Module org.apache.lucene.analysis.common

Package org.apache.lucene.analysis.miscellaneous

Class ConcatenatingTokenStream

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.miscellaneous.ConcatenatingTokenStream

All Implemented Interfaces:

Closeable, AutoCloseable

public final class ConcatenatingTokenStream
extends TokenStream

A TokenStream that takes an array of input TokenStreams as sources, and concatenates them together.

Offsets from the second and subsequent sources are incremented to behave as if all the inputs were from a single source.

All of the input TokenStreams must have the same attribute implementations

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field	Description
private int	currentSource
private int	initialPositionIncrement
private final OffsetAttribute	offsetAtt
private int	offsetIncrement
private final PositionIncrementAttribute	posIncAtt
private final PositionIncrementAttribute[]	sourceIncrements
private final OffsetAttribute[]	sourceOffsets
private final TokenStream[]	sources

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor	Description
ConcatenatingTokenStream(TokenStream... sources)	Create a new ConcatenatingTokenStream from a set of inputs

Method Summary

Modifier and Type	Method	Description
void	close()	Releases resources associated with this stream.
private static AttributeSource	combineSources(TokenStream... sources)
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()	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().

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

sources

private final TokenStream[] sources

sourceOffsets

private final OffsetAttribute[] sourceOffsets

sourceIncrements

private final PositionIncrementAttribute[] sourceIncrements

offsetAtt

private final OffsetAttribute offsetAtt

posIncAtt

private final PositionIncrementAttribute posIncAtt

currentSource

private int currentSource

offsetIncrement

private int offsetIncrement

initialPositionIncrement

private int initialPositionIncrement

Constructor Details

ConcatenatingTokenStream

public ConcatenatingTokenStream(TokenStream... sources)

Create a new ConcatenatingTokenStream from a set of inputs

Parameters:

sources - an array of TokenStream inputs to concatenate

Method Details

combineSources

private static AttributeSource combineSources(TokenStream... sources)

incrementToken

public 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

end

public void end()
         throws IOException

Description copied from class: TokenStream

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().

Overrides:

end in class TokenStream

Throws:

IOException - If an I/O error occurs

reset

public void reset()
           throws IOException

Description copied from class: TokenStream

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).

Overrides:

reset in class TokenStream

Throws:

IOException

close

public void close()
           throws IOException

Description copied from class: TokenStream

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).

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class TokenStream

Throws:

IOException