Class CJKWidthFilter
- 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.cjk.CJKWidthFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
public final class CJKWidthFilter extends TokenFilter
ATokenFilter
that normalizes CJK width differences:- Folds fullwidth ASCII variants into the equivalent basic latin
- Folds halfwidth Katakana variants into the equivalent kana
NOTE: this filter can be viewed as a (practical) subset of NFKC/NFKD Unicode normalization. See the normalization support in the ICU package for full normalization.
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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 static byte[]
KANA_COMBINE_HALF_VOICED
private static byte[]
KANA_COMBINE_VOICED
private static char[]
KANA_NORM
private CharTermAttribute
termAtt
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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 CJKWidthFilter(TokenStream input)
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description private static boolean
combine(char[] text, int pos, char ch)
returns true if we successfully combined the voice markboolean
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
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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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termAtt
private CharTermAttribute termAtt
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KANA_NORM
private static final char[] KANA_NORM
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KANA_COMBINE_VOICED
private static final byte[] KANA_COMBINE_VOICED
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KANA_COMBINE_HALF_VOICED
private static final byte[] KANA_COMBINE_HALF_VOICED
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Constructor Detail
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CJKWidthFilter
public CJKWidthFilter(TokenStream input)
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Method Detail
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incrementToken
public 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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combine
private static boolean combine(char[] text, int pos, char ch)
returns true if we successfully combined the voice mark
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