osrm-backend/include/engine/plugins/plugin_base.hpp

#ifndef BASE_PLUGIN_HPP
#define BASE_PLUGIN_HPP

#include "engine/phantom_node.hpp"

#include "osrm/coordinate.hpp"
#include "osrm/json_container.hpp"
#include "osrm/route_parameters.hpp"

#include <algorithm>
#include <string>
#include <vector>

class BasePlugin
{
  public:
    enum class Status : int
    {
      Ok = 200,
      EmptyResult = 207,
      NoSegment = 208,
      Error = 400
    };

    BasePlugin() {}
    // Maybe someone can explain the pure virtual destructor thing to me (dennis)
    virtual ~BasePlugin() {}
    virtual const std::string GetDescriptor() const = 0;
    virtual Status HandleRequest(const RouteParameters &, osrm::json::Object &) = 0;
    virtual bool check_all_coordinates(const std::vector<FixedPointCoordinate> &coordinates,
                                       const unsigned min = 2) const final
    {
        if (min > coordinates.size() || std::any_of(std::begin(coordinates), std::end(coordinates),
                                                    [](const FixedPointCoordinate &coordinate)
                                                    {
                                                        return !coordinate.is_valid();
                                                    }))
        {
            return false;
        }
        return true;
    }

    // Decides whether to use the phantom node from a big or small component if both are found.
    // Returns true if all phantom nodes are in the same component after snapping.
    std::vector<PhantomNode> snapPhantomNodes(
        const std::vector<std::pair<PhantomNode, PhantomNode>> &phantom_node_pair_list) const
    {
        const auto check_component_id_is_tiny =
            [](const std::pair<PhantomNode, PhantomNode> &phantom_pair)
        {
            return phantom_pair.first.component.is_tiny;
        };

        // are all phantoms from a tiny cc?
        const auto check_all_in_same_component =
            [](const std::vector<std::pair<PhantomNode, PhantomNode>> &nodes)
        {
            const auto component_id = nodes.front().first.component.id;

            return std::all_of(std::begin(nodes), std::end(nodes),
                               [component_id](const PhantomNodePair &phantom_pair)
                               {
                                   return component_id == phantom_pair.first.component.id;
                               });
        };

        const auto fallback_to_big_component =
            [](const std::pair<PhantomNode, PhantomNode> &phantom_pair)
        {
            if (phantom_pair.first.component.is_tiny && phantom_pair.second.is_valid() &&
                !phantom_pair.second.component.is_tiny)
            {
                return phantom_pair.second;
            }
            return phantom_pair.first;
        };

        const auto use_closed_phantom = [](const std::pair<PhantomNode, PhantomNode> &phantom_pair)
        {
            return phantom_pair.first;
        };

        const bool every_phantom_is_in_tiny_cc =
            std::all_of(std::begin(phantom_node_pair_list), std::end(phantom_node_pair_list),
                        check_component_id_is_tiny);
        auto all_in_same_component = check_all_in_same_component(phantom_node_pair_list);

        std::vector<PhantomNode> snapped_phantoms;
        snapped_phantoms.reserve(phantom_node_pair_list.size());

        // The only case we don't snap to the big component if all phantoms are in the same small
        // component
        if (every_phantom_is_in_tiny_cc && all_in_same_component)
        {
            std::transform(phantom_node_pair_list.begin(), phantom_node_pair_list.end(),
                           std::back_inserter(snapped_phantoms), use_closed_phantom);
        }
        else
        {
            std::transform(phantom_node_pair_list.begin(), phantom_node_pair_list.end(),
                           std::back_inserter(snapped_phantoms), fallback_to_big_component);
        }

        return snapped_phantoms;
    }
};

#endif /* BASE_PLUGIN_HPP */