media-type.hpp

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/*
 * RESTinio
 */

/*!
 * @file
 * @brief Stuff related to Media-Type value in HTTP-fields.
 *
 * @since v.0.6.1
 */

#pragma once

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

namespace restinio
{

namespace http_field_parsers
{

//
// media_type_value_t
//
/*!
 * @brief Tools for working with media-type in HTTP-fields.
 *
 * This struct represents parsed value of media-type.
 * Media-type is present in different HTTP-fields and has the following
 * format (see https://tools.ietf.org/html/rfc7231 section
 * `3.1.1.1. Media Type`):
@verbatim
     media-type = type "/" subtype *( OWS ";" OWS parameter )
     type       = token
     subtype    = token
     parameter  = token "=" ( token / quoted-string )
@endverbatim
 *
 * @since v.0.6.1
 */
struct media_type_value_t
{
    using parameter_t = parameter_with_mandatory_value_t;

    using parameter_container_t = parameter_with_mandatory_value_container_t;

    std::string type;
    std::string subtype;
    parameter_container_t parameters;

    /*!
     * @brief Make a default parser that doesn't handles weight parameter
     * a special way.
     *
     * This parser handles the following rules:
@verbatim
     media-type = type "/" subtype *( OWS ";" OWS parameter )
     type       = token
     subtype    = token
     parameter  = token "=" ( token / quoted-string )
@endverbatim
     * @since v.0.6.1
     */
    RESTINIO_NODISCARD
    static auto
    make_default_parser()
    {
        return produce< media_type_value_t >(
            token_p() >> to_lower() >> &media_type_value_t::type,
            symbol('/'),
            token_p() >> to_lower() >> &media_type_value_t::subtype,
            params_with_value_p() >> &media_type_value_t::parameters
        );
    }

    /*!
     * @brief Make a special parser that stops when weight parameter is found.
     *
     * This parser handles the following rules:
@verbatim
     media-type = type "/" subtype *( ![weight] OWS ";" OWS parameter )
     type       = token
     subtype    = token
     parameter  = token "=" ( token / quoted-string )
     weight = OWS ";" OWS "q=" qvalue
     qvalue = ( "0" [ "." 0*3DIGIT ] )
            / ( "1" [ "." 0*3("0") ] )
@endverbatim
     * @since v.0.6.1
     */
    RESTINIO_NODISCARD
    static auto
    make_weight_aware_parser()
    {
        return produce< media_type_value_t >(
            token_p() >> to_lower() >> &media_type_value_t::type,
            symbol('/'),
            token_p() >> to_lower() >> &media_type_value_t::subtype,
            produce< parameter_container_t >(
                repeat( 0, N,
                    produce< parameter_t >(
                        not_clause( weight_p() >> skip() ),
                        ows(),
                        symbol(';'),
                        ows(),
                        token_p() >> to_lower() >> &parameter_t::first,
                        symbol('='),
                        alternatives(
                            token_p() >> &parameter_t::second,
                            quoted_string_p() >> &parameter_t::second
                        )
                    ) >> to_container()
                )
            ) >> &media_type_value_t::parameters
        );
    }

    /*!
     * @brief An attempt to parse media-type value.
     *
     * @note
     * This method uses make_default_parser() for actual parser.
     *
     * @since v.0.6.1
     */
    RESTINIO_NODISCARD
    static expected_t< media_type_value_t, restinio::easy_parser::parse_error_t >
    try_parse( string_view_t what )
    {
        return restinio::easy_parser::try_parse( what, make_default_parser() );
    }
};

} /* namespace http_field_parsers */

} /* namespace restinio */