// Copyright (c) 2012 Jan Herrmann

// most parts of this example are borrowed from 
// http://svn.boost.org/svn/boost/sandbox/variadic_templates/libs/composite_storage/sandbox/pack/predator_prey.cpp


#include <iostream>
#include <string>

#include <boost/mpl/vector.hpp>

#include "gofvisitor.hpp"
#include "visitable_classes.hpp"
#include "accept_n.hpp"


// begin predator
namespace animals { namespace predator {
	struct Lion;
	struct Anaconda;
	struct Bear;
	
	struct Predator_Visitable_Classes
		: ::boost::mpl::vector<Lion,Anaconda,Bear> 
	{};
	
	struct Predator_Visitor
		: visitor::gofvisitor
			< Predator_Visitor // crtp
			, Predator_Visitable_Classes
			>
	{};
	
	struct Predator
	{
		virtual ~Predator() {}
		VISITOR_GOFVISITOR_PURE_VIRTUAL_ACCEPT(Predator_Visitor)
	};
	VISITOR_GOFVISITOR_NON_MEMBER_ACCEPT(Predator,Predator_Visitor)
}}

VISITOR_CREATE_VISITABLE_CLASSES_TRAIT(animals::predator::Predator,animals::predator::Predator_Visitable_Classes) 
namespace animals { namespace predator {
	struct Lion
		: Predator
	{
		VISITOR_GOFVISITOR_VIRTUAL_ACCEPT(Predator_Visitor)
	};

	struct Anaconda
		: Predator
	{
		VISITOR_GOFVISITOR_VIRTUAL_ACCEPT(Predator_Visitor)
	};

	struct Bear
		: Predator
	{
		VISITOR_GOFVISITOR_VIRTUAL_ACCEPT(Predator_Visitor)
	};
}}
// end predators

// begin prey
namespace animals { namespace prey {
	struct Gazelle;
	struct Girrafe;
  
	struct Prey_Visitable_Classes
		: ::boost::mpl::vector<Gazelle,Girrafe> 
	{};
	
	struct Prey_Visitor
		: visitor::gofvisitor
			< Prey_Visitor // crtp
			, Prey_Visitable_Classes
			>
	{};
  
	struct Prey 
	{
		virtual ~Prey() {}
		VISITOR_GOFVISITOR_PURE_VIRTUAL_ACCEPT(Prey_Visitor)
	};
	VISITOR_GOFVISITOR_NON_MEMBER_ACCEPT(Prey,Prey_Visitor);
}} 
VISITOR_CREATE_VISITABLE_CLASSES_TRAIT(animals::prey::Prey,animals::prey::Prey_Visitable_Classes) 
namespace animals { namespace prey {
	struct Gazelle 
		: Prey
	{
		VISITOR_GOFVISITOR_VIRTUAL_ACCEPT(Prey_Visitor)
	};
	struct Girrafe
		: Prey
	{
		VISITOR_GOFVISITOR_VIRTUAL_ACCEPT(Prey_Visitor)
	};
}}
// end prey


// start "method"
struct hunt_visitor 
{
	std::string result;

	// templated	
	template <class concrete_prey>
	void operator()(animals::predator::Lion const&, concrete_prey const& )
	{
		result
			= std::string("Lion jumps on ") 
			+ typeid(concrete_prey).name()
			+ " and bites it.";
	}

	
	// normal
	void operator()(animals::predator::Anaconda const&, animals::prey::Gazelle const& )
	{
		result="Anaconda injects venom into Gazelle.";
	}
	
	void operator()(animals::predator::Anaconda const&, animals::prey::Girrafe const& )
	{
		result="Anaconda ignores Girraffe.";
	}
	
	// inheritance
	void operator()(animals::predator::Bear const&, animals::prey::Prey const&)
	{
		result = "Bear sleeps and does nothing";
	}
};

std::string hunt(animals::predator::Predator const& aPredator, animals::prey::Prey const& aPrey)
{
	hunt_visitor sv;
	visitor::accept_2(aPredator, aPrey, sv);
	return sv.result;	
}
// end method

int main() {
	using namespace animals::predator;
	Lion l;
	Anaconda a;
	Bear b;
	Predator const& lion=l;
	Predator const& anaconda=a;
	Predator const& bear=b;
	
	using namespace animals::prey;
	Gazelle ga;
	Girrafe gi;
	Prey const& gazelle=ga;
	Prey const& giraffe=gi;
	
	std::cout << hunt(lion,gazelle) << std::endl;
	std::cout << hunt(lion,giraffe) << std::endl;

	std::cout << hunt(anaconda,gazelle) << std::endl;
	std::cout << hunt(anaconda,giraffe) << std::endl;
	
	std::cout << hunt(bear,gazelle) << std::endl;
	std::cout << hunt(bear,giraffe) << std::endl;
 	return 0;
}