Class ICUTokenizer
- 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.Tokenizer
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- org.apache.lucene.analysis.icu.segmentation.ICUTokenizer
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
public final class ICUTokenizer extends Tokenizer
Breaks text into words according to UAX #29: Unicode Text Segmentation (http://www.unicode.org/reports/tr29/)Words are broken across script boundaries, then segmented according to the BreakIterator and typing provided by the
ICUTokenizerConfig
- See Also:
ICUTokenizerConfig
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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 CompositeBreakIterator
breaker
private char[]
buffer
private ICUTokenizerConfig
config
private static int
IOBUFFER
private int
length
true length of text in the bufferprivate int
offset
accumulated offset of previous buffers for this reader, for offsetAttprivate OffsetAttribute
offsetAtt
private ScriptAttribute
scriptAtt
private CharTermAttribute
termAtt
private TypeAttribute
typeAtt
private int
usableLength
length in buffer that can be evaluated safely, up to a safe end point-
Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
Constructors Constructor Description ICUTokenizer()
Construct a new ICUTokenizer that breaks text into words from the given Reader.ICUTokenizer(ICUTokenizerConfig config)
Construct a new ICUTokenizer that breaks text into words from the given Reader, using a tailored BreakIterator configuration.ICUTokenizer(AttributeFactory factory, ICUTokenizerConfig config)
Construct a new ICUTokenizer that breaks text into words from the given Reader, using a tailored BreakIterator configuration.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
end()
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API).private int
findSafeEnd()
Returns the last unambiguous break position in the text.boolean
incrementToken()
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token.private boolean
incrementTokenBuffer()
private static int
read(java.io.Reader input, char[] buffer, int offset, int length)
commons-io's readFully, but without bugs if offset != 0private void
refill()
Refill the buffer, accumulating the offset and setting usableLength to the last unambiguous break positionvoid
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.Tokenizer
close, correctOffset, setReader
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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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IOBUFFER
private static final int IOBUFFER
- See Also:
- Constant Field Values
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buffer
private final char[] buffer
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length
private int length
true length of text in the buffer
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usableLength
private int usableLength
length in buffer that can be evaluated safely, up to a safe end point
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offset
private int offset
accumulated offset of previous buffers for this reader, for offsetAtt
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breaker
private final CompositeBreakIterator breaker
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config
private final ICUTokenizerConfig config
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offsetAtt
private final OffsetAttribute offsetAtt
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termAtt
private final CharTermAttribute termAtt
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typeAtt
private final TypeAttribute typeAtt
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scriptAtt
private final ScriptAttribute scriptAtt
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Constructor Detail
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ICUTokenizer
public ICUTokenizer()
Construct a new ICUTokenizer that breaks text into words from the given Reader.The default script-specific handling is used.
The default attribute factory is used.
- See Also:
DefaultICUTokenizerConfig
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ICUTokenizer
public ICUTokenizer(ICUTokenizerConfig config)
Construct a new ICUTokenizer that breaks text into words from the given Reader, using a tailored BreakIterator configuration.The default attribute factory is used.
- Parameters:
config
- Tailored BreakIterator configuration
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ICUTokenizer
public ICUTokenizer(AttributeFactory factory, ICUTokenizerConfig config)
Construct a new ICUTokenizer that breaks text into words from the given Reader, using a tailored BreakIterator configuration.- Parameters:
factory
- AttributeFactory to useconfig
- Tailored BreakIterator configuration
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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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reset
public void reset() throws java.io.IOException
Description copied from class:TokenStream
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).
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end
public void end() throws java.io.IOException
Description copied from class:TokenStream
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API). Streams implementing the old API should upgrade to use this feature.This method can be used to perform any end-of-stream operations, such as setting the final offset of a stream. The final offset of a stream might differ from the offset of the last token eg in case one or more whitespaces followed after the last token, but a WhitespaceTokenizer was used.
Additionally any skipped positions (such as those removed by a stopfilter) can be applied to the position increment, or any adjustment of other attributes where the end-of-stream value may be important.
If you override this method, always call
super.end()
.- Overrides:
end
in classTokenStream
- Throws:
java.io.IOException
- If an I/O error occurs
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findSafeEnd
private int findSafeEnd()
Returns the last unambiguous break position in the text.- Returns:
- position of character, or -1 if one does not exist
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refill
private void refill() throws java.io.IOException
Refill the buffer, accumulating the offset and setting usableLength to the last unambiguous break position- Throws:
java.io.IOException
- If there is a low-level I/O error.
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read
private static int read(java.io.Reader input, char[] buffer, int offset, int length) throws java.io.IOException
commons-io's readFully, but without bugs if offset != 0- Throws:
java.io.IOException
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incrementTokenBuffer
private boolean incrementTokenBuffer()
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