associated_allocator.hpp

//
// associated_allocator.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_ASSOCIATED_ALLOCATOR_HPP
#define ASIO_ASSOCIATED_ALLOCATOR_HPP

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

#include "asio/detail/config.hpp"
#include <memory>
#include "asio/detail/type_traits.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {
namespace detail {

template <typename T, typename E, typename = void>
struct associated_allocator_impl
{
  typedef E type;

  static type get(const T&, const E& e) ASIO_NOEXCEPT
  {
    return e;
  }
};

template <typename T, typename E>
struct associated_allocator_impl<T, E,
  typename void_type<typename T::allocator_type>::type>
{
  typedef typename T::allocator_type type;

  static type get(const T& t, const E&) ASIO_NOEXCEPT
  {
    return t.get_allocator();
  }
};

} // namespace detail


template <typename T, typename Allocator = std::allocator<void> >
struct associated_allocator
{
#if defined(GENERATING_DOCUMENTATION)
  typedef see_below type;
#else // defined(GENERATING_DOCUMENTATION)
  typedef typename detail::associated_allocator_impl<T, Allocator>::type type;
#endif // defined(GENERATING_DOCUMENTATION)

  static type get(const T& t,
      const Allocator& a = Allocator()) ASIO_NOEXCEPT
  {
    return detail::associated_allocator_impl<T, Allocator>::get(t, a);
  }
};


template <typename T>
inline typename associated_allocator<T>::type
get_associated_allocator(const T& t) ASIO_NOEXCEPT
{
  return associated_allocator<T>::get(t);
}


template <typename T, typename Allocator>
inline typename associated_allocator<T, Allocator>::type
get_associated_allocator(const T& t, const Allocator& a) ASIO_NOEXCEPT
{
  return associated_allocator<T, Allocator>::get(t, a);
}

#if defined(ASIO_HAS_ALIAS_TEMPLATES)

template <typename T, typename Allocator = std::allocator<void> >
using associated_allocator_t
  = typename associated_allocator<T, Allocator>::type;

#endif // defined(ASIO_HAS_ALIAS_TEMPLATES)

} // namespace asio

#include "asio/detail/pop_options.hpp"

#endif // ASIO_ASSOCIATED_ALLOCATOR_HPP