org.apache.lucene.analysis

Class TokenFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

All Implemented Interfaces:

Closeable

Direct Known Subclasses:

CachingTokenFilter

public abstract class TokenFilter
extends TokenStream

A TokenFilter is a TokenStream whose input is another TokenStream.

This is an abstract class; subclasses must override TokenStream.incrementToken().

See Also:

TokenStream

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
protected TokenStream	input The source of tokens for this filter.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	TokenFilter(TokenStream input) Construct a token stream filtering the given input.

Method Summary

Methods

Modifier and Type	Method and 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, after TokenStream.incrementToken() returned false (using the new TokenStream API).
void	reset() This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

Methods inherited from class org.apache.lucene.analysis.TokenStream

incrementToken

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

input

protected final TokenStream input

The source of tokens for this filter.

Constructor Detail

TokenFilter

protected TokenFilter(TokenStream input)

Construct a token stream filtering the given input.

Method Detail

end

public void end()
         throws IOException

This method is called by the consumer after the last token has been consumed, after TokenStream.incrementToken() returned false (using the new TokenStream 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().

NOTE: The default implementation chains the call to the input TokenStream, so be sure to call super.end() first when overriding this method.

Overrides:

end in class TokenStream

Throws:

IOException - If an I/O error occurs

close

public void close()
           throws IOException

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 throw IllegalStateException on reuse).

NOTE: The default implementation chains the call to the input TokenStream, so be sure to call super.close() when overriding this method.

Specified by:

close in interface Closeable

Overrides:

close in class TokenStream

Throws:

IOException

reset

public void reset()
           throws IOException

This method is called by a consumer before it begins consumption using TokenStream.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 throw IllegalStateException on further usage).

NOTE: The default implementation chains the call to the input TokenStream, so be sure to call super.reset() when overriding this method.

Overrides:

reset in class TokenStream

Throws:

IOException