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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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/** Options for @ref local_stream_acceptor::bind. */
 
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enum class bind_option
 
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{
 
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    /// Default: do not unlink the socket path.
 
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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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/** 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, or pass
 
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    @ref bind_option::unlink_existing to @ref bind.
 
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    @par Thread Safety
 
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    Distinct objects: Safe.@n
 
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    Shared objects: Unsafe. An acceptor must not have concurrent
 
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    accept operations.
 
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    @par Semantics
 
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    Wraps the platform Unix domain socket listener. Operations
 
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    dispatch to OS accept APIs via the io_context reactor.
 
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    Cancellation propagates through the IoAwaitable stop_token
 
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    or via @ref cancel; cancelled operations resume with
 
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    `errc::operation_canceled`.
 
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    @par Example
 
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    @code
 
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    io_context ioc;
 
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    local_stream_acceptor acc(ioc);
 
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    acc.open();
 
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    if (auto ec = acc.bind(
 
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            local_endpoint("/tmp/my.sock"),
 
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            bind_option::unlink_existing))
 
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        return ec;
 
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    if (auto ec = acc.listen())
 
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        return ec;
 
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    local_stream_socket peer(ioc);
 
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    auto [ec] = co_await acc.accept(peer);
 
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    if (!ec) {
 
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        // peer is now connected
 
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    }
 
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    @endcode
 
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    @see local_stream_socket, local_endpoint, local_stream
 
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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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            if (token_.stop_requested())
 
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            {
 
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                ec_ = make_error_code(std::errc::operation_canceled);
 
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                return h;
 
132 + 
            }
 
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            return acc_.get().accept(
 
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                h, env->executor, token_, &ec_, &peer_impl_);
 
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        }
 
136 + 
    };
 
137 +
 
138 + 
    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;
 
145 +
 
146 + 
        accept_awaitable(
 
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            local_stream_acceptor& acc, local_stream_socket& peer) noexcept
 
148 + 
            : acc_(acc)
 
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            , peer_(peer)
 
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        {
 
151 + 
        }
 
152 +
 
153 + 
        bool await_ready() const noexcept
 
154 + 
        {
 
155 + 
            return token_.stop_requested();
 
156 + 
        }
 
157 +
 
158 + 
        capy::io_result<> await_resume() const noexcept
 
159 + 
        {
 
160 + 
            if (token_.stop_requested())
 
161 + 
                return {make_error_code(std::errc::operation_canceled)};
 
162 +
 
163 + 
            if (!ec_ && peer_impl_)
 
164 + 
                peer_.h_.reset(peer_impl_);
 
165 + 
            return {ec_};
 
166 + 
        }
 
167 +
 
168 + 
        auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
 
169 + 
            -> std::coroutine_handle<>
 
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        {
 
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            token_ = env->stop_token;
 
172 + 
            if (token_.stop_requested())
 
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            {
 
174 + 
                ec_ = make_error_code(std::errc::operation_canceled);
 
175 + 
                return h;
 
176 + 
            }
 
177 + 
            return acc_.get().accept(
 
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                h, env->executor, token_, &ec_, &peer_impl_);
 
179 + 
        }
 
180 + 
    };
 
181 +
 
182 + 
public:
 
183 + 
    ~local_stream_acceptor() override;
 
184 +
 
185 + 
    explicit local_stream_acceptor(capy::execution_context& ctx);
 
186 +
 
187 + 
    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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    {
 
192 + 
    }
 
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194 + 
    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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218 + 
        @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.
 
223 +
 
224 + 
        @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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231 + 
        @throws std::logic_error if the acceptor is not open.
 
232 + 
    */
 
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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);
 
236 +
 
237 + 
    /** Start listening for incoming connections.
 
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        @param backlog The maximum pending connection queue length.
 
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241 + 
        @return An error code on failure, empty on success.
 
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243 + 
        @throws std::logic_error if the acceptor is not open.
 
244 + 
    */
 
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    [[nodiscard]] std::error_code listen(int backlog = 128);
 
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247 + 
    /// Close the acceptor.
 
248 + 
    void close();
 
249 +
 
250 + 
    /** Check if the acceptor has a native handle.
 
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252 + 
        Returns true once @ref open succeeds and until @ref close is
 
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        called. This does not indicate that @ref listen has been
 
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        invoked — an open-but-not-listening acceptor will still
 
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        report `true`.
 
256 + 
    */
 
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    bool is_open() const noexcept
 
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    {
 
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        return h_ && get().is_open();
 
260 + 
    }
 
261 +
 
262 + 
    /** Initiate an asynchronous accept operation.
 
263 +
 
264 + 
        @param peer The socket to receive the accepted connection.
 
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266 + 
        @return An awaitable that completes with io_result<>.
 
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268 + 
        @throws std::logic_error if the native acceptor handle is
 
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            absent (i.e., `!is_open()`). Calling accept on an
 
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            open-but-not-listening acceptor does not throw; the
 
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            awaitable completes with a kernel error such as
 
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            `errc::invalid_argument` (EINVAL).
 
273 + 
    */
 
274 + 
    auto accept(local_stream_socket& peer)
 
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    {
 
276 + 
        if (!is_open())
 
277 + 
            detail::throw_logic_error("accept: acceptor not open");
 
278 + 
        return accept_awaitable(*this, peer);
 
279 + 
    }
 
280 +
 
281 + 
    /** Initiate an asynchronous accept, returning the socket.
 
282 +
 
283 + 
        @return An awaitable that completes with
 
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            io_result<local_stream_socket>.
 
285 +
 
286 + 
        @throws std::logic_error if the native acceptor handle is
 
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            absent (i.e., `!is_open()`). Calling accept on an
 
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            open-but-not-listening acceptor does not throw; the
 
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            awaitable completes with a kernel error such as
 
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            `errc::invalid_argument` (EINVAL).
 
291 + 
    */
 
292 + 
    auto accept()
 
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    {
 
294 + 
        if (!is_open())
 
295 + 
            detail::throw_logic_error("accept: acceptor not open");
 
296 + 
        return move_accept_awaitable(*this);
 
297 + 
    }
 
298 +
 
299 + 
    void cancel();
 
300 +
 
301 + 
    /** Release ownership of the native socket handle.
 
302 +
 
303 + 
        Deregisters the acceptor from the reactor and cancels
 
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        pending operations without closing the fd.
 
305 +
 
306 + 
        @return The native handle.
 
307 +
 
308 + 
        @throws std::logic_error if the acceptor is not open.
 
309 + 
    */
 
310 + 
    native_handle_type release();
 
311 +
 
312 + 
    corosio::local_endpoint local_endpoint() const noexcept;
 
313 +
 
314 + 
    template<class Option>
 
315 + 
    void set_option(Option const& opt)
 
316 + 
    {
 
317 + 
        if (!is_open())
 
318 + 
            detail::throw_logic_error("set_option: acceptor not open");
 
319 + 
        std::error_code ec = get().set_option(
 
320 + 
            Option::level(), Option::name(), opt.data(), opt.size());
 
321 + 
        if (ec)
 
322 + 
            detail::throw_system_error(ec, "local_stream_acceptor::set_option");
 
323 + 
    }
 
324 +
 
325 + 
    template<class Option>
 
326 + 
    Option get_option() const
 
327 + 
    {
 
328 + 
        if (!is_open())
 
329 + 
            detail::throw_logic_error("get_option: acceptor not open");
 
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        Option opt{};
 
331 + 
        std::size_t sz = opt.size();
 
332 + 
        std::error_code ec =
 
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            get().get_option(Option::level(), Option::name(), opt.data(), &sz);
 
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        if (ec)
 
335 + 
            detail::throw_system_error(ec, "local_stream_acceptor::get_option");
 
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        opt.resize(sz);
 
337 + 
        return opt;
 
338 + 
    }
 
339 +
 
340 + 
    /** Define backend hooks for local stream acceptor operations. */
 
341 + 
    struct implementation : io_object::implementation
 
342 + 
    {
 
343 + 
        virtual std::coroutine_handle<> accept(
 
344 + 
            std::coroutine_handle<>,
 
345 + 
            capy::executor_ref,
 
346 + 
            std::stop_token,
 
347 + 
            std::error_code*,
 
348 + 
            io_object::implementation**) = 0;
 
349 +
 
350 + 
        virtual corosio::local_endpoint local_endpoint() const noexcept = 0;
 
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352 + 
        virtual bool is_open() const noexcept = 0;
 
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354 + 
        virtual native_handle_type release_socket() noexcept = 0;
 
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356 + 
        virtual void cancel() noexcept = 0;
 
357 +
 
358 + 
        virtual std::error_code set_option(
 
359 + 
            int level,
 
360 + 
            int optname,
 
361 + 
            void const* data,
 
362 + 
            std::size_t size) noexcept = 0;
 
363 +
 
364 + 
        virtual std::error_code
 
365 + 
        get_option(int level, int optname, void* data, std::size_t* size)
 
366 + 
            const noexcept = 0;
 
367 + 
    };
 
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protected:
 
370 + 
    local_stream_acceptor(handle h, capy::execution_context& ctx) noexcept
 
371 + 
        : io_object(std::move(h))
 
372 + 
        , ctx_(ctx)
 
373 + 
    {
 
374 + 
    }
 
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376 + 
    local_stream_acceptor(
 
377 + 
        capy::execution_context& ctx, local_stream_acceptor&& other) noexcept
 
378 + 
        : io_object(std::move(other))
 
379 + 
        , ctx_(ctx)
 
380 + 
    {
 
381 + 
    }
 
382 +
 
383 + 
    static void reset_peer_impl(
 
384 + 
        local_stream_socket& peer, io_object::implementation* impl) noexcept
 
385 + 
    {
 
386 + 
        if (impl)
 
387 + 
            peer.h_.reset(impl);
 
388 + 
    }
 
389 +
 
390 + 
private:
 
391 + 
    capy::execution_context& ctx_;
 
392 +
 
393 + 
    inline implementation& get() const noexcept
 
394 + 
    {
 
395 + 
        return *static_cast<implementation*>(h_.get());
 
396 + 
    }
 
397 + 
};
 
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} // namespace boost::corosio
 
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#endif // BOOST_COROSIO_LOCAL_STREAM_ACCEPTOR_HPP