336 lines
12 KiB
C++
336 lines
12 KiB
C++
#ifndef OSMIUM_RELATIONS_RELATIONS_DATABASE_HPP
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#define OSMIUM_RELATIONS_RELATIONS_DATABASE_HPP
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/*
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This file is part of Osmium (https://osmcode.org/libosmium).
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Copyright 2013-2022 Jochen Topf <jochen@topf.org> and others (see README).
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Boost Software License - Version 1.0 - August 17th, 2003
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Permission is hereby granted, free of charge, to any person or organization
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obtaining a copy of the software and accompanying documentation covered by
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this license (the "Software") to use, reproduce, display, distribute,
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execute, and transmit the Software, and to prepare derivative works of the
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Software, and to permit third-parties to whom the Software is furnished to
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do so, all subject to the following:
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The copyright notices in the Software and this entire statement, including
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the above license grant, this restriction and the following disclaimer,
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must be included in all copies of the Software, in whole or in part, and
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all derivative works of the Software, unless such copies or derivative
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works are solely in the form of machine-executable object code generated by
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a source language processor.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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DEALINGS IN THE SOFTWARE.
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*/
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#include <osmium/osm/relation.hpp>
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#include <osmium/storage/item_stash.hpp>
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#include <algorithm>
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#include <cassert>
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#include <cstddef>
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#include <utility>
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#include <vector>
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namespace osmium {
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namespace relations {
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class RelationHandle;
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/**
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* The RelationsDatabase is used for bringing relations and their
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* members together. It stores the relations in memory and keeps
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* track of how many members are needed to "complete" the relation.
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* It is intended to work together with the MembersDatabase template
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* class and usually used by relations manager classes.
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*
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* To access relations stored in the database a RelationHandle is
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* used. It is returned from the add() function. The handle is used
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* for all operations on the database contents, such as accessing
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* the stored relation, incrementing the member count or removing a
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* relation from the database.
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*
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* From the handle a "position" can be accessed, which, together with
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* the database object, can be turned into a handle again. The position
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* alone is smaller than the handle, so it can be stored elsewhere more
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* efficiently. Specifically this is used in the MembersDatabase.
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*
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* @code
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* osmium::ItemStash stash;
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* osmium::relations::RelationsDatabase db{stash};
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* auto handle = db.add(relation);
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* auto pos = handle.pos();
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* auto second_handle = db[pos];
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* @endcode
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*
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* Now the `handle` and `second_handle` refer to the same relation.
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*
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* See the RelationHandle for information about what you can do with
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* it.
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*/
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class RelationsDatabase {
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friend class RelationHandle;
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struct element {
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/// A handle to the relation in the ItemStash.
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osmium::ItemStash::handle_type handle;
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/**
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* The number of members still needed before the relation is
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* complete. This will be set to the number of members we are
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* interested in (which can be all members of a relation or
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* a subset of them) and then count down for every member we
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* find. When it is 0, the relation is complete.
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*/
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std::size_t members;
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}; // struct element
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osmium::ItemStash& m_stash;
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std::vector<element> m_elements;
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osmium::Relation& get_relation(std::size_t pos) {
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assert(pos < m_elements.size());
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return m_stash.get<osmium::Relation>(m_elements[pos].handle);
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}
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/**
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* Access the number of members of the entry at the specified
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* position. This returns a reference so it can be changed.
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*/
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std::size_t& members(std::size_t pos) noexcept {
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return m_elements[pos].members;
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}
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void remove(std::size_t pos) {
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auto& elem = m_elements[pos];
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m_stash.remove_item(elem.handle);
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elem = element{osmium::ItemStash::handle_type{}, 0};
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}
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public:
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/**
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* Construct a RelationsDatabase.
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*
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* @param stash Reference to an ItemStash object. All relations
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* will be stored in this stash. It must be available
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* until the RelationsDatabase is destroyed.
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*/
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explicit RelationsDatabase(osmium::ItemStash& stash) :
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m_stash(stash) {
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}
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/**
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* Return an estimate of the number of bytes currently needed for
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* the RelationsDatabase. This does NOT include the memory used
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* in the stash. Used for debugging.
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*
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* Complexity: Constant.
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*/
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std::size_t used_memory() const noexcept {
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return sizeof(element) * m_elements.capacity() +
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sizeof(RelationsDatabase);
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}
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/**
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* The number of relations stored in the database. Includes
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* relations marked as removed.
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*
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* Complexity: Constant.
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*/
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std::size_t size() const noexcept {
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return m_elements.size();
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}
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/**
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* Insert a relation into the database. The relation is copied
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* into the stash.
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*
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* Complexity: Amortized constant.
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*
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* @param relation The relation to be copied into the database.
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* @returns A handle to the relation.
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*/
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RelationHandle add(const osmium::Relation& relation);
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/**
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* Return a handle to the relation at the specified position in
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* the database.
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*
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* Complexity: Constant.
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*/
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RelationHandle operator[](std::size_t pos) noexcept;
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/**
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* Return the number of non-removed relations in the database.
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*
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* Complexity: Linear in the number of relations (as returned
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* by size()).
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*/
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std::size_t count_relations() const noexcept {
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return std::count_if(m_elements.cbegin(), m_elements.cend(), [&](const element& elem) {
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return elem.handle.valid();
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});
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}
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/**
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* Iterate over all (not-removed) relations in the database.
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*
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* @tparam TFunc Function with type void(const RelationHandle&).
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* @param func Callback function which will be called for every
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* not-removed relation with a RelationHandle.
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*/
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template <typename TFunc>
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void for_each_relation(TFunc&& func);
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}; // RelationsDatabase
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/**
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* A RelationHandle is used to access elements in a RelationsDatabase.
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*
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* RelationHandles can not be created by user code, they are only
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* given out by a RelationsDatabase object.
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*/
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class RelationHandle {
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friend class RelationsDatabase;
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RelationsDatabase* m_relation_database;
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std::size_t m_pos;
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RelationHandle(RelationsDatabase* relation_database, std::size_t pos) :
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m_relation_database(relation_database),
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m_pos(pos) {
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}
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public:
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/**
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* The RelationsDatabase this handle refers to.
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*/
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RelationsDatabase* relation_database() const noexcept {
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return m_relation_database;
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}
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/**
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* The position of the element in the RelationsDatabase. Use the
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* RelationsDatabase::operator[] to get the handle back from this
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* position:
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* @code
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* auto pos = handle.pos();
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* auto second_handle = relation_db[pos];
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* @endcode
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*/
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std::size_t pos() const noexcept {
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return m_pos;
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}
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/**
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* Access the relation stored in the database.
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*/
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Relation& operator*() {
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return m_relation_database->get_relation(m_pos);
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}
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/**
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* Access the relation stored in the database.
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*/
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const Relation& operator*() const {
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return m_relation_database->get_relation(m_pos);
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}
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/**
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* Call a function on the relation stored in the database.
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*/
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Relation* operator->() {
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return &m_relation_database->get_relation(m_pos);
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}
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/**
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* Call a function on the relation stored in the database.
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*/
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const Relation* operator->() const {
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return &m_relation_database->get_relation(m_pos);
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}
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/**
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* Remove the relation referred to by this handle from the database.
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* All handles referring to this database element become invalid.
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*/
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void remove() {
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m_relation_database->remove(pos());
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}
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/**
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* Set the number of relation members that we want to track.
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*/
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void set_members(std::size_t value) noexcept {
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m_relation_database->members(m_pos) = value;
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}
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/**
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* Increment the number of relation members that we want to track.
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*/
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void increment_members() noexcept {
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++(m_relation_database->members(m_pos));
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}
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/**
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* Decrement the number of relation members that we want to track.
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*
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* @pre @code has_all_members() == false @endcode
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*/
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void decrement_members() noexcept {
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assert(m_relation_database->members(m_pos) > 0);
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--(m_relation_database->members(m_pos));
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}
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/**
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* Do we have all members? This is true if the number of tracked
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* members is zero.
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*/
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bool has_all_members() const noexcept {
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return m_relation_database->members(m_pos) == 0;
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}
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}; // class RelationHandle
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inline RelationHandle RelationsDatabase::operator[](std::size_t pos) noexcept {
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assert(pos < m_elements.size());
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return {this, pos};
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}
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inline RelationHandle RelationsDatabase::add(const osmium::Relation& relation) {
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m_elements.push_back(element{m_stash.add_item(relation), 0});
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return {this, m_elements.size() - 1};
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}
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template <typename TFunc>
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void RelationsDatabase::for_each_relation(TFunc&& func) {
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for (std::size_t pos = 0; pos < m_elements.size(); ++pos) {
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if (m_elements[pos].handle.valid()) {
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func(RelationHandle{this, pos});
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}
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}
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}
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} // namespace relations
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} // namespace osmium
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#endif // OSMIUM_RELATIONS_RELATIONS_DATABASE_HPP
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