mirror of
https://github.com/matrix-construct/construct
synced 2024-11-30 02:32:43 +01:00
81 lines
3 KiB
C++
81 lines
3 KiB
C++
/*
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* Copyright (C) 2016 Charybdis Development Team
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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_CTX_CONTINUATION_H
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// This file is not included with the IRCd standard include stack because
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// it requires symbols we can't forward declare without boost headers. It
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// is part of the <ircd/asio.h> stack which can be included in your
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// definition file if necessary.
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namespace ircd::ctx
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{
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using yield_context = boost::asio::yield_context;
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struct continuation;
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struct to_asio;
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}
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namespace ircd
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{
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using ctx::yield_context;
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using ctx::continuation;
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using ctx::to_asio;
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}
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/// This object must be placed on the stack when the context is yielding (INTERNAL)
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///
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/// The continuation constructor is the last thing executed before a context
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/// yields. The continuation destructor is the first thing executed when a
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/// context continues. This is not placed by a normal user wishing to context
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/// switch, only a low-level library creator actually implementing the context
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/// switch itself. The placement of this object must be correct. Generally,
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/// we construct the `continuation` as an argument to `yield_context` as such
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/// `yield_context{continuation{}}`. This ensures the continuation destructor
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/// executes before control continues beyond the yield_context call itself and
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/// ties this sequence together neatly.
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///
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struct ircd::ctx::continuation
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{
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ctx *self;
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operator const boost::asio::yield_context &() const;
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operator boost::asio::yield_context &();
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continuation(ctx *const &self = ircd::ctx::current);
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~continuation() noexcept;
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};
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/// This type of continuation should be used when yielding a context to a
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/// boost::asio handler so we can have specific control over that type of
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/// context switch in possible contrast or extension of the regular
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/// continuation behavior.
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///
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/// The statement `yield_context{to_asio{}}` can be passed to any boost::asio
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/// callback handler. Those handlers have overloads to accept this, many of
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/// which are not documented.
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///
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struct ircd::ctx::to_asio
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:ircd::ctx::continuation
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{
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using continuation::continuation;
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};
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