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//
// immer: immutable data structures for C++
// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
//
// This software is distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
//
#pragma once
#include <immer/config.hpp>
#include <immer/heap/identity_heap.hpp>
#include <cassert>
#include <cstddef>
#include <type_traits>
#include <memory>
namespace immer {
#if IMMER_ENABLE_DEBUG_SIZE_HEAP
/*!
* A heap that in debug mode ensures that the sizes for allocation and
* deallocation do match.
*/
template <typename Base>
struct debug_size_heap
{
#if defined(__MINGW32__) && !defined(__MINGW64__)
// There is a bug in MinGW 32bit:
// https://sourceforge.net/p/mingw-w64/bugs/778/ It causes different
// versions of std::max_align_t to be defined, depending on inclusion order
// of stddef.h and stdint.h. As we have no control over the inclusion order
// here (as it might be set in stone by the outside world), we can't easily
// pin it to one of both versions of std::max_align_t. This means, we have
// to hardcode extra_size for MinGW 32bit builds until the mentioned bug is
// fixed.
constexpr static auto extra_size = 8;
#else
constexpr static auto extra_size = sizeof(
std::aligned_storage_t<sizeof(std::size_t), alignof(std::max_align_t)>);
#endif
template <typename... Tags>
static void* allocate(std::size_t size, Tags... tags)
{
auto p = (std::size_t*) Base::allocate(size + extra_size, tags...);
new (p) std::size_t{size};
return ((char*) p) + extra_size;
}
template <typename... Tags>
static void deallocate(std::size_t size, void* data, Tags... tags)
{
auto p = (std::size_t*) (((char*) data) - extra_size);
assert(*p == size);
Base::deallocate(size + extra_size, p, tags...);
}
};
#else // IMMER_ENABLE_DEBUG_SIZE_HEAP
template <typename Base>
using debug_size_heap = identity_heap<Base>;
#endif // !IMMER_ENABLE_DEBUG_SIZE_HEAP
} // namespace immer
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