osrm-backend/src/extractor/guidance/turn_lane_data.cpp

#include "extractor/guidance/turn_lane_data.hpp"
#include "util/guidance/turn_lanes.hpp"

#include <boost/numeric/conversion/cast.hpp>

#include <algorithm>
#include <cstddef>
#include <string>
#include <unordered_map>
#include <utility>

namespace osrm
{
namespace extractor
{
namespace guidance
{
namespace lanes
{

bool TurnLaneData::operator<(const TurnLaneData &other) const
{
    if (from < other.from)
        return true;
    if (from > other.from)
        return false;

    if (to < other.to)
        return true;
    if (to > other.to)
        return false;

    const constexpr TurnLaneType::Mask tag_by_modifier[] = {TurnLaneType::sharp_right,
                                                            TurnLaneType::right,
                                                            TurnLaneType::slight_right,
                                                            TurnLaneType::straight,
                                                            TurnLaneType::slight_left,
                                                            TurnLaneType::left,
                                                            TurnLaneType::sharp_left,
                                                            TurnLaneType::uturn};
    // U-Turns are supposed to be on the outside. So if the first lane is 0 and we are looking at a
    // u-turn, it has to be on the very left. If it is equal to the number of lanes, it has to be on
    // the right. These sorting function assume reverse to be on the outside always. Might need to
    // be reconsidered if there are situations that offer a reverse from some middle lane (seems
    // improbable)

    if (tag == TurnLaneType::uturn)
    {
        if (from == 0)
            return true;
        else
            return false;
    }

    if (other.tag == TurnLaneType::uturn)
    {
        if (other.from == 0)
            return false;
        else
            return true;
    }

    return std::find(tag_by_modifier, tag_by_modifier + 8, this->tag) <
           std::find(tag_by_modifier, tag_by_modifier + 8, other.tag);
}

LaneDataVector laneDataFromDescription(const TurnLaneDescription &turn_lane_description)
{
    typedef std::unordered_map<TurnLaneType::Mask, std::pair<LaneID, LaneID>> LaneMap;
    const auto num_lanes = boost::numeric_cast<LaneID>(turn_lane_description.size());
    const auto setLaneData = [&](
        LaneMap &map, TurnLaneType::Mask full_mask, const LaneID current_lane) {
        const auto isSet = [&](const TurnLaneType::Mask test_mask) -> bool {
            return (test_mask & full_mask) == test_mask;
        };

        for (std::size_t shift = 0; shift < TurnLaneType::detail::num_supported_lane_types; ++shift)
        {
            TurnLaneType::Mask mask = 1 << shift;
            if (isSet(mask))
            {
                auto map_iterator = map.find(mask);
                if (map_iterator == map.end())
                    map[mask] = std::make_pair(current_lane, current_lane);
                else
                {
                    map_iterator->second.first = current_lane;
                }
            }
        }
    };

    LaneMap lane_map;
    LaneID lane_nr = num_lanes - 1;
    if (turn_lane_description.empty())
        return {};

    for (auto full_mask : turn_lane_description)
    {
        setLaneData(lane_map, full_mask, lane_nr);
        --lane_nr;
    }

    // transform the map into the lane data vector
    LaneDataVector lane_data;
    for (const auto tag : lane_map)
        lane_data.push_back({tag.first, tag.second.first, tag.second.second});

    std::sort(lane_data.begin(), lane_data.end());

    // check whether a given turn lane string resulted in valid lane data
    const auto hasValidOverlaps = [](const LaneDataVector &lane_data) {
        // Allow an overlap of at most one. Larger overlaps would result in crossing another turn,
        // which is invalid
        for (std::size_t index = 1; index < lane_data.size(); ++index)
        {
            // u-turn located somewhere in the middle
            // Right now we can only handle u-turns at the sides. If we find a u-turn somewhere in
            // the middle of the tags, we abort the handling right here.
            if (index + 1 < lane_data.size() &&
                ((lane_data[index].tag & TurnLaneType::uturn) != TurnLaneType::empty))
                return false;

            if (lane_data[index - 1].to > lane_data[index].from)
                return false;
        }
        return true;
    };

    if (!hasValidOverlaps(lane_data))
        lane_data.clear();

    return lane_data;
}

LaneDataVector::iterator findTag(const TurnLaneType::Mask tag, LaneDataVector &data)
{
    return std::find_if(data.begin(), data.end(), [&](const TurnLaneData &lane_data) {
        return (tag & lane_data.tag) != TurnLaneType::empty;
    });
}
LaneDataVector::const_iterator findTag(const TurnLaneType::Mask tag, const LaneDataVector &data)
{
    return std::find_if(data.cbegin(), data.cend(), [&](const TurnLaneData &lane_data) {
        return (tag & lane_data.tag) != TurnLaneType::empty;
    });
}

bool hasTag(const TurnLaneType::Mask tag, const LaneDataVector &data)
{
    return findTag(tag, data) != data.cend();
}

} // namespace lanes
} // namespace guidance
} // namespace extractor
} // namespace osrm