libcxx/include/__functional/mem_fn.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___FUNCTIONAL_MEM_FN_H
  11 #define _LIBCPP___FUNCTIONAL_MEM_FN_H
  12
  13 #include <__config>
  14 #include <__functional/binary_function.h>
  15 #include <__functional/weak_result_type.h>
  16 #include <__type_traits/invoke.h>
  17 #include <__utility/forward.h>
  18
  19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  20 #  pragma GCC system_header
  21 #endif
  22
  23 _LIBCPP_BEGIN_NAMESPACE_STD
  24
  25 template <class _Tp>
  26 class __mem_fn : public __weak_result_type<_Tp> {
  27 public:
  28   // types
  29   typedef _Tp type;
  30
  31 private:
  32   type __f_;
  33
  34 public:
  35   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __mem_fn(type __f) _NOEXCEPT : __f_(__f) {}
  36
  37   // invoke
  38   template <class... _ArgTypes>
  39   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __invoke_of<const _Tp&, _ArgTypes...>::type
  40   operator()(_ArgTypes&&... __args) const _NOEXCEPT_(__nothrow_invokable<const _Tp&, _ArgTypes...>::value) {
  41     return std::__invoke(__f_, std::forward<_ArgTypes>(__args)...);
  42   }
  43 };
  44
  45 template <class _Rp, class _Tp>
  46 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __mem_fn<_Rp _Tp::*> mem_fn(_Rp _Tp::*__pm) _NOEXCEPT {
  47   return __mem_fn<_Rp _Tp::*>(__pm);
  48 }
  49
  50 _LIBCPP_END_NAMESPACE_STD
  51
  52 #endif // _LIBCPP___FUNCTIONAL_MEM_FN_H