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/invoke.h>
  16 #include <__functional/weak_result_type.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 {
  28 public:
  29     // types
  30     typedef _Tp type;
  31 private:
  32     type __f_;
  33
  34 public:
  35     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  36     __mem_fn(type __f) _NOEXCEPT : __f_(__f) {}
  37
  38     // invoke
  39     template <class... _ArgTypes>
  40     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  41
  42     typename __invoke_return<type, _ArgTypes...>::type
  43     operator() (_ArgTypes&&... __args) const {
  44         return std::__invoke(__f_, std::forward<_ArgTypes>(__args)...);
  45     }
  46 };
  47
  48 template<class _Rp, class _Tp>
  49 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  50 __mem_fn<_Rp _Tp::*>
  51 mem_fn(_Rp _Tp::* __pm) _NOEXCEPT
  52 {
  53     return __mem_fn<_Rp _Tp::*>(__pm);
  54 }
  55
  56 _LIBCPP_END_NAMESPACE_STD
  57
  58 #endif // _LIBCPP___FUNCTIONAL_MEM_FN_H