SQLite

**
** These interfaces are only useful from within the
** [xFilter|xFilter() method] of a [virtual table] implementation.
** The result of invoking these interfaces from any other context
** is undefined and probably harmful.
**
** The X parameter in a call to sqlite3_vtab_in_first(X,P) or
** sqlite3_vtab_in_next(X,P) should be one of the parameters to the
** xFilter method which invokes these routines, and specifically
** a parameter that was previously selected for all-at-once IN constraint
** processing use the [sqlite3_vtab_in()] interface in the
** [xBestIndex|xBestIndex method].  ^(If the X parameter is not
** an xFilter argument that was selected for all-at-once IN constraint
** processing, then these routines return [SQLITE_ERROR].)^

**
** ^(Use these routines to access all values on the right-hand side
** of the IN constraint using code like the following:
**
** <blockquote><pre>
** &nbsp;  for(rc=sqlite3_vtab_in_first(pList, &pVal);
** &nbsp;      rc==SQLITE_OK && pVal

  pC = p->apCsr[pOp->p1];
  pRhs = sqlite3_malloc64( sizeof(*pRhs) );
  if( pRhs==0 ) goto no_mem;
  pRhs->pCsr = pC->uc.pCursor;
  pRhs->pOut = &aMem[pOp->p3];
  pOut = out2Prerelease(p, pOp);
  pOut->flags = MEM_Null;
  sqlite3VdbeMemSetPointer(pOut, pRhs, "ValueList", sqlite3VdbeValueListFree);
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */


#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VFilter P1 P2 P3 P4 *

void sqlite3VdbeSorterReset(sqlite3 *, VdbeSorter *);
void sqlite3VdbeSorterClose(sqlite3 *, VdbeCursor *);
int sqlite3VdbeSorterRowkey(const VdbeCursor *, Mem *);
int sqlite3VdbeSorterNext(sqlite3 *, const VdbeCursor *);
int sqlite3VdbeSorterRewind(const VdbeCursor *, int *);
int sqlite3VdbeSorterWrite(const VdbeCursor *, Mem *);
int sqlite3VdbeSorterCompare(const VdbeCursor *, Mem *, int, int *);

void sqlite3VdbeValueListFree(void*);

#ifdef SQLITE_DEBUG
  void sqlite3VdbeIncrWriteCounter(Vdbe*, VdbeCursor*);
  void sqlite3VdbeAssertAbortable(Vdbe*);
#else
# define sqlite3VdbeIncrWriteCounter(V,C)
# define sqlite3VdbeAssertAbortable(V)

** performance by substituting a NULL result, or some other light-weight
** value, as a signal to the xUpdate routine that the column is unchanged.
*/
int sqlite3_vtab_nochange(sqlite3_context *p){
  assert( p );
  return sqlite3_value_nochange(p->pOut);
}

/*
** The destructor function for a ValueList object.  This needs to be
** a separate function, unknowable to the application, to ensure that
** calls to sqlite3_vtab_in_first()/sqlite3_vtab_in_next() that are not
** preceeded by activation of IN processing via sqlite3_vtab_int() do not
** try to access a fake ValueList object inserted by a hostile extension.
*/
void sqlite3VdbeValueListFree(void *pToDelete){
  sqlite3_free(pToDelete);
}

/*
** Implementation of sqlite3_vtab_in_first() (if bNext==0) and
** sqlite3_vtab_in_next() (if bNext!=0).
*/
static int valueFromValueList(
  sqlite3_value *pVal,        /* Pointer to the ValueList object */
  sqlite3_value **ppOut,      /* Store the next value from the list here */
  int bNext                   /* 1 for _next(). 0 for _first() */
){
  int rc;
  ValueList *pRhs;

  *ppOut = 0;
  if( pVal==0 ) return SQLITE_MISUSE;
  if( pVal->xDel!=sqlite3VdbeValueListFree ){
    return SQLITE_ERROR;
  }else{
    assert( (pVal->flags&(MEM_TypeMask|MEM_Term|MEM_Subtype)) ==
                 (MEM_Null|MEM_Term|MEM_Subtype) );
    assert( pVal->eSubtype=='p' );
    assert( pVal->u.zPType!=0 && strcmp(pVal->u.zPType,"ValueList")==0 );
    pRhs = (ValueList*)pVal->z;
  }
  if( bNext ){
    rc = sqlite3BtreeNext(pRhs->pCsr, 0);
  }else{
    int dummy = 0;
    rc = sqlite3BtreeFirst(pRhs->pCsr, &dummy);
    assert( rc==SQLITE_OK || sqlite3BtreeEof(pRhs->pCsr) );
    if( sqlite3BtreeEof(pRhs->pCsr) ) rc = SQLITE_DONE;