Class CachingTokenFilter
- 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.CachingTokenFilter
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- All Implemented Interfaces:
Closeable
,AutoCloseable
public final class CachingTokenFilter extends TokenFilter
This class can be used if the token attributes of a TokenStream are intended to be consumed more than once. It caches all token attribute states locally in a List.CachingTokenFilter implements the optional method
TokenStream.reset()
, which repositions the stream to the first Token.
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.AttributeFactory, AttributeSource.State
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Field Summary
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Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
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Constructor Summary
Constructors Constructor Description CachingTokenFilter(TokenStream input)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
end()
Performs end-of-stream operations, if any, and calls thenend()
on the input TokenStream.boolean
incrementToken()
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token.void
reset()
Reset the filter as well as the input TokenStream.-
Methods inherited from class org.apache.lucene.analysis.TokenFilter
close
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Methods inherited from class org.apache.lucene.util.AttributeSource
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString
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Constructor Detail
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CachingTokenFilter
public CachingTokenFilter(TokenStream input)
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Method Detail
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incrementToken
public final 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 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:
IOException
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end
public final void end() throws IOException
Description copied from class:TokenFilter
Performs end-of-stream operations, if any, and calls thenend()
on the input TokenStream. NOTE: Be sure to callsuper.end()
first when overriding this method.- Overrides:
end
in classTokenFilter
- Throws:
IOException
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reset
public void reset() throws IOException
Description copied from class:TokenFilter
Reset the filter as well as the input TokenStream.- Overrides:
reset
in classTokenFilter
- Throws:
IOException
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