44 lines
1 KiB
C++
44 lines
1 KiB
C++
|
//
|
||
|
|
// 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 <cstdio>
|
||
|
|
|
||
|
|
namespace immer {
|
||
|
|
|
||
|
|
/*!
|
||
|
|
* Appends a default constructed extra object of type `T` at the
|
||
|
|
* *before* the requested region.
|
||
|
|
*
|
||
|
|
* @tparam T Type of the appended data.
|
||
|
|
* @tparam Base Type of the parent heap.
|
||
|
|
*/
|
||
|
|
template <typename T, typename Base>
|
||
|
|
struct with_data : Base
|
||
|
|
{
|
||
|
|
using base_t = Base;
|
||
|
|
|
||
|
|
template <typename... Tags>
|
||
|
|
static void* allocate(std::size_t size, Tags... tags)
|
||
|
|
{
|
||
|
|
auto p = base_t::allocate(size + sizeof(T), tags...);
|
||
|
|
return new (p) T{} + 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
template <typename... Tags>
|
||
|
|
static void deallocate(std::size_t size, void* p, Tags... tags)
|
||
|
|
{
|
||
|
|
auto dp = static_cast<T*>(p) - 1;
|
||
|
|
dp->~T();
|
||
|
|
base_t::deallocate(size + sizeof(T), dp, tags...);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace immer
|