delegate_template.hxx

/*
    (c) Sergey Ryazanov (http://home.onego.ru/~ryazanov)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

For details, see "The Impossibly Fast C++ Delegates" at
http://www.codeproject.com/Articles/11015/The-Impossibly-Fast-C-Delegates
*/

#if VIGRA_DELEGATE_PARAM_COUNT > 0
#define VIGRA_DELEGATE_SEPARATOR ,
#else
#define VIGRA_DELEGATE_SEPARATOR
#endif

// see BOOST_JOIN for explanation
#define VIGRA_DELEGATE_JOIN_MACRO( X, Y) VIGRA_DELEGATE_DO_JOIN( X, Y )
#define VIGRA_DELEGATE_DO_JOIN( X, Y ) VIGRA_DELEGATE_DO_JOIN2(X,Y)
#define VIGRA_DELEGATE_DO_JOIN2( X, Y ) X##Y

namespace vigra
{
#ifdef VIGRA_DELEGATE_PREFERRED_SYNTAX
#define VIGRA_DELEGATE_CLASS_NAME delegate
#define VIGRA_DELEGATE_INVOKER_CLASS_NAME delegate_invoker
#else
#define VIGRA_DELEGATE_CLASS_NAME VIGRA_DELEGATE_JOIN_MACRO(delegate,VIGRA_DELEGATE_PARAM_COUNT)
#define VIGRA_DELEGATE_INVOKER_CLASS_NAME VIGRA_DELEGATE_JOIN_MACRO(delegate_invoker,VIGRA_DELEGATE_PARAM_COUNT)
    template <typename R VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_TEMPLATE_PARAMS>
    class VIGRA_DELEGATE_INVOKER_CLASS_NAME;
#endif

    template <typename R VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_TEMPLATE_PARAMS>
#ifdef VIGRA_DELEGATE_PREFERRED_SYNTAX
    class VIGRA_DELEGATE_CLASS_NAME<R (VIGRA_DELEGATE_TEMPLATE_ARGS)>
#else
    class VIGRA_DELEGATE_CLASS_NAME
#endif
    {
    public:
        typedef R return_type;
#ifdef VIGRA_DELEGATE_PREFERRED_SYNTAX
        typedef return_type (VIGRA_DELEGATE_CALLTYPE *signature_type)(VIGRA_DELEGATE_TEMPLATE_ARGS);
        typedef VIGRA_DELEGATE_INVOKER_CLASS_NAME<signature_type> invoker_type;
#else
        typedef VIGRA_DELEGATE_INVOKER_CLASS_NAME<R VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_TEMPLATE_ARGS> invoker_type;
#endif

        VIGRA_DELEGATE_CLASS_NAME()
            : object_ptr(0)
            , stub_ptr(0)
        {}

        template <return_type (*TMethod)(VIGRA_DELEGATE_TEMPLATE_ARGS)>
        static VIGRA_DELEGATE_CLASS_NAME from_function()
        {
            return from_stub(0, &function_stub<TMethod>);
        }

        template <class T, return_type (T::*TMethod)(VIGRA_DELEGATE_TEMPLATE_ARGS)>
        static VIGRA_DELEGATE_CLASS_NAME from_method(T* object_ptr)
        {
            return from_stub(object_ptr, &method_stub<T, TMethod>);
        }

        template <class T, return_type (T::*TMethod)(VIGRA_DELEGATE_TEMPLATE_ARGS) const>
        static VIGRA_DELEGATE_CLASS_NAME from_const_method(T const* object_ptr)
        {
            return from_stub(const_cast<T*>(object_ptr), &const_method_stub<T, TMethod>);
        }

        return_type operator()(VIGRA_DELEGATE_PARAMS) const
        {
            return (*stub_ptr)(object_ptr VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_ARGS);
        }

        operator bool () const
        {
            return stub_ptr != 0;
        }

        bool operator!() const
        {
            return !(operator bool());
        }

    private:
        
        typedef return_type (VIGRA_DELEGATE_CALLTYPE *stub_type)(void* object_ptr VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_PARAMS);

        void* object_ptr;
        stub_type stub_ptr;

        static VIGRA_DELEGATE_CLASS_NAME from_stub(void* object_ptr, stub_type stub_ptr)
        {
            VIGRA_DELEGATE_CLASS_NAME d;
            d.object_ptr = object_ptr;
            d.stub_ptr = stub_ptr;
            return d;
        }

        template <return_type (*TMethod)(VIGRA_DELEGATE_TEMPLATE_ARGS)>
        static return_type VIGRA_DELEGATE_CALLTYPE function_stub(void* VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_PARAMS)
        {
            return (TMethod)(VIGRA_DELEGATE_ARGS);
        }

        template <class T, return_type (T::*TMethod)(VIGRA_DELEGATE_TEMPLATE_ARGS)>
        static return_type VIGRA_DELEGATE_CALLTYPE method_stub(void* object_ptr VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_PARAMS)
        {
            T* p = static_cast<T*>(object_ptr);
            return (p->*TMethod)(VIGRA_DELEGATE_ARGS);
        }

        template <class T, return_type (T::*TMethod)(VIGRA_DELEGATE_TEMPLATE_ARGS) const>
        static return_type VIGRA_DELEGATE_CALLTYPE const_method_stub(void* object_ptr VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_PARAMS)
        {
            T const* p = static_cast<T*>(object_ptr);
            return (p->*TMethod)(VIGRA_DELEGATE_ARGS);
        }
    };

    template <typename R VIGRA_DELEGATE_SEPARATOR VIGRA_DELEGATE_TEMPLATE_PARAMS>
#ifdef VIGRA_DELEGATE_PREFERRED_SYNTAX
    class VIGRA_DELEGATE_INVOKER_CLASS_NAME<R (VIGRA_DELEGATE_TEMPLATE_ARGS)>
#else
    class VIGRA_DELEGATE_INVOKER_CLASS_NAME
#endif
    {
        VIGRA_DELEGATE_INVOKER_DATA

    public:
        VIGRA_DELEGATE_INVOKER_CLASS_NAME(VIGRA_DELEGATE_PARAMS)
#if VIGRA_DELEGATE_PARAM_COUNT > 0
            :
#endif
            VIGRA_DELEGATE_INVOKER_INITIALIZATION_LIST
        {
        }

        template <class TDelegate>
        R operator()(TDelegate d) const
        {
            return d(VIGRA_DELEGATE_ARGS);
        }
    };
}

#undef VIGRA_DELEGATE_CLASS_NAME
#undef VIGRA_DELEGATE_SEPARATOR
#undef VIGRA_DELEGATE_JOIN_MACRO
#undef VIGRA_DELEGATE_DO_JOIN
#undef VIGRA_DELEGATE_DO_JOIN2