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131 lines
3.7 KiB
131 lines
3.7 KiB
// |
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// associated_allocator.hpp |
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// ~~~~~~~~~~~~~~~~~~~~~~~~ |
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// |
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// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
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// |
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// Distributed under the Boost Software License, Version 1.0. (See accompanying |
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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// |
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#ifndef ASIO_ASSOCIATED_ALLOCATOR_HPP |
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#define ASIO_ASSOCIATED_ALLOCATOR_HPP |
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#if defined(_MSC_VER) && (_MSC_VER >= 1200) |
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# pragma once |
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200) |
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#include "asio/detail/config.hpp" |
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#include <memory> |
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#include "asio/detail/type_traits.hpp" |
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#include "asio/detail/push_options.hpp" |
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namespace asio { |
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namespace detail { |
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template <typename> |
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struct associated_allocator_check |
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{ |
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typedef void type; |
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}; |
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template <typename T, typename E, typename = void> |
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struct associated_allocator_impl |
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{ |
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typedef E type; |
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static type get(const T&, const E& e) ASIO_NOEXCEPT |
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{ |
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return e; |
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} |
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}; |
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template <typename T, typename E> |
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struct associated_allocator_impl<T, E, |
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typename associated_allocator_check<typename T::allocator_type>::type> |
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{ |
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typedef typename T::allocator_type type; |
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static type get(const T& t, const E&) ASIO_NOEXCEPT |
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{ |
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return t.get_allocator(); |
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} |
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}; |
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} // namespace detail |
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/// Traits type used to obtain the allocator associated with an object. |
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/** |
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* A program may specialise this traits type if the @c T template parameter in |
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* the specialisation is a user-defined type. The template parameter @c |
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* Allocator shall be a type meeting the Allocator requirements. |
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* |
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* Specialisations shall meet the following requirements, where @c t is a const |
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* reference to an object of type @c T, and @c a is an object of type @c |
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* Allocator. |
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* |
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* @li Provide a nested typedef @c type that identifies a type meeting the |
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* Allocator requirements. |
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* |
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* @li Provide a noexcept static member function named @c get, callable as @c |
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* get(t) and with return type @c type. |
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* |
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* @li Provide a noexcept static member function named @c get, callable as @c |
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* get(t,a) and with return type @c type. |
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*/ |
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template <typename T, typename Allocator = std::allocator<void> > |
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struct associated_allocator |
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{ |
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/// If @c T has a nested type @c allocator_type, <tt>T::allocator_type</tt>. |
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/// Otherwise @c Allocator. |
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#if defined(GENERATING_DOCUMENTATION) |
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typedef see_below type; |
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#else // defined(GENERATING_DOCUMENTATION) |
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typedef typename detail::associated_allocator_impl<T, Allocator>::type type; |
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#endif // defined(GENERATING_DOCUMENTATION) |
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/// If @c T has a nested type @c allocator_type, returns |
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/// <tt>t.get_allocator()</tt>. Otherwise returns @c a. |
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static type get(const T& t, |
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const Allocator& a = Allocator()) ASIO_NOEXCEPT |
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{ |
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return detail::associated_allocator_impl<T, Allocator>::get(t, a); |
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} |
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}; |
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/// Helper function to obtain an object's associated allocator. |
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/** |
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* @returns <tt>associated_allocator<T>::get(t)</tt> |
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*/ |
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template <typename T> |
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inline typename associated_allocator<T>::type |
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get_associated_allocator(const T& t) ASIO_NOEXCEPT |
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{ |
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return associated_allocator<T>::get(t); |
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} |
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/// Helper function to obtain an object's associated allocator. |
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/** |
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* @returns <tt>associated_allocator<T, Allocator>::get(t, a)</tt> |
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*/ |
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template <typename T, typename Allocator> |
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inline typename associated_allocator<T, Allocator>::type |
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get_associated_allocator(const T& t, const Allocator& a) ASIO_NOEXCEPT |
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{ |
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return associated_allocator<T, Allocator>::get(t, a); |
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} |
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#if defined(ASIO_HAS_ALIAS_TEMPLATES) |
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template <typename T, typename Allocator = std::allocator<void> > |
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using associated_allocator_t |
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= typename associated_allocator<T, Allocator>::type; |
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#endif // defined(ASIO_HAS_ALIAS_TEMPLATES) |
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} // namespace asio |
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#include "asio/detail/pop_options.hpp" |
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#endif // ASIO_ASSOCIATED_ALLOCATOR_HPP
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