edu.stanford.nlp.util

Class Interner<T>

java.lang.Object

edu.stanford.nlp.util.Interner<T>

public class Interner<T>
extends java.lang.Object

For interning (canonicalizing) things.
It maps any object to a unique interned version which .equals the presented object. If presented with a new object which has no previous interned version, the presented object becomes the interned version. You can tell if your object has been chosen as the new unique representative by checking whether o == intern(o). The interners use WeakHashMap, meaning that if the only pointers to an interned item are the interners' backing maps, that item can still be garbage collected. Since the gc thread can silently remove things from the backing map, there's no public way to get the backing map, but feel free to add one at your own risk.
Note that in general it is just as good or better to use the static Interner.globalIntern() method rather than making an instance of Interner and using the instance-level intern().
Author: Dan Klein Date: 9/28/03

Author:

Dan Klein

Field Summary

Fields

Modifier and Type	Field and Description
protected static Interner<java.lang.Object>	interner
protected java.util.Map<T,java.lang.ref.WeakReference<T>>	map

Constructor Summary

Constructors

Constructor and Description
Interner()
Interner(int initialCapacity)

Method Summary

Modifier and Type	Method and Description
void	clear()
void	clear(int initialCapacity)
static Interner<java.lang.Object>	getGlobal() For getting the instance that global methods use.
static <T> T	globalIntern(T o) Returns a unique object o' that .equals the argument o.
T	intern(T o) Returns a unique object o' that .equals the argument o.
java.util.Set<T>	internAll(java.util.Set<T> s) Returns a Set such that each element in the returned set is a unique object e' that .equals the corresponding element e in the original set.
static void	main(java.lang.String[] args) Test method: interns its arguments and says whether they == themselves.
static Interner<java.lang.Object>	setGlobal(Interner<java.lang.Object> interner) For supplying a new instance for the global methods to use.
int	size()

Methods inherited from class java.lang.Object

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

Field Detail

interner

protected static Interner<java.lang.Object> interner

map

protected java.util.Map<T,java.lang.ref.WeakReference<T>> map

Constructor Detail

Interner

public Interner()

Interner

public Interner(int initialCapacity)

Method Detail

getGlobal

public static Interner<java.lang.Object> getGlobal()

For getting the instance that global methods use.

setGlobal

public static Interner<java.lang.Object> setGlobal(Interner<java.lang.Object> interner)

For supplying a new instance for the global methods to use.

Returns:

the previous global interner.

globalIntern

public static <T> T globalIntern(T o)

Returns a unique object o' that .equals the argument o. If o itself is returned, this is the first request for an object .equals to o.

clear

public void clear()

clear

public void clear(int initialCapacity)

intern

public T intern(T o)

Returns a unique object o' that .equals the argument o. If o itself is returned, this is the first request for an object .equals to o.

internAll

public java.util.Set<T> internAll(java.util.Set<T> s)

Returns a Set such that each element in the returned set is a unique object e' that .equals the corresponding element e in the original set.

size

public int size()

main

public static void main(java.lang.String[] args)

Test method: interns its arguments and says whether they == themselves.