// ----------------------------------------------------------------------
// 
// HSingleList implementation:
// 
// Last Revision : Feb,10 1992 J.P Tirault
//                 Implementation of ShallowCopy, ShallowDump
//                 methods.
// -------------------------------------------------------------------------

#include <Standard_NoSuchObject.hxx>
#include <Standard_NotImplemented.hxx>
#include <Standard_ProgramError.hxx>
#include <Standard_OStream.hxx>

// -------------------------------------------------------------------------
//                                                                         -
// Constructor Returns an empty list                                       -
// ----------                                                              -
//                                                                         -
// -------------------------------------------------------------------------
PCollection_HSingleList::PCollection_HSingleList ()
{
 Next.Nullify();
}


// -------------------------------------------------------------------------
//                                                                         -
// Construct : Add an item at the beginning of the list                    -
// ---------                                                               -
//                                                                         -
// -------------------------------------------------------------------------
Handle(PCollection_HSingleList) 
  PCollection_HSingleList::Construct(const Item& T)const
{


 Handle(PCollection_HSingleList) me , L ;
 me = this;
#ifndef OBJS
 L = new PCollection_HSingleList;
#else
 L = new (os_segment::of(this)) PCollection_HSingleList;
#endif
 L->ChangeForwardPointer ( me );
 L->SetValue ( T );			
 return L;
}


// -------------------------------------------------------------------------
//                                                                         -
// Shallowcopy : Redefinition of the shallowcopy dump                      -
// -----------                                                             -

//                                                                         -
// -------------------------------------------------------------------------
Handle(Standard_Persistent) PCollection_HSingleList::ShallowCopy() const
{
  Handle(PCollection_HSingleList) TheList,          // Traversal depth of <this>
                                TheCopy,          // The list returned
                                Pred,             // Backward pointer
                                Succ;             // Forward pointer
#ifndef OBJS
  TheCopy = new PCollection_HSingleList;            // Initialization of the list
#else
  TheCopy = new (os_segment::of(this)) PCollection_HSingleList;            // Initialization of the list
#endif
                                                  // that will be returned
  Standard_Boolean FirstTime = Standard_True;                 

  TheList = this;                                 // Start at the beginning
  Pred = Succ = TheCopy;
  
  while ( ! TheList->IsEmpty() ) {                // Append each item at the
    Succ = Succ->Construct(TheList->Value());     // end of the list
    if ( FirstTime ){
      FirstTime = Standard_False;
      TheCopy   = Succ;
    }
    else{
      Pred->ChangeForwardPointer(Succ);           // Make the link between 
    }                                             // Pred and Succ
    Pred = Succ;
    Succ = Succ->Tail();
    TheList = TheList->Tail();                   
  }
  return TheCopy;                                 // Returns the header
}

// -------------------------------------------------------------------------
//                                                                         -
// ShallowDump Redefinition of the shallowdump method                      -
// -----------                                                             -
//                                                                         -
// -------------------------------------------------------------------------
void PCollection_HSingleList::ShallowDump(Standard_OStream& S) const
{
  Handle(PCollection_HSingleList) TheList;
  TheList = this;
  S << "begin class HSingleList " << endl;
  while ( ! TheList->IsEmpty() ) {                
    ::ShallowDump(TheList->Value(), S);
    TheList = TheList->Tail();
  }
  S << "end class HSingleList" << endl;
  
}



/* Anciens INLINE */

Item PCollection_HSingleList::Value() const {
  Standard_NoSuchObject_Raise_if(IsEmpty(),
                                 "Empty Element in HSingleList::Value");
     return Data;
}

Handle(PCollection_HSingleList) PCollection_HSingleList::Tail() const {
  Standard_NoSuchObject_Raise_if (IsEmpty(),
                                  "Empty Element in HSingleList::Value");
  return Next;
}


Standard_Boolean PCollection_HSingleList::IsEmpty()const
{
  return Next.IsNull();
}


void PCollection_HSingleList::SetValue(const Item& T)
{
  Standard_NoSuchObject_Raise_if (IsEmpty(),
                                  "Empty Element in HSingleList::SetValue");
  Data = T;
}


// -------------------------------------------------------------------------
//                                                                         -
// SwapTail : Exchange the tail of the current list with an another list   -
// --------                                                                -
//                                                                         -
// -------------------------------------------------------------------------
void PCollection_HSingleList::SwapTail(Handle(PCollection_HSingleList)&
                                            WithList)
{
  Standard_NoSuchObject_Raise_if (IsEmpty(),
                                  "Empty Element in HSingleList::SwapTail");
  Handle(PCollection_HSingleList) L = Next;
  Next     = WithList;
  WithList = L;
}


void PCollection_HSingleList::ChangeForwardPointer
   (const Handle(PCollection_HSingleList)& L)
{
     Next = L;
}