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#pragma once 
 
#include "typetraits.h" 
#include "typelist.h" 
 
#include <functional> 
 
namespace NPrivate { 
    template <class F> 
    struct TRemoveClassImpl { 
        using TSignature = F; 
    }; 
 
    template <typename C, typename R, typename... Args> 
    struct TRemoveClassImpl<R (C::*)(Args...)> { 
        typedef R TSignature(Args...); 
    }; 
 
    template <typename C, typename R, typename... Args> 
    struct TRemoveClassImpl<R (C::*)(Args...) const> { 
        typedef R TSignature(Args...); 
    }; 
 
    template <class T>
    struct TRemoveNoExceptImpl {
        using Type = T;
    };

    template <typename R, typename... Args>
    struct TRemoveNoExceptImpl<R(Args...) noexcept> {
        using Type = R(Args...);
    };

    template <typename R, typename C, typename... Args>
    struct TRemoveNoExceptImpl<R (C::*)(Args...) noexcept> {
        using Type = R (C::*)(Args...);
    };

    template <class T>
    using TRemoveNoExcept = typename TRemoveNoExceptImpl<T>::Type;

    template <class F> 
    using TRemoveClass = typename TRemoveClassImpl<TRemoveNoExcept<F>>::TSignature;
 
    template <class C> 
    struct TFuncInfo { 
        using TSignature = TRemoveClass<decltype(&C::operator())>; 
    }; 
 
    template <class R, typename... Args> 
    struct TFuncInfo<R(Args...)> { 
        using TResult = R; 
        typedef R TSignature(Args...); 
    }; 
} 
 
template <class C> 
using TFunctionSignature = typename ::NPrivate::TFuncInfo<::NPrivate::TRemoveClass<std::remove_reference_t<std::remove_pointer_t<C>>>>::TSignature; 
 
template <typename F> 
struct TCallableTraits: public TCallableTraits<TFunctionSignature<F>> { 
}; 
 
template <typename R, typename... Args> 
struct TCallableTraits<R(Args...)> { 
    using TResult = R; 
    using TArgs = TTypeList<Args...>; 
    typedef R TSignature(Args...); 
}; 
 
template <typename C> 
using TFunctionResult = typename TCallableTraits<C>::TResult; 
 
template <typename C> 
using TFunctionArgs = typename TCallableTraits<C>::TArgs; 
 
template <typename C, size_t N> 
struct TFunctionArgImpl { 
    using TArgs = TFunctionArgs<C>; 
    using TResult = typename TArgs::template TGet<N>; 
}; 
 
template <typename C, size_t N> 
using TFunctionArg = typename TFunctionArgImpl<C, N>::TResult; 

// temporary before std::apply appearance

template <typename F, typename Tuple, size_t... I>
auto ApplyImpl(F&& f, Tuple&& t, std::index_sequence<I...>) {
    return f(std::get<I>(std::forward<Tuple>(t))...);
}

// change to std::apply after c++ 17
template <typename F, typename Tuple>
auto Apply(F&& f, Tuple&& t) { 
    return ApplyImpl(f, t, std::make_index_sequence<std::tuple_size<std::decay_t<Tuple>>::value>{}); 
}

// change to std::apply after c++ 17
template <typename F>
auto Apply(F&& f, std::tuple<>) { 
    return f();
}