org.apache.lucene.analysis

Class GraphTokenFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.GraphTokenFilter

All Implemented Interfaces:

Closeable, AutoCloseable

public abstract class GraphTokenFilter
extends TokenFilter

An abstract TokenFilter that exposes its input stream as a graph Call incrementBaseToken() to move the root of the graph to the next position in the TokenStream, incrementGraphToken() to move along the current graph, and incrementGraph() to reset to the next graph based at the current root. For example, given the stream 'a b/c:2 d e`, then with the base token at 'a', incrementGraphToken() will produce the stream 'a b d e', and then after calling incrementGraph() will produce the stream 'a c e'.

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_GRAPH_STACK_SIZE The maximum permitted number of routes through a graph
static int	MAX_TOKEN_CACHE_SIZE The maximum permitted read-ahead in the token stream

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
GraphTokenFilter(TokenStream input) Create a new GraphTokenFilter

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).
int	getTrailingPositions() Return the number of trailing positions at the end of the graph NB this should only be called after incrementGraphToken() has returned false
protected boolean	incrementBaseToken() Move the root of the graph to the next token in the wrapped TokenStream
protected boolean	incrementGraph() Reset to the root token again, and move down the next route through the graph
protected boolean	incrementGraphToken() Move to the next token in the current route through the graph
void	reset() This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

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

close

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, 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 Detail

MAX_GRAPH_STACK_SIZE

public static final int MAX_GRAPH_STACK_SIZE

The maximum permitted number of routes through a graph

See Also:

Constant Field Values

MAX_TOKEN_CACHE_SIZE

public static final int MAX_TOKEN_CACHE_SIZE

The maximum permitted read-ahead in the token stream

See Also:

Constant Field Values

Constructor Detail

GraphTokenFilter

public GraphTokenFilter(TokenStream input)

Create a new GraphTokenFilter

Method Detail

incrementBaseToken

protected final boolean incrementBaseToken()
                                    throws IOException

Move the root of the graph to the next token in the wrapped TokenStream

Returns:

false if the underlying stream is exhausted

Throws:

IOException

incrementGraphToken

protected final boolean incrementGraphToken()
                                     throws IOException

Move to the next token in the current route through the graph

Returns:

false if there are not more tokens in the current graph

Throws:

IOException

incrementGraph

protected final boolean incrementGraph()
                                throws IOException

Reset to the root token again, and move down the next route through the graph

Returns:

false if there are no more routes through the graph

Throws:

IOException

getTrailingPositions

public int getTrailingPositions()

Return the number of trailing positions at the end of the graph NB this should only be called after incrementGraphToken() has returned false

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

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