// File:	TCollection_Queue.gxx
// Created:	Mon Jan 18 14:55:37 1993
// Author:	Remi LEQUETTE
//		<rle@phylox>

#include <Standard_NoSuchObject.hxx>

//=======================================================================
//function : TCollection_Queue
//purpose  : 
//=======================================================================

TCollection_Queue::TCollection_Queue() :
       myFront(NULL),
       myEnd(NULL),
       myLength(0)
{
}

//=======================================================================
//function : TCollection_Queue
//purpose  : 
//=======================================================================

TCollection_Queue::TCollection_Queue(const TCollection_Queue& Other)
{
  if (!Other.IsEmpty()) {
    cout << "WARNING copy constructor of non empty Queue !"<<endl;
  }
  TCollection_QueueNode* p = (TCollection_QueueNode*) Other.myFront;
  TCollection_QueueNode* q = NULL;
  TCollection_QueueNode* r = NULL;
  myFront = NULL;
  while (p) {
    q = new TCollection_QueueNode(p->Value(),(TCollection_MapNode*)0L);
    if (r) r->Next() = q;
    else   myFront = q;
    r = q;
    p = (TCollection_QueueNode*)p->Next();
  }
  myEnd = q;
  myLength = Other.myLength;
}

//=======================================================================
//function : Assign
//purpose  : 
//=======================================================================

const TCollection_Queue& TCollection_Queue::Assign
  (const TCollection_Queue& Other)
{
  if (this == &Other) return *this;
  Clear();
  TCollection_QueueNode* p = (TCollection_QueueNode*) Other.myFront;
  TCollection_QueueNode* q=NULL;
  TCollection_QueueNode* r = NULL;
  while (p) {
    q = new TCollection_QueueNode(p->Value(),(TCollection_MapNode*)0L);
    if (r) r->Next() = q;
    else   myFront   = q;
    r = q;
    p = (TCollection_QueueNode*)p->Next();
  }
  myEnd = q;
  myLength = Other.myLength;
  return *this;
}



//=======================================================================
//function : Front
//purpose  : 
//=======================================================================

const Item& TCollection_Queue::Front() const
{
  Standard_NoSuchObject_Raise_if(IsEmpty(),"TCollection_Queue");
  return ((TCollection_QueueNode*)myFront)->Value();
}

//=======================================================================
//function : Push
//purpose  : 
//=======================================================================

void TCollection_Queue::Push(const Item& I)
{
  TCollection_QueueNode* p = new TCollection_QueueNode(I,(TCollection_MapNode*)0L);
  if (myLength) ((TCollection_QueueNode*)myEnd)->Next() = p;
  else          myFront = p;
  myEnd = p;
  myLength++;
}

//=======================================================================
//function : Pop
//purpose  : 
//=======================================================================

void TCollection_Queue::Pop()
{
  Standard_NoSuchObject_Raise_if(IsEmpty(),"TCollection_Queue");
  TCollection_QueueNode* p = (TCollection_QueueNode*) myFront;
  myFront = p->Next();
  delete p;
  myLength--;
  if (myLength == 0) myEnd = NULL;
}

//=======================================================================
//function : Clear
//purpose  : 
//=======================================================================

void TCollection_Queue::Clear()
{
  TCollection_QueueNode* p = (TCollection_QueueNode*) myFront;
  TCollection_QueueNode* q = 0L;
  while(p) {
    q = (TCollection_QueueNode*)p->Next();
    delete p;
    p = q;
  }
  myLength = 0;
  myFront = myEnd = NULL;
}

//=======================================================================
//function : ChangeFront
//purpose  : 
//=======================================================================

Item& TCollection_Queue::ChangeFront()
{
  Standard_NoSuchObject_Raise_if(IsEmpty(),"TCollection_Queue");
  return ((TCollection_QueueNode*)myFront)->Value();
}