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 T, typename Output, typename... Arguments>
    concept Function_Concept_ =
        requires(T t, Arguments... arguments) {
        //! Returns the value of the function at given arguments.
        {addConst(t)(arguments...)} -> std::convertible_to<Output>;
    };

    template <typename T, typename Output, typename... Arguments>
    concept Function_Concept =
        Function_Concept_<RemoveCvRef<T>, Output, Arguments...>;

}

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