org.apache.lucene.analysis
Class TeeTokenFilter
java.lang.Object
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.TokenFilter
org.apache.lucene.analysis.TeeTokenFilter
public class TeeTokenFilter
- extends TokenFilter
Works in conjunction with the SinkTokenizer to provide the ability to set aside tokens
that have already been analyzed. This is useful in situations where multiple fields share
many common analysis steps and then go their separate ways.
It is also useful for doing things like entity extraction or proper noun analysis as
part of the analysis workflow and saving off those tokens for use in another field.
SinkTokenizer sink1 = new SinkTokenizer(null);
SinkTokenizer sink2 = new SinkTokenizer(null);
TokenStream source1 = new TeeTokenFilter(new TeeTokenFilter(new WhitespaceTokenizer(reader1), sink1), sink2);
TokenStream source2 = new TeeTokenFilter(new TeeTokenFilter(new WhitespaceTokenizer(reader2), sink1), sink2);
TokenStream final1 = new LowerCaseFilter(source1);
TokenStream final2 = source2;
TokenStream final3 = new EntityDetect(sink1);
TokenStream final4 = new URLDetect(sink2);
d.add(new Field("f1", final1));
d.add(new Field("f2", final2));
d.add(new Field("f3", final3));
d.add(new Field("f4", final4));
In this example, sink1 and sink2 will both get tokens from both reader1 and reader2 after whitespace tokenizer
and now we can further wrap any of these in extra analysis, and more "sources" can be inserted if desired.
Note, the EntityDetect and URLDetect TokenStreams are for the example and do not currently exist in Lucene
See http://issues.apache.org/jira/browse/LUCENE-1058
- See Also:
SinkTokenizer
Method Summary |
Token |
next(Token result)
Returns the next token in the stream, or null at EOS. |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
TeeTokenFilter
public TeeTokenFilter(TokenStream input,
SinkTokenizer sink)
next
public Token next(Token result)
throws IOException
- Description copied from class:
TokenStream
- Returns the next token in the stream, or null at EOS.
When possible, the input Token should be used as the
returned Token (this gives fastest tokenization
performance), but this is not required and a new Token
may be returned. Callers may re-use a single Token
instance for successive calls to this method.
This implicitly defines a "contract" between
consumers (callers of this method) and
producers (implementations of this method
that are the source for tokens):
- A consumer must fully consume the previously
returned Token before calling this method again.
- A producer must call
Token.clear()
before setting the fields in it & returning it
Note that a TokenFilter
is considered a consumer.
- Overrides:
next
in class TokenStream
- Parameters:
result
- a Token that may or may not be used to return
- Returns:
- next token in the stream or null if end-of-stream was hit
- Throws:
IOException
Copyright © 2000-2008 Apache Software Foundation. All Rights Reserved.