Class ClassicTokenizer
- 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.standard.ClassicTokenizer
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
public final class ClassicTokenizer extends Tokenizer
A grammar-based tokenizer constructed with JFlexThis should be a good tokenizer for most European-language documents:
- Splits words at punctuation characters, removing punctuation. However, a dot that's not followed by whitespace is considered part of a token.
- Splits words at hyphens, unless there's a number in the token, in which case the whole token is interpreted as a product number and is not split.
- Recognizes email addresses and internet hostnames as one token.
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. ClassicTokenizer was named StandardTokenizer in Lucene versions prior to 3.1. As of 3.1,
StandardTokenizer
implements Unicode text segmentation, as specified by UAX#29.
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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 static int
ACRONYM
static int
ACRONYM_DEP
static int
ALPHANUM
static int
APOSTROPHE
static int
CJ
static int
COMPANY
static int
EMAIL
static int
HOST
private int
maxTokenLength
static int
NUM
private OffsetAttribute
offsetAtt
private PositionIncrementAttribute
posIncrAtt
private ClassicTokenizerImpl
scanner
A private instance of the JFlex-constructed scannerprivate int
skippedPositions
private CharTermAttribute
termAtt
static java.lang.String[]
TOKEN_TYPES
String token types that correspond to token type int constantsprivate TypeAttribute
typeAtt
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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 ClassicTokenizer()
Creates a new instance of theClassicTokenizer
.ClassicTokenizer(AttributeFactory factory)
Creates a new ClassicTokenizer with a givenAttributeFactory
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
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).int
getMaxTokenLength()
boolean
incrementToken()
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token.private void
init()
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
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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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scanner
private ClassicTokenizerImpl scanner
A private instance of the JFlex-constructed scanner
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ALPHANUM
public static final int ALPHANUM
- See Also:
- Constant Field Values
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APOSTROPHE
public static final int APOSTROPHE
- See Also:
- Constant Field Values
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ACRONYM
public static final int ACRONYM
- See Also:
- Constant Field Values
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COMPANY
public static final int COMPANY
- See Also:
- Constant Field Values
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EMAIL
public static final int EMAIL
- See Also:
- Constant Field Values
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HOST
public static final int HOST
- See Also:
- Constant Field Values
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NUM
public static final int NUM
- See Also:
- Constant Field Values
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CJ
public static final int CJ
- See Also:
- Constant Field Values
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ACRONYM_DEP
public static final int ACRONYM_DEP
- See Also:
- Constant Field Values
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TOKEN_TYPES
public static final java.lang.String[] TOKEN_TYPES
String token types that correspond to token type int constants
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skippedPositions
private int skippedPositions
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maxTokenLength
private int maxTokenLength
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termAtt
private final CharTermAttribute termAtt
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offsetAtt
private final OffsetAttribute offsetAtt
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posIncrAtt
private final PositionIncrementAttribute posIncrAtt
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typeAtt
private final TypeAttribute typeAtt
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Constructor Detail
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ClassicTokenizer
public ClassicTokenizer()
Creates a new instance of theClassicTokenizer
. Attaches theinput
to the newly created JFlex scanner. See http://issues.apache.org/jira/browse/LUCENE-1068
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ClassicTokenizer
public ClassicTokenizer(AttributeFactory factory)
Creates a new ClassicTokenizer with a givenAttributeFactory
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Method Detail
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setMaxTokenLength
public void setMaxTokenLength(int length)
Set the max allowed token length. Any token longer than this is skipped.
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getMaxTokenLength
public int getMaxTokenLength()
- See Also:
setMaxTokenLength(int)
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init
private void init()
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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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end
public final 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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close
public void close() throws java.io.IOException
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.
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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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