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_ALLOCATOR_ARG_T_H
11 #define _LIBCPP___FUNCTIONAL_ALLOCATOR_ARG_T_H
12 
13 #include <__config>
14 #include <__memory/uses_allocator.h>
15 #include <__type_traits/integral_constant.h>
16 #include <__type_traits/is_constructible.h>
17 #include <__type_traits/remove_cvref.h>
18 #include <__utility/forward.h>
19 
20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21 #  pragma GCC system_header
22 #endif
23 
24 _LIBCPP_BEGIN_NAMESPACE_STD
25 
26 struct _LIBCPP_TEMPLATE_VIS allocator_arg_t { explicit allocator_arg_t() = default; };
27 
28 #if _LIBCPP_STD_VER >= 17
29 inline constexpr allocator_arg_t allocator_arg = allocator_arg_t();
30 #elif !defined(_LIBCPP_CXX03_LANG)
31 constexpr allocator_arg_t allocator_arg = allocator_arg_t();
32 #endif
33 
34 #ifndef _LIBCPP_CXX03_LANG
35 
36 // allocator construction
37 
38 template <class _Tp, class _Alloc, class ..._Args>
39 struct __uses_alloc_ctor_imp
40 {
41     typedef _LIBCPP_NODEBUG __remove_cvref_t<_Alloc> _RawAlloc;
42     static const bool __ua = uses_allocator<_Tp, _RawAlloc>::value;
43     static const bool __ic =
44         is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value;
45     static const int value = __ua ? 2 - __ic : 0;
46 };
47 
48 template <class _Tp, class _Alloc, class ..._Args>
49 struct __uses_alloc_ctor
50     : integral_constant<int, __uses_alloc_ctor_imp<_Tp, _Alloc, _Args...>::value>
51     {};
52 
53 template <class _Tp, class _Allocator, class... _Args>
54 inline _LIBCPP_INLINE_VISIBILITY
55 void __user_alloc_construct_impl (integral_constant<int, 0>, _Tp *__storage, const _Allocator &, _Args &&... __args )
56 {
57     new (__storage) _Tp (_VSTD::forward<_Args>(__args)...);
58 }
59 
60 // FIXME: This should have a version which takes a non-const alloc.
61 template <class _Tp, class _Allocator, class... _Args>
62 inline _LIBCPP_INLINE_VISIBILITY
63 void __user_alloc_construct_impl (integral_constant<int, 1>, _Tp *__storage, const _Allocator &__a, _Args &&... __args )
64 {
65     new (__storage) _Tp (allocator_arg, __a, _VSTD::forward<_Args>(__args)...);
66 }
67 
68 // FIXME: This should have a version which takes a non-const alloc.
69 template <class _Tp, class _Allocator, class... _Args>
70 inline _LIBCPP_INLINE_VISIBILITY
71 void __user_alloc_construct_impl (integral_constant<int, 2>, _Tp *__storage, const _Allocator &__a, _Args &&... __args )
72 {
73     new (__storage) _Tp (_VSTD::forward<_Args>(__args)..., __a);
74 }
75 
76 #endif // _LIBCPP_CXX03_LANG
77 
78 _LIBCPP_END_NAMESPACE_STD
79 
80 #endif // _LIBCPP___FUNCTIONAL_ALLOCATOR_ARG_T_H
81