null_allocator.hpp

/*****************************************************************************
 * \file
 * \brief This header defines the null allocator policy, null_allocator
 *****************************************************************************/

/*
  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_NULL_ALLOCATOR_HPP
#define BIT_MEMORY_ALLOCATORS_NULL_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/allocator_info.hpp" // allocator_info
#include "../utilities/macros.hpp"         // BIT_MEMORY_UNUSED
#include "../utilities/owner.hpp"          // owner

#include <cstddef>     // std::size_t
#include <type_traits> // std::true_type

namespace bit {
  namespace memory {

    class null_allocator
    {
      //-----------------------------------------------------------------------
      // Public Static Members
      //-----------------------------------------------------------------------
    public:

      using default_alignment = std::integral_constant<std::size_t,1>;

      //-----------------------------------------------------------------------
      // Constructor / Assignment
      //-----------------------------------------------------------------------
    public:

      null_allocator() = default;

      null_allocator( null_allocator&& other ) noexcept = default;

      null_allocator( const null_allocator& other ) noexcept = default;

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

      null_allocator& operator=( null_allocator&& other ) noexcept = default;

      null_allocator& operator=( const null_allocator& other ) noexcept = default;

      //----------------------------------------------------------------------
      // Allocation
      //----------------------------------------------------------------------
    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 n ) noexcept;

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

      bool owns( const void* p ) const noexcept;

      bool owns( std::nullptr_t ) const noexcept;

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

      allocator_info info() const noexcept;
    };

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

    using named_null_allocator = detail::named_allocator<null_allocator>;

  } // namespace memory
} // namespace bit

#include "detail/null_allocator.inl"

#endif /* BIT_MEMORY_ALLOCATORS_NULL_ALLOCATOR_HPP */