  if( p->pPrior ) return 0;              /* Not a compound SELECT */
  if( p->selFlags & (SF_Distinct|SF_Aggregate) ){
      return 0; /* No DISTINCT keyword and no aggregate functions */
  }
  if( p->pGroupBy ) return 0;            /* Has no GROUP BY clause */
  if( p->pLimit ) return 0;              /* Has no LIMIT clause */
  if( p->pOffset ) return 0;
  if( p->pWhere ) return 0;              /* Has no WHERE clause */
  pSrc = p->pSrc;
  if( pSrc==0 ) return 0;                /* A single table in the FROM clause */
  if( pSrc->nSrc!=1 ) return 0;
  if( pSrc->a[0].pSelect ) return 0;     /* FROM clause is not a subquery */
  pTab = pSrc->a[0].pTab;
  if( pTab==0 ) return 0;
  if( pTab->pSelect ) return 0;          /* FROM clause is not a view */
  if( IsVirtual(pTab) ) return 0;        /* FROM clause not a virtual table */
  pEList = p->pEList;
  if( pEList->nExpr!=1 ) return 0;       /* One column in the result set */

    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){
  int i;
  assert( pParse->pVdbe!=0 );
  if( !usedAsColumnCache(pParse, iCurrent, iCurrent) ){
    return iCurrent;
  }
  if( iCurrent!=iTarget ){
    sqlite3VdbeAddOp2(pParse->pVdbe, OP_SCopy, iCurrent, iTarget);
  }
  for(i=0; i<pParse->nColCache; i++){
    if( pParse->aColCache[i].iReg==iTarget ){
      pParse->aColCache[i] = pParse->aColCache[--pParse->nColCache];
      pParse->iColCache = pParse->nColCache;
    }
  }
  return iTarget;

}

/*
** If the last instruction coded is an ephemeral copy of any of
** the registers in the nReg registers beginning with iReg, then
** convert the last instruction from OP_SCopy to OP_Copy.
*/

  if( pParse->nTempReg==0 ){
    return ++pParse->nMem;
  }
  return pParse->aTempReg[--pParse->nTempReg];
}
void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
  if( iReg && pParse->nTempReg<ArraySize(pParse->aTempReg) ){
    sqlite3ExprWritableRegister(pParse, iReg, iReg);
    pParse->aTempReg[pParse->nTempReg++] = iReg;
  }
}

/*
** Allocate or deallocate a block of nReg consecutive registers
*/

/*
** 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 1.821 2009/01/09 14:11:05 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Include the configuration header output by 'configure' if we're using the
** autoconf-based build

/*
** Possible values for FuncDef.flags
*/
#define SQLITE_FUNC_LIKE     0x01 /* Candidate for the LIKE optimization */
#define SQLITE_FUNC_CASE     0x02 /* Case-sensitive LIKE-type function */
#define SQLITE_FUNC_EPHEM    0x04 /* Ephemeral.  Delete with VDBE */
#define SQLITE_FUNC_NEEDCOLL 0x08 /* sqlite3GetFuncCollSeq() might be called */


/*
** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
** used to create the initializers for the FuncDef structures.
**
**   FUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Used to create a scalar function definition of a function zName 

WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, ExprList**, u8, int);
void sqlite3WhereEnd(WhereInfo*);
int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int, int);
void sqlite3ExprCodeMove(Parse*, int, int, int);
void sqlite3ExprCodeCopy(Parse*, int, int, int);
void sqlite3ExprClearColumnCache(Parse*, int);
void sqlite3ExprCacheAffinityChange(Parse*, int, int);
int sqlite3ExprWritableRegister(Parse*,int,int);
void sqlite3ExprHardCopy(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, int);

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.341 2009/01/09 21:41:17 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>

/*

#endif
#ifdef SQLITE_DEBUG
  extern int sqlite3WhereTrace;
  extern int sqlite3OSTrace;
  extern int sqlite3VdbeAddopTrace;
#endif
#ifdef SQLITE_TEST
  extern int sqlite3_enable_in_opt;
  extern char sqlite3_query_plan[];
  static char *query_plan = sqlite3_query_plan;
#ifdef SQLITE_ENABLE_FTS3
  extern int sqlite3_fts3_enable_parentheses;
#endif
#endif

      (char*)&sqlite3_temp_directory, TCL_LINK_STRING);
  Tcl_LinkVar(interp, "bitmask_size",
      (char*)&bitmask_size, TCL_LINK_INT|TCL_LINK_READ_ONLY);
  Tcl_LinkVar(interp, "sqlite_sync_count",
      (char*)&sqlite3_sync_count, TCL_LINK_INT);
  Tcl_LinkVar(interp, "sqlite_fullsync_count",
      (char*)&sqlite3_fullsync_count, TCL_LINK_INT);
#ifdef SQLITE_TEST
  Tcl_LinkVar(interp, "sqlite_enable_in_opt",
      (char*)&sqlite3_enable_in_opt, TCL_LINK_INT);
#ifdef SQLITE_ENABLE_FTS3
  Tcl_LinkVar(interp, "sqlite_fts3_enable_parentheses",
      (char*)&sqlite3_fts3_enable_parentheses, TCL_LINK_INT);
#endif
#endif
  return TCL_OK;
}