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 1.215 2005/08/12 22:56:09 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

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

  if( p->token.dyn ) sqliteFree((char*)p->token.z);
  sqlite3ExprDelete(p->pLeft);
  sqlite3ExprDelete(p->pRight);
  sqlite3ExprListDelete(p->pList);
  sqlite3SelectDelete(p->pSelect);
  sqliteFree(p);
}

/*
** The Expr.token field might be a string literal that is quoted.
** If so, remove the quotation marks.
*/
void sqlite3DequoteExpr(Expr *p){
  if( ExprHasAnyProperty(p, EP_Dequoted) ){
    return;
  }
  ExprSetProperty(p, EP_Dequoted);
  if( p->token.dyn==0 ){
    if( p->op==TK_BLOB ){
      p->token.n--;
      p->token.z++;
    }
    sqlite3TokenCopy(&p->token, &p->token);
  }
  sqlite3Dequote((char*)p->token.z);
}


/*
** The following group of routines make deep copies of expressions,
** expression lists, ID lists, and select statements.  The copies can
** be deleted (by being passed to their respective ...Delete() routines)
** without effecting the originals.

      codeInteger(v, pExpr->token.z, pExpr->token.n);
      break;
    }
    case TK_FLOAT:
    case TK_STRING: {
      assert( TK_FLOAT==OP_Real );
      assert( TK_STRING==OP_String8 );
      sqlite3DequoteExpr(pExpr);
      sqlite3VdbeOp3(v, op, 0, 0, pExpr->token.z, pExpr->token.n);

      break;
    }
    case TK_NULL: {
      sqlite3VdbeAddOp(v, OP_Null, 0, 0);
      break;
    }
#ifndef SQLITE_OMIT_BLOB_LITERAL
    case TK_BLOB: {
      assert( TK_BLOB==OP_HexBlob );
      sqlite3VdbeOp3(v, op, 0, 0, pExpr->token.z+2, pExpr->token.n-3);

      break;
    }
#endif
    case TK_VARIABLE: {
      sqlite3VdbeAddOp(v, OP_Variable, pExpr->iTable, 0);
      if( pExpr->token.n>1 ){
        sqlite3VdbeChangeP3(v, -1, pExpr->token.z, pExpr->token.n);

                       "RAISE() may only be used within a trigger-program");
	return;
      }
      if( pExpr->iColumn!=OE_Ignore ){
         assert( pExpr->iColumn==OE_Rollback ||
                 pExpr->iColumn == OE_Abort ||
                 pExpr->iColumn == OE_Fail );
         sqlite3DequoteExpr(pExpr);
         sqlite3VdbeOp3(v, OP_Halt, SQLITE_CONSTRAINT, pExpr->iColumn,
                        pExpr->token.z, pExpr->token.n);
//         sqlite3VdbeDequoteP3(v, -1);
      } else {
         assert( pExpr->iColumn == OE_Ignore );
         sqlite3VdbeAddOp(v, OP_ContextPop, 0, 0);
         sqlite3VdbeAddOp(v, OP_Goto, 0, pParse->trigStack->ignoreJump);
         VdbeComment((v, "# raise(IGNORE)"));
      }
    }

/*
** 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 1.401 2005/08/12 22:56:09 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

*/
#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_Dequoted     0x40  /* True if the string has been dequoted */

/*
** 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)

char *sqlite3MPrintf(const char*, ...);
char *sqlite3VMPrintf(const char*, va_list);
void sqlite3DebugPrintf(const char*, ...);
void *sqlite3TextToPtr(const char*);
void sqlite3SetString(char **, ...);
void sqlite3ErrorMsg(Parse*, const char*, ...);
void sqlite3Dequote(char*);
void sqlite3DequoteExpr(Expr*);
int sqlite3KeywordCode(const char*, int);
int sqlite3RunParser(Parse*, const char*, char **);
void sqlite3FinishCoding(Parse*);
Expr *sqlite3Expr(int, Expr*, Expr*, const Token*);
Expr *sqlite3RegisterExpr(Parse*,Token*);
Expr *sqlite3ExprAnd(Expr*, Expr*);
void sqlite3ExprSpan(Expr*,Token*,Token*);

*************************************************************************
** Header file for the Virtual DataBase Engine (VDBE)
**
** This header defines the interface to the virtual database engine
** or VDBE.  The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
**
** $Id: vdbe.h,v 1.96 2005/08/12 22:56:09 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
#include <stdio.h>

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines

void sqlite3VdbeCreateCallback(Vdbe*, int*);
int sqlite3VdbeAddOp(Vdbe*,int,int,int);
int sqlite3VdbeOp3(Vdbe*,int,int,int,const char *zP3,int);
int sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp);
void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
void sqlite3VdbeChangeP3(Vdbe*, int addr, const char *zP1, int N);

int sqlite3VdbeFindOp(Vdbe*, int, int, int);
VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
int sqlite3VdbeMakeLabel(Vdbe*);
void sqlite3VdbeDelete(Vdbe*);
void sqlite3VdbeMakeReady(Vdbe*,int,int,int,int,int);
int sqlite3VdbeFinalize(Vdbe*);
void sqlite3VdbeResolveLabel(Vdbe*, int);

  assert( p->aOp==0 || p->aOp[p->nOp-1].p3==0 );
  va_start(ap, zFormat);
  sqlite3VdbeChangeP3(p, -1, sqlite3VMPrintf(zFormat, ap), P3_DYNAMIC);
  va_end(ap);
}
#endif




























/*
** Search the current program starting at instruction addr for the given
** opcode and P2 value.  Return the address plus 1 if found and 0 if not
** found.
*/
int sqlite3VdbeFindOp(Vdbe *p, int addr, int op, int p2){
  int i;

** 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 1.160 2005/08/12 22:56:09 drh Exp $
*/
#include "sqliteInt.h"

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  (sizeof(Bitmask)*8)

  WhereTerm *pTerm;
  int i;
  for(i=pWC->nTerm-1, pTerm=pWC->a; i>=0; i--, pTerm++){
    exprAnalyze(pTabList, pMaskSet, pTerm);
  }
}

#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
/*
** Check to see if the given expression is a LIKE or GLOB operator that
** can be optimized using inequality constraints.  Return TRUE if it is
** so and false if not.
**
** In order for the operator to be optimizible, the RHS must be a string
** literal that does not begin with a wildcard.  
*/
static int isLikeOrGlob(
  Expr *pExpr,      /* Test this expression */
  int *pnPattern,   /* Number of non-wildcard prefix characters */
  int *pisComplete  /* True if the only wildcard is % in the last character */
){
  const char *z;
  Expr *pRight, *pLeft;
  int c, cnt;
  char wc1, wc2, wc3;
  if( pExpr->op!=TK_FUNCTION ){
    return 0;
  }
  if( pExpr->pList->nExpr!=2 ){
    return 0;
  }
  if( pExpr->token.n!=4 ){
    return 0;
  }
  z = pExpr->token.z;
  if( sqlite3StrNICmp(z, "glob", 4)==0 ){
    wc1 = '*';
    wc2 = '?';
    wc3 = '[';
  }
#ifdef SQLITE_CASE_SENSITIVE_LIKE
  else if( sqlite3StrNICmp(z, "like", 4)==0 ){
    wc1 = '%';
    wc2 = '_';
    wc3 = '_';
  }
#endif
  else{
    return 0;
  }
  pRight = pExpr->pList->a[0].pExpr;
  if( pRight->op!=TK_STRING ){
    return 0;
  }
  pLeft = pExpr->pList->a[1].pExpr;
  if( pLeft->op!=TK_COLUMN ){
    return 0;
  }
  sqlite3DequoteExpr(pRight);
  z = pRight->token.z;
  for(cnt=0; (c=z[cnt])!=0 && c!=wc1 && c!=wc2 && c!=wc3; cnt++){}
  if( cnt==0 || 255==(u8)z[cnt] ){
    return 0;
  }
  *pisComplete = z[cnt]==wc1 && z[cnt+1]==0;
  *pnPattern = cnt;
  return 1;
}
#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */

/*
** The input to this routine is an WhereTerm structure with only the
** "pExpr" field filled in.  The job of this routine is to analyze the
** subexpression and populate all the other fields of the WhereTerm
** structure.
**
** If the expression is of the form "<expr> <op> X" it gets commuted

  ExprMaskSet *pMaskSet,    /* table masks */
  WhereTerm *pTerm          /* the WHERE clause term to be analyzed */
){
  Expr *pExpr = pTerm->pExpr;
  Bitmask prereqLeft;
  Bitmask prereqAll;
  int idxRight;
  int nPattern;
  int isComplete;

  prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft);
  pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight);
  pTerm->prereqAll = prereqAll = exprTableUsage(pMaskSet, pExpr);
  pTerm->leftCursor = -1;
  pTerm->iParent = -1;
  pTerm->operator = 0;

      pNew->leftColumn = pLeft->iColumn;
      pNew->prereqRight = prereqLeft;
      pNew->prereqAll = prereqAll;
      pNew->operator = operatorMask(pDup->op);
    }
  }

#ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
  /* If a term is the BETWEEN operator, create two new virtual terms
  ** that define the range that the BETWEEN implements.
  */
  else if( pExpr->op==TK_BETWEEN ){
    ExprList *pList = pExpr->pList;
    int i;
    static const u8 ops[] = {TK_GE, TK_LE};

      pNewTerm = whereClauseInsert(pTerm->pWC, pNewExpr,
                                   TERM_VIRTUAL|TERM_DYNAMIC);
      exprAnalyze(pSrc, pMaskSet, pNewTerm);
      pNewTerm->iParent = pTerm->idx;
    }
    pTerm->nChild = 2;
  }
#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */

#ifndef SQLITE_OMIT_OR_OPTIMIZATION
  /* Attempt to convert OR-connected terms into an IN operator so that
  ** they can make use of indices.
  */
  else if( pExpr->op==TK_OR ){
    int ok;
    int i, j;
    int iColumn, iCursor;

      pTerm->pExpr = pNew;
      pTerm->flags |= TERM_DYNAMIC;
      exprAnalyze(pSrc, pMaskSet, pTerm);
    }
or_not_possible:
    whereClauseClear(&sOr);
  }
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */

#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
  /* Add constraints to reduce the search space on a LIKE or GLOB
  ** operator.
  */
  if( isLikeOrGlob(pExpr, &nPattern, &isComplete) ){
    Expr *pLeft, *pRight;
    Expr *pStr1, *pStr2;
    Expr *pNewExpr1, *pNewExpr2;
    WhereTerm *pNewTerm1, *pNewTerm2;
    pLeft = pExpr->pList->a[1].pExpr;
    pRight = pExpr->pList->a[0].pExpr;
    pStr1 = sqlite3Expr(TK_STRING, 0, 0, 0);
    if( pStr1 ){
      sqlite3TokenCopy(&pStr1->token, &pRight->token);
      pStr1->token.n = nPattern;
    }
    pStr2 = sqlite3ExprDup(pStr1);
    if( pStr2 ){
      assert( pStr2->token.dyn );
      ++*(u8*)&pStr2->token.z[nPattern-1];
    }
    pNewExpr1 = sqlite3Expr(TK_GE, sqlite3ExprDup(pLeft), pStr1, 0);
    pNewTerm1 = whereClauseInsert(pTerm->pWC, pNewExpr1,
                                  TERM_VIRTUAL|TERM_DYNAMIC);
    exprAnalyze(pSrc, pMaskSet, pNewTerm1);
    pNewExpr2 = sqlite3Expr(TK_LT, sqlite3ExprDup(pLeft), pStr2, 0);
    pNewTerm2 = whereClauseInsert(pTerm->pWC, pNewExpr2,
                                 TERM_VIRTUAL|TERM_DYNAMIC);
    exprAnalyze(pSrc, pMaskSet, pNewTerm2);
    if( isComplete ){
      pNewTerm2->iParent = pTerm->idx;
      pNewTerm1->iParent = pTerm->idx;
      pTerm->nChild = 2;
    }
  }
#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
}


/*
** This routine decides if pIdx can be used to satisfy the ORDER BY
** clause.  If it can, it returns 1.  If pIdx cannot satisfy the
** ORDER BY clause, this routine returns 0.