public final class CachingTokenFilter extends TokenFilterThis 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.
CachingTokenFilter implements the optional method
TokenStream.reset(), which repositions the stream to the first Token.
All Methods Instance Methods Concrete Methods Modifier and Type Method Description
end()This method is called by the consumer after the last token has been consumed, after
false(using the new
IndexWriter) use this method to advance the stream to the next token.
reset()Rewinds the iterator to the beginning of the cached list.
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
public final boolean incrementToken() throws IOExceptionDescription copied from class:
IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate
AttributeImpls 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.getAttribute(Class), references to all
AttributeImpls 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
public final void end()Description copied from class:
TokenFilterThis method is called by the consumer after the last token has been consumed, after
false(using the new
TokenStreamAPI). 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
NOTE: The default implementation chains the call to the input TokenStream, so be sure to call
super.end()first when overriding this method.