Class StandardTokenizer
- All Implemented Interfaces:
Closeable
,AutoCloseable
This class implements the Word Break rules from the Unicode Text Segmentation algorithm, as specified in Unicode Standard Annex #29.
Many applications have specific tokenizer needs. If this tokenizer does not suit your application, please consider copying this source code directory to your project and maintaining your own grammar-based tokenizer.
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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
Modifier and TypeFieldDescriptionstatic final int
Alpha/numeric token typestatic final int
Emoji token type.static final int
Hangul token typestatic final int
Hiragana token typestatic final int
Ideographic token typestatic final int
Katakana token typestatic final int
Absolute maximum sized tokenstatic final int
Numeric token typestatic final int
Southeast Asian token typestatic final String[]
String token types that correspond to token type int constantsFields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
ConstructorDescriptionCreates a new instance of theStandardTokenizer
.StandardTokenizer
(AttributeFactory factory) Creates a new StandardTokenizer with a givenAttributeFactory
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Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Releases resources associated with this stream.final void
end()
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API).int
Returns the current maximum token lengthfinal 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()
.void
setMaxTokenLength
(int length) Set the max allowed token length.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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ALPHANUM
public static final int ALPHANUMAlpha/numeric token type- See Also:
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NUM
public static final int NUMNumeric token type- See Also:
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SOUTHEAST_ASIAN
public static final int SOUTHEAST_ASIANSoutheast Asian token type- See Also:
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IDEOGRAPHIC
public static final int IDEOGRAPHICIdeographic token type- See Also:
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HIRAGANA
public static final int HIRAGANAHiragana token type- See Also:
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KATAKANA
public static final int KATAKANAKatakana token type- See Also:
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HANGUL
public static final int HANGULHangul token type- See Also:
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EMOJI
public static final int EMOJIEmoji token type.- See Also:
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TOKEN_TYPES
String token types that correspond to token type int constants -
MAX_TOKEN_LENGTH_LIMIT
public static final int MAX_TOKEN_LENGTH_LIMITAbsolute maximum sized token- See Also:
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Constructor Details
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StandardTokenizer
public StandardTokenizer()Creates a new instance of theStandardTokenizer
. Attaches theinput
to the newly created JFlex scanner.See http://issues.apache.org/jira/browse/LUCENE-1068
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StandardTokenizer
Creates a new StandardTokenizer with a givenAttributeFactory
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Method Details
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setMaxTokenLength
public void setMaxTokenLength(int length) Set the max allowed token length. Tokens larger than this will be chopped up at this token length and emitted as multiple tokens. If you need to skip such large tokens, you could increase this max length, and then useLengthFilter
to remove long tokens. The default isStandardAnalyzer.DEFAULT_MAX_TOKEN_LENGTH
.- Throws:
IllegalArgumentException
- if the given length is outside of the range [1, 1048576].
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getMaxTokenLength
public int getMaxTokenLength()Returns the current maximum token length- See Also:
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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
- Throws:
IOException
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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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