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// Copyright (C) 2015-2025 Jonathan Müller and foonathan/memory contributors
// SPDX-License-Identifier: Zlib
#ifndef FOONATHAN_MEMORY_ALIGNED_ALLOCATOR_HPP_INCLUDED
#define FOONATHAN_MEMORY_ALIGNED_ALLOCATOR_HPP_INCLUDED
/// \file
/// Class \ref foonathan::memory::aligned_allocator and related functions.
#include <type_traits>
#include "detail/assert.hpp"
#include "detail/utility.hpp"
#include "allocator_traits.hpp"
#include "config.hpp"
namespace foonathan
{
namespace memory
{
/// A \concept{concept_rawallocator,RawAllocator} adapter that ensures a minimum alignment.
/// It adjusts the alignment value so that it is always larger than the minimum and forwards to the specified allocator.
/// \ingroup adapter
template <class RawAllocator>
class aligned_allocator : FOONATHAN_EBO(allocator_traits<RawAllocator>::allocator_type)
{
using traits = allocator_traits<RawAllocator>;
using composable_traits = composable_allocator_traits<RawAllocator>;
using composable = is_composable_allocator<typename traits::allocator_type>;
public:
using allocator_type = typename allocator_traits<RawAllocator>::allocator_type;
using is_stateful = std::true_type;
/// \effects Creates it passing it the minimum alignment value and the allocator object.
/// \requires \c min_alignment must be less than \c this->max_alignment().
explicit aligned_allocator(std::size_t min_alignment, allocator_type&& alloc = {})
: allocator_type(detail::move(alloc)), min_alignment_(min_alignment)
{
FOONATHAN_MEMORY_ASSERT(min_alignment_ <= max_alignment());
}
/// @{
/// \effects Moves the \c aligned_allocator object.
/// It simply moves the underlying allocator.
aligned_allocator(aligned_allocator&& other) noexcept
: allocator_type(detail::move(other)), min_alignment_(other.min_alignment_)
{
}
aligned_allocator& operator=(aligned_allocator&& other) noexcept
{
allocator_type::operator=(detail::move(other));
min_alignment_ = other.min_alignment_;
return *this;
}
/// @}
/// @{
/// \effects Forwards to the underlying allocator through the \ref allocator_traits.
/// If the \c alignment is less than the \c min_alignment(), it is set to the minimum alignment.
void* allocate_node(std::size_t size, std::size_t alignment)
{
if (min_alignment_ > alignment)
alignment = min_alignment_;
return traits::allocate_node(get_allocator(), size, alignment);
}
void* allocate_array(std::size_t count, std::size_t size, std::size_t alignment)
{
if (min_alignment_ > alignment)
alignment = min_alignment_;
return traits::allocate_array(get_allocator(), count, size, alignment);
}
void deallocate_node(void* ptr, std::size_t size, std::size_t alignment) noexcept
{
if (min_alignment_ > alignment)
alignment = min_alignment_;
traits::deallocate_node(get_allocator(), ptr, size, alignment);
}
void deallocate_array(void* ptr, std::size_t count, std::size_t size,
std::size_t alignment) noexcept
{
if (min_alignment_ > alignment)
alignment = min_alignment_;
traits::deallocate_array(get_allocator(), ptr, count, size, alignment);
}
/// @}
/// @{
/// \effects Forwards to the underlying allocator through the \ref composable_allocator_traits.
/// If the \c alignment is less than the \c min_alignment(), it is set to the minimum alignment.
/// \requires The underyling allocator must be composable.
FOONATHAN_ENABLE_IF(composable::value)
void* try_allocate_node(std::size_t size, std::size_t alignment) noexcept
{
if (min_alignment_ > alignment)
alignment = min_alignment_;
return composable_traits::try_allocate_node(get_allocator(), size, alignment);
}
FOONATHAN_ENABLE_IF(composable::value)
void* try_allocate_array(std::size_t count, std::size_t size,
std::size_t alignment) noexcept
{
if (min_alignment_ > alignment)
alignment = min_alignment_;
return composable_traits::try_allocate_array(get_allocator(), count, size,
alignment);
}
FOONATHAN_ENABLE_IF(composable::value)
bool try_deallocate_node(void* ptr, std::size_t size, std::size_t alignment) noexcept
{
if (min_alignment_ > alignment)
alignment = min_alignment_;
return composable_traits::try_deallocate_node(get_allocator(), ptr, size,
alignment);
}
FOONATHAN_ENABLE_IF(composable::value)
bool try_deallocate_array(void* ptr, std::size_t count, std::size_t size,
std::size_t alignment) noexcept
{
if (min_alignment_ > alignment)
alignment = min_alignment_;
return composable_traits::try_deallocate_array(get_allocator(), ptr, count, size,
alignment);
}
/// @}
/// @{
/// \returns The value returned by the \ref allocator_traits for the underlying allocator.
std::size_t max_node_size() const
{
return traits::max_node_size(get_allocator());
}
std::size_t max_array_size() const
{
return traits::max_array_size(get_allocator());
}
std::size_t max_alignment() const
{
return traits::max_alignment(get_allocator());
}
/// @}
/// @{
/// \returns A reference to the underlying allocator.
allocator_type& get_allocator() noexcept
{
return *this;
}
const allocator_type& get_allocator() const noexcept
{
return *this;
}
/// @}
/// \returns The minimum alignment.
std::size_t min_alignment() const noexcept
{
return min_alignment_;
}
/// \effects Sets the minimum alignment to a new value.
/// \requires \c min_alignment must be less than \c this->max_alignment().
void set_min_alignment(std::size_t min_alignment)
{
FOONATHAN_MEMORY_ASSERT(min_alignment <= max_alignment());
min_alignment_ = min_alignment;
}
private:
std::size_t min_alignment_;
};
/// \returns A new \ref aligned_allocator created by forwarding the parameters to the constructor.
/// \relates aligned_allocator
template <class RawAllocator>
auto make_aligned_allocator(std::size_t min_alignment, RawAllocator&& allocator) noexcept
-> aligned_allocator<typename std::decay<RawAllocator>::type>
{
return aligned_allocator<
typename std::decay<RawAllocator>::type>{min_alignment,
detail::forward<RawAllocator>(allocator)};
}
} // namespace memory
} // namespace foonathan
#endif // FOONATHAN_MEMORY_ALIGNED_ALLOCATOR_HPP_INCLUDED
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