// Copyright: 	Matra-Datavision 1992
// Created:	Wed May,13 1992
// Created by:  Jean-Pierre TIRAULT
//              <jpt@topsn1>
// Revised:	Wed Oct,21 1992
// By     :     Mireille MERCIEN
//              <mip@sdsun3>

#include <Standard_NoMoreObject.hxx>
#include <Standard_NoSuchObject.hxx>
typedef PCollection_AVLNodeStack Stack;
typedef PCollection_HAVLSearchTree Tree;
typedef Handle(PCollection_HAVLSearchTree) Handle(Tree);
typedef PCollection_AVLNode Node;
typedef Handle(PCollection_AVLNode) Handle(Node);

//-----------------------------------------------------------------------------
PCollection_AVLIterator::
              PCollection_AVLIterator ( const Handle(Tree)& aTree) 
{
  CurrentStack = new Stack;                     // Create an empty Stack
  Handle(Node) Root = aTree->GetRoot();     // Current node = root of tree
  if (Root.IsNull()) {
     HasMore = False;
  }
  else {
     HasMore = True;
     // CURRENTSTACK MANAGEMENT
     Append( Root);
  }
}

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

//-----------------------------------------------------------------------------
Handle(Node) PCollection_AVLIterator::Value () const 
{
  if (!HasMore) NoSuchObject::Raise();
  return CurrentNode;
}

//-----------------------------------------------------------------------------
void PCollection_AVLIterator::Clear () 
{
  CurrentNode.Nullify();
  CurrentStack.Nullify();
  HasMore = False;
}

//-----------------------------------------------------------------------------
void PCollection_AVLIterator::Next () 
{
  if (!HasMore) NoMoreObject::Raise();
  Handle(Node) Right = CurrentNode->RightChild();

  // WHAT ARE THE FOLLOWING ELEMENTS ?
  if ( Right.IsNull()) {
    RecursiveRemove(CurrentNode);
    // MAYBE IT'S THE END
    if (CurrentStack->IsEmpty()) 
       HasMore = False;
    else 
       CurrentNode = CurrentStack->Top();
  }
  else {
    Append (Right);
  }
}


// PRIVATE TOOLS TO ITERATE


void PCollection_AVLIterator::Append ( const Handle(Node)& Root) 
{
  RecursiveAppend( Root);
  CurrentNode = CurrentStack->Top();
}


void PCollection_AVLIterator::RecursiveAppend(const Handle(Node)& ANode) 
{
  if (!ANode.IsNull()) {
    CurrentStack->Push(ANode);
    Handle(Node) Left = ANode->LeftChild();
    RecursiveAppend( Left);
  }
}


void PCollection_AVLIterator::RecursiveRemove(const Handle(Node)& theNode) 
{       
     CurrentStack->Pop();
     if (CurrentStack->IsEmpty()) return;
     Handle(Node) NewNode = CurrentStack->Top();
     if (theNode == NewNode->RightChild()) {
        RecursiveRemove(NewNode);
     }
}