xref: /llvm-project/libcxx/include/__memory_resource/memory_resource.h (revision e99c4906e44ae3f921fa05356909d006cda8d954)
1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef _LIBCPP___MEMORY_RESOURCE_MEMORY_RESOURCE_H
10 #define _LIBCPP___MEMORY_RESOURCE_MEMORY_RESOURCE_H
11 
12 #include <__config>
13 #include <__cstddef/max_align_t.h>
14 #include <__cstddef/size_t.h>
15 #include <__fwd/memory_resource.h>
16 
17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18 #  pragma GCC system_header
19 #endif
20 
21 #if _LIBCPP_STD_VER >= 17
22 
23 _LIBCPP_BEGIN_NAMESPACE_STD
24 
25 namespace pmr {
26 
27 // [mem.res.class]
28 
29 class _LIBCPP_AVAILABILITY_PMR _LIBCPP_EXPORTED_FROM_ABI memory_resource {
30   static const size_t __max_align = alignof(max_align_t);
31 
32 public:
33   virtual ~memory_resource();
34 
35   [[nodiscard]] [[using __gnu__: __returns_nonnull__, __alloc_size__(2), __alloc_align__(3)]]
36   _LIBCPP_HIDE_FROM_ABI void* allocate(size_t __bytes, size_t __align = __max_align) {
37     return do_allocate(__bytes, __align);
38   }
39 
40   [[__gnu__::__nonnull__]] _LIBCPP_HIDE_FROM_ABI void
41   deallocate(void* __p, size_t __bytes, size_t __align = __max_align) {
42     do_deallocate(__p, __bytes, __align);
43   }
44 
45   _LIBCPP_HIDE_FROM_ABI bool is_equal(const memory_resource& __other) const noexcept { return do_is_equal(__other); }
46 
47 private:
48   virtual void* do_allocate(size_t, size_t)                       = 0;
49   virtual void do_deallocate(void*, size_t, size_t)               = 0;
50   virtual bool do_is_equal(memory_resource const&) const noexcept = 0;
51 };
52 
53 // [mem.res.eq]
54 
55 inline _LIBCPP_AVAILABILITY_PMR _LIBCPP_HIDE_FROM_ABI bool
56 operator==(const memory_resource& __lhs, const memory_resource& __rhs) noexcept {
57   return &__lhs == &__rhs || __lhs.is_equal(__rhs);
58 }
59 
60 #  if _LIBCPP_STD_VER <= 17
61 
62 inline _LIBCPP_AVAILABILITY_PMR _LIBCPP_HIDE_FROM_ABI bool
63 operator!=(const memory_resource& __lhs, const memory_resource& __rhs) noexcept {
64   return !(__lhs == __rhs);
65 }
66 
67 #  endif
68 
69 // [mem.res.global]
70 
71 [[__gnu__::__returns_nonnull__]] _LIBCPP_AVAILABILITY_PMR _LIBCPP_EXPORTED_FROM_ABI memory_resource*
72 get_default_resource() noexcept;
73 
74 [[__gnu__::__returns_nonnull__]] _LIBCPP_AVAILABILITY_PMR _LIBCPP_EXPORTED_FROM_ABI memory_resource*
75 set_default_resource(memory_resource*) noexcept;
76 
77 [[using __gnu__: __returns_nonnull__, __const__]] _LIBCPP_AVAILABILITY_PMR _LIBCPP_EXPORTED_FROM_ABI memory_resource*
78 new_delete_resource() noexcept;
79 
80 [[using __gnu__: __returns_nonnull__, __const__]] _LIBCPP_AVAILABILITY_PMR _LIBCPP_EXPORTED_FROM_ABI memory_resource*
81 null_memory_resource() noexcept;
82 
83 } // namespace pmr
84 
85 _LIBCPP_END_NAMESPACE_STD
86 
87 #endif // _LIBCPP_STD_VER >= 17
88 
89 #endif // _LIBCPP___MEMORY_RESOURCE_MEMORY_RESOURCE_H
90