libcruft-util/alloc/raw/linear.hpp

112 lines
3.0 KiB
C++

/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2015 Danny Robson <danny@nerdcruft.net>
*/
#ifndef CRUFT_UTIL_ALLOC_RAW_LINEAR_HPP
#define CRUFT_UTIL_ALLOC_RAW_LINEAR_HPP
#include "../../view.hpp"
#include "../../pointer.hpp"
#include <cstddef>
#include <iterator>
namespace cruft::alloc::raw {
// allocate progressively across a buffer without concern for deallocation.
// deallocation is a noop; the only way to free allocations is via reset.
class linear {
public:
linear (const linear&) = delete;
linear& operator= (const linear&) = delete;
linear (linear&&);
linear& operator= (linear&&);
linear (cruft::view<std::byte*> _data);
template <typename T>
cruft::view<T*>
allocate (size_t count)
{
auto const bytes = count * sizeof (T);
if (m_cursor + bytes > m_end)
throw std::bad_alloc ();
auto ptr = m_cursor;
m_cursor += bytes;
return { cruft::cast::alignment<T*> (ptr), count };
}
template <typename T>
cruft::view<T*>
allocate (size_t count, size_t alignment)
{
auto const bytes = count * sizeof (T);
auto ptr = cruft::align (m_cursor, alignment);
if (ptr + bytes > m_end)
throw std::bad_alloc ();
m_cursor = ptr + bytes;
return { cruft::cast::alignment<T*> (ptr), count };
}
template <typename T>
void deallocate (cruft::view<T*> ptr)
{
(void)ptr;
}
std::byte* data (void);
std::byte* begin (void);
std::byte* end (void);
std::byte* cursor (void);
const std::byte* data (void) const;
const std::byte* begin (void) const;
const std::byte* end (void) const;
const std::byte* cursor (void) const;
size_t offset (const void*) const;
template <typename ValueT>
size_t
offset (ValueT const *ptr) const
{
CHECK_MOD (reinterpret_cast<uintptr_t> (ptr), sizeof (ValueT));
CHECK_MOD (reinterpret_cast<uintptr_t> (data ()), sizeof (ValueT));
return ptr - cruft::cast::alignment<ValueT const*> (data ());
}
template <typename T>
size_t
offset (cruft::view<T*> ptr) const
{
return offset (ptr.data ());
}
void reset (void);
size_t capacity (void) const;
size_t used (void) const;
size_t remain (void) const;
protected:
// The begin and end iterators should be constant but that interferes
// with move operators so we need to leave them mutable.
std::byte *m_begin;
std::byte *m_end;
std::byte *m_cursor;
};
}
#endif