accept.hpp

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/*
 * RESTinio
 */

/*!
 * @file
 * @brief Stuff related to value of Accept HTTP-field.
 *
 * @since v.0.6.1
 */

#pragma once

#include <restinio/helpers/http_field_parsers/media-type.hpp>

namespace restinio
{

namespace http_field_parsers
{

//
// accept_value_t
//
/*!
 * @brief Tools for working with the value of Accept HTTP-field.
 *
 * This struct represents parsed value of HTTP-field Accept
 * (see https://tools.ietf.org/html/rfc7231#section-5.3.2):
@verbatim
     Accept = #( media-range [ accept-params ] )

     media-range    = ( "*" "/" "*"
                      / ( type "/" "*" )
                      / ( type "/" subtype )
                      ) *( OWS ";" OWS parameter )
     accept-params  = weight *( accept-ext )
     accept-ext = OWS ";" OWS token [ "=" ( token / quoted-string ) ]

     weight = OWS ";" OWS "q=" qvalue
     qvalue = ( "0" [ "." 0*3DIGIT ] )
            / ( "1" [ "." 0*3("0") ] )
@endverbatim
 *
 * @note
 * Parameter names are converted to lower case during the parsing.
 * Parameter values are left as they are.
 *
 * @since v.0.6.1
 */
struct accept_value_t
{
    struct item_t
    {
        using accept_ext_t = parameter_with_optional_value_t;

        using accept_ext_container_t = parameter_with_optional_value_container_t;

        media_type_value_t media_type;
        std::optional< qvalue_t > weight;
        accept_ext_container_t accept_params;
    };

    using item_container_t = std::vector< item_t >;

    item_container_t items;

    /*!
     * @brief A factory function for a parser of Accept value.
     *
     * @since v.0.6.1
     */
    [[nodiscard]]
    static auto
    make_parser()
    {
        const auto media_type = media_type_value_t::make_weight_aware_parser();

        return produce< accept_value_t >(
            maybe_empty_comma_separated_list_p< item_container_t >(
                produce< item_t >(
                    media_type >> &item_t::media_type,
                    maybe(
                        weight_p() >> &item_t::weight,
                        params_with_opt_value_p() >> &item_t::accept_params
                    )
                )
            ) >> &accept_value_t::items
        );
    }

    /*!
     * @brief An attempt to parse Accept HTTP-field.
     *
     * @since v.0.6.1
     */
    [[nodiscard]]
    static expected_t< accept_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 */