org.apache.lucene.analysis

Class CachingTokenFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.CachingTokenFilter

All Implemented Interfaces:

Closeable, AutoCloseable

public final class CachingTokenFilter
extends TokenFilter

This class can be used if the token attributes of a TokenStream are intended to be consumed more than once. It caches all token attribute states locally in a List when the first call to incrementToken() is called. Subsequent calls will used the cache.

Important: Like any proper TokenFilter, reset() propagates to the input, although only before incrementToken() is called the first time. Prior to Lucene 5, it was never propagated.

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields inherited from class org.apache.lucene.analysis.TokenFilter

input

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor and Description
CachingTokenFilter(TokenStream input) Create a new CachingTokenFilter around input.

Method Summary

Modifier and Type	Method and Description
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).
boolean	incrementToken() The first time called, it'll read and cache all tokens from the input.
boolean	isCached() If the underlying token stream was consumed and cached.
void	reset() Propagates reset if incrementToken has not yet been called.

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

close

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

Methods inherited from class java.lang.Object

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

Constructor Detail

CachingTokenFilter

public CachingTokenFilter(TokenStream input)

Create a new CachingTokenFilter around input. As with any normal TokenFilter, do not call reset on the input; this filter will do it normally.

Method Detail

reset

public void reset()
           throws IOException

Propagates reset if incrementToken has not yet been called. Otherwise it rewinds the iterator to the beginning of the cached list.

Overrides:

reset in class TokenFilter

Throws:

IOException

incrementToken

public final boolean incrementToken()
                             throws IOException

The first time called, it'll read and cache all tokens from the input.

Specified by:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Throws:

IOException

end

public final void end()

Description copied from class: TokenFilter

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 TokenFilter

isCached

public boolean isCached()

If the underlying token stream was consumed and cached.