libcxx/include/__functional/mem_fn.h

// -*- 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_MEM_FN_H
#define _LIBCPP___FUNCTIONAL_MEM_FN_H

#include <__config>
#include <__functional/binary_function.h>
#include <__functional/invoke.h>
#include <__functional/weak_result_type.h>
#include <__utility/forward.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

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

public:
    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
    __mem_fn(type __f) _NOEXCEPT : __f_(__f) {}

    // invoke
    template <class... _ArgTypes>
    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20

    typename __invoke_return<type, _ArgTypes...>::type
    operator() (_ArgTypes&&... __args) const {
        return std::__invoke(__f_, std::forward<_ArgTypes>(__args)...);
    }
};

template<class _Rp, class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
__mem_fn<_Rp _Tp::*>
mem_fn(_Rp _Tp::* __pm) _NOEXCEPT
{
    return __mem_fn<_Rp _Tp::*>(__pm);
}

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___FUNCTIONAL_MEM_FN_H