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_BIND_FRONT_H
11 #define _LIBCPP___FUNCTIONAL_BIND_FRONT_H
12 
13 #include <__config>
14 #include <__functional/perfect_forward.h>
15 #include <__functional/invoke.h>
16 #include <type_traits>
17 #include <utility>
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 #if _LIBCPP_STD_VER > 17
26 
27 struct __bind_front_op
28 {
29     template<class... _Args>
30     constexpr static auto __call(_Args&&... __args)
31     noexcept(noexcept(_VSTD::invoke(_VSTD::forward<_Args>(__args)...)))
32     -> decltype(      _VSTD::invoke(_VSTD::forward<_Args>(__args)...))
33     { return          _VSTD::invoke(_VSTD::forward<_Args>(__args)...); }
34 };
35 
36 template<class _Fn, class... _Args,
37          class = _EnableIf<conjunction<is_constructible<decay_t<_Fn>, _Fn>,
38                                        is_move_constructible<decay_t<_Fn>>,
39                                        is_constructible<decay_t<_Args>, _Args>...,
40                                        is_move_constructible<decay_t<_Args>>...
41                                        >::value>>
42 constexpr auto bind_front(_Fn&& __f, _Args&&... __args)
43 {
44     return __perfect_forward<__bind_front_op, _Fn, _Args...>(_VSTD::forward<_Fn>(__f),
45                                                              _VSTD::forward<_Args>(__args)...);
46 }
47 
48 #endif // _LIBCPP_STD_VER > 17
49 
50 _LIBCPP_END_NAMESPACE_STD
51 
52 #endif // _LIBCPP___FUNCTIONAL_BIND_FRONT_H
53