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//
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//
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// Copyright (c) 2026 Steve Gerbino
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// Copyright (c) 2026 Steve Gerbino
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//
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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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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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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//
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// Official repository: https://github.com/cppalliance/corosio
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// Official repository: https://github.com/cppalliance/corosio
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//
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//
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#ifndef BOOST_COROSIO_IO_IO_READ_STREAM_HPP
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#ifndef BOOST_COROSIO_IO_IO_READ_STREAM_HPP
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#define BOOST_COROSIO_IO_IO_READ_STREAM_HPP
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#define BOOST_COROSIO_IO_IO_READ_STREAM_HPP
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#include <boost/corosio/detail/config.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/corosio/io/io_object.hpp>
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#include <boost/corosio/io_buffer_param.hpp>
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#include <boost/corosio/io_buffer_param.hpp>
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#include <boost/capy/io_result.hpp>
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#include <boost/capy/io_result.hpp>
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#include <boost/capy/ex/executor_ref.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 <boost/capy/ex/io_env.hpp>
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#include <coroutine>
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#include <coroutine>
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#include <cstddef>
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#include <cstddef>
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#include <stop_token>
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#include <stop_token>
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#include <system_error>
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#include <system_error>
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namespace boost::corosio {
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namespace boost::corosio {
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/** Abstract base for streams that support async reads.
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/** Abstract base for streams that support async reads.
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    Provides the `read_some` operation via a pure virtual
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    Provides the `read_some` operation via a pure virtual
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    `do_read_some` dispatch point. Concrete classes override
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    `do_read_some` dispatch point. Concrete classes override
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    `do_read_some` to route through their implementation.
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    `do_read_some` to route through their implementation.
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    Uses virtual inheritance from @ref io_object so that
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    Uses virtual inheritance from @ref io_object so that
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    @ref io_stream can combine this with @ref io_write_stream
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    @ref io_stream can combine this with @ref io_write_stream
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    without duplicating the `io_object` base.
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    without duplicating the `io_object` base.
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    @par Thread Safety
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    @par Thread Safety
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    Distinct objects: Safe.
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    Distinct objects: Safe.
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    Shared objects: Unsafe.
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    Shared objects: Unsafe.
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    @see io_write_stream, io_stream, io_object
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    @see io_write_stream, io_stream, io_object
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*/
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*/
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class BOOST_COROSIO_DECL io_read_stream : virtual public io_object
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class BOOST_COROSIO_DECL io_read_stream : virtual public io_object
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{
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{
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protected:
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protected:
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    /// Awaitable for async read operations.
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    /// Awaitable for async read operations.
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    template<class MutableBufferSequence>
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    template<class MutableBufferSequence>
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    struct read_some_awaitable
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    struct read_some_awaitable
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    {
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    {
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        io_read_stream& ios_;
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        io_read_stream& ios_;
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        MutableBufferSequence buffers_;
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        MutableBufferSequence buffers_;
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        std::stop_token token_;
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        std::stop_token token_;
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        mutable std::error_code ec_;
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        mutable std::error_code ec_;
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        mutable std::size_t bytes_transferred_ = 0;
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        mutable std::size_t bytes_transferred_ = 0;
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        read_some_awaitable(
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        read_some_awaitable(
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            io_read_stream& ios, MutableBufferSequence buffers) noexcept
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            io_read_stream& ios, MutableBufferSequence buffers) noexcept
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            : ios_(ios)
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            : ios_(ios)
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            , buffers_(std::move(buffers))
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            , buffers_(std::move(buffers))
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        {
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        {
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        }
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        }
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        bool await_ready() const noexcept
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        bool await_ready() const noexcept
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        {
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        {
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            return token_.stop_requested();
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            return token_.stop_requested();
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        }
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        }
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        capy::io_result<std::size_t> await_resume() const noexcept
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        capy::io_result<std::size_t> await_resume() const noexcept
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        {
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        {
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            if (token_.stop_requested())
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            if (token_.stop_requested())
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                return {make_error_code(std::errc::operation_canceled), 0};
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                return {make_error_code(std::errc::operation_canceled), 0};
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            return {ec_, bytes_transferred_};
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            return {ec_, bytes_transferred_};
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        }
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        }
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        auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
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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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            -> std::coroutine_handle<>
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        {
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        {
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            token_ = env->stop_token;
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            token_ = env->stop_token;
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            return ios_.do_read_some(
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            return ios_.do_read_some(
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                h, env->executor, buffers_, token_, &ec_, &bytes_transferred_);
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                h, env->executor, buffers_, token_, &ec_, &bytes_transferred_);
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        }
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        }
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    };
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    };
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    /** Dispatch a read through the concrete implementation.
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    /** Dispatch a read through the concrete implementation.
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        @param h Coroutine handle to resume on completion.
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        @param h Coroutine handle to resume on completion.
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        @param ex Executor for dispatching the completion.
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        @param ex Executor for dispatching the completion.
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        @param buffers Target buffer sequence.
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        @param buffers Target buffer sequence.
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        @param token Stop token for cancellation.
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        @param token Stop token for cancellation.
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        @param ec Output error code.
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        @param ec Output error code.
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        @param bytes Output bytes transferred.
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        @param bytes Output bytes transferred.
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        @return Coroutine handle to resume immediately.
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        @return Coroutine handle to resume immediately.
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    */
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    */
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    virtual std::coroutine_handle<> do_read_some(
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    virtual std::coroutine_handle<> do_read_some(
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        std::coroutine_handle<>,
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        std::coroutine_handle<>,
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        capy::executor_ref,
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        capy::executor_ref,
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        io_buffer_param,
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        io_buffer_param,
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        std::stop_token,
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        std::stop_token,
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        std::error_code*,
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        std::error_code*,
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        std::size_t*) = 0;
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        std::size_t*) = 0;
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    io_read_stream() noexcept = default;
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    io_read_stream() noexcept = default;
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    /// Construct from a handle.
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    /// Construct from a handle.
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    explicit io_read_stream(handle h) noexcept : io_object(std::move(h)) {}
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    explicit io_read_stream(handle h) noexcept : io_object(std::move(h)) {}
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public:
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public:
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    /** Asynchronously read data from the stream.
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    /** Asynchronously read data from the stream.
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        Suspends the calling coroutine and initiates a kernel-level
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        Suspends the calling coroutine and initiates a kernel-level
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        read. The coroutine resumes when at least one byte is read,
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        read. The coroutine resumes when at least one byte is read,
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        an error occurs, or the operation is cancelled.
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        an error occurs, or the operation is cancelled.
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        This stream must outlive the returned awaitable. The memory
 
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        referenced by @p buffers must remain valid until the operation
 
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        completes.
 
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        @param buffers The buffer sequence to read data into.
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        @param buffers The buffer sequence to read data into.
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        @return An awaitable yielding `(error_code, std::size_t)`.
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        @return An awaitable yielding `(error_code, std::size_t)`.
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        @see io_stream::write_some
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        @see io_stream::write_some
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    */
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    */
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    template<capy::MutableBufferSequence MB>
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    template<capy::MutableBufferSequence MB>
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    auto read_some(MB const& buffers)
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    auto read_some(MB const& buffers)
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    {
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    {
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        return read_some_awaitable<MB>(*this, buffers);
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        return read_some_awaitable<MB>(*this, buffers);
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    }
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    }
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};
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};
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} // namespace boost::corosio
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} // namespace boost::corosio
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#endif
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#endif