members_database.hpp

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#ifndef OSMIUM_RELATIONS_MEMBERS_DATABASE_HPP
#define OSMIUM_RELATIONS_MEMBERS_DATABASE_HPP
 
/*
 
This file is part of Osmium (https://osmcode.org/libosmium).
 
Copyright 2013-2025 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 <osmium/osm/object.hpp>
#include <osmium/osm/relation.hpp>
#include <osmium/osm/types.hpp>
#include <osmium/relations/relations_database.hpp>
#include <osmium/storage/item_stash.hpp>
#include <osmium/util/iterator.hpp>
 
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <limits>
#include <tuple>
#include <type_traits>
#include <utility>
#include <vector>
 
namespace osmium {
 
    namespace relations {
 
        class MembersDatabaseCommon {
 
            struct element {
 
                enum {
                    removed_value = std::numeric_limits<std::size_t>::max()
                };
 
                osmium::object_id_type member_id;
 
                std::size_t member_num;
 
                std::size_t relation_pos;
 
                osmium::ItemStash::handle_type object_handle;
 
                explicit element(std::size_t rel_pos, osmium::object_id_type memb_id, std::size_t memb_num) noexcept :
                    member_id(memb_id),
                    member_num(memb_num),
                    relation_pos(rel_pos) {
                }
 
                explicit element(osmium::object_id_type m_id) noexcept :
                    member_id(m_id),
                    member_num(0),
                    relation_pos(0) {
                }
 
                bool is_removed() const noexcept {
                    return member_num == removed_value;
                }
 
                void remove() noexcept {
                    member_num = removed_value;
                }
 
                bool operator<(const element& other) const noexcept {
                    return std::tie(member_id, member_num, relation_pos) <
                           std::tie(other.member_id, other.member_num, other.relation_pos);
                }
 
            }; // struct element
 
            // comparison function only comparing member_id.
            struct compare_member_id {
                bool operator()(const element& a, const element& b) const noexcept {
                    return a.member_id < b.member_id;
                }
            };
 
            std::vector<element> m_elements;
 
        protected:
 
            osmium::ItemStash& m_stash;
            osmium::relations::RelationsDatabase& m_relations_db;
 
#ifndef NDEBUG
            // This is used only in debug builds to make sure the
            // prepare_for_lookup() function is called at the right place.
            bool m_init_phase = true;
#endif
 
            using iterator = std::vector<element>::iterator;
            using const_iterator = std::vector<element>::const_iterator;
 
            iterator_range<iterator> find(osmium::object_id_type id) {
                return make_range(std::equal_range(m_elements.begin(), m_elements.end(), element{id}, compare_member_id{}));
            }
 
            iterator_range<const_iterator> find(osmium::object_id_type id) const {
                return make_range(std::equal_range(m_elements.cbegin(), m_elements.cend(), element{id}, compare_member_id{}));
            }
 
            static typename std::iterator_traits<iterator>::difference_type count_not_removed(const iterator_range<iterator>& range) noexcept {
                return std::count_if(range.begin(), range.end(), [](const element& elem) {
                    return !elem.is_removed();
                });
            }
 
            void add_object(const osmium::OSMObject& object, iterator_range<iterator>& range) {
                const auto handle = m_stash.add_item(object);
                for (auto& elem : range) {
                    elem.object_handle = handle;
                }
            }
 
            MembersDatabaseCommon(osmium::ItemStash& stash, osmium::relations::RelationsDatabase& relations_db) :
                m_stash(stash),
                m_relations_db(relations_db) {
            }
 
        public:
 
            std::size_t used_memory() const noexcept {
                return (sizeof(element) * m_elements.capacity()) +
                       sizeof(MembersDatabaseCommon);
            }
 
            std::size_t size() const noexcept {
                return m_elements.size();
            }
 
            struct counts {
                std::size_t tracked = 0;
                std::size_t available = 0;
                std::size_t removed = 0;
            };
 
            counts count() const noexcept {
                counts c;
 
                for (const auto& elem : m_elements) {
                    if (elem.is_removed()) {
                        ++c.removed;
                    } else if (elem.object_handle.valid()) {
                        ++c.available;
                    } else {
                        ++c.tracked;
                    }
                }
 
                return c;
            }
 
            void track(RelationHandle& rel_handle, osmium::object_id_type member_id, std::size_t member_num) {
                assert(m_init_phase && "Can not call MembersDatabase::track() after MembersDatabase::prepare_for_lookup().");
                assert(rel_handle.relation_database() == &m_relations_db);
                m_elements.emplace_back(rel_handle.pos(), member_id, member_num);
                rel_handle.increment_members();
            }
 
            void prepare_for_lookup() {
                assert(m_init_phase && "Can not call MembersDatabase::prepare_for_lookup() twice.");
                std::sort(m_elements.begin(), m_elements.end());
#ifndef NDEBUG
                m_init_phase = false;
#endif
            }
 
            void remove(osmium::object_id_type member_id, osmium::object_id_type relation_id) {
                assert(!m_init_phase && "Call MembersDatabase::prepare_for_lookup() before calling remove().");
                const auto range = find(member_id);
 
                if (range.empty()) {
                    return;
                }
 
                // If this is the last time this object was needed, remove it
                // from the stash.
                if (count_not_removed(range) == 1) {
                    m_stash.remove_item(range.begin()->object_handle);
                }
 
                for (auto& elem : range) {
                    if (!elem.is_removed() && relation_id == m_relations_db[elem.relation_pos]->id()) {
                        elem.remove();
                        break;
                    }
                }
            }
 
            const osmium::OSMObject* get_object(osmium::object_id_type id) const {
                assert(!m_init_phase && "Call MembersDatabase::prepare_for_lookup() before calling get_object().");
                const auto range = find(id);
                if (range.empty()) {
                    return nullptr;
                }
                const auto handle = range.begin()->object_handle;
                if (handle.valid()) {
                    return &m_stash.get<osmium::OSMObject>(handle);
                }
                return nullptr;
            }
 
        }; // class MembersDatabaseCommon
 
        template <typename TObject>
        class MembersDatabase : public MembersDatabaseCommon {
 
 
        public:
 
            MembersDatabase(osmium::ItemStash& stash, osmium::relations::RelationsDatabase& relation_db) :
                MembersDatabaseCommon(stash, relation_db) {
            }
 
            template <typename TFunc>
            bool add(const TObject& object, TFunc&& func) {
                assert(!m_init_phase && "Call MembersDatabase::prepare_for_lookup() before calling add().");
                auto range = find(object.id());
 
                if (range.empty()) {
                    // No relation needs this object.
                    return false;
                }
 
                // At least one relation needs this object. Store it and
                // "tell" all relations.
                add_object(object, range);
 
                for (auto& elem : range) {
                    assert(!elem.is_removed());
                    assert(elem.member_id == object.id());
 
                    auto rel_handle = m_relations_db[elem.relation_pos];
                    assert(elem.member_num < rel_handle->members().size());
                    rel_handle.decrement_members();
 
                    if (rel_handle.has_all_members()) {
                        std::forward<TFunc>(func)(rel_handle);
                    }
                }
 
                return true;
            }
 
            const TObject* get(osmium::object_id_type id) const {
                assert(!m_init_phase && "Call MembersDatabase::prepare_for_lookup() before calling get().");
                return static_cast<const TObject*>(get_object(id));
            }
 
        }; // class MembersDatabase
 
    } // namespace relations
 
} // namespace osmium
 
#endif // OSMIUM_RELATIONS_MEMBERS_DATABASE_HPP