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java.lang.Objectorg.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.TokenFilter
org.apache.lucene.analysis.CachingTokenFilter
public final class CachingTokenFilter
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.
Nested Class Summary |
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource |
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AttributeSource.AttributeFactory, AttributeSource.State |
Field Summary |
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Fields inherited from class org.apache.lucene.analysis.TokenFilter |
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input |
Constructor Summary | |
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CachingTokenFilter(TokenStream input)
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Method Summary | |
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void |
end()
Performs end-of-stream operations, if any, and calls then end() on the
input TokenStream.
NOTE: Be sure to call super.end() first when overriding this method. |
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 |
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close |
Methods inherited from class org.apache.lucene.util.AttributeSource |
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addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public CachingTokenFilter(TokenStream input)
Method Detail |
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public final boolean incrementToken() throws IOException
TokenStream
IndexWriter
) use this method to advance the stream to
the next token. Implementing classes must implement this method and update
the appropriate AttributeImpl
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)
and AttributeSource.getAttribute(Class)
,
references to all AttributeImpl
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()
.
incrementToken
in class TokenStream
IOException
public final void end()
TokenFilter
end()
on the
input TokenStream.
NOTE: Be sure to call super.end()
first when overriding this method.
end
in class TokenFilter
public void reset()
TokenFilter
reset
in class TokenFilter
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