org.apache.lucene.analysis.commongrams

Class CommonGramsQueryFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.commongrams.CommonGramsQueryFilter

All Implemented Interfaces:

Closeable, AutoCloseable

public final class CommonGramsQueryFilter
extends TokenFilter

Wrap a CommonGramsFilter optimizing phrase queries by only returning single words when they are not a member of a bigram. Example:

• query input to CommonGramsFilter: "the rain in spain falls mainly"
• output of CommomGramsFilter/input to CommonGramsQueryFilter: |"the, "the-rain"|"rain" "rain-in"|"in, "in-spain"|"spain"|"falls"|"mainly"
• output of CommonGramsQueryFilter:"the-rain", "rain-in" ,"in-spain", "falls", "mainly"

Nested Class Summary

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

AttributeSource.State

Field Summary

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 and Description
CommonGramsQueryFilter(CommonGramsFilter input) Constructs a new CommonGramsQueryFilter based on the provided CommomGramsFilter

Method Summary

Methods

Modifier and Type	Method and Description
boolean	incrementToken() Output bigrams whenever possible to optimize queries.
boolean	isGramType() Convenience method to check if the current type is a gram type
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, 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

Constructor Detail

CommonGramsQueryFilter

public CommonGramsQueryFilter(CommonGramsFilter input)

Constructs a new CommonGramsQueryFilter based on the provided CommomGramsFilter

Parameters:

input - CommonGramsFilter the QueryFilter will use

Method Detail

reset

public void reset()
           throws IOException

Overrides:

reset in class TokenFilter

Throws:

IOException

incrementToken

public boolean incrementToken()
                       throws IOException

Output bigrams whenever possible to optimize queries. Only output unigrams when they are not a member of a bigram. Example:

• input: "the rain in spain falls mainly"
• output:"the-rain", "rain-in" ,"in-spain", "falls", "mainly"

Specified by:

incrementToken in class TokenStream

Throws:

IOException

isGramType

public boolean isGramType()

Convenience method to check if the current type is a gram type

Returns:

true if the current type is a gram type, false otherwise