SQLite

** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** This file contains C code routines used for processing expressions
**
** $Id: expr.c,v 1.8 2000/06/06 03:31:22 drh Exp $
*/
#include "sqliteInt.h"

/*
** Walk an expression tree.  Return 1 if the expression is constant
** and 0 if it involves variables.
*/

    case TK_IN: {
      Vdbe *v = pParse->pVdbe;
      if( v==0 ){
        v = pParse->pVdbe = sqliteVdbeCreate(pParse->db->pBe);
      }
      if( v==0 ) return 1;
      if( sqliteExprResolveIds(pParse, pTabList, pExpr->pLeft) ){
        return 1;
      }
      if( pExpr->pSelect ){
        /* Case 1:     expr IN (SELECT ...)
        **
        ** Generate code to write the results of the select into a temporary
        ** table.  The cursor number of the temporary table is stored in 
        ** iTable.
        */

              sqliteExprCode(pParse, pE2);
              sqliteVdbeAddOp(v, OP_SetInsert, iSet, 0, 0, 0);
              break;
            }
          }
        }
      }
      break;
    }

    case TK_SELECT: {
      /* This has to be a scalar SELECT.  Generate code to put the
      ** value of this select in a memory cell and record the number
      ** of the memory cell in iField.
      */

    case TK_ISNULL:
    case TK_NOTNULL: {
      sqliteExprCode(pParse, pExpr->pLeft);
      sqliteVdbeAddOp(v, op, 0, dest, 0, 0);
      break;
    }
    case TK_IN: {
      sqliteExprCode(pParse, pExpr->pLeft);
      if( pExpr->pSelect ){
        sqliteVdbeAddOp(v, OP_Found, pExpr->iTable, dest, 0, 0);
      }else{
        sqliteVdbeAddOp(v, OP_SetFound, pExpr->iTable, dest, 0, 0);
      }
      break;
    }

    case TK_ISNULL:
    case TK_NOTNULL: {
      sqliteExprCode(pParse, pExpr->pLeft);
      sqliteVdbeAddOp(v, op, 0, dest, 0, 0);
      break;
    }
    case TK_IN: {
      sqliteExprCode(pParse, pExpr->pLeft);
      if( pExpr->pSelect ){
        sqliteVdbeAddOp(v, OP_NotFound, pExpr->iTable, dest, 0, 0);
      }else{
        sqliteVdbeAddOp(v, OP_SetNotFound, pExpr->iTable, dest, 0, 0);
      }
      break;
    }

** inplicit conversion from one type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.19 2000/06/06 03:31:22 drh Exp $
*/
#include "sqliteInt.h"
#include <unistd.h>

/*
** SQL is translated into a sequence of instructions to be
** executed by a virtual machine.  Each instruction is an instance

*/
static void SetInsert(Set *p, char *zKey){
  SetElem *pElem;
  int h = sqliteHashNoCase(zKey, 0) % ArraySize(p->apHash);
  for(pElem=p->apHash[h]; pElem; pElem=pElem->pHash){
    if( strcmp(pElem->zKey, zKey)==0 ) return;
  }
  pElem = sqliteMalloc( sizeof(*pElem) + strlen(zKey) );
  if( pElem==0 ) return;
  strcpy(pElem->zKey, zKey);
  pElem->pNext = p->pAll;
  p->pAll = pElem;
  pElem->pHash = p->apHash[h];
  p->apHash[h] = pElem;
}

        int tos = p->tos;
        if( tos<0 ) goto not_enough_stack;
        Stringify(p, tos);
        if( i>=0 && i<p->nSet && SetTest(&p->aSet[i], p->zStack[tos]) ){
          pc = pOp->p2 - 1;
        }
        PopStack(p, 1);
        break;
      }

      /* Opcode: SetNotFound P1 P2 *
      **
      ** Pop the stack once and compare the value popped off with the
      ** contents of set P1.  If the element popped does not exists in 
      ** set P1, then jump to P2.  Otherwise fall through.
      */
      case OP_SetNotFound: {
        int i = pOp->p1;
        int tos = p->tos;
        if( tos<0 ) goto not_enough_stack;
        Stringify(p, tos);
        if( i>=0 && i<p->nSet && !SetTest(&p->aSet[i], p->zStack[tos]) ){
          pc = pOp->p2 - 1;
        }
        PopStack(p, 1);
        break;
      }

      /* An other opcode is illegal...
      */
      default: {
        sprintf(zBuf,"%d",pOp->opcode);
        sqliteSetString(pzErrMsg, "unknown opcode ", zBuf, 0);