Module org.apache.lucene.analysis.common

Package 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:

Closeable, 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	Description
static interface	ConcatenateGraphFilter.BytesRefBuilderTermAttribute	Attribute providing access to the term builder and UTF-16 conversion
static final class	ConcatenateGraphFilter.BytesRefBuilderTermAttributeImpl	Implementation of ConcatenateGraphFilter.BytesRefBuilderTermAttribute
private static final class	ConcatenateGraphFilter.EscapingTokenStreamToAutomaton	Just escapes the SEP_LABEL byte with an extra.

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field	Description
private final ConcatenateGraphFilter.BytesRefBuilderTermAttribute	bytesAtt
private CharTermAttribute	charTermAttribute
static final int	DEFAULT_MAX_GRAPH_EXPANSIONS
static final boolean	DEFAULT_PRESERVE_POSITION_INCREMENTS
static final boolean	DEFAULT_PRESERVE_SEP
static final Character	DEFAULT_TOKEN_SEPARATOR
private int	endOffset
private LimitedFiniteStringsIterator	finiteStrings
private final TokenStream	inputTokenStream
private final int	maxGraphExpansions
private final OffsetAttribute	offsetAtt
private final PositionIncrementAttribute	posIncrAtt
private final boolean	preservePositionIncrements
static final int	SEP_LABEL	Represents the default separator between tokens.
private final Character	tokenSeparator
private boolean	wasReset

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor	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)	Calls ConcatenateGraphFilter(org.apache.lucene.analysis.TokenStream, java.lang.Character, boolean, int)
ConcatenateGraphFilter(TokenStream inputTokenStream, Character tokenSeparator, 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	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.
private static Automaton	replaceSep(Automaton a, Character tokenSeparator)
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 Details

SEP_LABEL

public static final int SEP_LABEL

Represents the default separator between tokens.

See Also:

• Constant Field Values

DEFAULT_MAX_GRAPH_EXPANSIONS

public static final int DEFAULT_MAX_GRAPH_EXPANSIONS

See Also:

• Constant Field Values

DEFAULT_TOKEN_SEPARATOR

public static final Character DEFAULT_TOKEN_SEPARATOR

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

bytesAtt

private final ConcatenateGraphFilter.BytesRefBuilderTermAttribute bytesAtt

posIncrAtt

private final PositionIncrementAttribute posIncrAtt

offsetAtt

private final OffsetAttribute offsetAtt

inputTokenStream

private final TokenStream inputTokenStream

tokenSeparator

private final Character tokenSeparator

preservePositionIncrements

private final boolean preservePositionIncrements

maxGraphExpansions

private final int maxGraphExpansions

finiteStrings

private LimitedFiniteStringsIterator finiteStrings

charTermAttribute

private CharTermAttribute charTermAttribute

wasReset

private boolean wasReset

endOffset

private int endOffset

Constructor Details

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,
 Character tokenSeparator,
 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

tokenSeparator - Separator to use for concatenation. Can be null, in this case tokens will be concatenated without any separators.

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

ConcatenateGraphFilter

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

Calls ConcatenateGraphFilter(org.apache.lucene.analysis.TokenStream, java.lang.Character, boolean, int)

Parameters:

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

Method Details

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

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

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

toAutomaton

public Automaton toAutomaton()
                      throws IOException

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

Throws:

IOException

toAutomaton

public Automaton toAutomaton(boolean unicodeAware)
                      throws IOException

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

Throws:

IOException

replaceSep

private static Automaton replaceSep(Automaton a,
 Character tokenSeparator)