Module org.apache.lucene.analysis.common

Package org.apache.lucene.analysis.miscellaneous

Class ConditionalTokenFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.miscellaneous.ConditionalTokenFilter

All Implemented Interfaces:

Closeable, AutoCloseable, Unwrappable<TokenStream>

Direct Known Subclasses:

ProtectedTermFilter

public abstract class ConditionalTokenFilter
extends TokenFilter

Allows skipping TokenFilters based on the current set of attributes.

To use, implement the shouldFilter() method. If it returns true, then calling incrementToken() will use the wrapped TokenFilter(s) to make changes to the tokenstream. If it returns false, then the wrapped filter(s) will be skipped.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private final class	ConditionalTokenFilter.OneTimeWrapper
private static enum	ConditionalTokenFilter.TokenState

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	adjustPosition
private AttributeSource.State	bufferedState
private final TokenStream	delegate
private int	endOffset
private AttributeSource.State	endState
private boolean	exhausted
private boolean	lastTokenFiltered
private final PositionIncrementAttribute	posIncAtt
private ConditionalTokenFilter.TokenState	state

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

Modifier	Constructor	Description
protected	ConditionalTokenFilter(TokenStream input, Function<TokenStream,TokenStream> inputFactory)	Create a new ConditionalTokenFilter

Method Summary

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, after TokenStream.incrementToken() returned false (using the new TokenStream API).
private boolean	endDelegating()
final boolean	incrementToken()	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 using TokenStream.incrementToken().
protected abstract boolean	shouldFilter()	Whether or not to execute the wrapped TokenFilter(s) for the current token

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

unwrap

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

Field Details

delegate

private final TokenStream delegate

state

private ConditionalTokenFilter.TokenState state

lastTokenFiltered

private boolean lastTokenFiltered

bufferedState

private AttributeSource.State bufferedState

exhausted

private boolean exhausted

adjustPosition

private boolean adjustPosition

endState

private AttributeSource.State endState

endOffset

private int endOffset

posIncAtt

private final PositionIncrementAttribute posIncAtt

Constructor Details

ConditionalTokenFilter

protected ConditionalTokenFilter(TokenStream input,
 Function<TokenStream,TokenStream> inputFactory)

Create a new ConditionalTokenFilter

Parameters:

input - the input TokenStream

inputFactory - a factory function to create the wrapped filter(s)

Method Details

shouldFilter

protected abstract boolean shouldFilter()
                                 throws IOException

Whether or not to execute the wrapped TokenFilter(s) for the current token

Throws:

IOException

reset

public void reset()
           throws IOException

Description copied from class: TokenFilter

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 TokenFilter

Throws:

IOException

end

public void end()
         throws IOException

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

Throws:

IOException - If an I/O error occurs

close

public void close()
           throws IOException

Description copied from class: TokenFilter

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 AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class TokenFilter

Throws:

IOException

incrementToken

public final boolean incrementToken()
                             throws 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 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.addAttribute(Class) and 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 TokenStream.incrementToken().

Specified by:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Throws:

IOException

endDelegating

private boolean endDelegating()
                       throws IOException

Throws:

IOException