93 lines
2.8 KiB
C++
93 lines
2.8 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License Version 2.0 with LLVM Exceptions
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* https://llvm.org/LICENSE.txt
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <unifex/detail/unifex_fwd.hpp>
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#include <unifex/stop_token_concepts.hpp>
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#include <unifex/inplace_stop_token.hpp>
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#include <unifex/tag_invoke.hpp>
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#include <unifex/type_traits.hpp>
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#include <unifex/coroutine.hpp>
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#include <unifex/unstoppable_token.hpp>
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#include <unifex/detail/prologue.hpp>
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namespace unifex {
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namespace _get_stop_token {
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inline const struct _fn {
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#if !UNIFEX_NO_COROUTINES
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private:
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class _awaitable {
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template <typename StopToken>
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struct _awaiter {
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StopToken stoken_;
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bool await_ready() const noexcept {
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return true;
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}
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void await_suspend(coro::coroutine_handle<>) const noexcept {
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}
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StopToken await_resume() noexcept {
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return (StopToken&&) stoken_;
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}
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};
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template (typename Tag, typename Promise)
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(requires same_as<Tag, tag_t<await_transform>>)
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friend auto tag_invoke(Tag, Promise& promise, _awaitable) noexcept {
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return _awaiter<callable_result_t<_fn, Promise&>>{_fn{}(promise)};
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}
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};
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public:
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// `co_await get_stop_token()` to fetch a coroutine's current stop token.
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[[nodiscard]] constexpr _awaitable operator()() const noexcept {
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return {};
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}
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#endif
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template (typename T)
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(requires (!tag_invocable<_fn, const T&>))
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constexpr auto operator()(const T&) const noexcept
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-> unstoppable_token {
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return unstoppable_token{};
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}
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template (typename T)
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(requires tag_invocable<_fn, const T&>)
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constexpr auto operator()(const T& object) const noexcept
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-> tag_invoke_result_t<_fn, const T&> {
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static_assert(
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is_nothrow_tag_invocable_v<_fn, const T&>,
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"get_stop_token() customisations must be declared noexcept");
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return tag_invoke(_fn{}, object);
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}
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} get_stop_token{};
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} // namespace _get_stop_token
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using _get_stop_token::get_stop_token;
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template <typename T>
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using get_stop_token_result_t =
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callable_result_t<tag_t<get_stop_token>, T>;
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template <typename Receiver>
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using stop_token_type_t =
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remove_cvref_t<get_stop_token_result_t<Receiver>>;
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} // namespace unifex
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#include <unifex/detail/epilogue.hpp>
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