osmium::relations::RelationsDatabase Class Reference

#include <relations_database.hpp>

Collaboration diagram for osmium::relations::RelationsDatabase:

Classes
struct	element

Public Member Functions
	RelationsDatabase (osmium::ItemStash &stash)
std::size_t	used_memory () const noexcept
std::size_t	size () const noexcept
RelationHandle	add (const osmium::Relation &relation)
RelationHandle	operator[] (std::size_t pos) noexcept
std::size_t	count_relations () const noexcept
template<typename TFunc >
void	for_each_relation (TFunc &&func)

Private Member Functions
osmium::Relation &	get_relation (std::size_t pos)
std::size_t &	members (std::size_t pos) noexcept
void	remove (std::size_t pos)

Private Attributes
osmium::ItemStash &	m_stash
std::vector< element >	m_elements

Friends
class	RelationHandle

Detailed Description

The RelationsDatabase is used for bringing relations and their members together. It stores the relations in memory and keeps track of how many members are needed to "complete" the relation. It is intended to work together with the MembersDatabase template class and usually used by relations manager classes.

To access relations stored in the database a RelationHandle is used. It is returned from the add() function. The handle is used for all operations on the database contents, such as accessing the stored relation, incrementing the member count or removing a relation from the database.

From the handle a "position" can be accessed, which, together with the database object, can be turned into a handle again. The position alone is smaller than the handle, so it can be stored elsewhere more efficiently. Specifically this is used in the MembersDatabase.

osmium::ItemStash stash;
osmium::relations::RelationsDatabase db{stash};
auto handle = db.add(relation);
auto pos = handle.pos();
auto second_handle = db[pos];

Now the handle and second_handle refer to the same relation.

See the RelationHandle for information about what you can do with it.

Constructor & Destructor Documentation

RelationsDatabase()

osmium::relations::RelationsDatabase::RelationsDatabase ( osmium::ItemStash &  stash )

inlineexplicit

Construct a RelationsDatabase.

Parameters

stash

Reference to an ItemStash object. All relations will be stored in this stash. It must be available until the RelationsDatabase is destroyed.

Member Function Documentation

add()

RelationHandle osmium::relations::RelationsDatabase::add ( const osmium::Relation &  relation )

inline

Insert a relation into the database. The relation is copied into the stash.

Complexity: Amortized constant.

Parameters

relation

The relation to be copied into the database.

Returns

A handle to the relation.

count_relations()

std::size_t osmium::relations::RelationsDatabase::count_relations ( ) const

inlinenoexcept

Return the number of non-removed relations in the database.

Complexity: Linear in the number of relations (as returned by size()).

for_each_relation()

template<typename TFunc >

void osmium::relations::RelationsDatabase::for_each_relation

(

TFunc &&

func

)

Iterate over all (not-removed) relations in the database.

Template Parameters

TFunc

Function with type void(const RelationHandle&).

Parameters

func	Callback function which will be called for every not-removed relation with a RelationHandle.

get_relation()

osmium::Relation & osmium::relations::RelationsDatabase::get_relation ( std::size_t  pos )

inlineprivate

members()

std::size_t & osmium::relations::RelationsDatabase::members ( std::size_t  pos )

inlineprivatenoexcept

Access the number of members of the entry at the specified position. This returns a reference so it can be changed.

operator[]()

RelationHandle osmium::relations::RelationsDatabase::operator[] ( std::size_t  pos )

inlinenoexcept

Return a handle to the relation at the specified position in the database.

Complexity: Constant.

remove()

void osmium::relations::RelationsDatabase::remove ( std::size_t  pos )

inlineprivate

size()

std::size_t osmium::relations::RelationsDatabase::size ( ) const

inlinenoexcept

The number of relations stored in the database. Includes relations marked as removed.

Complexity: Constant.

used_memory()

std::size_t osmium::relations::RelationsDatabase::used_memory ( ) const

inlinenoexcept

Return an estimate of the number of bytes currently needed for the RelationsDatabase. This does NOT include the memory used in the stash. Used for debugging.

Complexity: Constant.

Friends And Related Function Documentation

RelationHandle

friend class RelationHandle

friend

Member Data Documentation

m_elements

std::vector<element> osmium::relations::RelationsDatabase::m_elements

private

m_stash

osmium::ItemStash& osmium::relations::RelationsDatabase::m_stash

private

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The documentation for this class was generated from the following file:

• include/osmium/relations/relations_database.hpp