org.apache.arrow.vector.util

Class MultiMapWithOrdinal<K,V>

java.lang.Object

org.apache.arrow.vector.util.MultiMapWithOrdinal<K,V>

Type Parameters:

K - key type

V - value type

All Implemented Interfaces:

MapWithOrdinal<K,V>

public class MultiMapWithOrdinal<K,V>
extends Object
implements MapWithOrdinal<K,V>

An implementation of a multimap that supports constant time look-up by a generic key or an ordinal.

This class extends the functionality a regular Map with ordinal lookup support. Upon insertion an unused ordinal is assigned to the inserted (key, value) tuple. Upon update the same ordinal id is re-used while value is replaced. Upon deletion of an existing item, its corresponding ordinal is recycled and could be used by another item.

For any instance with N items, this implementation guarantees that ordinals are in the range of [0, N). However, the ordinal assignment is dynamic and may change after an insertion or deletion. Consumers of this class are responsible for explicitly checking the ordinal corresponding to a key via getOrdinal(Object) before attempting to execute a lookup with an ordinal.

Constructor Summary

Constructors

Constructor and Description
MultiMapWithOrdinal()

Method Summary

Modifier and Type	Method and Description
void	clear()
boolean	containsKey(K key)
V	get(K key) get set of values for key.
Collection<V>	getAll(K key) get set of values for key.
V	getByOrdinal(int id) Returns the value corresponding to the given ordinal.
int	getOrdinal(K key) Returns the ordinal corresponding to the given key.
boolean	isEmpty()
Set<K>	keys()
boolean	put(K key, V value, boolean overwrite) Inserts the tuple (key, value) into the multimap with automatic ordinal assignment.
boolean	remove(K key, V value) Removes the element corresponding to the key/value if exists with ordinal re-cycling.
boolean	removeAll(K key) remove all entries of key.
int	size()
Collection<V>	values()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MultiMapWithOrdinal

public MultiMapWithOrdinal()

Method Detail

getByOrdinal

public V getByOrdinal(int id)

Returns the value corresponding to the given ordinal.

Specified by:

getByOrdinal in interface MapWithOrdinal<K,V>

Parameters:

id - ordinal value for lookup

Returns:

an instance of V

getOrdinal

public int getOrdinal(K key)

Returns the ordinal corresponding to the given key.

Specified by:

getOrdinal in interface MapWithOrdinal<K,V>

Parameters:

key - key for ordinal lookup

Returns:

ordinal value corresponding to key if it exists or -1

size

public int size()

Specified by:

size in interface MapWithOrdinal<K,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface MapWithOrdinal<K,V>

get

public V get(K key)

get set of values for key.

Specified by:

get in interface MapWithOrdinal<K,V>

getAll

public Collection<V> getAll(K key)

get set of values for key.

Specified by:

getAll in interface MapWithOrdinal<K,V>

put

public boolean put(K key,
                   V value,
                   boolean overwrite)

Inserts the tuple (key, value) into the multimap with automatic ordinal assignment. A new ordinal is assigned if key/value pair does not exists. If overwrite is true the existing key will be overwritten with value else value will be appended to the multimap.

Specified by:

put in interface MapWithOrdinal<K,V>

values

public Collection<V> values()

Specified by:

values in interface MapWithOrdinal<K,V>

containsKey

public boolean containsKey(K key)

Specified by:

containsKey in interface MapWithOrdinal<K,V>

remove

public boolean remove(K key,
                      V value)

Removes the element corresponding to the key/value if exists with ordinal re-cycling. The ordinal corresponding to the given key may be re-assigned to another tuple. It is important that consumer checks the ordinal value via getOrdinal(Object) before attempting to look-up by ordinal. If the multimap is changed return true.

Specified by:

remove in interface MapWithOrdinal<K,V>

removeAll

public boolean removeAll(K key)

remove all entries of key.

Specified by:

removeAll in interface MapWithOrdinal<K,V>

clear

public void clear()

Specified by:

clear in interface MapWithOrdinal<K,V>

keys

public Set<K> keys()

Specified by:

keys in interface MapWithOrdinal<K,V>