Package org.apache.lucene.analysis.synonym

Class SynonymGraphFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.synonym.SynonymGraphFilter

All Implemented Interfaces:

Closeable, AutoCloseable

public final class SynonymGraphFilter
extends TokenFilter

Applies single- or multi-token synonyms from a SynonymMap to an incoming TokenStream, producing a fully correct graph output. This is a replacement for SynonymFilter, which produces incorrect graphs for multi-token synonyms.

However, if you use this during indexing, you must follow it with FlattenGraphFilter to squash tokens on top of one another like SynonymFilter, because the indexer can't directly consume a graph. To get fully correct positional queries when your synonym replacements are multiple tokens, you should instead apply synonyms using this TokenFilter at query time and translate the resulting graph to a TermAutomatonQuery e.g. using TokenStreamToTermAutomatonQuery.

NOTE: this cannot consume an incoming graph; results will be undefined.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field	Description
static String	TYPE_SYNONYM

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
SynonymGraphFilter(TokenStream input, SynonymMap synonyms, boolean ignoreCase)	Apply previously built synonyms to incoming tokens.

Method Summary

Modifier and Type	Method	Description
boolean	incrementToken()
void	reset()

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, 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 Detail

TYPE_SYNONYM

public static final String TYPE_SYNONYM

See Also:

Constant Field Values

Constructor Detail

SynonymGraphFilter

public SynonymGraphFilter(TokenStream input,
                          SynonymMap synonyms,
                          boolean ignoreCase)

Apply previously built synonyms to incoming tokens.

Parameters:

input - input tokenstream

synonyms - synonym map

ignoreCase - case-folds input for matching with Character.toLowerCase(int). Note, if you set this to true, it's your responsibility to lowercase the input entries when you create the SynonymMap

Method Detail

incrementToken

public boolean incrementToken()
                       throws IOException

Specified by:

incrementToken in class TokenStream

Throws:

IOException

reset

public void reset()
           throws IOException

Overrides:

reset in class TokenFilter

Throws:

IOException