Class PatternTokenizer
- All Implemented Interfaces:
Closeable
,AutoCloseable
- "pattern" is the regular expression.
- "group" says which group to extract into tokens.
group=-1 (the default) is equivalent to "split". In this case, the tokens will be equivalent
to the output from (without empty tokens): String.split(java.lang.String)
Using group >= 0 selects the matching group as the token. For example, if you have:
pattern = \'([^\']+)\' group = 0 input = aaa 'bbb' 'ccc'the output will be two tokens: 'bbb' and 'ccc' (including the ' marks). With the same input but using group=1, the output would be: bbb and ccc (no ' marks)
NOTE: This Tokenizer does not output tokens that are of zero length.
- See Also:
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
FieldsModifier and TypeFieldDescription(package private) final char[]
private final int
private int
private final Matcher
private final OffsetAttribute
private final StringBuilder
private final CharTermAttribute
Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
ConstructorsConstructorDescriptionPatternTokenizer
(Pattern pattern, int group) creates a new PatternTokenizer returning tokens from group (-1 for split functionality)PatternTokenizer
(AttributeFactory factory, Pattern pattern, int group) creates a new PatternTokenizer returning tokens from group (-1 for split functionality) -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Releases resources associated with this stream.void
end()
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API).private void
fillBuffer
(Reader input) boolean
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()
.Methods inherited from class org.apache.lucene.analysis.Tokenizer
correctOffset, setReader, setReaderTestPoint
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 Details
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termAtt
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offsetAtt
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str
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index
private int index -
group
private final int group -
matcher
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buffer
final char[] buffer
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Constructor Details
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PatternTokenizer
creates a new PatternTokenizer returning tokens from group (-1 for split functionality) -
PatternTokenizer
creates a new PatternTokenizer returning tokens from group (-1 for split functionality)
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Method Details
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incrementToken
public boolean incrementToken()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
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end
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:
IOException
- If an I/O error occurs
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close
Description copied from class:Tokenizer
Releases resources associated with this stream.If you override this method, always call
super.close()
, otherwise some internal state will not be correctly reset (e.g.,Tokenizer
will throwIllegalStateException
on reuse).NOTE: The default implementation closes the input Reader, so be sure to call
super.close()
when overriding this method.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classTokenizer
- Throws:
IOException
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reset
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).- Overrides:
reset
in classTokenizer
- Throws:
IOException
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fillBuffer
- Throws:
IOException
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