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___MEMORY_USES_ALLOCATOR_H
11 #define _LIBCPP___MEMORY_USES_ALLOCATOR_H
12 
13 #include <__config>
14 #include <__type_traits/is_convertible.h>
15 #include <cstddef>
16 
17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18 #  pragma GCC system_header
19 #endif
20 
21 _LIBCPP_BEGIN_NAMESPACE_STD
22 
23 template <class _Tp>
24 struct __has_allocator_type
25 {
26 private:
27     template <class _Up> static false_type __test(...);
28     template <class _Up> static true_type __test(typename _Up::allocator_type* = 0);
29 public:
30     static const bool value = decltype(__test<_Tp>(0))::value;
31 };
32 
33 template <class _Tp, class _Alloc, bool = __has_allocator_type<_Tp>::value>
34 struct __uses_allocator
35     : public integral_constant<bool,
36         is_convertible<_Alloc, typename _Tp::allocator_type>::value>
37 {
38 };
39 
40 template <class _Tp, class _Alloc>
41 struct __uses_allocator<_Tp, _Alloc, false>
42     : public false_type
43 {
44 };
45 
46 template <class _Tp, class _Alloc>
47 struct _LIBCPP_TEMPLATE_VIS uses_allocator
48     : public __uses_allocator<_Tp, _Alloc>
49 {
50 };
51 
52 #if _LIBCPP_STD_VER >= 17
53 template <class _Tp, class _Alloc>
54 inline constexpr bool uses_allocator_v = uses_allocator<_Tp, _Alloc>::value;
55 #endif
56 
57 _LIBCPP_END_NAMESPACE_STD
58 
59 #endif // _LIBCPP___MEMORY_USES_ALLOCATOR_H
60