org.apache.lucene.analysis.snowball
Class SnowballFilter

java.lang.Object
  org.apache.lucene.util.AttributeSource
      org.apache.lucene.analysis.TokenStream
          org.apache.lucene.analysis.TokenFilter
              org.apache.lucene.analysis.snowball.SnowballFilter

public class SnowballFilter
extends TokenFilter

A filter that stems words using a Snowball-generated stemmer. Available stemmers are listed in org.tartarus.snowball.ext.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

Fields inherited from class org.apache.lucene.analysis.TokenFilter

input

Constructor Summary

SnowballFilter(TokenStream input, SnowballProgram stemmer)

SnowballFilter(TokenStream in, String name)
Construct the named stemming filter.

Method Summary

boolean	incrementToken() Returns the next input Token, after being stemmed
Token	next() Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.
Token	next(Token reusableToken) Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.

Methods inherited from class org.apache.lucene.analysis.TokenFilter

close, end, reset

Methods inherited from class org.apache.lucene.analysis.TokenStream

getOnlyUseNewAPI, setOnlyUseNewAPI

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, restoreState, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

SnowballFilter

public SnowballFilter(TokenStream input,
                      SnowballProgram stemmer)

SnowballFilter

public SnowballFilter(TokenStream in,
                      String name)

Construct the named stemming filter. Available stemmers are listed in org.tartarus.snowball.ext. The name of a stemmer is the part of the class name before "Stemmer", e.g., the stemmer in EnglishStemmer is named "English".

Parameters:

in - the input tokens to stem

name - the name of a stemmer

Method Detail

incrementToken

public final boolean incrementToken()
                             throws IOException

Returns the next input Token, after being stemmed

Overrides:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Note that this method will be defined abstract in Lucene 3.0.

Throws:

IOException

next

public final Token next(Token reusableToken)
                 throws IOException

Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.

Description copied from class: TokenStream

Returns the next token in the stream, or null at EOS. When possible, the input Token should be used as the returned Token (this gives fastest tokenization performance), but this is not required and a new Token may be returned. Callers may re-use a single Token instance for successive calls to this method.

This implicitly defines a "contract" between consumers (callers of this method) and producers (implementations of this method that are the source for tokens):

• A consumer must fully consume the previously returned Token before calling this method again.
• A producer must call Token.clear() before setting the fields in it and returning it

Also, the producer must make no assumptions about a Token after it has been returned: the caller may arbitrarily change it. If the producer needs to hold onto the Token for subsequent calls, it must clone() it before storing it. Note that a TokenFilter is considered a consumer.

Overrides:

next in class TokenStream

Parameters:

reusableToken - a Token that may or may not be used to return; this parameter should never be null (the callee is not required to check for null before using it, but it is a good idea to assert that it is not null.)

Returns:

next Token in the stream or null if end-of-stream was hit

Throws:

IOException

next

public final Token next()
                 throws IOException

Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.

Description copied from class: TokenStream

Returns the next Token in the stream, or null at EOS.

Overrides:

next in class TokenStream

Throws:

IOException