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//
 
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// Copyright (c) 2026 Michael Vandeberg
 
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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_LOCAL_STREAM_ACCEPTOR_HPP
 
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#define BOOST_COROSIO_LOCAL_STREAM_ACCEPTOR_HPP
 
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#include <boost/corosio/detail/config.hpp>
 
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#include <boost/corosio/detail/except.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/corosio/local_endpoint.hpp>
 
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#include <boost/corosio/local_stream.hpp>
 
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#include <boost/corosio/local_stream_socket.hpp>
 
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#include <boost/capy/ex/executor_ref.hpp>
 
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#include <boost/capy/ex/execution_context.hpp>
 
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#include <boost/capy/ex/io_env.hpp>
 
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#include <boost/capy/concept/executor.hpp>
 
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#include <system_error>
 
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#include <cassert>
 
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#include <concepts>
 
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#include <coroutine>
 
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#include <cstddef>
 
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#include <stop_token>
 
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#include <type_traits>
 
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namespace boost::corosio {
 
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/* An asynchronous Unix stream acceptor for coroutine I/O.
 
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   This class provides asynchronous Unix domain stream accept
 
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   operations that return awaitable types. The acceptor binds
 
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   to a local endpoint (filesystem path) and listens for
 
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   incoming connections.
 
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   The library does NOT automatically unlink the socket path
 
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   on close. Callers are responsible for removing the socket
 
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   file before bind or after close.
 
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   Thread Safety:
 
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     Distinct objects: Safe.
 
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     Shared objects: Unsafe. An acceptor must not have
 
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     concurrent accept operations.
 
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*/
 
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/** Options for local_stream_acceptor::bind(). */
 
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enum class bind_option
 
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{
 
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    none,
 
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    /// Unlink the socket path before binding (ignored for abstract paths).
 
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    unlink_existing
 
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};
 
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class BOOST_COROSIO_DECL local_stream_acceptor : public io_object
 
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{
 
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    struct move_accept_awaitable
 
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    {
 
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        local_stream_acceptor& acc_;
 
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        std::stop_token token_;
 
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        mutable std::error_code ec_;
 
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        mutable io_object::implementation* peer_impl_ = nullptr;
 
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        explicit move_accept_awaitable(
 
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            local_stream_acceptor& acc) noexcept
 
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            : acc_(acc)
 
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        {
 
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        }
 
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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<local_stream_socket> await_resume() const noexcept
 
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        {
 
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            if (token_.stop_requested())
 
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                return {make_error_code(std::errc::operation_canceled),
 
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                        local_stream_socket()};
 
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            if (ec_ || !peer_impl_)
 
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                return {ec_, local_stream_socket()};
 
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            local_stream_socket peer(acc_.ctx_);
 
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            reset_peer_impl(peer, peer_impl_);
 
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            return {ec_, std::move(peer)};
 
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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 acc_.get().accept(
 
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                h, env->executor, token_, &ec_, &peer_impl_);
 
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        }
 
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    };
 
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    struct accept_awaitable
 
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    {
 
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        local_stream_acceptor& acc_;
 
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        local_stream_socket& peer_;
 
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        std::stop_token token_;
 
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        mutable std::error_code ec_;
 
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        mutable io_object::implementation* peer_impl_ = nullptr;
 
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        accept_awaitable(
 
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            local_stream_acceptor& acc, local_stream_socket& peer) noexcept
 
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            : acc_(acc)
 
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            , peer_(peer)
 
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        {
 
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        }
 
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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<> await_resume() const noexcept
 
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        {
 
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            if (token_.stop_requested())
 
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                return {make_error_code(std::errc::operation_canceled)};
 
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            if (!ec_ && peer_impl_)
 
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                peer_.h_.reset(peer_impl_);
 
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            return {ec_};
 
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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 acc_.get().accept(
 
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                h, env->executor, token_, &ec_, &peer_impl_);
 
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        }
 
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    };
 
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public:
 
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    ~local_stream_acceptor() override;
 
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    explicit local_stream_acceptor(capy::execution_context& ctx);
 
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    template<class Ex>
 
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        requires(!std::same_as<std::remove_cvref_t<Ex>, local_stream_acceptor>) &&
 
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        capy::Executor<Ex>
 
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    explicit local_stream_acceptor(Ex const& ex) : local_stream_acceptor(ex.context())
 
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    {
 
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    }
 
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    local_stream_acceptor(local_stream_acceptor&& other) noexcept
 
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        : local_stream_acceptor(other.ctx_, std::move(other))
 
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    {
 
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    }
 
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    local_stream_acceptor& operator=(local_stream_acceptor&& other) noexcept
 
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    {
 
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        assert(&ctx_ == &other.ctx_ &&
 
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            "move-assign requires the same execution_context");
 
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        if (this != &other)
 
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        {
 
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            close();
 
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            io_object::operator=(std::move(other));
 
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        }
 
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        return *this;
 
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    }
 
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    local_stream_acceptor(local_stream_acceptor const&)            = delete;
 
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    local_stream_acceptor& operator=(local_stream_acceptor const&) = delete;
 
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    /** Create the acceptor socket.
 
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        @param proto The protocol. Defaults to local_stream{}.
 
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        @throws std::system_error on failure.
 
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    */
 
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    void open(local_stream proto = {});
 
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    /** Bind to a local endpoint.
 
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        @param ep The local endpoint (path) to bind to.
 
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        @param opt Bind options. Pass bind_option::unlink_existing
 
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            to unlink the socket path before binding (ignored for
 
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            abstract sockets and empty endpoints).
 
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        @return An error code on failure, empty on success.
 
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        @throws std::logic_error if the acceptor is not open.
 
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    */
 
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    [[nodiscard]] std::error_code
 
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    bind(corosio::local_endpoint ep,
 
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         bind_option opt = bind_option::none);
 
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    /** Start listening for incoming connections.
 
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        @param backlog The maximum pending connection queue length.
 
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        @return An error code on failure, empty on success.
 
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        @throws std::logic_error if the acceptor is not open.
 
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    */
 
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    [[nodiscard]] std::error_code listen(int backlog = 128);
 
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    /// Close the acceptor.
 
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    void close();
 
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    /// Check if the acceptor is listening.
 
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    bool is_open() const noexcept
 
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    {
 
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        return h_ && get().is_open();
 
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    }
 
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    /** Initiate an asynchronous accept operation.
 
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        @param peer The socket to receive the accepted connection.
 
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        @return An awaitable that completes with io_result<>.
 
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        @throws std::logic_error if the acceptor is not listening.
 
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    */
 
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    auto accept(local_stream_socket& peer)
 
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    {
 
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        if (!is_open())
 
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            detail::throw_logic_error("accept: acceptor not listening");
 
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        return accept_awaitable(*this, peer);
 
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    }
 
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    /** Initiate an asynchronous accept, returning the socket.
 
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        @return An awaitable that completes with
 
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            io_result<local_stream_socket>.
 
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        @throws std::logic_error if the acceptor is not listening.
 
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    */
 
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    auto accept()
 
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    {
 
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        if (!is_open())
 
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            detail::throw_logic_error("accept: acceptor not listening");
 
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        return move_accept_awaitable(*this);
 
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    }
 
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    void cancel();
 
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    /** Release ownership of the native socket handle.
 
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        Deregisters the acceptor from the reactor and cancels
 
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        pending operations without closing the fd.
 
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        @return The native handle, or -1 if not open.
 
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        @throws std::logic_error if the acceptor is not open.
 
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    */
 
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    native_handle_type release();
 
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    corosio::local_endpoint local_endpoint() const noexcept;
 
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    template<class Option>
 
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    void set_option(Option const& opt)
 
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    {
 
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        if (!is_open())
 
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            detail::throw_logic_error("set_option: acceptor not open");
 
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        std::error_code ec = get().set_option(
 
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            Option::level(), Option::name(), opt.data(), opt.size());
 
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        if (ec)
 
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            detail::throw_system_error(ec, "local_stream_acceptor::set_option");
 
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    }
 
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    template<class Option>
 
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    Option get_option() const
 
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    {
 
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        if (!is_open())
 
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            detail::throw_logic_error("get_option: acceptor not open");
 
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        Option opt{};
 
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        std::size_t sz = opt.size();
 
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        std::error_code ec =
 
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            get().get_option(Option::level(), Option::name(), opt.data(), &sz);
 
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        if (ec)
 
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            detail::throw_system_error(ec, "local_stream_acceptor::get_option");
 
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        opt.resize(sz);
 
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        return opt;
 
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    }
 
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    /** Define backend hooks for local stream acceptor operations. */
 
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    struct implementation : io_object::implementation
 
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    {
 
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        virtual std::coroutine_handle<> accept(
 
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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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            io_object::implementation**) = 0;
 
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        virtual corosio::local_endpoint local_endpoint() const noexcept = 0;
 
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        virtual bool is_open() const noexcept = 0;
 
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        virtual native_handle_type release_socket() noexcept = 0;
 
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        virtual void cancel() noexcept = 0;
 
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        virtual std::error_code set_option(
 
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            int level,
 
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            int optname,
 
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            void const* data,
 
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            std::size_t size) noexcept = 0;
 
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310 + 
        virtual std::error_code
 
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        get_option(int level, int optname, void* data, std::size_t* size)
 
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            const noexcept = 0;
 
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    };
 
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protected:
 
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    local_stream_acceptor(handle h, capy::execution_context& ctx) noexcept
 
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        : io_object(std::move(h))
 
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        , ctx_(ctx)
 
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    {
 
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    }
 
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    local_stream_acceptor(
 
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        capy::execution_context& ctx, local_stream_acceptor&& other) noexcept
 
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        : io_object(std::move(other))
 
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        , ctx_(ctx)
 
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    {
 
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    }
 
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329 + 
    static void reset_peer_impl(
 
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        local_stream_socket& peer, io_object::implementation* impl) noexcept
 
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    {
 
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        if (impl)
 
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            peer.h_.reset(impl);
 
334 + 
    }
 
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private:
 
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    capy::execution_context& ctx_;
 
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339 + 
    inline implementation& get() const noexcept
 
340 + 
    {
 
341 + 
        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 // BOOST_COROSIO_LOCAL_STREAM_ACCEPTOR_HPP