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 1.151 2004/07/19 00:39:45 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

char const *sqlite3AffinityString(char affinity){
  switch( affinity ){
    case SQLITE_AFF_INTEGER: return "i";

    case TK_OR:
    case TK_PLUS:
    case TK_STAR:
    case TK_MINUS:
    case TK_REM:
    case TK_BITAND:
    case TK_BITOR:
    case TK_SLASH: {
      sqlite3ExprCode(pParse, pExpr->pLeft);
      sqlite3ExprCode(pParse, pExpr->pRight);
      sqlite3VdbeAddOp(v, op, 0, 0);
      break;
    }
    case TK_LSHIFT:
    case TK_RSHIFT: {
      sqlite3ExprCode(pParse, pExpr->pRight);
      sqlite3ExprCode(pParse, pExpr->pLeft);
      sqlite3VdbeAddOp(v, op, 0, 0);
      break;
    }
    case TK_CONCAT: {
      sqlite3ExprCode(pParse, pExpr->pLeft);
      sqlite3ExprCode(pParse, pExpr->pRight);
      sqlite3VdbeAddOp(v, OP_Concat8, 2, 0);

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.402 2004/07/19 17:25:25 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

** SQLITE_AFF_NUMERIC
** SQLITE_AFF_TEXT
** SQLITE_AFF_NONE
** SQLITE_AFF_INTEGER
**
*/
static void applyAffinity(Mem *pRec, char affinity, u8 enc){
  switch( affinity ){

    case SQLITE_AFF_INTEGER:








    case SQLITE_AFF_NUMERIC:
      if( 0==(pRec->flags&(MEM_Real|MEM_Int)) ){
        /* pRec does not have a valid integer or real representation. 
        ** Attempt a conversion if pRec has a string representation and
        ** it looks like a number.
        */
        int realnum;
        sqlite3VdbeMemNulTerminate(pRec);
        if( pRec->flags&MEM_Str && sqlite3IsNumber(pRec->z, &realnum, enc) ){
          if( realnum ){
            Realify(pRec);
          }else{
            Integerify(pRec);
          }
        }
      }

      if( affinity==SQLITE_AFF_INTEGER ){
        /* For INTEGER affinity, try to convert a real value to an int */
        if( (pRec->flags&MEM_Real) && !(pRec->flags&MEM_Int) ){
          pRec->i = pRec->r;
          if( ((double)pRec->i)==pRec->r ){
            pRec->flags |= MEM_Int;
          }
        }
      }
      break;

    case SQLITE_AFF_TEXT:
      /* Only attempt the conversion if there is an integer or real
      ** representation (blob and NULL do not get converted) but no string
      ** representation.
      */
      if( 0==(pRec->flags&MEM_Str) && (pRec->flags&(MEM_Real|MEM_Int)) ){
        sqlite3VdbeMemStringify(pRec, enc);
      }
      pRec->flags &= ~(MEM_Real|MEM_Int);

      break;

    case SQLITE_AFF_NONE:
      /* Affinity NONE. Do nothing. */
      break;

    default:
      assert(0);
  }
}

#ifndef NDEBUG
/*
** Write a nice string representation of the contents of cell pMem
** into buffer zBuf, length nBuf.

**
** The return address stack is of limited depth.  If too many
** OP_Gosub operations occur without intervening OP_Returns, then
** the return address stack will fill up and processing will abort
** with a fatal error.
*/
case OP_Gosub: {
  if( p->returnDepth>=sizeof(p->returnStack)/sizeof(p->returnStack[0]) ){
    sqlite3SetString(&p->zErrMsg, "return address stack overflow", (char*)0);
    p->rc = SQLITE_INTERNAL;
    return SQLITE_ERROR;
  }
  p->returnStack[p->returnDepth++] = pc+1;
  pc = pOp->p2 - 1;
  break;
}

/* Opcode:  Return * * *
**
** Jump immediately to the next instruction after the last unreturned
** OP_Gosub.  If an OP_Return has occurred for all OP_Gosubs, then
** processing aborts with a fatal error.
*/
case OP_Return: {
  if( p->returnDepth<=0 ){
    sqlite3SetString(&p->zErrMsg, "return address stack underflow", (char*)0);
    p->rc = SQLITE_INTERNAL;
    return SQLITE_ERROR;
  }
  p->returnDepth--;
  pc = p->returnStack[p->returnDepth] - 1;
  break;
}

/* Opcode:  Halt P1 P2 *
**

*/
case OP_Halt: {
  p->magic = VDBE_MAGIC_HALT;
  p->pTos = pTos;
  if( pOp->p1!=SQLITE_OK ){
    p->rc = pOp->p1;
    p->errorAction = pOp->p2;
    if( pOp->p3 ){
      sqlite3SetString(&p->zErrMsg, pOp->p3, (char*)0);
    }
    return SQLITE_ERROR;
  }else{
    p->rc = SQLITE_OK;
    return SQLITE_DONE;
  }
}

** sqlite3_bind() API.
*/
case OP_Variable: {
  int j = pOp->p1 - 1;
  assert( j>=0 && j<p->nVar );

  pTos++;

  memcpy(pTos, &p->apVar[j], sizeof(*pTos)-NBFS);
  pTos->xDel = 0;
  if( pTos->flags&(MEM_Str|MEM_Blob) ){
    pTos->flags &= ~(MEM_Dyn|MEM_Ephem|MEM_Short);
    pTos->flags |= MEM_Static;
  }
  break;

** to integers.  Push back onto the stack the bit-wise OR of the
** two elements.
** If either operand is NULL, the result is NULL.
*/
/* Opcode: ShiftLeft * * *
**
** Pop the top two elements from the stack.  Convert both elements
** to integers.  Push back onto the stack the top element shifted
** left by N bits where N is the second element on the stack.
** If either operand is NULL, the result is NULL.
*/
/* Opcode: ShiftRight * * *
**
** Pop the top two elements from the stack.  Convert both elements
** to integers.  Push back onto the stack the top element shifted
** right by N bits where N is the second element on the stack.
** If either operand is NULL, the result is NULL.
*/
case OP_BitAnd:
case OP_BitOr:
case OP_ShiftLeft:
case OP_ShiftRight: {
  Mem *pNos = &pTos[-1];
  int a, b;

  assert( pNos>=p->aStack );
  if( (pTos->flags | pNos->flags) & MEM_Null ){
    popStack(&pTos, 2);
    pTos++;
    pTos->flags = MEM_Null;
    break;
  }
  a = sqlite3VdbeIntValue(pTos);
  b = sqlite3VdbeIntValue(pNos);
  switch( pOp->opcode ){
    case OP_BitAnd:      a &= b;     break;
    case OP_BitOr:       a |= b;     break;
    case OP_ShiftLeft:   a <<= b;    break;
    case OP_ShiftRight:  a >>= b;    break;
    default:   /* CANT HAPPEN */     break;
  }

** convert it into the least integer that is greater than or equal to its
** current value if P1==0, or to the least integer that is strictly
** greater than its current value if P1==1.
*/
case OP_ForceInt: {
  int v;
  assert( pTos>=p->aStack );

  if( (pTos->flags & (MEM_Int|MEM_Real))==0 && ((pTos->flags & MEM_Str)==0 
      || sqlite3IsNumber(pTos->z, 0, db->enc)==0) ){
    Release(pTos);
    pTos--;
    pc = pOp->p2 - 1;
    break;
  }
  if( pTos->flags & MEM_Int ){
    v = pTos->i + (pOp->p1!=0);

**
** If the top of the stack is not an integer and P2 is not zero and
** P1 is 1, then the stack is popped.  In all other cases, the depth
** of the stack is unchanged.
*/
case OP_MustBeInt: {
  assert( pTos>=p->aStack );
  if( pTos->flags & MEM_Int ){
    /* Do nothing */
  }else if( pTos->flags & MEM_Real ){
    int i = (int)pTos->r;
    double r = (double)i;
    if( r!=pTos->r ){
      goto mismatch;
    }
    pTos->i = i;
  }else if( pTos->flags & MEM_Str ){
    i64 v;
    if( sqlite3VdbeChangeEncoding(pTos, SQLITE_UTF8)
       || sqlite3VdbeMemNulTerminate(pTos) ){
      goto no_mem;
    }
    if( !sqlite3atoi64(pTos->z, &v) ){
      double r;
      if( !sqlite3IsNumber(pTos->z, 0, SQLITE_UTF8) ){
        goto mismatch;
      }
      Realify(pTos);
      v = (int)pTos->r;
      r = (double)v;
      if( r!=pTos->r ){
        goto mismatch;
      }
    }
    pTos->i = v;
  }else{
    goto mismatch;
  }
  Release(pTos);
  pTos->flags = MEM_Int;
  break;

mismatch:
  if( pOp->p2==0 ){
    rc = SQLITE_MISMATCH;
    goto abort_due_to_error;
  }else{
    if( pOp->p1 ) popStack(&pTos, 1);
    pc = pOp->p2 - 1;




  }
  break;
}

/* Opcode: Eq P1 P2 P3
**
** Pop the top two elements from the stack.  If they are equal, then