libcxx/include/__memory/allocate_at_least.h

   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_ALLOCATE_AT_LEAST_H
  10 #define _LIBCPP___MEMORY_ALLOCATE_AT_LEAST_H
  11
  12 #include <__config>
  13 #include <__memory/allocator_traits.h>
  14 #include <cstddef>
  15
  16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  17 #  pragma GCC system_header
  18 #endif
  19
  20 _LIBCPP_BEGIN_NAMESPACE_STD
  21
  22 #if _LIBCPP_STD_VER >= 23
  23 template <class _Pointer>
  24 struct allocation_result {
  25   _Pointer ptr;
  26   size_t count;
  27 };
  28 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(allocation_result);
  29
  30 template <class _Alloc>
  31 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr
  32 allocation_result<typename allocator_traits<_Alloc>::pointer> allocate_at_least(_Alloc& __alloc, size_t __n) {
  33   if constexpr (requires { __alloc.allocate_at_least(__n); }) {
  34     return __alloc.allocate_at_least(__n);
  35   } else {
  36     return {__alloc.allocate(__n), __n};
  37   }
  38 }
  39
  40 template <class _Alloc>
  41 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr
  42 auto __allocate_at_least(_Alloc& __alloc, size_t __n) {
  43   return std::allocate_at_least(__alloc, __n);
  44 }
  45 #else
  46 template <class _Pointer>
  47 struct __allocation_result {
  48   _Pointer ptr;
  49   size_t count;
  50 };
  51
  52 template <class _Alloc>
  53 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR
  54 __allocation_result<typename allocator_traits<_Alloc>::pointer> __allocate_at_least(_Alloc& __alloc, size_t __n) {
  55   return {__alloc.allocate(__n), __n};
  56 }
  57
  58 #endif // _LIBCPP_STD_VER >= 23
  59
  60 _LIBCPP_END_NAMESPACE_STD
  61
  62 #endif // _LIBCPP___MEMORY_ALLOCATE_AT_LEAST_H