llvm-project/libcxx/include/__functional_base_03

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_FUNCTIONAL_BASE_03
#define _LIBCPP_FUNCTIONAL_BASE_03

// manual variadic expansion for <functional>

// __invoke

template <class _Ret, class _T1, bool _IsFunc, bool _IsBase>
struct __enable_invoke_imp;

template <class _Ret, class _T1>
struct __enable_invoke_imp<_Ret, _T1, true, true> {
    typedef _Ret _Bullet1;
    typedef _Bullet1 type;
};

template <class _Ret, class _T1>
struct __enable_invoke_imp<_Ret, _T1, true, false>  {
    typedef _Ret _Bullet2;
    typedef _Bullet2 type;
};

template <class _Ret, class _T1>
struct __enable_invoke_imp<_Ret, _T1, false, true>  {
    typedef typename add_lvalue_reference<
                typename __apply_cv<_T1, _Ret>::type
            >::type _Bullet3;
    typedef _Bullet3 type;
};

template <class _Ret, class _T1>
struct __enable_invoke_imp<_Ret, _T1, false, false>  {
    typedef typename add_lvalue_reference<
                typename __apply_cv<decltype(*_VSTD::declval<_T1>()), _Ret>::type
            >::type _Bullet4;
    typedef _Bullet4 type;
};

template <class _Ret, class _T1>
struct __enable_invoke_imp<_Ret, _T1*, false, false>  {
    typedef typename add_lvalue_reference<
                typename __apply_cv<_T1, _Ret>::type
            >::type _Bullet4;
    typedef _Bullet4  type;
};

template <class _Fn, class _T1,
          class _Traits = __member_pointer_traits<_Fn>,
          class _Ret = typename _Traits::_ReturnType,
          class _Class = typename _Traits::_ClassType>
struct __enable_invoke : __enable_invoke_imp<
    _Ret, _T1,
    is_member_function_pointer<_Fn>::value,
    is_base_of<_Class, typename remove_reference<_T1>::type>::value>
{
};

__nat __invoke(__any, ...);

// first bullet

template <class _Fn, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet1
__invoke(_Fn __f, _T1& __t1) {
    return (__t1.*__f)();
}

template <class _Fn, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet1
__invoke(_Fn __f, _T1& __t1, _A0& __a0) {
    return (__t1.*__f)(__a0);
}

template <class _Fn, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet1
__invoke(_Fn __f, _T1& __t1, _A0& __a0, _A1& __a1) {
    return (__t1.*__f)(__a0, __a1);
}

template <class _Fn, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet1
__invoke(_Fn __f, _T1& __t1, _A0& __a0, _A1& __a1, _A2& __a2) {
    return (__t1.*__f)(__a0, __a1, __a2);
}

template <class _Fn, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet2
__invoke(_Fn __f, _T1& __t1) {
    return ((*__t1).*__f)();
}

template <class _Fn, class _T1, class _A0>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet2
__invoke(_Fn __f, _T1& __t1, _A0& __a0) {
    return ((*__t1).*__f)(__a0);
}

template <class _Fn, class _T1, class _A0, class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet2
__invoke(_Fn __f, _T1& __t1, _A0& __a0, _A1& __a1) {
    return ((*__t1).*__f)(__a0, __a1);
}

template <class _Fn, class _T1, class _A0, class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet2
__invoke(_Fn __f, _T1& __t1, _A0& __a0, _A1& __a1, _A2& __a2) {
    return ((*__t1).*__f)(__a0, __a1, __a2);
}

template <class _Fn, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet3
__invoke(_Fn __f, _T1& __t1) {
    return __t1.*__f;
}

template <class _Fn, class _T1>
inline _LIBCPP_INLINE_VISIBILITY
typename __enable_invoke<_Fn, _T1>::_Bullet4
__invoke(_Fn __f, _T1& __t1) {
    return (*__t1).*__f;
}

// fifth bullet

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

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

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

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 __enable_invoke<_Rp _Tp::*, _A0>::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 _Rp, class _Class, class _A0, class _A1>
struct __invoke_return1<_Rp _Class::*, _A0, _A1> {
    typedef typename __enable_invoke<_Rp _Class::*, _A0>::type 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, class _Class, class _A0, class _A1, class _A2>
struct __invoke_return2<_Ret _Class::*, _A0, _A1, _A2> {
    typedef typename __enable_invoke<_Ret _Class::*, _A0>::type type;
};
#endif  // _LIBCPP_FUNCTIONAL_BASE_03