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 <__utility/forward.h>
16 #include <type_traits>
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 struct _LIBCPP_TEMPLATE_VIS allocator_arg_t { explicit allocator_arg_t() = default; };
25 
26 #if defined(_LIBCPP_CXX03_LANG) || defined(_LIBCPP_BUILDING_LIBRARY)
27 extern _LIBCPP_EXPORTED_FROM_ABI const allocator_arg_t allocator_arg;
28 #else
29 /* _LIBCPP_INLINE_VAR */ constexpr allocator_arg_t allocator_arg = allocator_arg_t();
30 #endif
31 
32 #ifndef _LIBCPP_CXX03_LANG
33 
34 // allocator construction
35 
36 template <class _Tp, class _Alloc, class ..._Args>
37 struct __uses_alloc_ctor_imp
38 {
39     typedef _LIBCPP_NODEBUG_TYPE typename __uncvref<_Alloc>::type _RawAlloc;
40     static const bool __ua = uses_allocator<_Tp, _RawAlloc>::value;
41     static const bool __ic =
42         is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value;
43     static const int value = __ua ? 2 - __ic : 0;
44 };
45 
46 template <class _Tp, class _Alloc, class ..._Args>
47 struct __uses_alloc_ctor
48     : integral_constant<int, __uses_alloc_ctor_imp<_Tp, _Alloc, _Args...>::value>
49     {};
50 
51 template <class _Tp, class _Allocator, class... _Args>
52 inline _LIBCPP_INLINE_VISIBILITY
53 void __user_alloc_construct_impl (integral_constant<int, 0>, _Tp *__storage, const _Allocator &, _Args &&... __args )
54 {
55     new (__storage) _Tp (_VSTD::forward<_Args>(__args)...);
56 }
57 
58 // FIXME: This should have a version which takes a non-const alloc.
59 template <class _Tp, class _Allocator, class... _Args>
60 inline _LIBCPP_INLINE_VISIBILITY
61 void __user_alloc_construct_impl (integral_constant<int, 1>, _Tp *__storage, const _Allocator &__a, _Args &&... __args )
62 {
63     new (__storage) _Tp (allocator_arg, __a, _VSTD::forward<_Args>(__args)...);
64 }
65 
66 // FIXME: This should have a version which takes a non-const alloc.
67 template <class _Tp, class _Allocator, class... _Args>
68 inline _LIBCPP_INLINE_VISIBILITY
69 void __user_alloc_construct_impl (integral_constant<int, 2>, _Tp *__storage, const _Allocator &__a, _Args &&... __args )
70 {
71     new (__storage) _Tp (_VSTD::forward<_Args>(__args)..., __a);
72 }
73 
74 #endif // _LIBCPP_CXX03_LANG
75 
76 _LIBCPP_END_NAMESPACE_STD
77 
78 #endif // _LIBCPP___FUNCTIONAL___ALLOCATOR_ARG_T_H
79