Class ConditionalTokenFilter
- java.lang.Object
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- org.apache.lucene.util.AttributeSource
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- org.apache.lucene.analysis.TokenStream
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- org.apache.lucene.analysis.TokenFilter
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- org.apache.lucene.analysis.miscellaneous.ConditionalTokenFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.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 returnstrue
, then callingincrementToken()
will use the wrapped TokenFilter(s) to make changes to the tokenstream. If it returnsfalse
, then the wrapped filter(s) will be skipped.
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Nested Class Summary
Nested Classes Modifier and Type Class Description private class
ConditionalTokenFilter.OneTimeWrapper
private static class
ConditionalTokenFilter.TokenState
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
Fields Modifier and Type Field Description private boolean
adjustPosition
private AttributeSource.State
bufferedState
private TokenStream
delegate
private int
endOffset
private AttributeSource.State
endState
private boolean
exhausted
private boolean
lastTokenFiltered
private PositionIncrementAttribute
posIncAtt
private ConditionalTokenFilter.TokenState
state
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Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
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Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
Constructors Modifier Constructor Description protected
ConditionalTokenFilter(TokenStream input, java.util.function.Function<TokenStream,TokenStream> inputFactory)
Create a new ConditionalTokenFilter
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods 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, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API).private boolean
endDelegating()
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 usingTokenStream.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
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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
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Field Detail
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delegate
private final TokenStream delegate
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state
private ConditionalTokenFilter.TokenState state
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lastTokenFiltered
private boolean lastTokenFiltered
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bufferedState
private AttributeSource.State bufferedState
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exhausted
private boolean exhausted
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adjustPosition
private boolean adjustPosition
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endState
private AttributeSource.State endState
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endOffset
private int endOffset
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posIncAtt
private final PositionIncrementAttribute posIncAtt
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Constructor Detail
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ConditionalTokenFilter
protected ConditionalTokenFilter(TokenStream input, java.util.function.Function<TokenStream,TokenStream> inputFactory)
Create a new ConditionalTokenFilter- Parameters:
input
- the input TokenStreaminputFactory
- a factory function to create the wrapped filter(s)
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Method Detail
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shouldFilter
protected abstract boolean shouldFilter() throws java.io.IOException
Whether or not to execute the wrapped TokenFilter(s) for the current token- Throws:
java.io.IOException
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reset
public void reset() throws java.io.IOException
Description copied from class:TokenFilter
This method is called by a consumer before it begins consumption usingTokenStream.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 throwIllegalStateException
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 classTokenFilter
- Throws:
java.io.IOException
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end
public void end() throws java.io.IOException
Description copied from class:TokenFilter
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
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 classTokenFilter
- Throws:
java.io.IOException
- If an I/O error occurs
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close
public void close() throws java.io.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 throwIllegalStateException
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 interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
- Overrides:
close
in classTokenFilter
- Throws:
java.io.IOException
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incrementToken
public final 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 appropriateAttributeImpl
s 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)
andAttributeSource.getAttribute(Class)
, references to allAttributeImpl
s 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 classTokenStream
- Returns:
- false for end of stream; true otherwise
- Throws:
java.io.IOException
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endDelegating
private boolean endDelegating() throws java.io.IOException
- Throws:
java.io.IOException
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