mirror of
https://github.com/matrix-construct/construct
synced 2024-12-11 08:02:59 +01:00
70 lines
1.8 KiB
C++
70 lines
1.8 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_UTIL_SCOPE_RESTORE_H
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namespace ircd {
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inline namespace util
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{
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template<class T> struct scope_restore;
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}}
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/// Overwrite a value for the duration of the instance restoring the
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/// original value at destruction. Device cannot be moved or copied.
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///
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template<class T>
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struct ircd::util::scope_restore
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{
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T *restore {nullptr};
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T theirs;
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scope_restore(T &restore) noexcept;
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scope_restore(T &restore, T&& ours);
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template<class... args> scope_restore(T &restore, args&&... ours);
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scope_restore(const scope_restore &) = delete;
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scope_restore(scope_restore &&) noexcept = delete;
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~scope_restore() noexcept;
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};
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template<class T>
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ircd::util::scope_restore<T>::scope_restore(T &restore)
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noexcept
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:restore{&restore}
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,theirs{std::move(restore)}
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{
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}
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template<class T>
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ircd::util::scope_restore<T>::scope_restore(T &restore,
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T&& ours)
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:restore{&restore}
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,theirs{std::move(restore)}
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{
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restore = std::forward<T>(ours);
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}
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template<class T>
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template<class... args>
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ircd::util::scope_restore<T>::scope_restore(T &restore,
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args&&... ours)
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:restore{&restore}
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,theirs{std::move(restore)}
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{
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new (&restore) T(std::forward<args>(ours)...);
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}
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template<class T>
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ircd::util::scope_restore<T>::~scope_restore()
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noexcept
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{
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assert(restore);
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*restore = std::move(theirs);
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}
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