Tools/DoubleDispatcher.hpp

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//
// Thor C++ Library
// Copyright (c) 2011-2012 Jan Haller
// 
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
// 
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
// 
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would be
//    appreciated but is not required.
// 
// 2. Altered source versions must be plainly marked as such, and must not be
//    misrepresented as being the original software.
// 
// 3. This notice may not be removed or altered from any source distribution.
//


#ifndef THOR_DOUBLEDISPATCHER_HPP
#define THOR_DOUBLEDISPATCHER_HPP

#include <Thor/Tools/NonCopyable.hpp>
#include <Thor/Tools/Exceptions.hpp>
#include <Thor/Tools/ForEach.hpp>
#include <Thor/Tools/Rtti.hpp>
#include <Thor/SmartPtr/CopiedPtr.hpp>
#include <Thor/Detail/BinaryFunction.hpp>
#include <Thor/Detail/AssociativeHelpers.hpp>
#include <Thor/Detail/Metaprogramming.hpp>
#include <Thor/Detail/TypeInfo.hpp>
#include <Thor/Config.hpp>

#include <vector>
#include <algorithm>
#include <cassert>


namespace thor
{


template <class B, typename R = void>
class DoubleDispatcher : private NonCopyable
{
    // ---------------------------------------------------------------------------------------------------------------------------
    // Static assertions
    
    // Make sure that B is either T* or T&, where T is a polymorphic base class (containing virtual functions).
    THOR_STATIC_ASSERT( 
        std::tr1::is_pointer<B>::value && std::tr1::is_polymorphic< typename std::tr1::remove_pointer<B>::type >::value
     || std::tr1::is_reference<B>::value && std::tr1::is_polymorphic< typename std::tr1::remove_reference<B>::type >::value )


    // ---------------------------------------------------------------------------------------------------------------------------
    // Public member functions
    public:
        explicit                    DoubleDispatcher(bool symmetric = true, bool supportDerivedToBase = false);

        template <class D1, class D2>
        void                        Register(R (*globalFunction)( THOR_REPLICATE(B,D1), THOR_REPLICATE(B,D2) ));

        template <class D1, class D2, class C>
        void                        Register(R (C::*memberFunction)( THOR_REPLICATE(B,D1), THOR_REPLICATE(B,D2) ), C& object);

        template <class D1, class D2, typename Fn>
        void                        Register(const Fn& functionObject);

        R                           Call(B arg1, B arg2) const;


    // ---------------------------------------------------------------------------------------------------------------------------
    // Private types
    private:
        typedef detail::TypeInfo                                            TypeInfo;
        typedef std::pair<TypeInfo, TypeInfo>                               Key;
        typedef CopiedPtr<detail::BinaryFunctionBase<B, R>, DynamicCopy>    Value;
        typedef detail::KeyValuePair<Key, Value>                            Pair;
        typedef std::vector<Pair>                                           FnMap;


    // ---------------------------------------------------------------------------------------------------------------------------
    // Private member functions
    private:
        // Registers the type-id key with its associated function value.
        void                            InternalRegister(FnMap& fnMap, TypeInfo key1, TypeInfo key2, Value value) const;

        // Finds the key in the map. Returns end() if not found.
        typename FnMap::const_iterator  Find(TypeInfo key1, TypeInfo key2, bool useCache = false) const;

        // Make sure the cached map is updated
        void                            EnsureCacheUpdate() const;

        // Makes sure that the keys are sorted in case we use symmetric argument dispatching.
        Key                             MakeArgumentPair(TypeInfo key1, TypeInfo key2) const;


    // ---------------------------------------------------------------------------------------------------------------------------
    // Private variables
    private:
        FnMap                       mMap;
        mutable FnMap               mCachedMap;
        mutable bool                mNeedsCacheUpdate;
        bool                        mSymmetric;
        bool                        mDerivedToBase;
};



} // namespace thor

#include <Thor/Detail/DoubleDispatcher.inl>
#endif // THOR_DOUBLEDISPATCHER_HPP