user-agent.hpp

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/*
 * RESTinio
 */

/*!
 * @file
 * @brief Stuff related to value of User-Agent HTTP-field.
 *
 * @since v.0.6.4
 */

#pragma once

#include <restinio/helpers/http_field_parsers/basics.hpp>

#include <variant>

namespace restinio
{

namespace http_field_parsers
{

//
// user_agent_value_t
//
/*!
 * @brief Tools for working with the value of User-Agent HTTP-field.
 *
 * This struct represents parsed value of HTTP-field User-Agent
 * (see https://tools.ietf.org/html/rfc7231#section-5.5.3):
@verbatim
     User-Agent = product *( RWS ( product / comment ) )

     product         = token ["/" product-version]
     product-version = token
@endverbatim
 *
 * @since v.0.6.4
 */
struct user_agent_value_t
{
    /*!
     * @brief A type for holding an info about a product.
     *
     * @since v.0.6.4
     */
    struct product_t
    {
        std::string product;
        std::optional<std::string> product_version;
    };

    /*!
     * @brief A type for holding an info about a product or a comment.
     *
     * @since v.0.6.4
     */
    using tail_item_t = std::variant< product_t, std::string >;

    product_t product;
    std::vector< tail_item_t > tail;

    /*!
     * @brief A factory function for a parser of User-Agent value.
     *
     * @since v.0.6.4
     */
    [[nodiscard]]
    static auto
    make_parser()
    {
        auto product_producer = produce< product_t >(
                token_p() >> &product_t::product,
                maybe(
                    symbol('/'),
                    token_p() >> &product_t::product_version
                )
            );

        return produce< user_agent_value_t >(
                product_producer >> &user_agent_value_t::product,
                produce< std::vector< tail_item_t > >(
                    repeat( 0, N,
                        space(),
                        ows(),
                        alternatives(
                            product_producer >> to_container(),
                            comment_p() >> to_container()
                        )
                    )
                ) >> &user_agent_value_t::tail
        );
    }

    /*!
     * @brief An attempt to parse User-Agent HTTP-field.
     *
     * @since v.0.6.4
     */
    [[nodiscard]]
    static expected_t< user_agent_value_t, restinio::easy_parser::parse_error_t >
    try_parse( string_view_t what )
    {
        return restinio::easy_parser::try_parse( what, make_parser() );
    }
};

} /* namespace http_field_parsers */

} /* namespace restinio */