Class CommonGramsQueryFilter
- java.lang.Object
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- org.apache.lucene.util.AttributeSource
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- org.apache.lucene.analysis.TokenStream
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- org.apache.lucene.analysis.TokenFilter
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- org.apache.lucene.analysis.commongrams.CommonGramsQueryFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,Unwrappable<TokenStream>
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"
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
Fields Modifier and Type Field Description private boolean
exhausted
private PositionIncrementAttribute
posIncAttribute
private PositionLengthAttribute
posLengthAttribute
private AttributeSource.State
previous
private java.lang.String
previousType
private TypeAttribute
typeAttribute
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Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
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Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
Constructors Constructor Description CommonGramsQueryFilter(CommonGramsFilter input)
Constructs a new CommonGramsQueryFilter based on the provided CommomGramsFilter
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
incrementToken()
Output bigrams whenever possible to optimize queries.boolean
isGramType()
Convenience method to check if the current type is a gram typevoid
reset()
This method is called by a consumer before it begins consumption usingTokenStream.incrementToken()
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Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end, unwrap
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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
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Field Detail
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typeAttribute
private final TypeAttribute typeAttribute
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posIncAttribute
private final PositionIncrementAttribute posIncAttribute
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posLengthAttribute
private final PositionLengthAttribute posLengthAttribute
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previous
private AttributeSource.State previous
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previousType
private java.lang.String previousType
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exhausted
private boolean exhausted
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Constructor Detail
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CommonGramsQueryFilter
public CommonGramsQueryFilter(CommonGramsFilter input)
Constructs a new CommonGramsQueryFilter based on the provided CommomGramsFilter- Parameters:
input
- CommonGramsFilter the QueryFilter will use
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Method Detail
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reset
public void reset() throws java.io.IOException
Description copied from class:TokenFilter
This method is called by a consumer before it begins consumption usingTokenStream.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 throwIllegalStateException
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 classTokenFilter
- Throws:
java.io.IOException
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incrementToken
public boolean incrementToken() throws java.io.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 classTokenStream
- Returns:
- false for end of stream; true otherwise
- Throws:
java.io.IOException
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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
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