OpenSceneGraph/include/osgIntrospection/Comparator

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2005 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/
//osgIntrospection - Copyright (C) 2005 Marco Jez

#ifndef OSGINTROSPECTION_COMPARATOR_
#define OSGINTROSPECTION_COMPARATOR_


namespace osgIntrospection
{

	class Value;

	struct Comparator
	{
		virtual bool isEqualTo(const Value &l, const Value &r) const = 0;
		virtual bool isLessThanOrEqualTo(const Value &l, const Value &r) const = 0;
	};
	
	template<typename T>
	struct TotalOrderComparator: Comparator
	{
		virtual bool isEqualTo(const Value &l, const Value &r) const
		{
			const T &vl = variant_cast<const T &>(l);
			const T &vr = variant_cast<const T &>(r);
			return vl <= vr && vr <= vl;
		}

		virtual bool isLessThanOrEqualTo(const Value &l, const Value &r) const
		{
			return variant_cast<const T &>(l) <= variant_cast<const T &>(r);
		}
	};
	
	template<typename T>
	struct PartialOrderComparator: Comparator
	{
		virtual bool isEqualTo(const Value &l, const Value &r) const
		{
			return variant_cast<const T &>(l) == variant_cast<const T &>(r);
		}

		virtual bool isLessThanOrEqualTo(const Value &, const Value &) const
		{
			throw ComparisonOperatorNotSupportedException(typeid(T), "less than or equal to");
		}
	};

}

#endif