mirror of
https://github.com/matrix-construct/construct
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51 lines
1.3 KiB
C++
51 lines
1.3 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_COUNT_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_count;
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}}
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/// Increment a counter when constructed and decrement it when destructed.
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/// This takes a runtime reference to that counter. The counter thus maintains
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/// the number of reentrances (or entrances across different contexts).
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///
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template<class T>
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struct ircd::util::scope_count
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{
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T *count {nullptr};
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T inc {1};
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scope_count(T &count, const T & = 1);
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scope_count(const scope_count &) = delete;
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scope_count(scope_count &&) noexcept = delete;
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~scope_count() noexcept;
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};
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template<class T>
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ircd::util::scope_count<T>::scope_count(T &count,
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const T &inc)
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:count{&count}
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,inc{inc}
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{
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count += inc;
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}
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template<class T>
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ircd::util::scope_count<T>::~scope_count()
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noexcept
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{
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assert(count);
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(*count) -= inc;
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}
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