Package opennlp.tools.stemmer.snowball

Class SnowballStemmer

java.lang.Object

opennlp.tools.stemmer.snowball.SnowballStemmer

All Implemented Interfaces:

opennlp.tools.stemmer.Stemmer

@ThreadSafe
public class SnowballStemmer
extends Object
implements opennlp.tools.stemmer.Stemmer

A Stemmer backed by the generated Snowball engines.

The generated engines hold mutable per-call buffers, so this class routes each call to a per-thread engine, the same pattern the thread-safe *ME components use. A single SnowballStemmer instance is therefore safe to share across threads.

As with the *ME components, long-running environments such as application containers should call clearThreadLocalState() when a pooled thread no longer uses this stemmer; otherwise the thread retains its engine until the instance is unreachable, which can pin the defining classloader on redeploys.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	SnowballStemmer.ALGORITHM

Constructor Summary

Constructors

Constructor	Description
SnowballStemmer(SnowballStemmer.ALGORITHM algorithm)	Creates a stemmer for the given algorithm with repeat = 1.
SnowballStemmer(SnowballStemmer.ALGORITHM algorithm, int repeat)	Creates a stemmer for the given algorithm and repeat count.

Method Summary

Modifier and Type	Method	Description
void	clearThreadLocalState()	Removes this thread's engine to prevent classloader leaks in container environments.
CharSequence	stem(CharSequence word)

Methods inherited from class java.lang.Object

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

Methods inherited from interface opennlp.tools.stemmer.Stemmer

stemAll

Constructor Details

SnowballStemmer

public SnowballStemmer(SnowballStemmer.ALGORITHM algorithm,
 int repeat)

Creates a stemmer for the given algorithm and repeat count.

Parameters:

algorithm - The Snowball algorithm. Must not be null.

repeat - How many times to apply the stemmer per word; must be positive.

Throws:

IllegalArgumentException - Thrown if algorithm is null or repeat is not positive.

SnowballStemmer

public SnowballStemmer(SnowballStemmer.ALGORITHM algorithm)

Creates a stemmer for the given algorithm with repeat = 1.

Parameters:

algorithm - The Snowball algorithm. Must not be null.

Throws:

IllegalArgumentException - Thrown if algorithm is null.

Method Details

stem

public CharSequence stem(CharSequence word)

Specified by:

stem in interface opennlp.tools.stemmer.Stemmer

clearThreadLocalState

public void clearThreadLocalState()

Removes this thread's engine to prevent classloader leaks in container environments. Call when the thread is returned to a pool or the stemmer is no longer needed, mirroring clearThreadLocalState() on the thread-safe *ME components.