org.apache.lucene.analysis.nl

Class DutchStemFilter

java.lang.Object

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.nl.DutchStemFilter

public final class DutchStemFilter
extends TokenFilter

A filter that stems Dutch words. It supports a table of words that should not be stemmed at all. The stemmer used can be changed at runtime after the filter object is created (as long as it is a DutchStemmer).

Field Summary

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

input

Constructor Summary

Constructors

Constructor and Description
DutchStemFilter(TokenStream _in)
DutchStemFilter(TokenStream _in, Set exclusiontable) Builds a DutchStemFilter that uses an exclusion table.
DutchStemFilter(TokenStream _in, Set exclusiontable, Map stemdictionary)

Method Summary

Methods

Modifier and Type	Method and Description
Token	next(Token reusableToken) Returns the next token in the stream, or null at EOS.
void	setExclusionTable(HashSet exclusiontable) Set an alternative exclusion list for this filter.
void	setStemDictionary(HashMap dict) Set dictionary for stemming, this dictionary overrules the algorithm, so you can correct for a particular unwanted word-stem pair.
void	setStemmer(DutchStemmer stemmer) Set a alternative/custom DutchStemmer for this filter.

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

close, reset

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

next

Methods inherited from class java.lang.Object

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

Constructor Detail

DutchStemFilter

public DutchStemFilter(TokenStream _in)

DutchStemFilter

public DutchStemFilter(TokenStream _in,
               Set exclusiontable)

Builds a DutchStemFilter that uses an exclusion table.

DutchStemFilter

public DutchStemFilter(TokenStream _in,
               Set exclusiontable,
               Map stemdictionary)

Parameters:

stemdictionary - Dictionary of word stem pairs, that overrule the algorithm

Method Detail

next

public Token next(Token reusableToken)
           throws IOException

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 & 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:

Returns the next token in the stream, or null at EOS

Throws:

IOException

setStemmer

public void setStemmer(DutchStemmer stemmer)

Set a alternative/custom DutchStemmer for this filter.

setExclusionTable

public void setExclusionTable(HashSet exclusiontable)

Set an alternative exclusion list for this filter.

setStemDictionary

public void setStemDictionary(HashMap dict)

Set dictionary for stemming, this dictionary overrules the algorithm, so you can correct for a particular unwanted word-stem pair.