allocator_reference.hpp

/*****************************************************************************
 * \file
 * \brief This header contains the implementation of a type-erased 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_ALLOCATOR_REFERENCE_HPP
#define BIT_MEMORY_ALLOCATORS_ALLOCATOR_REFERENCE_HPP

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

#include "../utilities/owner.hpp"            // owner
#include "../utilities/allocator_info.hpp"   // allocator_info
#include "../utilities/macros.hpp"           // BIT_MEMORY_UNUSED

#include "../concepts/Allocator.hpp" // is_allocator
#include "../concepts/Stateless.hpp" // is_stateless

#include "../traits/allocator_traits.hpp" // allocator_traits

#include <cstddef>     // std::size_t, std::ptrdiff_t
#include <type_traits> // std::integral_constant, std::is_same, etc
#include <memory>      // std::addressof

namespace bit {
  namespace memory {
    namespace detail {
      struct allocator_vtable;
    } // namespace detail

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

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

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

      template<typename Allocator,
               typename = std::enable_if_t<is_allocator<std::decay_t<Allocator>>::value &&
                          !std::is_same<allocator_reference,std::decay_t<Allocator>>::value>>
      allocator_reference( Allocator& allocator ) noexcept;

      allocator_reference( const allocator_reference& other ) noexcept = default;

      allocator_reference( allocator_reference&& other ) noexcept = default;

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

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

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

      //----------------------------------------------------------------------
      // Allocation / Deallocation
      //----------------------------------------------------------------------
    public:

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

      owner<void*> allocate( std::size_t size, std::size_t align );

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

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

      allocator_info info() const noexcept;

      //----------------------------------------------------------------------
      // Private Member Types
      //----------------------------------------------------------------------
    private:

      using vtable_type = detail::allocator_vtable;

      template<typename Allocator>
      struct stateless_type;

      //----------------------------------------------------------------------
      // Private Constructor
      //----------------------------------------------------------------------
    private:

      template<typename Allocator>
      explicit allocator_reference( stateless_type<Allocator> ) noexcept;

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

      void*              m_ptr;
      const vtable_type* m_vtable;

      friend bool operator==( const allocator_reference&, const allocator_reference& ) noexcept;

      template<typename>
      friend allocator_reference make_stateless_allocator_reference() noexcept;
    };

    //-------------------------------------------------------------------------
    // Equality Comparison
    //-------------------------------------------------------------------------

    bool operator==( const allocator_reference& lhs, const allocator_reference& rhs ) noexcept;
    bool operator!=( const allocator_reference& lhs, const allocator_reference& rhs ) noexcept;

    //-------------------------------------------------------------------------
    // Utility
    //-------------------------------------------------------------------------

    template<typename StatelessAllocator>
    allocator_reference make_stateless_allocator_reference() noexcept;

  } // namespace memory
} // namespace bit

#include "detail/allocator_reference.inl"

#endif /* BIT_MEMORY_ALLOCATORS_ALLOCATOR_REFERENCE_HPP */