**
** 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 1.254 2004/01/31 20:20:30 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
    /* Call the progress callback if it is configured and the required number
    ** of VDBE ops have been executed (either since this invocation of
    ** sqliteVdbeExec() or since last time the progress callback was called).
    ** If the progress callback returns non-zero, exit the virtual machine with
    ** a return code SQLITE_ABORT.
    */

    if( db->xProgress && (db->nProgressOps==nProgressOps) ){
      if( db->xProgress(db->pProgressArg)!=0 ){
        rc = SQLITE_ABORT;
        continue; /* skip to the next iteration of the for loop */
      }
      nProgressOps = 0;
    }
    nProgressOps++;

#endif

    switch( pOp->opcode ){

/*****************************************************************************
** What follows is a massive switch statement where each case implements a
** separate instruction in the virtual machine.  If we follow the usual
................................................................................
  Mem *pMem;
  int i = pOp->p2;
  if( pFocus==0 ) goto no_mem;
  assert( i>=0 && i<p->agg.nMem );
  pTos++;
  pMem = &pFocus->aMem[i];
  *pTos = *pMem;

  pTos->flags &= ~(MEM_Dyn|MEM_Static|MEM_Short);
  pTos->flags |= MEM_Ephem;

  break;
}

/* Opcode: AggNext * P2 *
**
** Make the next aggregate value the current aggregate.  The prior
** aggregate is deleted.  If all aggregate values have been consumed,
................................................................................

    /* The following code adds nothing to the actual functionality
    ** of the program.  It is only here for testing and debugging.
    ** On the other hand, it does burn CPU cycles every time through
    ** the evaluator loop.  So we can leave it out when NDEBUG is defined.
    */
#ifndef NDEBUG


















    if( pc<-1 || pc>=p->nOp ){
      sqliteSetString(&p->zErrMsg, "jump destination out of range", (char*)0);
      rc = SQLITE_INTERNAL;
    }
    if( p->trace && pTos>=p->aStack ){
      int i;
      fprintf(p->trace, "Stack:");

**
** 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 1.255 2004/01/31 20:40:42 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
    /* Call the progress callback if it is configured and the required number
    ** of VDBE ops have been executed (either since this invocation of
    ** sqliteVdbeExec() or since last time the progress callback was called).
    ** If the progress callback returns non-zero, exit the virtual machine with
    ** a return code SQLITE_ABORT.
    */
    if( db->xProgress ){
      if( db->nProgressOps==nProgressOps ){
        if( db->xProgress(db->pProgressArg)!=0 ){
          rc = SQLITE_ABORT;
          continue; /* skip to the next iteration of the for loop */
        }
        nProgressOps = 0;
      }
      nProgressOps++;
    }
#endif

    switch( pOp->opcode ){

/*****************************************************************************
** What follows is a massive switch statement where each case implements a
** separate instruction in the virtual machine.  If we follow the usual
................................................................................
  Mem *pMem;
  int i = pOp->p2;
  if( pFocus==0 ) goto no_mem;
  assert( i>=0 && i<p->agg.nMem );
  pTos++;
  pMem = &pFocus->aMem[i];
  *pTos = *pMem;
  if( pTos->flags & MEM_Str ){
    pTos->flags &= ~(MEM_Dyn|MEM_Static|MEM_Short);
    pTos->flags |= MEM_Ephem;
  }
  break;
}

/* Opcode: AggNext * P2 *
**
** Make the next aggregate value the current aggregate.  The prior
** aggregate is deleted.  If all aggregate values have been consumed,
................................................................................

    /* The following code adds nothing to the actual functionality
    ** of the program.  It is only here for testing and debugging.
    ** On the other hand, it does burn CPU cycles every time through
    ** the evaluator loop.  So we can leave it out when NDEBUG is defined.
    */
#ifndef NDEBUG
    /* Sanity checking on the top element of the stack */
    if( pTos>=p->aStack ){
      assert( pTos->flags!=0 );  /* Must define some type */
      if( pTos->flags & MEM_Str ){
        int x = pTos->flags & (MEM_Static|MEM_Dyn|MEM_Ephem|MEM_Short);
        assert( x!=0 );            /* Strings must define a string subtype */
        assert( (x & (x-1))==0 );  /* Only one string subtype can be defined */
        assert( pTos->z!=0 );      /* Strings must have a value */
        /* Mem.z points to Mem.zShort iff the subtype is MEM_Short */
        assert( (pTos->flags & MEM_Short)==0 || pTos->z==pTos->zShort );
        assert( (pTos->flags & MEM_Short)!=0 || pTos->z!=pTos->zShort );
      }else{
        /* Cannot define a string subtype for non-string objects */
        assert( (pTos->flags & (MEM_Static|MEM_Dyn|MEM_Ephem|MEM_Short))==0 );
      }
      /* MEM_Null excludes all other types */
      assert( pTos->flags==MEM_Null || (pTos->flags&MEM_Null)==0 );
    }
    if( pc<-1 || pc>=p->nOp ){
      sqliteSetString(&p->zErrMsg, "jump destination out of range", (char*)0);
      rc = SQLITE_INTERNAL;
    }
    if( p->trace && pTos>=p->aStack ){
      int i;
      fprintf(p->trace, "Stack:");