function_concept.h

// Description: Function concept
// Documentation: functions.txt

#ifndef PASTELSYS_FUNCTION_CONCEPT_H
#define PASTELSYS_FUNCTION_CONCEPT_H

#include "pastel/sys/concept/concept.h"

namespace Pastel
{

    template <typename Return>
    struct Function_Concept
    {
        template <
            typename Type,
            typename... ArgumentSet>
        auto requires_(Type&& t, ArgumentSet&&... argumentSet) -> decltype
        (
            conceptCheck(
                //! Returns the value of the function at given arguments.
                Concept::convertsTo<Return>(
                    addConst(t)(std::forward<ArgumentSet>(argumentSet)...)
                )
            )
        );
    };

    template <>
    struct Function_Concept<void>
    {
        template <
            typename Type,
            typename... ArgumentSet>
        auto requires_(Type&& t, ArgumentSet&&... argumentSet) -> decltype
        (
            conceptCheck(
                //! Calls the function with the given arguments.
                (addConst(t)(std::forward<ArgumentSet>(argumentSet)...), 0)
            )
        );
    };

}

namespace Pastel
{

    template <
        typename Return,
        typename... ArgumentSet
    >
    struct Function_Archetype
    {
        Return operator()(
            const ArgumentSet&... argumentSet) const
        {
            return Return();
        }
    };

    template <
        typename... ArgumentSet
    >
    struct Function_Archetype<void, ArgumentSet...>
    {
        void operator()(
            const ArgumentSet&... argumentSet) const
        {
        }
    };

}

#endif