org.apache.lucene.analysis.miscellaneous

Class ConcatenateGraphFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.miscellaneous.ConcatenateGraphFilter

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public final class ConcatenateGraphFilter
extends TokenStream

Concatenates/Joins every incoming token with a separator into one output token for every path through the token stream (which is a graph). In simple cases this yields one token, but in the presence of any tokens with a zero positionIncrmeent (e.g. synonyms) it will be more. This filter uses the token bytes, position increment, and position length of the incoming stream. Other attributes are not used or manipulated.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ConcatenateGraphFilter.BytesRefBuilderTermAttribute Attribute providing access to the term builder and UTF-16 conversion
static class	ConcatenateGraphFilter.BytesRefBuilderTermAttributeImpl Implementation of ConcatenateGraphFilter.BytesRefBuilderTermAttribute

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_GRAPH_EXPANSIONS
static boolean	DEFAULT_PRESERVE_POSITION_INCREMENTS
static boolean	DEFAULT_PRESERVE_SEP
static int	SEP_LABEL Represents the separation between tokens, if preserveSep is true.

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor and Description
ConcatenateGraphFilter(TokenStream inputTokenStream) Creates a token stream to convert input to a token stream of accepted strings by its token stream graph.
ConcatenateGraphFilter(TokenStream inputTokenStream, boolean preserveSep, boolean preservePositionIncrements, int maxGraphExpansions) Creates a token stream to convert input to a token stream of accepted strings by its token stream graph.

Method Summary

Modifier and Type	Method and 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).
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().
Automaton	toAutomaton() Converts the tokenStream to an automaton, treating the transition labels as utf-8.
Automaton	toAutomaton(boolean unicodeAware) Converts the tokenStream to an automaton.

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

SEP_LABEL

public static final int SEP_LABEL

Represents the separation between tokens, if preserveSep is true.

See Also:

Constant Field Values

DEFAULT_MAX_GRAPH_EXPANSIONS

public static final int DEFAULT_MAX_GRAPH_EXPANSIONS

See Also:

Constant Field Values

DEFAULT_PRESERVE_SEP

public static final boolean DEFAULT_PRESERVE_SEP

See Also:

Constant Field Values

DEFAULT_PRESERVE_POSITION_INCREMENTS

public static final boolean DEFAULT_PRESERVE_POSITION_INCREMENTS

See Also:

Constant Field Values

Constructor Detail

ConcatenateGraphFilter

public ConcatenateGraphFilter(TokenStream inputTokenStream)

Creates a token stream to convert input to a token stream of accepted strings by its token stream graph.

This constructor uses the default settings of the constants in this class.

ConcatenateGraphFilter

public ConcatenateGraphFilter(TokenStream inputTokenStream,
                              boolean preserveSep,
                              boolean preservePositionIncrements,
                              int maxGraphExpansions)

Creates a token stream to convert input to a token stream of accepted strings by its token stream graph.

Parameters:

inputTokenStream - The input/incoming TokenStream

preserveSep - Whether SEP_LABEL should separate the input tokens in the concatenated token

preservePositionIncrements - Whether to add an empty token for missing positions. The effect is a consecutive SEP_LABEL. When false, it's as if there were no missing positions (we pretend the surrounding tokens were adjacent).

maxGraphExpansions - If the tokenStream graph has more than this many possible paths through, then we'll throw TooComplexToDeterminizeException to preserve the stability and memory of the machine.

Throws:

TooComplexToDeterminizeException - if the tokenStream graph has more than maxGraphExpansions expansions

Method Detail

reset

public void reset()
           throws java.io.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:

java.io.IOException

incrementToken

public boolean incrementToken()
                       throws java.io.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:

java.io.IOException

end

public void end()
         throws java.io.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:

java.io.IOException - If an I/O error occurs

close

public void close()
           throws java.io.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 java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class TokenStream

Throws:

java.io.IOException

toAutomaton

public Automaton toAutomaton()
                      throws java.io.IOException

Converts the tokenStream to an automaton, treating the transition labels as utf-8. Does *not* close it.

Throws:

java.io.IOException

toAutomaton

public Automaton toAutomaton(boolean unicodeAware)
                      throws java.io.IOException

Converts the tokenStream to an automaton. Does *not* close it.

Throws:

java.io.IOException