// Null Node
//
// Douglas Thrift
//
// $Id$

#ifndef _NullNode_hpp_
#define _NullNode_hpp_

#include "Node.hpp"

template<typename Type>
class NullNode : public Node<Type>
{
public:
	void setNext(NullNode<Type>* next) { this->next = dynamic_cast<Node<Type>*>(next); }
	void setPrevious(NullNode<Type>* previous) { this->previous = dynamic_cast<Node<Type>*>(previous); }
	bool contains(const Type& value, Node<Type>* end, bool forward);
	void remove(const Type& value, Node<Type>* end, bool forward);
	void accept(Visitor<Type>* visitor, Node<Type>* end, bool forward);
};

template<typename Type>
bool NullNode<Type>::contains(const Type& value, Node<Type>* end, bool forward)
{
	Node<Type>* another = forward ? Node<Type>::next : Node<Type>::previous;

	if (end == this) return false; else return another->contains(value, end, forward);
}

template<typename Type>
void NullNode<Type>::remove(const Type& value, Node<Type>* end, bool forward)
{
	Node<Type>* another = forward ? Node<Type>::next : Node<Type>::previous;

	if (end != this) another->remove(value, end, forward);
}

template<typename Type>
void NullNode<Type>::accept(Visitor<Type>* visitor, Node<Type>* end, bool forward)
{
	Node<Type>* another = forward ? Node<Type>::next : Node<Type>::previous;

	if (end != this) another->accept(visitor, end, forward);
}

#endif // _NullNode_hpp_