// Copyright: 	Matra-Datavision 1991
// File:	PCollection_DepthFirstIterator.gxx
// Created:	Wed May 29 17:42:50 1991
// Author:	Denis PASCAL
//		<dp>
// Revised by:  Mireille MERCIEN
//              Sep,7 1992

#include <Standard_NoMoreObject.hxx>
#include <Standard_NoSuchObject.hxx>


//---------------------------------------------------------------------------
// Constructor
//---------------------------------------------------------------------------
PCollection_DepthFirstIterator::
     PCollection_DepthFirstIterator(const Handle(PCollection_Vertex)& V) 
{
  Visited = new PCollection_SetOfVertex;
  Ready = new PCollection_StackOfVertex;
  Visited->Add(V);
  Ready->Push(V);
  HasMore = ! (Ready->IsEmpty());
}

//---------------------------------------------------------------------------
// More
//---------------------------------------------------------------------------
Boolean PCollection_DepthFirstIterator::More () const 
{
  return HasMore;
}

//---------------------------------------------------------------------------
// Next
//---------------------------------------------------------------------------
void PCollection_DepthFirstIterator::Next () 
{
  if (!HasMore) Standard_NoMoreObject::Raise();
  Handle(PCollection_Vertex) w1 = Ready->Top();
  Ready->Pop();
  PCollection_FrontEdgesIterator It(w1);
  while (It.More()) {
    Handle(PCollection_Vertex) w2 = It.Value()->Destination();
    if (! (Visited->Contains(w2))) {
      Ready->Push(w2);
      Visited->Add(w2);
    }
    It.Next();
  }
  HasMore = !(Ready->IsEmpty());
}

//---------------------------------------------------------------------------
// Value
//---------------------------------------------------------------------------
Handle(PCollection_Vertex) PCollection_DepthFirstIterator::Value () const 
{
  if (HasMore) 
     return Ready->Top();
  else 
     Standard_NoSuchObject::Raise();
}

//---------------------------------------------------------------------------
// Clear
//---------------------------------------------------------------------------
 void PCollection_DepthFirstIterator::Clear () 
{
  HasMore = False;
  Ready->Nullify();
  Visited->Nullify();
}