mirror of
https://github.com/matrix-construct/construct
synced 2024-06-02 10:08:56 +02:00
78 lines
2.5 KiB
C++
78 lines
2.5 KiB
C++
// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk
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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.
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//
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// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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// IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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#pragma once
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#define HAVE_IRCD_UTIL_INSTANCE_LIST_H
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namespace ircd::util
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{
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template<class T> struct instance_list;
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}
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/// The instance_list pattern is where every instance of a class registers
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/// itself in a static list of all instances and removes itself on dtor.
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/// IRCd Ex. All clients use instance_list so all clients can be listed for
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/// an administrator or be interrupted and disconnected on server shutdown.
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///
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/// `struct myobj : ircd::instance_list<myobj> {};`
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///
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/// * The creator of the class no longer has to manually specify what is
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/// defined here using unique_iterator; however, one still must provide
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/// linkage for the static list.
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///
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/// * The container pointer used by unique_iterator is eliminated here
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/// because of the static list.
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///
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template<class T>
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struct ircd::util::instance_list
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{
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static std::list<T *> list;
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protected:
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typename decltype(list)::iterator it;
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instance_list(typename decltype(list)::iterator it)
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:it{std::move(it)}
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{}
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instance_list()
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:it{list.emplace(end(list), static_cast<T *>(this))}
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{}
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instance_list(const instance_list &) = delete;
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instance_list(instance_list &&o) noexcept
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:it{std::move(o.it)}
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{
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o.it = end(list);
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}
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instance_list &operator=(const instance_list &) = delete;
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instance_list &operator=(instance_list &&o) noexcept
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{
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std::swap(it, o.it);
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return *this;
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}
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~instance_list() noexcept
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{
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if(it != end(list))
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list.erase(it);
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}
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};
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