mirror of
https://github.com/matrix-construct/construct
synced 2024-06-17 17:38:22 +02:00
66 lines
2.6 KiB
C++
66 lines
2.6 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_JS_CONTRACT_H
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namespace ircd {
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namespace js {
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// contract is a promise from C to a future in JS. When a task has no more pending contracts,
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// it ceases to exist.
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//
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// * The promise is the `struct contract` instantiated in C.
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// * The future is returned into JS as an object trapped by "future" (future.so)
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// * C unconditionally enters the closure to report result.
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// * * if the C closure returns a `value` the "value" field is set in JS
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// * * if the C closure throws an exception the "error" field conveys the exception in JS
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// *
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// * "id": uint
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// * "value": object [optional]
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// * "error": exception object [optional]
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//
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struct contract
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:std::weak_ptr<struct task>
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{
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using closure = std::function<value ()>;
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object future;
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operator const object &() const { return future; }
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operator object &() { return future; }
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operator value() const { return future; }
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// Enter this closure and return or throw to complete the result contract.
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void operator()(const closure &) noexcept;
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// The future object is constructed using the "future" trap.
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// The task is automatically found with task::get() in the overload without a task argument.
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contract(struct task &, object::handle future);
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contract(object::handle future);
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contract(contract &&) = default;
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contract(const contract &) = default;
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~contract() noexcept;
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};
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} // namespace js
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} // namespace ircd
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