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

// ------------
// constructor
// -----------

PCollection_HStack::PCollection_HStack() 
{
    TheDepth = 0;
    TheTop = new PCollection_StackNode;
}

// ------------------------------------
// Push : insert an item on the top
// ------------------------------------
void PCollection_HStack::Push(const Item& T)
{   
    TheTop = TheTop->Construct(T);
    TheDepth = TheDepth + 1;
          
  }

// ------------------------------------
// Pop : remove an item from the top
// ------------------------------------
void PCollection_HStack::Pop()
{   
    if (TheTop->IsEmpty()) Standard_NoSuchObject::Raise();
    Handle(PCollection_StackNode) temp = TheTop;
    TheTop = TheTop->Tail();
    temp.Delete();
    TheDepth = TheDepth - 1;
}


// -----------------------------
// IsEmpty : is the stack empty ? 
// -----------------------------
Standard_Boolean PCollection_HStack::IsEmpty() const 
{
    return TheTop->IsEmpty();
} 

// ------------------------------------
// Clear : remove all items
// ------------------------------------
void PCollection_HStack::Clear() 
{   
   Handle(PCollection_StackNode) temp; 
   while (TheDepth != 0) {    
      temp = TheTop;
      TheTop = TheTop->Tail();
      temp.Delete();
      --TheDepth;
   }  
}

// ------------------------------------
// ChangeTop : replace the top by T
// ------------------------------------
void PCollection_HStack::ChangeTop(const Item& T)
{   
    if (TheTop->IsEmpty()) Standard_NoSuchObject::Raise();
    TheTop->SetValue(T);       
}

// -----------------------------
// Top : item on the Top 
// -----------------------------
Item PCollection_HStack::Top() const 
{
    if (TheTop->IsEmpty()) Standard_NoSuchObject::Raise();
    return TheTop->Value();
} 


// ------------------------------------
// ShallowCopy redefinition
// ------------------------------------
Handle(Standard_Persistent) PCollection_HStack::ShallowCopy() const
{
  PCollection_HStack* TheCopy = new PCollection_HStack (*this);
  TheCopy->TheTop = 
    Handle(PCollection_StackNode)::DownCast(::ShallowCopy(TheTop));
  return TheCopy;
}

// ------------------------------------
// ShallowDump redefinition
// ------------------------------------
void PCollection_HStack::ShallowDump(Standard_OStream& S) const
{
  S << "begin class Stack "<< endl;
  S << "Length of Stack : "<< TheDepth << endl;
  TheTop->ShallowDump(S);
  S << "end of class Stack." << endl;
}



// -----------------------------
// Depth : numbers of items 
// -----------------------------
Standard_Integer PCollection_HStack::Depth() const {
    return TheDepth;
} 

// -----------------------------
// FTop : Top of the Stack  
// -----------------------------
Handle(PCollection_StackNode) PCollection_HStack::FTop() const {
    return TheTop;
}