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/invoke.h>
15 #include <__functional/perfect_forward.h>
16 #include <__utility/forward.h>
17
18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19 # pragma GCC system_header
20 #endif
21
22 _LIBCPP_BEGIN_NAMESPACE_STD
23
24 #if _LIBCPP_STD_VER >= 20
25
26 struct __bind_front_op {
27 template <class ..._Args>
28 _LIBCPP_HIDE_FROM_ABI
29 constexpr auto operator()(_Args&& ...__args) const
30 noexcept(noexcept(_VSTD::invoke(_VSTD::forward<_Args>(__args)...)))
31 -> decltype( _VSTD::invoke(_VSTD::forward<_Args>(__args)...))
32 { return _VSTD::invoke(_VSTD::forward<_Args>(__args)...); }
33 };
34
35 template <class _Fn, class ..._BoundArgs>
36 struct __bind_front_t : __perfect_forward<__bind_front_op, _Fn, _BoundArgs...> {
37 using __perfect_forward<__bind_front_op, _Fn, _BoundArgs...>::__perfect_forward;
38 };
39
40 template <class _Fn, class... _Args, class = enable_if_t<
41 _And<
42 is_constructible<decay_t<_Fn>, _Fn>,
43 is_move_constructible<decay_t<_Fn>>,
44 is_constructible<decay_t<_Args>, _Args>...,
45 is_move_constructible<decay_t<_Args>>...
46 >::value
47 >>
48 _LIBCPP_HIDE_FROM_ABI
bind_front(_Fn && __f,_Args &&...__args)49 constexpr auto bind_front(_Fn&& __f, _Args&&... __args) {
50 return __bind_front_t<decay_t<_Fn>, decay_t<_Args>...>(_VSTD::forward<_Fn>(__f), _VSTD::forward<_Args>(__args)...);
51 }
52
53 #endif // _LIBCPP_STD_VER >= 20
54
55 _LIBCPP_END_NAMESPACE_STD
56
57 #endif // _LIBCPP___FUNCTIONAL_BIND_FRONT_H
58