AllocatorStorage.hpp

/*****************************************************************************
 * \file
 * \brief This header defines the concept of an 'AllocatorStorage', which is
 *        used to contain allocator types within composites.
 *****************************************************************************/

/*
  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_CONCEPTS_ALLOCATOR_STORAGE_HPP
#define BIT_MEMORY_CONCEPTS_ALLOCATOR_STORAGE_HPP

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

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

#include "Allocator.hpp" // is_allocator

#include <type_traits> // std::declval, std::true_type

namespace bit {
  namespace memory {

#if __cplusplus >= 202000L
    // TODO(bitwize) replace 202000L with the correct __cplusplus when certified

    template<typename T>
    concept bool AllocatorStorage = requires( T& s, const T& cs )
    {
      { s.get_allocator() } -> typename T::allocator_type&;
      { cs.get_allocator() } -> const typename T::allocator_type&;
    } && std::is_nothrow_copy_constructible<T>::value &&
         std::is_nothrow_move_constructible<T>::value &&
         std::is_nothrow_copy_assignable<T>::value &&
         std::is_nothrow_move_assignable<T>::value;
#endif

    namespace detail {

      template<typename T, typename = void>
      struct is_allocator_storage_impl : std::false_type{};

      template<typename T>
      struct is_allocator_storage_impl<T,
        void_t<
          decltype( std::declval<T&>().get_allocator() ),
          decltype( std::declval<const T&>().get_allocator() )
        >
      > : std::integral_constant<bool,
        is_allocator<typename T::allocator_type>::value &&
        std::is_convertible<decltype( std::declval<T&>().get_allocator()),
                            typename T::allocator_type&>::value &&
        std::is_convertible<decltype( std::declval<const T&>().get_allocator()),
                            const typename T::allocator_type&>::value &&
        std::is_nothrow_copy_constructible<T>::value &&
        std::is_nothrow_move_constructible<T>::value &&
        std::is_nothrow_copy_assignable<T>::value &&
        std::is_nothrow_move_assignable<T>::value>{};
    } // namespace detail

    template<typename T>
    struct is_allocator_storage : detail::is_allocator_storage_impl<T>{};

    template<typename T>
    constexpr bool is_allocator_storage_v = is_allocator_storage<T>::value;

  } // namespace memory
} // namespace bit

#endif /* BIT_MEMORY_CONCEPTS_ALLOCATOR_STORAGE_HPP */