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- //
- // associated_allocator.hpp
- // ~~~~~~~~~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2019 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>
- struct associated_allocator_check
- {
- typedef void type;
- };
-
- 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 associated_allocator_check<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
-
- /// Traits type used to obtain the allocator associated with an object.
- /**
- * A program may specialise this traits type if the @c T template parameter in
- * the specialisation is a user-defined type. The template parameter @c
- * Allocator shall be a type meeting the Allocator requirements.
- *
- * Specialisations shall meet the following requirements, where @c t is a const
- * reference to an object of type @c T, and @c a is an object of type @c
- * Allocator.
- *
- * @li Provide a nested typedef @c type that identifies a type meeting the
- * Allocator requirements.
- *
- * @li Provide a noexcept static member function named @c get, callable as @c
- * get(t) and with return type @c type.
- *
- * @li Provide a noexcept static member function named @c get, callable as @c
- * get(t,a) and with return type @c type.
- */
- template <typename T, typename Allocator = std::allocator<void> >
- struct associated_allocator
- {
- /// If @c T has a nested type @c allocator_type, <tt>T::allocator_type</tt>.
- /// Otherwise @c 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)
-
- /// If @c T has a nested type @c allocator_type, returns
- /// <tt>t.get_allocator()</tt>. Otherwise returns @c a.
- static type get(const T& t,
- const Allocator& a = Allocator()) ASIO_NOEXCEPT
- {
- return detail::associated_allocator_impl<T, Allocator>::get(t, a);
- }
- };
-
- /// Helper function to obtain an object's associated allocator.
- /**
- * @returns <tt>associated_allocator<T>::get(t)</tt>
- */
- template <typename T>
- inline typename associated_allocator<T>::type
- get_associated_allocator(const T& t) ASIO_NOEXCEPT
- {
- return associated_allocator<T>::get(t);
- }
-
- /// Helper function to obtain an object's associated allocator.
- /**
- * @returns <tt>associated_allocator<T, Allocator>::get(t, a)</tt>
- */
- 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
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