60 lines
1.2 KiB
C++
60 lines
1.2 KiB
C++
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//
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// detail/null_global.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2021 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_DETAIL_NULL_GLOBAL_HPP
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#define ASIO_DETAIL_NULL_GLOBAL_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 "asio/detail/push_options.hpp"
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namespace asio {
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namespace detail {
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template <typename T>
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struct null_global_impl
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{
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null_global_impl()
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: ptr_(0)
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{
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}
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// Destructor automatically cleans up the global.
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~null_global_impl()
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{
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delete ptr_;
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}
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static null_global_impl instance_;
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T* ptr_;
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};
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template <typename T>
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null_global_impl<T> null_global_impl<T>::instance_;
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template <typename T>
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T& null_global()
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{
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if (null_global_impl<T>::instance_.ptr_ == 0)
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null_global_impl<T>::instance_.ptr_ = new T;
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return *null_global_impl<T>::instance_.ptr_;
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}
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} // namespace detail
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} // namespace asio
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#include "asio/detail/pop_options.hpp"
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#endif // ASIO_DETAIL_NULL_GLOBAL_HPP
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