Package org.apache.lucene.analysis.hunspell

Class HunspellStemFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.hunspell.HunspellStemFilter

All Implemented Interfaces:

Closeable, AutoCloseable

public final class HunspellStemFilter
extends TokenFilter

TokenFilter that uses hunspell affix rules and words to stem tokens. Since hunspell supports a word having multiple stems, this filter can emit multiple tokens for each consumed token

Note: This filter is aware of the KeywordAttribute. To prevent certain terms from being passed to the stemmer KeywordAttribute.isKeyword() should be set to true in a previous TokenStream. Note: For including the original term as well as the stemmed version, see KeywordRepeatFilterFactory

Nested Class Summary

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

AttributeSource.AttributeFactory, AttributeSource.State

Constructor Summary

Constructors

Constructor	Description
HunspellStemFilter(TokenStream input, HunspellDictionary dictionary)	Create a HunspellStemFilter which deduplicates stems and has a maximum recursion level of 2.
HunspellStemFilter(TokenStream input, HunspellDictionary dictionary, boolean dedup)	Create a HunspellStemFilter which has a maximum recursion level of 2.
HunspellStemFilter(TokenStream input, HunspellDictionary dictionary, boolean dedup, int recursionCap)	Creates a new HunspellStemFilter that will stem tokens from the given TokenStream using affix rules in the provided HunspellDictionary
HunspellStemFilter(TokenStream input, HunspellDictionary dictionary, int recursionCap)	Creates a new HunspellStemFilter that will stem tokens from the given TokenStream using affix rules in the provided HunspellDictionary

Method Summary

Modifier and Type	Method	Description
boolean	incrementToken()	Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.
void	reset()	This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

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

close, end

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

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

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Details

HunspellStemFilter

public HunspellStemFilter(TokenStream input,
 HunspellDictionary dictionary)

Create a HunspellStemFilter which deduplicates stems and has a maximum recursion level of 2.

See Also:

• HunspellStemFilter(TokenStream, HunspellDictionary, int)

HunspellStemFilter

public HunspellStemFilter(TokenStream input,
 HunspellDictionary dictionary,
 int recursionCap)

Creates a new HunspellStemFilter that will stem tokens from the given TokenStream using affix rules in the provided HunspellDictionary

Parameters:

input - TokenStream whose tokens will be stemmed

dictionary - HunspellDictionary containing the affix rules and words that will be used to stem the tokens

recursionCap - maximum level of recursion stemmer can go into, defaults to 2

HunspellStemFilter

public HunspellStemFilter(TokenStream input,
 HunspellDictionary dictionary,
 boolean dedup)

Create a HunspellStemFilter which has a maximum recursion level of 2.

See Also:

• HunspellStemFilter(TokenStream, HunspellDictionary, boolean, int)

HunspellStemFilter

public HunspellStemFilter(TokenStream input,
 HunspellDictionary dictionary,
 boolean dedup,
 int recursionCap)

Creates a new HunspellStemFilter that will stem tokens from the given TokenStream using affix rules in the provided HunspellDictionary

Parameters:

input - TokenStream whose tokens will be stemmed

dictionary - HunspellDictionary containing the affix rules and words that will be used to stem the tokens

dedup - true if only unique terms should be output.

recursionCap - maximum level of recursion stemmer can go into, defaults to 2

Method Details

incrementToken

public boolean incrementToken()
                       throws IOException

Consumers (i.e., IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate AttributeImpls with the attributes of the next token.

The producer must make no assumptions about the attributes after the method has been returned: the caller may arbitrarily change it. If the producer needs to preserve the state for subsequent calls, it can use AttributeSource.captureState() to create a copy of the current attribute state.

This method is called for every token of a document, so an efficient implementation is crucial for good performance. To avoid calls to AttributeSource.addAttribute(Class) and AttributeSource.getAttribute(Class), references to all AttributeImpls that this stream uses should be retrieved during instantiation.

To ensure that filters and consumers know which attributes are available, the attributes must be added during instantiation. Filters and consumers are not required to check for availability of attributes in TokenStream.incrementToken().

Specified by:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Throws:

IOException

reset

public void reset()
           throws IOException

This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.

If you override this method, always call super.reset(), otherwise some internal state will not be correctly reset (e.g., Tokenizer will throw IllegalStateException on further usage).

NOTE: The default implementation chains the call to the input TokenStream, so be sure to call super.reset() when overriding this method.

Overrides:

reset in class TokenFilter

Throws:

IOException