boost_beast/include/beast/http/message_parser.hpp

//
// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BEAST_HTTP_MESSAGE_PARSER_HPP
#define BEAST_HTTP_MESSAGE_PARSER_HPP

#include <beast/config.hpp>
#include <beast/http/message.hpp>
#include <beast/http/header_parser.hpp>
#include <beast/core/detail/clamp.hpp>
#include <boost/optional.hpp>
#include <array>
#include <type_traits>
#include <utility>

namespace beast {
namespace http {

/** A parser for producing HTTP/1 messages.

    This class uses the basic HTTP/1 wire format parser to convert
    a series of octets into a @ref message.

    @tparam isRequest Indicates whether a request or response
    will be parsed.

    @tparam Body The type used to represent the body.

    @tparam Fields The type of container used to represent the fields.

    @note A new instance of the parser is required for each message.
*/
template<bool isRequest, class Body, class Fields>
class message_parser
    : public basic_parser<isRequest,
        Body::writer::is_direct,
            message_parser<isRequest, Body, Fields>>
{
    using base_type = basic_parser<isRequest, true,
        message_parser<isRequest, Body, Fields>>;

    using writer_type = typename Body::writer;

    message<isRequest, Body, Fields> m_;
    boost::optional<writer_type> wr_;

public:
    /// The type of message returned by the parser
    using value_type = message<isRequest, Body, Fields>;

    /// The type of buffer sequence representing the body
    using mutable_buffers_type =
        typename writer_type::mutable_buffers_type;

    /// Constructor (default)
    message_parser() = default;

    /// Copy constructor (disallowed)
    message_parser(message_parser const&) = delete;

    /// Copy assignment (disallowed)
    message_parser& operator=(message_parser const&) = delete;

    /** Move constructor.

        After the move, the only valid operation
        on the moved-from object is destruction.
    */
    message_parser(message_parser&& other);

    /** Constructor

        @param args Optional arguments forwarded to the 
        @ref http::header constructor.

        @note This function participates in overload
        resolution only if the first argument is not a
        @ref http::header_parser or @ref message_parser.
    */
#if BEAST_DOXYGEN
    template<class... Args>
    explicit
    msesage_parser(Args&&... args);
#else
    template<class Arg1, class... ArgN,
        class = typename std::enable_if<
            ! std::is_same<typename
                std::decay<Arg1>::type,
                    header_parser<isRequest, Fields>>::value &&
            ! std::is_same<typename
                std::decay<Arg1>::type, message_parser>::value
                    >::type>
    explicit
    message_parser(Arg1&& arg1, ArgN&&... argn);
#endif

    /** Construct a message parser from a @ref header_parser.

        @param parser The header parser to construct from.

        @param args Optional arguments forwarded to the message
        constructor.
    */
    template<class... Args>
    explicit
    message_parser(header_parser<
        isRequest, Fields>&& parser, Args&&... args);

    /** Returns the parsed message.

        Depending on the progress of the parser, portions
        of this object may be incomplete.
    */
    value_type const&
    get() const
    {
        return m_;
    }

    /** Returns the parsed message.

        Depending on the progress of the parser, portions
        of this object may be incomplete.
    */
    value_type&
    get()
    {
        return m_;
    }

    /** Returns ownership of the parsed message.

        Ownership is transferred to the caller.
        Depending on the progress of the parser, portions
        of this object may be incomplete.

        @par Requires

        @ref value_type is @b MoveConstructible
    */
    value_type
    release()
    {
        static_assert(std::is_move_constructible<decltype(m_)>::value,
            "MoveConstructible requirements not met");
        return std::move(m_);
    }

private:
    friend class basic_parser<
        isRequest, Body::writer::is_direct,
            message_parser>;

    void
    on_request(
        string_view const& method,
            string_view const& target,
                int version, error_code&)
    {
        m_.target(target);
        m_.method(method);
        m_.version = version;
    }

    void
    on_response(int status,
        string_view const& reason,
            int version, error_code&)
    {
        m_.status = status;
        m_.version = version;
        m_.reason(reason);
    }

    void
    on_field(string_view const& name,
        string_view const& value,
            error_code&)
    {
        m_.fields.insert(name, value);
    }

    void
    on_header(error_code& ec)
    {
    }

    void
    on_body()
    {
        wr_.emplace(m_);
        wr_->init();
    }

    void
    on_body(std::uint64_t content_length)
    {
        wr_.emplace(m_);
        wr_->init(content_length);
    }

    void
    on_body(error_code& ec)
    {
        wr_.emplace(m_);
        wr_->init(ec);
        if(ec)
            return;
    }

    void
    on_body(std::uint64_t content_length,
        error_code& ec)
    {
        wr_.emplace(m_);
        wr_->init(content_length, ec);
        if(ec)
            return;
    }

    void
    on_data(string_view const& s,
        error_code& ec)
    {
        BOOST_STATIC_ASSERT(! Body::writer::is_direct);
        wr_->write(s, ec);
    }

    mutable_buffers_type
    on_prepare(std::size_t n)
    {
        return wr_->prepare(n);
    }

    void
    on_commit(std::size_t n)
    {
        wr_->commit(n);
    }

    void
    on_chunk(std::uint64_t,
        string_view const&,
            error_code&)
    {
    }

    void
    on_complete(error_code& ec)
    {
        if(wr_)
            do_on_complete(ec,
                std::integral_constant<bool,
                    Body::writer::is_direct>{});
    }

    void
    do_on_complete(
        error_code& ec, std::true_type)
    {
        wr_->finish();
    }

    void
    do_on_complete(
        error_code& ec, std::false_type)
    {
        wr_->finish(ec);
        if(ec)
            return;
    }
};

} // http
} // beast

#include <beast/http/impl/message_parser.ipp>

#endif