Module org.apache.lucene.analysis.common

Package org.apache.lucene.analysis.miscellaneous

Class StemmerOverrideFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.miscellaneous.StemmerOverrideFilter

All Implemented Interfaces:

Closeable, AutoCloseable, Unwrappable<TokenStream>

public final class StemmerOverrideFilter
extends TokenFilter

Provides the ability to override any KeywordAttribute aware stemmer with custom dictionary-based stemming.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	StemmerOverrideFilter.Builder	This builder builds an FST for the StemmerOverrideFilter
static final class	StemmerOverrideFilter.StemmerOverrideMap	A read-only 4-byte FST backed map that allows fast case-insensitive key value lookups for StemmerOverrideFilter

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field	Description
private final FST.BytesReader	fstReader
private final KeywordAttribute	keywordAtt
private final FST.Arc<BytesRef>	scratchArc
private char[]	spare
private final StemmerOverrideFilter.StemmerOverrideMap	stemmerOverrideMap
private final CharTermAttribute	termAtt

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

input

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor	Description
StemmerOverrideFilter(TokenStream input, StemmerOverrideFilter.StemmerOverrideMap stemmerOverrideMap)	Create a new StemmerOverrideFilter, performing dictionary-based stemming with the provided dictionary.

Method Summary

Modifier and Type	Method	Description
boolean	incrementToken()	Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.

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

close, end, reset, unwrap

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

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

Methods inherited from class java.lang.Object

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

Field Details

stemmerOverrideMap

private final StemmerOverrideFilter.StemmerOverrideMap stemmerOverrideMap

termAtt

private final CharTermAttribute termAtt

keywordAtt

private final KeywordAttribute keywordAtt

fstReader

private final FST.BytesReader fstReader

scratchArc

private final FST.Arc<BytesRef> scratchArc

spare

private char[] spare

Constructor Details

StemmerOverrideFilter

public StemmerOverrideFilter(TokenStream input,
 StemmerOverrideFilter.StemmerOverrideMap stemmerOverrideMap)

Create a new StemmerOverrideFilter, performing dictionary-based stemming with the provided dictionary.

Any dictionary-stemmed terms will be marked with KeywordAttribute so that they will not be stemmed with stemmers down the chain.

Method Details

incrementToken

public boolean incrementToken()
                       throws IOException

Description copied from class: TokenStream

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