bump_down_lifo_allocator.hpp

/*****************************************************************************
 * \file
 * \brief This header contains the definition of a bump-down allocator that
 *        allows for stack-based LIFO deallocations alongside truncated
 *        deallocations
 *****************************************************************************/

/*
  The MIT License (MIT)

  Copyright (c) 2018 Matthew Rodusek

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
#ifndef BIT_MEMORY_ALLOCATORS_BUMP_DOWN_LIFO_ALLOCATOR_HPP
#define BIT_MEMORY_ALLOCATORS_BUMP_DOWN_LIFO_ALLOCATOR_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "detail/named_allocator.hpp" // detail::named_allocator

#include "../utilities/macros.hpp"            // BIT_MEMORY_UNLIKELY
#include "../utilities/memory_block.hpp"      // memory_block
#include "../utilities/owner.hpp"             // owner
#include "../utilities/pointer_utilities.hpp" // offset_align_backward

#include <cassert>     // assert
#include <cstddef>     // std::size_t, std::ptrdiff_t
#include <type_traits> // std:integral_constant, std::true_type, etc

namespace bit {
  namespace memory {

    class bump_down_lifo_allocator
    {
      //-----------------------------------------------------------------------
      // Public Member Types
      //-----------------------------------------------------------------------
    public:

      // limited to 256 byte alignment due to requiring an adjustment byte
      using max_alignment = std::integral_constant<std::size_t,256>;

      //-----------------------------------------------------------------------
      // Constructors
      //-----------------------------------------------------------------------
    public:

      explicit bump_down_lifo_allocator( memory_block block ) noexcept;

      bump_down_lifo_allocator( bump_down_lifo_allocator&& other ) noexcept = default;

      // Deleted copy constructor
      bump_down_lifo_allocator( const bump_down_lifo_allocator& other ) = delete;

      // Deleted nullblock constructor
      bump_down_lifo_allocator( nullblock_t ) = delete;

      //----------------------------------------------------------------------

      // Deleted copy assignment
      bump_down_lifo_allocator& operator=( const bump_down_lifo_allocator& ) = delete;

      // Deleted move assignment
      bump_down_lifo_allocator& operator=( bump_down_lifo_allocator&& other ) = delete;

      //-----------------------------------------------------------------------
      // Allocations / Deallocations
      //-----------------------------------------------------------------------
    public:

      owner<void*> try_allocate( std::size_t size,
                                 std::size_t align,
                                 std::size_t offset = 0 ) noexcept;

      void deallocate( owner<void*> p, std::size_t size );

      void deallocate_all() noexcept;

      //-----------------------------------------------------------------------
      // Observers
      //-----------------------------------------------------------------------
    public:

      bool owns( const void* p ) const noexcept;

      allocator_info info() const noexcept;

      //-----------------------------------------------------------------------
      // Private Members
      //-----------------------------------------------------------------------
    private:

      memory_block m_block;
      void*        m_current;
    };

    //-------------------------------------------------------------------------
    // Utilities
    //-------------------------------------------------------------------------

    using named_bump_down_lifo_allocator = detail::named_allocator<bump_down_lifo_allocator>;

  } // namespace memory
} // namespace bit

#include "detail/bump_down_lifo_allocator.inl"

#endif /* BIT_MEMORY_ALLOCATORS_BUMP_DOWN_LIFO_ALLOCATOR_HPP */