edu.stanford.nlp.util

Class DeltaMap<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

edu.stanford.nlp.util.DeltaMap<K,V>

All Implemented Interfaces:

Map<K,V>

public class DeltaMap<K,V>
extends AbstractMap<K,V>

A Map which wraps an original Map, and only stores the changes (deltas) from the original Map. This increases Map access time (roughly doubles it) but eliminates Map creation time and decreases memory usage (if you're keeping the original Map in memory anyway).

Author:

Teg Grenager (grenager@cs.stanford.edu)

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
DeltaMap(Map<K,V> originalMap)
DeltaMap(Map<K,V> originalMap, MapFactory<K,V> mf) This is very cheap.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() This is more expensive than normal.
boolean	containsKey(Object key) This is more expensive.
Set<Map.Entry<K,V>>	entrySet() This is cheap.
V	get(Object key) This may cost twice what it would in the original Map.
static void	main(String[] args) For testing only.
V	put(K key, V value) This may cost twice what it would in the original Map because we have to find the original value for this key.
V	remove(Object key)

Methods inherited from class java.util.AbstractMap

clone, containsValue, equals, hashCode, isEmpty, keySet, putAll, size, toString, values

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

DeltaMap

public DeltaMap(Map<K,V> originalMap,
        MapFactory<K,V> mf)

This is very cheap.

Parameters:

originalMap - will serve as the basis for this DeltaMap

DeltaMap

public DeltaMap(Map<K,V> originalMap)

Method Detail

containsKey

public boolean containsKey(Object key)

This is more expensive.

Specified by:

containsKey in interface Map<K,V>

Overrides:

containsKey in class AbstractMap<K,V>

Parameters:

key - key whose presence in this map is to be tested.

Returns:

true if this map contains a mapping for the specified key.

get

public V get(Object key)

This may cost twice what it would in the original Map.

Specified by:

get in interface Map<K,V>

Overrides:

get in class AbstractMap<K,V>

Parameters:

key - key whose associated value is to be returned.

Returns:

the value to which this map maps the specified key, or null if the map contains no mapping for this key.

put

public V put(K key,
    V value)

This may cost twice what it would in the original Map because we have to find the original value for this key.

Specified by:

put in interface Map<K,V>

Overrides:

put in class AbstractMap<K,V>

Parameters:

key - key with which the specified value is to be associated.

value - value to be associated with the specified key.

Returns:

previous value associated with specified key, or null if there was no mapping for key. A null return can also indicate that the map previously associated null with the specified key, if the implementation supports null values.

remove

public V remove(Object key)

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class AbstractMap<K,V>

clear

public void clear()

This is more expensive than normal.

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class AbstractMap<K,V>

entrySet

public Set<Map.Entry<K,V>> entrySet()

This is cheap.

Specified by:

entrySet in interface Map<K,V>

Specified by:

entrySet in class AbstractMap<K,V>

Returns:

a set view of the mappings contained in this map.

main

public static void main(String[] args)

For testing only.

Parameters:

args - from command line