cxx/include/__functional_base_03

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_FUNCTIONAL_BASE_03
#define _LIBCPP_FUNCTIONAL_BASE_03

// manual variadic expansion for <functional>

// __weak_result_type

template <class _Tp>
struct __derives_from_unary_function
{
private:
    struct __two {char __lx; char __lxx;};
    static __two __test(...);
    template <class _Ap, class _Rp>
        static unary_function<_Ap, _Rp>
        __test(const volatile unary_function<_Ap, _Rp>*);
public:
    static const bool value = !is_same<decltype(__test((_Tp*)0)), __two>::value;
    typedef decltype(__test((_Tp*)0)) type;
};

template <class _Tp>
struct __derives_from_binary_function
{
private:
    struct __two {char __lx; char __lxx;};
    static __two __test(...);
    template <class _A1, class _A2, class _Rp>
        static binary_function<_A1, _A2, _Rp>
        __test(const volatile binary_function<_A1, _A2, _Rp>*);
public:
    static const bool value = !is_same<decltype(__test((_Tp*)0)), __two>::value;
    typedef decltype(__test((_Tp*)0)) type;
};

template <class _Tp, bool = __derives_from_unary_function<_Tp>::value>
struct __maybe_derive_from_unary_function  // bool is true
    : public __derives_from_unary_function<_Tp>::type
{
};

template <class _Tp>
struct __maybe_derive_from_unary_function<_Tp, false>
{
};

template <class _Tp, bool = __derives_from_binary_function<_Tp>::value>
struct __maybe_derive_from_binary_function  // bool is true
    : public __derives_from_binary_function<_Tp>::type
{
};

template <class _Tp>
struct __maybe_derive_from_binary_function<_Tp, false>
{
};

template <class _Tp, bool = __has_result_type<_Tp>::value>
struct __weak_result_type_imp // bool is true
    : public __maybe_derive_from_unary_function<_Tp>,
      public __maybe_derive_from_binary_function<_Tp>
{
    typedef typename _Tp::result_type result_type;
};

template <class _Tp>
struct __weak_result_type_imp<_Tp, false>
    : public __maybe_derive_from_unary_function<_Tp>,
      public __maybe_derive_from_binary_function<_Tp>
{
};

template <class _Tp>
struct __weak_result_type
    : public __weak_result_type_imp<typename remove_reference<_Tp>::type>
{
};

// 0 argument case

template <class _Rp>
struct __weak_result_type<_Rp ()>
{
    typedef _Rp result_type;
};

template <class _Rp>
struct __weak_result_type<_Rp (&)()>
{
    typedef _Rp result_type;
};

template <class _Rp>
struct __weak_result_type<_Rp (*)()>
{
    typedef _Rp result_type;
};

// 1 argument case

template <class _Rp, class _A1>
struct __weak_result_type<_Rp (_A1)>
    : public unary_function<_A1, _Rp>
{
};

template <class _Rp, class _A1>
struct __weak_result_type<_Rp (&)(_A1)>
    : public unary_function<_A1, _Rp>
{
};

template <class _Rp, class _A1>
struct __weak_result_type<_Rp (*)(_A1)>
    : public unary_function<_A1, _Rp>
{
};

template <class _Rp, class _Cp>
struct __weak_result_type<_Rp (_Cp::*)()>
    : public unary_function<_Cp*, _Rp>
{
};

template <class _Rp, class _Cp>
struct __weak_result_type<_Rp (_Cp::*)() const>
    : public unary_function<const _Cp*, _Rp>
{
};

template <class _Rp, class _Cp>
struct __weak_result_type<_Rp (_Cp::*)() volatile>
    : public unary_function<volatile _Cp*, _Rp>
{
};

template <class _Rp, class _Cp>
struct __weak_result_type<_Rp (_Cp::*)() const volatile>
    : public unary_function<const volatile _Cp*, _Rp>
{
};

// 2 argument case

template <class _Rp, class _A1, class _A2>
struct __weak_result_type<_Rp (_A1, _A2)>
    : public binary_function<_A1, _A2, _Rp>
{
};

template <class _Rp, class _A1, class _A2>
struct __weak_result_type<_Rp (*)(_A1, _A2)>
    : public binary_function<_A1, _A2, _Rp>
{
};

template <class _Rp, class _A1, class _A2>
struct __weak_result_type<_Rp (&)(_A1, _A2)>
    : public binary_function<_A1, _A2, _Rp>
{
};

template <class _Rp, class _Cp, class _A1>
struct __weak_result_type<_Rp (_Cp::*)(_A1)>
    : public binary_function<_Cp*, _A1, _Rp>
{
};

template <class _Rp, class _Cp, class _A1>
struct __weak_result_type<_Rp (_Cp::*)(_A1) const>
    : public binary_function<const _Cp*, _A1, _Rp>
{
};

template <class _Rp, class _Cp, class _A1>
struct __weak_result_type<_Rp (_Cp::*)(_A1) volatile>
    : public binary_function<volatile _Cp*, _A1, _Rp>
{
};

template <class _Rp, class _Cp, class _A1>
struct __weak_result_type<_Rp (_Cp::*)(_A1) const volatile>
    : public binary_function<const volatile _Cp*, _A1, _Rp>
{
};

// 3 or more arguments

template <class _Rp, class _A1, class _A2, class _A3>
struct __weak_result_type<_Rp (_A1, _A2, _A3)>
{
    typedef _Rp result_type;
};

template <class _Rp, class _A1, class _A2, class _A3>
struct __weak_result_type<_Rp (&)(_A1, _A2, _A3)>
{
    typedef _Rp result_type;
};

template <class _Rp, class _A1, class _A2, class _A3>
struct __weak_result_type<_Rp (*)(_A1, _A2, _A3)>
{
    typedef _Rp result_type;
};

template <class _Rp, class _Cp, class _A1, class _A2>
struct __weak_result_type<_Rp (_Cp::*)(_A1, _A2)>
{
    typedef _Rp result_type;
};

template <class _Rp, class _Cp, class _A1, class _A2>
struct __weak_result_type<_Rp (_Cp::*)(_A1, _A2) const>
{
    typedef _Rp result_type;
};

template <class _Rp, class _Cp, class _A1, class _A2>
struct __weak_result_type<_Rp (_Cp::*)(_A1, _A2) volatile>
{
    typedef _Rp result_type;
};

// __invoke


// first bullet

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(), _T1& __t1)
{
    return (__t1.*__f)();
}

template <class _Rp, class _Tp, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0), _T1& __t1, _A0& __a0)
{
    return (__t1.*__f)(__a0);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1), _T1& __t1, _A0& __a0, _A1& __a1)
{
    return (__t1.*__f)(__a0, __a1);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1, _A2), _T1& __t1, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return (__t1.*__f)(__a0, __a1, __a2);
}

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)() const, _T1& __t1)
{
    return (__t1.*__f)();
}

template <class _Rp, class _Tp, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0) const, _T1& __t1, _A0& __a0)
{
    return (__t1.*__f)(__a0);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1) const, _T1& __t1, _A0& __a0, _A1& __a1)
{
    return (__t1.*__f)(__a0, __a1);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1, _A2) const, _T1& __t1, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return (__t1.*__f)(__a0, __a1, __a2);
}

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)() volatile, _T1& __t1)
{
    return (__t1.*__f)();
}

template <class _Rp, class _Tp, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0) volatile, _T1& __t1, _A0& __a0)
{
    return (__t1.*__f)(__a0);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1) volatile, _T1& __t1, _A0& __a0, _A1& __a1)
{
    return (__t1.*__f)(__a0, __a1);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1, _A2) volatile, _T1& __t1, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return (__t1.*__f)(__a0, __a1, __a2);
}

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)() const volatile, _T1& __t1)
{
    return (__t1.*__f)();
}

template <class _Rp, class _Tp, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0) const volatile, _T1& __t1, _A0& __a0)
{
    return (__t1.*__f)(__a0);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1) const volatile, _T1& __t1, _A0& __a0, _A1& __a1)
{
    return (__t1.*__f)(__a0, __a1);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1, _A2) const volatile, _T1& __t1, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return (__t1.*__f)(__a0, __a1, __a2);
}

// second bullet

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(), _T1 __t1)
{
    return ((*__t1).*__f)();
}

template <class _Rp, class _Tp, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0), _T1 __t1, _A0& __a0)
{
    return ((*__t1).*__f)(__a0);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1), _T1 __t1, _A0& __a0, _A1& __a1)
{
    return ((*__t1).*__f)(__a0, __a1);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1, _A2), _T1 __t1, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return ((*__t1).*__f)(__a0, __a1, __a2);
}

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)() const, _T1 __t1)
{
    return ((*__t1).*__f)();
}

template <class _Rp, class _Tp, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0) const, _T1 __t1, _A0& __a0)
{
    return ((*__t1).*__f)(__a0);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1) const, _T1 __t1, _A0& __a0, _A1& __a1)
{
    return ((*__t1).*__f)(__a0, __a1);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1, _A2) const, _T1 __t1, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return ((*__t1).*__f)(__a0, __a1, __a2);
}

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)() volatile, _T1 __t1)
{
    return ((*__t1).*__f)();
}

template <class _Rp, class _Tp, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0) volatile, _T1 __t1, _A0& __a0)
{
    return ((*__t1).*__f)(__a0);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1) volatile, _T1 __t1, _A0& __a0, _A1& __a1)
{
    return ((*__t1).*__f)(__a0, __a1);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1, _A2) volatile, _T1 __t1, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return ((*__t1).*__f)(__a0, __a1, __a2);
}

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)() const volatile, _T1 __t1)
{
    return ((*__t1).*__f)();
}

template <class _Rp, class _Tp, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0) const volatile, _T1 __t1, _A0& __a0)
{
    return ((*__t1).*__f)(__a0);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1) const volatile, _T1 __t1, _A0& __a0, _A1& __a1)
{
    return ((*__t1).*__f)(__a0, __a1);
}

template <class _Rp, class _Tp, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    !is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    _Rp
>::type
__invoke(_Rp (_Tp::*__f)(_A0, _A1, _A2) const volatile, _T1 __t1, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return ((*__t1).*__f)(__a0, __a1, __a2);
}

// third bullet

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename enable_if
<
    is_base_of<_Tp, typename remove_reference<_T1>::type>::value,
    typename __apply_cv<_T1, _Rp>::type&
>::type
__invoke(_Rp _Tp::* __f, _T1& __t1)
{
    return __t1.*__f;
}

template <class _Rp, class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
void
__invoke(_Rp _Tp::*)
{
}

// forth bullet

template <class _T1, class _Rp, bool>
struct __4th_helper
{
};

template <class _T1, class _Rp>
struct __4th_helper<_T1, _Rp, true>
{
    typedef typename __apply_cv<decltype(*_VSTD::declval<_T1>()), _Rp>::type type;
};

template <class _Rp, class _Tp, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename __4th_helper<_T1, _Rp,
                      !is_base_of<_Tp,
                                  typename remove_reference<_T1>::type
                                 >::value
                     >::type&
__invoke(_Rp _Tp::* __f, _T1& __t1)
{
    return (*__t1).*__f;
}

// fifth bullet

template <class _Fp>
inline _LIBCPP_INLINE_VISIBILITY
decltype(declval<_Fp>()())
__invoke(_Fp __f)
{
    return __f();
}

template <class _Fp, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
decltype(declval<_Fp>()(declval<_A0&>()))
__invoke(_Fp __f, _A0& __a0)
{
    return __f(__a0);
}

template <class _Fp, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
decltype(declval<_Fp>()(declval<_A0&>(), declval<_A1&>()))
__invoke(_Fp __f, _A0& __a0, _A1& __a1)
{
    return __f(__a0, __a1);
}

template <class _Fp, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
decltype(declval<_Fp>()(declval<_A0&>(), declval<_A1&>(), declval<_A2&>()))
__invoke(_Fp __f, _A0& __a0, _A1& __a1, _A2& __a2)
{
    return __f(__a0, __a1, __a2);
}

template <class _Tp>
struct __has_type
{
private:
    struct __two {char __lx; char __lxx;};
    template <class _Up> static __two __test(...);
    template <class _Up> static char __test(typename _Up::type* = 0);
public:
    static const bool value = sizeof(__test<_Tp>(0)) == 1;
};

template <class _Fp, bool = __has_result_type<__weak_result_type<_Fp> >::value>
struct __invoke_return
{
    typedef typename __weak_result_type<_Fp>::result_type type;
};

template <class _Fp>
struct __invoke_return<_Fp, false>
{
    typedef decltype(__invoke(_VSTD::declval<_Fp>())) type;
};

template <class _Tp, class _A0>
struct __invoke_return0
{
    typedef decltype(__invoke(_VSTD::declval<_Tp>(), _VSTD::declval<_A0>())) type;
};

template <class _Rp, class _Tp, class _A0>
struct __invoke_return0<_Rp _Tp::*, _A0>
{
    typedef typename __apply_cv<_A0, _Rp>::type& type;
};

template <class _Rp, class _Tp, class _A0>
struct __invoke_return0<_Rp _Tp::*, _A0*>
{
    typedef typename __apply_cv<_A0, _Rp>::type& type;
};

template <class _Tp, class _A0, class _A1>
struct __invoke_return1
{
    typedef decltype(__invoke(_VSTD::declval<_Tp>(), _VSTD::declval<_A0>(),
                                                    _VSTD::declval<_A1>())) type;
};

template <class _Tp, class _A0, class _A1, class _A2>
struct __invoke_return2
{
    typedef decltype(__invoke(_VSTD::declval<_Tp>(), _VSTD::declval<_A0>(),
                                                    _VSTD::declval<_A1>(),
                                                    _VSTD::declval<_A2>())) type;
};

template <class _Ret>
struct __invoke_void_return_wrapper
{
    template <class _Fn>
    static _Ret __call(_Fn __f)
    {
        return __invoke(__f);
    }

    template <class _Fn, class _A0>
    static _Ret __call(_Fn __f, _A0& __a0)
    {
        return __invoke(__f, __a0);
    }

    template <class _Fn, class _A0, class _A1>
    static _Ret __call(_Fn __f, _A0& __a0, _A1& __a1)
    {
        return __invoke(__f, __a0, __a1);
    }

    template <class _Fn, class _A0, class _A1, class _A2>
    static _Ret __call(_Fn __f, _A0& __a0, _A1& __a1, _A2& __a2)
    {
        return __invoke(__f, __a0, __a1, __a2);
    }
};


template <>
struct __invoke_void_return_wrapper<void>
{
    template <class _Fn>
    static void __call(_Fn __f)
    {
        __invoke(__f);
    }

    template <class _Fn, class _A0>
    static void __call(_Fn __f, _A0& __a0)
    {
        __invoke(__f, __a0);
    }

    template <class _Fn, class _A0, class _A1>
    static void __call(_Fn __f, _A0& __a0, _A1& __a1)
    {
        __invoke(__f, __a0, __a1);
    }

    template <class _Fn, class _A0, class _A1, class _A2>
    static void __call(_Fn __f, _A0& __a0, _A1& __a1, _A2& __a2)
    {
        __invoke(__f, __a0, __a1, __a2);
    }
};

template <class _Tp>
class _LIBCPP_TYPE_VIS_ONLY reference_wrapper
    : public __weak_result_type<_Tp>
{
public:
    // types
    typedef _Tp type;
private:
    type* __f_;

public:
    // construct/copy/destroy
    _LIBCPP_INLINE_VISIBILITY reference_wrapper(type& __f) : __f_(&__f) {}

    // access
    _LIBCPP_INLINE_VISIBILITY operator type&    () const {return *__f_;}
    _LIBCPP_INLINE_VISIBILITY          type& get() const {return *__f_;}

    // invoke

    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return<type&>::type
       operator() () const
       {
           return __invoke(get());
       }

    template <class _A0>
       _LIBCPP_INLINE_VISIBILITY
       typename __invoke_return0<type&, _A0>::type
          operator() (_A0& __a0) const
          {
              return __invoke<type&, _A0>(get(), __a0);
          }

    template <class _A0, class _A1>
       _LIBCPP_INLINE_VISIBILITY
       typename __invoke_return1<type&, _A0, _A1>::type
          operator() (_A0& __a0, _A1& __a1) const
          {
              return __invoke<type&, _A0, _A1>(get(), __a0, __a1);
          }

    template <class _A0, class _A1, class _A2>
       _LIBCPP_INLINE_VISIBILITY
       typename __invoke_return2<type&, _A0, _A1, _A2>::type
          operator() (_A0& __a0, _A1& __a1, _A2& __a2) const
          {
              return __invoke<type&, _A0, _A1, _A2>(get(), __a0, __a1, __a2);
          }
};

template <class _Tp> struct __is_reference_wrapper_impl : public false_type {};
template <class _Tp> struct __is_reference_wrapper_impl<reference_wrapper<_Tp> > : public true_type {};
template <class _Tp> struct __is_reference_wrapper
    : public __is_reference_wrapper_impl<typename remove_cv<_Tp>::type> {};

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
reference_wrapper<_Tp>
ref(_Tp& __t)
{
    return reference_wrapper<_Tp>(__t);
}

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
reference_wrapper<_Tp>
ref(reference_wrapper<_Tp> __t)
{
    return ref(__t.get());
}

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
reference_wrapper<const _Tp>
cref(const _Tp& __t)
{
    return reference_wrapper<const _Tp>(__t);
}

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
reference_wrapper<const _Tp>
cref(reference_wrapper<_Tp> __t)
{
    return cref(__t.get());
}

#endif  // _LIBCPP_FUNCTIONAL_BASE_03