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//
 
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// Copyright (c) 2026 Steve Gerbino
 
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//
 
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
 
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
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//
 
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// Official repository: https://github.com/cppalliance/corosio
 
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//
 
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#ifndef BOOST_COROSIO_IO_IO_SIGNAL_SET_HPP
 
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#define BOOST_COROSIO_IO_IO_SIGNAL_SET_HPP
 
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#include <boost/corosio/detail/config.hpp>
 
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#include <boost/corosio/io/io_object.hpp>
 
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#include <boost/capy/io_result.hpp>
 
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#include <boost/capy/error.hpp>
 
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#include <boost/capy/ex/executor_ref.hpp>
 
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#include <boost/capy/ex/io_env.hpp>
 
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#include <coroutine>
 
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#include <stop_token>
 
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#include <system_error>
 
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namespace boost::corosio {
 
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/** Abstract base for asynchronous signal sets.
 
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    Provides the common signal set interface: `wait` and `cancel`.
 
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    Concrete classes like @ref signal_set add signal registration
 
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    (add, remove, clear) and platform-specific flags.
 
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    @par Thread Safety
 
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    Distinct objects: Safe.
 
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    Shared objects: Unsafe.
 
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    @see signal_set, io_object
 
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*/
 
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class BOOST_COROSIO_DECL io_signal_set : public io_object
 
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{
 
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    struct wait_awaitable
 
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    {
 
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        io_signal_set& s_;
 
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        std::stop_token token_;
 
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        mutable std::error_code ec_;
 
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        mutable int signal_number_ = 0;
 
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        explicit wait_awaitable(io_signal_set& s) noexcept : s_(s) {}
 
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        bool await_ready() const noexcept
 
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        {
 
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            return token_.stop_requested();
 
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        }
 
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        capy::io_result<int> await_resume() const noexcept
 
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        {
 
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            if (token_.stop_requested())
 
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                return {capy::error::canceled};
 
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            return {ec_, signal_number_};
 
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        }
 
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        auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
 
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            -> std::coroutine_handle<>
 
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        {
 
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            token_ = env->stop_token;
 
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            return s_.get().wait(
 
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                h, env->executor, token_, &ec_, &signal_number_);
 
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        }
 
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    };
 
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public:
 
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    struct implementation : io_object::implementation
 
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    {
 
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        virtual std::coroutine_handle<> wait(
 
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            std::coroutine_handle<>,
 
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            capy::executor_ref,
 
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            std::stop_token,
 
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            std::error_code*,
 
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            int*) = 0;
 
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        virtual void cancel() = 0;
 
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    };
 
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    /** Cancel all operations associated with the signal set.
 
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        Forces the completion of any pending asynchronous wait
 
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        operations. Each cancelled operation completes with an error
 
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        code that compares equal to `capy::cond::canceled`.
 
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        Cancellation does not alter the set of registered signals.
 
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    */
 
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    void cancel()
 
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    {
 
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        do_cancel();
 
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    }
 
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    /** Wait for a signal to be delivered.
 
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        The operation supports cancellation via `std::stop_token` through
 
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        the affine awaitable protocol. If the associated stop token is
 
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        triggered, the operation completes immediately with an error
 
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        that compares equal to `capy::cond::canceled`.
 
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        @return An awaitable that completes with `io_result<int>`.
 
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            Returns the signal number when a signal is delivered,
 
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            or an error code on failure.
 
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    */
 
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    auto wait()
 
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    {
 
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        return wait_awaitable(*this);
 
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    }
 
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protected:
 
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    /** Dispatch cancel to the concrete implementation. */
 
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    virtual void do_cancel() = 0;
 
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    explicit io_signal_set(handle h) noexcept : io_object(std::move(h)) {}
 
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    /// Move construct.
 
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    io_signal_set(io_signal_set&& other) noexcept : io_object(std::move(other))
 
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    {
 
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    }
 
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    /// Move assign.
 
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    io_signal_set& operator=(io_signal_set&& other) noexcept
 
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    {
 
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        if (this != &other)
 
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            h_ = std::move(other.h_);
 
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        return *this;
 
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    }
 
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    io_signal_set(io_signal_set const&)            = delete;
 
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    io_signal_set& operator=(io_signal_set const&) = delete;
 
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private:
 
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    implementation& get() const noexcept
 
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    {
 
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        return *static_cast<implementation*>(h_.get());
 
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    }
 
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};
 
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} // namespace boost::corosio
 
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#endif