mirror of
https://github.com/matrix-construct/construct
synced 2024-06-01 09:38:58 +02:00
130 lines
2.7 KiB
C++
130 lines
2.7 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_IOV_H
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namespace ircd
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{
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template<class T> struct iov;
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}
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/// iov (iovector) is a forward list composed on a trip up the stack
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/// presenting an iteration of items to a scatter/gather operation like a
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/// socket or JSON generator etc. Add items to the iov by constructing nodes
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/// on your stack.
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///
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template<class T>
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struct ircd::iov
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:std::forward_list<T, typename allocator::node<T>::allocator>
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{
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struct node;
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using allocator_state = allocator::node<T>;
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using allocator_type = typename allocator_state::allocator;
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using list = std::forward_list<T, allocator_type>;
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using list_node = typename list::iterator::_Node; //TODO: YYY
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auto size() const
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{
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return std::distance(std::begin(*this), std::end(*this));
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}
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allocator_state a;
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iov(): list{a} {}
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};
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template<class T>
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struct ircd::iov<T>::node
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:iov::list_node
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{
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iov *const i {nullptr};
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operator const T &() const;
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operator T &();
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node() = default;
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template<class... args> node(iov *const &, args&&...);
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template<class... args> node(iov &, args&&...);
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node(node &&) = delete;
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node(const node &) = delete;
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node &operator=(node &&) = delete;
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node &operator=(const node &) = delete;
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~node() noexcept;
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};
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template<class T>
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template<class... args>
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ircd::iov<T>::node::node(iov &iov,
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args&&... a)
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:node
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{
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&iov, std::forward<args>(a)...
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}
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{}
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template<class T>
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template<class... args>
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ircd::iov<T>::node::node(iov *const &iov,
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args&&... a)
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:i{iov}
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{
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if(!iov)
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return;
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auto &list
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{
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*static_cast<iov::list *>(iov)
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};
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auto &list_node
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{
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*static_cast<iov::list_node *>(this)
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};
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const auto &address
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{
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reinterpret_cast<uint8_t *>(&list_node)
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};
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list.get_allocator().s->next = reinterpret_cast<T *>(address);
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list.emplace_front(std::forward<args>(a)...);
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}
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template<class T>
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ircd::iov<T>::node::~node()
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noexcept
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{
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if(i) i->remove_if([this](const T &x)
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{
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return &x == &static_cast<const T &>(*this);
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});
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}
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template<class T>
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ircd::iov<T>::node::operator
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T &()
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{
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assert(i);
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auto &list_node(static_cast<iov::list_node &>(*this));
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return *list_node._M_valptr(); //TODO: XXX
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}
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template<class T>
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ircd::iov<T>::node::operator
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const T &()
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const
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{
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assert(i);
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const auto &list_node(static_cast<const iov::list_node &>(*this));
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return *list_node._M_valptr(); //TODO: XXX
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}
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