mirror of
https://github.com/matrix-construct/construct
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107 lines
3.1 KiB
C++
107 lines
3.1 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) 2016-2018 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_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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using allocator_state = ircd::allocator::node<T *>;
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using allocator_type = typename allocator_state::allocator;
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using list_type = std::list<T *, allocator_type>;
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using list_node = typename list_type::iterator::_Node;
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static allocator_state allocator;
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static list_type list;
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protected:
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list_node node;
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typename list_type::iterator it;
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instance_list();
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instance_list(instance_list &&) noexcept;
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instance_list(const instance_list &);
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instance_list &operator=(instance_list &&) noexcept;
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instance_list &operator=(const instance_list &);
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~instance_list() noexcept;
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};
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template<class T>
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ircd::util::instance_list<T>::instance_list()
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{
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const auto &address(reinterpret_cast<uint8_t *>(&node));
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list.get_allocator().s->next = reinterpret_cast<T **>(address);
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it = list.emplace(end(list), static_cast<T *>(this));
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list.get_allocator().s->next = nullptr;
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}
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template<class T>
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ircd::util::instance_list<T>::instance_list(instance_list &&other)
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noexcept
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{
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const auto &address(reinterpret_cast<uint8_t *>(&node));
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list.get_allocator().s->next = reinterpret_cast<T **>(address);
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it = list.emplace(end(list), static_cast<T *>(this));
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list.get_allocator().s->next = nullptr;
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}
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template<class T>
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ircd::util::instance_list<T>::instance_list(const instance_list &other)
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{
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const auto &address(reinterpret_cast<uint8_t *>(&node));
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list.get_allocator().s->next = reinterpret_cast<T **>(address);
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it = list.emplace(end(list), static_cast<T *>(this));
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list.get_allocator().s->next = nullptr;
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}
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template<class T>
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ircd::util::instance_list<T> &
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ircd::util::instance_list<T>::operator=(instance_list &&other)
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noexcept
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{
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assert(it != end(list));
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return *this;
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}
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template<class T>
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ircd::util::instance_list<T> &
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ircd::util::instance_list<T>::operator=(const instance_list &other)
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{
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assert(it != end(list));
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return *this;
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}
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template<class T>
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ircd::util::instance_list<T>::~instance_list()
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noexcept
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{
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assert(it != end(list));
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list.erase(it);
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}
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