osrm-backend/include/osmium/osm/area.hpp

#ifndef OSMIUM_OSM_AREA_HPP
#define OSMIUM_OSM_AREA_HPP

/*

This file is part of Osmium (http://osmcode.org/libosmium).

Copyright 2013,2014 Jochen Topf <jochen@topf.org> and others (see README).

Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

*/

#include <cassert>
#include <cstdlib>
#include <utility>

#include <osmium/memory/collection.hpp>
#include <osmium/memory/item.hpp>
#include <osmium/osm/item_type.hpp>
#include <osmium/osm/object.hpp>
#include <osmium/osm/types.hpp>
#include <osmium/osm/node_ref_list.hpp>

namespace osmium {

    namespace builder {
        template <class T> class ObjectBuilder;
    }

    /**
     * An outer ring of an Area.
     */
    class OuterRing : public NodeRefList<osmium::item_type::outer_ring> {

    public:

        OuterRing():
            NodeRefList<osmium::item_type::outer_ring>() {
        }

    }; // class OuterRing

    static_assert(sizeof(OuterRing) % osmium::memory::align_bytes == 0, "Class osmium::OuterRing has wrong size to be aligned properly!");

    /**
     * An inner ring of an Area.
     */
    class InnerRing : public NodeRefList<osmium::item_type::inner_ring> {

    public:

        InnerRing():
            NodeRefList<osmium::item_type::inner_ring>() {
        }

    }; // class InnerRing

    static_assert(sizeof(InnerRing) % osmium::memory::align_bytes == 0, "Class osmium::InnerRing has wrong size to be aligned properly!");

    /**
     * Convert way or (multipolygon) relation id into unique area id.
     *
     * @param id Id of a way or relation
     * @param type Type of object (way or relation)
     * @returns Area id
     */
    inline osmium::object_id_type object_id_to_area_id(osmium::object_id_type id, osmium::item_type type) {
        osmium::object_id_type area_id = std::abs(id) * 2;
        if (type == osmium::item_type::relation) {
            ++area_id;
        }
        return id < 0 ? -area_id : area_id;
    }

    /**
     * Convert area id into id of the way or relation it was created from.
     *
     * @param id Area id
     * @returns Way or Relation id.
     */
    inline osmium::object_id_type area_id_to_object_id(osmium::object_id_type id) {
        return id / 2;
    }

    /**
     * An OSM area created out of a closed way or a multipolygon relation.
     */
    class Area : public OSMObject {

        friend class osmium::builder::ObjectBuilder<osmium::Area>;

        Area() :
            OSMObject(sizeof(Area), osmium::item_type::area) {
        }

    public:

        static constexpr osmium::item_type itemtype = osmium::item_type::area;

        /**
         * Was this area created from a way? (In contrast to areas
         * created from a relation and their members.)
         */
        bool from_way() const noexcept {
            return (positive_id() & 0x1) == 0;
        }

        /**
         * Return the Id of the way or relation this area was created from.
         */
        osmium::object_id_type orig_id() const {
            return osmium::area_id_to_object_id(id());
        }

        /**
         * Count the number of outer and inner rings of this area.
         */
        std::pair<int, int> num_rings() const {
            std::pair<int, int> counter;

            for (auto it = cbegin(); it != cend(); ++it) {
                switch (it->type()) {
                    case osmium::item_type::outer_ring:
                        ++counter.first;
                        break;
                    case osmium::item_type::inner_ring:
                        ++counter.second;
                        break;
                    case osmium::item_type::tag_list:
                        // ignore tags
                        break;
                    case osmium::item_type::undefined:
                    case osmium::item_type::node:
                    case osmium::item_type::way:
                    case osmium::item_type::relation:
                    case osmium::item_type::area:
                    case osmium::item_type::changeset:
                    case osmium::item_type::way_node_list:
                    case osmium::item_type::relation_member_list:
                    case osmium::item_type::relation_member_list_with_full_members:
                        assert(false && "Children of Area can only be outer/inner_ring and tag_list.");
                        break;
                }
            }

            return counter;
        }

        /**
         * Is this area a multipolygon, ie. has it more than one outer ring?
         */
        bool is_multipolygon() const {
            return num_rings().first > 1;
        }

        osmium::memory::ItemIterator<const osmium::InnerRing> inner_ring_cbegin(const osmium::memory::ItemIterator<const osmium::OuterRing>& it) const {
            return it.cast<const osmium::InnerRing>();
        }

        osmium::memory::ItemIterator<const osmium::InnerRing> inner_ring_cend(const osmium::memory::ItemIterator<const osmium::OuterRing>& it) const {
            return std::next(it).cast<const osmium::InnerRing>();
        }

    }; // class Area

    static_assert(sizeof(Area) % osmium::memory::align_bytes == 0, "Class osmium::Area has wrong size to be aligned properly!");

} // namespace osmium

#endif // OSMIUM_OSM_AREA_HPP