libs/capy/include/boost/capy/detail/frame_memory_resource.hpp

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1		//
2		// Copyright (c) 2025 Vinnie Falco (vinnie dot falco at gmail dot com)
3		//
4		// Distributed under the Boost Software License, Version 1.0. (See accompanying
5		// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6		//
7		// Official repository: https://github.com/cppalliance/capy
8		//
9
10		#ifndef BOOST_CAPY_DETAIL_FRAME_MEMORY_RESOURCE_HPP
11		#define BOOST_CAPY_DETAIL_FRAME_MEMORY_RESOURCE_HPP
12
13		#include <boost/capy/detail/config.hpp>
14
15		#include <cstddef>
16		#include <memory>
17		#include <memory_resource>
18		#include <type_traits>
19
20		namespace boost {
21		namespace capy {
22		namespace detail {
23
24		/** Wrapper that adapts a standard Allocator to memory_resource.
25
26		This wrapper is used to store value-type allocators in the
27		execution context or trampoline frame. It rebinds the allocator
28		to std::byte for raw memory allocation.
29
30		@tparam Alloc The standard allocator type.
31		*/
32		template<class Alloc>
33		class frame_memory_resource : public std::pmr::memory_resource
34		{
35		using traits = std::allocator_traits<Alloc>;
36		using byte_alloc = typename traits::template rebind_alloc<std::byte>;
37		using byte_traits = std::allocator_traits<byte_alloc>;
38
39		static_assert(
40		requires { typename traits::value_type; },
41		"Alloc must satisfy allocator requirements");
42
43		static_assert(
44		std::is_copy_constructible_v<Alloc>,
45		"Alloc must be copy constructible");
46
47		byte_alloc alloc_;
48
49		public:
50		/** Construct from an allocator.
51
52		The allocator is rebind-copied to std::byte.
53
54		@param a The allocator to adapt.
55		*/
56		explicit
57	59	frame_memory_resource(Alloc const& a)
58	59	: alloc_(a)
59		{
60	59	}
61
62		protected:
63		void*
64	✗	do_allocate(std::size_t bytes, std::size_t) override
65		{
66	✗	return byte_traits::allocate(alloc_, bytes);
67		}
68
69		void
70	✗	do_deallocate(void* p, std::size_t bytes, std::size_t) override
71		{
72	✗	byte_traits::deallocate(alloc_, static_cast<std::byte*>(p), bytes);
73	✗	}
74
75		bool
76	✗	do_is_equal(const memory_resource& other) const noexcept override
77		{
78	✗	return this == &other;
79		}
80		};
81
82		} // namespace detail
83		} // namespace capy
84		} // namespace boost
85
86		#endif
87