Composites and Visitors - a Templatized Approach

#pragma once

#include "GenericVisitor.h"
#include "Visitor.h"

// Normally the Loki visitor allows forward declares to be used for the visitable objects
// but I have put everything in the header of this simple demonstration
#include "NodeBase.h"

#include <iostream>

using namespace std;

class CVisitorBase :
	public Loki::BaseVisitor,
	public Loki::Visitor<CNodeBase>,
	public Loki::Visitor<CNodeDerived1>,
	public Loki::Visitor<CNodeDerived2>
{
public:
	CVisitorBase() {}
	virtual ~CVisitorBase() {}

	virtual void Visit( CNodeBase &node ) {}
	virtual void Visit( CNodeDerived1 &node ) { Visit( (CNodeBase&) node ); }
	virtual void Visit( CNodeDerived2 &node ) { Visit( (CNodeBase&) node ); }
};

class CVisitorDerived1 :
	public CVisitorBase
{
public:
	CVisitorDerived1() {}
	virtual ~CVisitorDerived1() {}

	virtual void Visit( CNodeBase &node ) { cout << "Visiting base " << node.GetId() << endl; }
	virtual void Visit( CNodeDerived1 &node ) { cout << "Visiting derived1 " << node.GetId() << endl; }
	// Note that by not implementing the CNodeDerived2 visit function, the base will be called
};

class CVisitorDerived2 :
	public CVisitorBase
{
public:
	CVisitorDerived2() {}
	virtual ~CVisitorDerived2() {}

	virtual void Visit( CNodeBase &node ) { cout << "Visiting base " << node.GetId() << endl; }
	virtual void Visit( CNodeDerived1 &node ) { cout << "Visiting derived1 " << node.GetId() << endl; }
	virtual void Visit( CNodeDerived2 &node ) { cout << "Visiting derived2 " << node.GetId() << endl; }
};

class CVisitorDerived1TopToBottom :
	public CVisitorDerived1,
	public Types::CVisitorTopToBottom<CVisitorDerived1TopToBottom,CNodeBase>
{
};

class CVisitorDerived2BottomToTop :
	public CVisitorDerived2,
	public Types::CVisitorBottomToTop<CVisitorDerived2BottomToTop,CNodeBase>
{
};

class CVisitorDerived2LeftToRight :
	public CVisitorDerived2,
	public Types::CVisitorLeftToRight<CVisitorDerived2LeftToRight,CNodeBase>
{
};