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 private:
26   template <class _Up>
27   static false_type __test(...);
28   template <class _Up>
29   static true_type __test(typename _Up::allocator_type* = 0);
30 
31 public:
32   static const bool value = decltype(__test<_Tp>(0))::value;
33 };
34 
35 template <class _Tp, class _Alloc, bool = __has_allocator_type<_Tp>::value>
36 struct __uses_allocator : public integral_constant<bool, is_convertible<_Alloc, typename _Tp::allocator_type>::value> {
37 };
38 
39 template <class _Tp, class _Alloc>
40 struct __uses_allocator<_Tp, _Alloc, false> : public false_type {};
41 
42 template <class _Tp, class _Alloc>
43 struct _LIBCPP_TEMPLATE_VIS uses_allocator : public __uses_allocator<_Tp, _Alloc> {};
44 
45 #if _LIBCPP_STD_VER >= 17
46 template <class _Tp, class _Alloc>
47 inline constexpr bool uses_allocator_v = uses_allocator<_Tp, _Alloc>::value;
48 #endif
49 
50 _LIBCPP_END_NAMESPACE_STD
51 
52 #endif // _LIBCPP___MEMORY_USES_ALLOCATOR_H
53