Class TruncateTokenFilter
- 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.miscellaneous.TruncateTokenFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,Unwrappable<TokenStream>
public final class TruncateTokenFilter extends TokenFilter
A token filter for truncating the terms into a specific length. Fixed prefix truncation, as a stemming method, produces good results on Turkish language. It is reported that F5, using first 5 characters, produced best results in Information Retrieval on Turkish Texts
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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 KeywordAttribute
keywordAttr
private int
length
private CharTermAttribute
termAttribute
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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 TruncateTokenFilter(TokenStream input, int length)
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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.-
Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end, reset, 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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termAttribute
private final CharTermAttribute termAttribute
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keywordAttr
private final KeywordAttribute keywordAttr
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length
private final int length
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Constructor Detail
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TruncateTokenFilter
public TruncateTokenFilter(TokenStream input, int length)
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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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