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1 | // |
2 | // detail/std_global.hpp | |
3 | // ~~~~~~~~~~~~~~~~~~~~~ | |
4 | // | |
92f5a8d4 | 5 | // Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
b32b8144 FG |
6 | // |
7 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
8 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
9 | // | |
10 | ||
11 | #ifndef BOOST_ASIO_DETAIL_STD_GLOBAL_HPP | |
12 | #define BOOST_ASIO_DETAIL_STD_GLOBAL_HPP | |
13 | ||
14 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) | |
15 | # pragma once | |
16 | #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) | |
17 | ||
18 | #include <boost/asio/detail/config.hpp> | |
19 | ||
20 | #if defined(BOOST_ASIO_HAS_STD_CALL_ONCE) | |
21 | ||
22 | #include <exception> | |
23 | #include <mutex> | |
24 | ||
25 | #include <boost/asio/detail/push_options.hpp> | |
26 | ||
27 | namespace boost { | |
28 | namespace asio { | |
29 | namespace detail { | |
30 | ||
31 | template <typename T> | |
32 | struct std_global_impl | |
33 | { | |
34 | // Helper function to perform initialisation. | |
35 | static void do_init() | |
36 | { | |
37 | instance_.ptr_ = new T; | |
38 | } | |
39 | ||
40 | // Destructor automatically cleans up the global. | |
41 | ~std_global_impl() | |
42 | { | |
43 | delete ptr_; | |
44 | } | |
45 | ||
46 | static std::once_flag init_once_; | |
47 | static std_global_impl instance_; | |
48 | T* ptr_; | |
49 | }; | |
50 | ||
51 | template <typename T> | |
52 | std::once_flag std_global_impl<T>::init_once_; | |
53 | ||
54 | template <typename T> | |
55 | std_global_impl<T> std_global_impl<T>::instance_; | |
56 | ||
57 | template <typename T> | |
58 | T& std_global() | |
59 | { | |
60 | std::call_once(std_global_impl<T>::init_once_, &std_global_impl<T>::do_init); | |
61 | return *std_global_impl<T>::instance_.ptr_; | |
62 | } | |
63 | ||
64 | } // namespace detail | |
65 | } // namespace asio | |
66 | } // namespace boost | |
67 | ||
68 | #include <boost/asio/detail/pop_options.hpp> | |
69 | ||
70 | #endif // defined(BOOST_ASIO_HAS_STD_CALL_ONCE) | |
71 | ||
72 | #endif // BOOST_ASIO_DETAIL_STD_GLOBAL_HPP |