Class EdgeNGramTokenFilter
- 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.ngram.EdgeNGramTokenFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
public final class EdgeNGramTokenFilter extends TokenFilter
Tokenizes the given token into n-grams of given size(s).This
TokenFilter
create n-grams from the beginning edge or ending edge of a input token.As of Lucene 4.4, this filter does not support
EdgeNGramTokenFilter.Side.BACK
(you can useReverseStringFilter
up-front and afterward to get the same behavior), handles supplementary characters correctly and does not update offsets anymore.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
EdgeNGramTokenFilter.Side
Specifies which side of the input the n-gram should be generated from-
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.AttributeFactory, AttributeSource.State
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Field Summary
Fields Modifier and Type Field Description static int
DEFAULT_MAX_GRAM_SIZE
static int
DEFAULT_MIN_GRAM_SIZE
static EdgeNGramTokenFilter.Side
DEFAULT_SIDE
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Constructor Summary
Constructors Constructor Description EdgeNGramTokenFilter(Version version, TokenStream input, int minGram, int maxGram)
Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given rangeEdgeNGramTokenFilter(Version version, TokenStream input, java.lang.String sideLabel, int minGram, int maxGram)
Deprecated.EdgeNGramTokenFilter(Version version, TokenStream input, EdgeNGramTokenFilter.Side side, int minGram, int maxGram)
Deprecated.
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Method Summary
All Methods Instance Methods Concrete Methods 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 usingTokenStream.incrementToken()
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Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end
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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
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Field Detail
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DEFAULT_SIDE
public static final EdgeNGramTokenFilter.Side DEFAULT_SIDE
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DEFAULT_MAX_GRAM_SIZE
public static final int DEFAULT_MAX_GRAM_SIZE
- See Also:
- Constant Field Values
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DEFAULT_MIN_GRAM_SIZE
public static final int DEFAULT_MIN_GRAM_SIZE
- See Also:
- Constant Field Values
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Constructor Detail
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EdgeNGramTokenFilter
@Deprecated public EdgeNGramTokenFilter(Version version, TokenStream input, EdgeNGramTokenFilter.Side side, int minGram, int maxGram)
Deprecated.Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range- Parameters:
version
- the Lucene match versioninput
-TokenStream
holding the input to be tokenizedside
- theEdgeNGramTokenFilter.Side
from which to chop off an n-gramminGram
- the smallest n-gram to generatemaxGram
- the largest n-gram to generate
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EdgeNGramTokenFilter
@Deprecated public EdgeNGramTokenFilter(Version version, TokenStream input, java.lang.String sideLabel, int minGram, int maxGram)
Deprecated.Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range- Parameters:
version
- the Lucene match versioninput
-TokenStream
holding the input to be tokenizedsideLabel
- the name of theEdgeNGramTokenFilter.Side
from which to chop off an n-gramminGram
- the smallest n-gram to generatemaxGram
- the largest n-gram to generate
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EdgeNGramTokenFilter
public EdgeNGramTokenFilter(Version version, TokenStream input, int minGram, int maxGram)
Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range- Parameters:
version
- the Lucene match versioninput
-TokenStream
holding the input to be tokenizedminGram
- the smallest n-gram to generatemaxGram
- the largest n-gram to generate
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Method Detail
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incrementToken
public final boolean incrementToken() throws java.io.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 appropriateAttributeImpl
s 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)
andAttributeSource.getAttribute(Class)
, references to allAttributeImpl
s 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 classTokenStream
- Returns:
- false for end of stream; true otherwise
- Throws:
java.io.IOException
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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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