osrm-backend/include/server/api/base_parameters_grammar.hpp

#ifndef SERVER_API_BASE_PARAMETERS_GRAMMAR_HPP
#define SERVER_API_BASE_PARAMETERS_GRAMMAR_HPP

#include "engine/api/base_parameters.hpp"

#include "engine/bearing.hpp"
#include "engine/hint.hpp"
#include "engine/polyline_compressor.hpp"

#include <boost/optional.hpp>
#include <boost/phoenix.hpp>
#include <boost/spirit/include/qi.hpp>

#include <limits>
#include <string>

namespace osrm::server::api
{

namespace
{
namespace ph = boost::phoenix;
namespace qi = boost::spirit::qi;
} // namespace

template <typename T, char... Fmt> struct no_trailing_dot_policy : qi::real_policies<T>
{
    template <typename Iterator> static bool parse_dot(Iterator &first, Iterator const &last)
    {
        auto diff = std::distance(first, last);
        if (diff <= 0 || *first != '.')
            return false;

        static const constexpr char fmt[sizeof...(Fmt)] = {Fmt...};

        if (sizeof(fmt) < static_cast<size_t>(diff) &&
            std::equal(fmt, fmt + sizeof(fmt), first + 1u))
            return false;

        ++first;
        return true;
    }

    template <typename Iterator> static bool parse_exp(Iterator &, const Iterator &)
    {
        return false;
    }

    template <typename Iterator, typename Attribute>
    static bool parse_exp_n(Iterator &, const Iterator &, Attribute &)
    {
        return false;
    }

    template <typename Iterator, typename Attribute>
    static bool parse_nan(Iterator &, const Iterator &, Attribute &)
    {
        return false;
    }

    template <typename Iterator, typename Attribute>
    static bool parse_inf(Iterator &, const Iterator &, Attribute &)
    {
        return false;
    }
};

template <typename Iterator, typename Signature>
struct BaseParametersGrammar : boost::spirit::qi::grammar<Iterator, Signature>
{
    using json_policy = no_trailing_dot_policy<double, 'j', 's', 'o', 'n'>;

    BaseParametersGrammar(qi::rule<Iterator, Signature> &root_rule)
        : BaseParametersGrammar::base_type(root_rule)
    {
        const auto add_hint = [](engine::api::BaseParameters &base_parameters,
                                 const std::vector<std::string> &hint_strings)
        {
            if (!hint_strings.empty())
            {
                std::vector<engine::SegmentHint> location_hints(hint_strings.size());
                std::transform(hint_strings.begin(),
                               hint_strings.end(),
                               location_hints.begin(),
                               [](const auto &hint_string)
                               { return engine::SegmentHint::FromBase64(hint_string); });
                base_parameters.hints.push_back(engine::Hint{std::move(location_hints)});
            }
            else
            {
                base_parameters.hints.emplace_back(boost::none);
            }
        };

        const auto add_bearing =
            [](engine::api::BaseParameters &base_parameters,
               boost::optional<boost::fusion::vector2<short, short>> bearing_range)
        {
            boost::optional<engine::Bearing> bearing;
            if (bearing_range)
            {
                bearing = engine::Bearing{boost::fusion::at_c<0>(*bearing_range),
                                          boost::fusion::at_c<1>(*bearing_range)};
            }
            base_parameters.bearings.push_back(std::move(bearing));
        };

        polyline_chars = qi::char_("a-zA-Z0-9_.--[]{}@?|\\%~`^");
        base64_char = qi::char_("a-zA-Z0-9--_=");
        unlimited_rule = qi::lit("unlimited")[qi::_val = std::numeric_limits<double>::infinity()];

        bearing_rule =
            (qi::short_ > ',' > qi::short_)[qi::_val = ph::bind(
                                                [](short bearing, short range) {
                                                    return osrm::engine::Bearing{bearing, range};
                                                },
                                                qi::_1,
                                                qi::_2)];

        location_rule = (double_ > qi::lit(',') >
                         double_)[qi::_val = ph::bind(
                                      [](double lon, double lat)
                                      {
                                          return util::Coordinate(
                                              util::toFixed(util::UnsafeFloatLongitude{lon}),
                                              util::toFixed(util::UnsafeFloatLatitude{lat}));
                                      },
                                      qi::_1,
                                      qi::_2)];

        polyline_rule =
            qi::as_string[qi::lit("polyline(") > +polyline_chars > ')']
                         [qi::_val = ph::bind([](const std::string &polyline)
                                              { return engine::decodePolyline(polyline); },
                                              qi::_1)];

        polyline6_rule =
            qi::as_string[qi::lit("polyline6(") > +polyline_chars > ')']
                         [qi::_val = ph::bind([](const std::string &polyline)
                                              { return engine::decodePolyline<1000000>(polyline); },
                                              qi::_1)];

        query_rule =
            ((location_rule % ';') | polyline_rule |
             polyline6_rule)[ph::bind(&engine::api::BaseParameters::coordinates, qi::_r1) = qi::_1];

        radiuses_rule = qi::lit("radiuses=") >
                        (-(qi::double_ | unlimited_rule) %
                         ';')[ph::bind(&engine::api::BaseParameters::radiuses, qi::_r1) = qi::_1];

        hints_rule =
            qi::lit("hints=") >
            (*qi::as_string[qi::repeat(engine::ENCODED_SEGMENT_HINT_SIZE)[base64_char]])[ph::bind(
                add_hint, qi::_r1, qi::_1)] %
                ';';

        generate_hints_rule =
            qi::lit("generate_hints=") >
            qi::bool_[ph::bind(&engine::api::BaseParameters::generate_hints, qi::_r1) = qi::_1];

        skip_waypoints_rule =
            qi::lit("skip_waypoints=") >
            qi::bool_[ph::bind(&engine::api::BaseParameters::skip_waypoints, qi::_r1) = qi::_1];

        bearings_rule =
            qi::lit("bearings=") >
            (-(qi::short_ > ',' > qi::short_))[ph::bind(add_bearing, qi::_r1, qi::_1)] % ';';

        approach_type.add("unrestricted", engine::Approach::UNRESTRICTED)(
            "curb", engine::Approach::CURB)("opposite", engine::Approach::OPPOSITE);

        approach_rule = qi::lit("approaches=") >
                        (-approach_type %
                         ';')[ph::bind(&engine::api::BaseParameters::approaches, qi::_r1) = qi::_1];

        snapping_type.add("default", engine::api::BaseParameters::SnappingType::Default)(
            "any", engine::api::BaseParameters::SnappingType::Any);

        snapping_rule =
            qi::lit("snapping=") >
            snapping_type[ph::bind(&engine::api::BaseParameters::snapping, qi::_r1) = qi::_1];

        format_type.add(".json", engine::api::BaseParameters::OutputFormatType::JSON)(
            ".flatbuffers", engine::api::BaseParameters::OutputFormatType::FLATBUFFERS);

        format_rule =
            -format_type[ph::bind(&engine::api::BaseParameters::format, qi::_r1) = qi::_1];

        exclude_rule = qi::lit("exclude=") >
                       (qi::as_string[+qi::char_("a-zA-Z0-9")] %
                        ',')[ph::bind(&engine::api::BaseParameters::exclude, qi::_r1) = qi::_1];

        base_rule = radiuses_rule(qi::_r1)         //
                    | hints_rule(qi::_r1)          //
                    | bearings_rule(qi::_r1)       //
                    | generate_hints_rule(qi::_r1) //
                    | skip_waypoints_rule(qi::_r1) //
                    | approach_rule(qi::_r1)       //
                    | exclude_rule(qi::_r1)        //
                    | snapping_rule(qi::_r1);
    }

  protected:
    qi::rule<Iterator, Signature> base_rule;
    qi::rule<Iterator, Signature> query_rule;
    qi::rule<Iterator, Signature> format_rule;

    qi::symbols<char, engine::api::BaseParameters::OutputFormatType> format_type;

    qi::real_parser<double, json_policy> double_;

  private:
    qi::rule<Iterator, Signature> bearings_rule;
    qi::rule<Iterator, Signature> radiuses_rule;
    qi::rule<Iterator, Signature> hints_rule;

    qi::rule<Iterator, Signature> generate_hints_rule;
    qi::rule<Iterator, Signature> skip_waypoints_rule;
    qi::rule<Iterator, Signature> approach_rule;
    qi::rule<Iterator, Signature> exclude_rule;

    qi::rule<Iterator, osrm::engine::Bearing()> bearing_rule;
    qi::rule<Iterator, osrm::util::Coordinate()> location_rule;
    qi::rule<Iterator, std::vector<osrm::util::Coordinate>()> polyline_rule;
    qi::rule<Iterator, std::vector<osrm::util::Coordinate>()> polyline6_rule;

    qi::rule<Iterator, unsigned char()> base64_char;
    qi::rule<Iterator, std::string()> polyline_chars;
    qi::rule<Iterator, double()> unlimited_rule;
    qi::rule<Iterator, Signature> snapping_rule;

    qi::symbols<char, engine::Approach> approach_type;
    qi::symbols<char, engine::api::BaseParameters::SnappingType> snapping_type;
};
} // namespace osrm::server::api

#endif