mirror of
https://github.com/matrix-construct/construct
synced 2024-06-10 14:08:56 +02:00
125 lines
3 KiB
C++
125 lines
3 KiB
C++
/*
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* charybdis5
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* Copyright (C) 2016 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.
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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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*/
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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 &, 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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:i{&iov}
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{
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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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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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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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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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