libcruft-util/alloc/raw/linear.hpp

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/*
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* 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/.
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*
* Copyright 2015-2018 Danny Robson <danny@nerdcruft.net>
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*/
#pragma once
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#include "../../std.hpp"
#include "../../view.hpp"
#include "../../pointer.hpp"
#include "../../memory/buffer/traits.hpp"
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#include <cstddef>
#include <iterator>
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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.
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class linear {
public:
linear (const linear&) = delete;
linear& operator= (const linear&) = delete;
linear (linear&&);
linear& operator= (linear&&);
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linear (cruft::view<u08*> _data);
template <
typename BufferT,
typename = std::enable_if_t<
memory::buffer::is_buffer_v<BufferT>
>
>
linear (BufferT &_buffer)
: linear (cruft::view (_buffer))
{ ; }
cruft::view<u08*>
allocate (size_t bytes)
{
if (m_cursor + bytes > m_end)
throw std::bad_alloc ();
auto ptr = m_cursor;
m_cursor += bytes;
return { ptr, bytes };
}
cruft::view<u08*>
allocate (size_t bytes, std::size_t alignment)
{
auto ptr = cruft::align::up (m_cursor, alignment);
if (ptr + bytes > m_end)
throw std::bad_alloc ();
m_cursor = ptr + bytes;
return { ptr, bytes };
}
void deallocate (void *ptr, std::size_t bytes, std::size_t alignment)
{
(void)ptr;
(void)bytes;
(void)alignment;
}
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void deallocate (void *ptr, std::size_t bytes)
{
return deallocate (ptr, bytes, alignof (std::max_align_t));
}
u08* data (void);
u08* begin (void);
u08* end (void);
u08* cursor (void);
u08 const* data (void) const;
u08 const* begin (void) const;
u08 const* end (void) const;
u08 const* cursor (void) const;
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size_t offset (const void*) const;
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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 ());
}
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void reset (void);
size_t capacity (void) const;
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size_t used (void) const;
size_t remain (void) const;
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protected:
// The begin and end iterators should be constant but that interferes
// with move operators so we need to leave them mutable.
u08 *m_begin;
u08 *m_end;
u08 *m_cursor;
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};
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}