Namespace Lucene.Net.Analysis.Sinks

TeeSinkTokenFilter and implementations of TeeSinkTokenFilter.SinkFilter that might be useful.

Classes

DateRecognizerSinkFilter

Attempts to parse the Lucene.Net.Analysis.TokenAttributes.ICharTermAttribute.Buffer as a Date using either the TryParse(string, IFormatProvider, DateTimeStyles, out DateTime) or TryParseExact(string, string[], IFormatProvider, DateTimeStyles, out DateTime) methods. If a format is passed, TryParseExact(string, string[], IFormatProvider, DateTimeStyles, out DateTime) will be used, and the format must strictly match one of the specified formats as specified in the MSDN documentation. If the value is a Date, it will add it to the sink.

This TokenFilter provides the ability to set aside attribute states 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.

TeeSinkTokenFilter source1 = new TeeSinkTokenFilter(new WhitespaceTokenizer(version, reader1));
       TeeSinkTokenFilter.SinkTokenStream sink1 = source1.NewSinkTokenStream();
       TeeSinkTokenFilter.SinkTokenStream sink2 = source1.NewSinkTokenStream();
   TeeSinkTokenFilter source2 = new TeeSinkTokenFilter(new WhitespaceTokenizer(version, reader2));
   source2.AddSinkTokenStream(sink1);
   source2.AddSinkTokenStream(sink2);

   TokenStream final1 = new LowerCaseFilter(version, source1);
   TokenStream final2 = source2;
   TokenStream final3 = new EntityDetect(sink1);
   TokenStream final4 = new URLDetect(sink2);

   d.Add(new TextField("f1", final1, Field.Store.NO));
   d.Add(new TextField("f2", final2, Field.Store.NO));
   d.Add(new TextField("f3", final3, Field.Store.NO));
   d.Add(new TextField("f4", final4, Field.Store.NO));</code></pre>

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.
It is important, that tees are consumed before sinks (in the above example, the field names must be
less the sink's field names). If you are not sure, which stream is consumed first, you can simply
add another sink and then pass all tokens to the sinks at once using ConsumeAllTokens().
This Lucene.Net.Analysis.TokenFilter is exhausted after this. In the above example, change
the example above to:
...
TokenStream final1 = new LowerCaseFilter(version, source1.NewSinkTokenStream());
TokenStream final2 = source2.NewSinkTokenStream();
sink1.ConsumeAllTokens();
sink2.ConsumeAllTokens();
...
In this case, the fields can be added in any order, because the sources are not used anymore and all sinks are ready.
Note, the EntityDetect and URLDetect TokenStreams are for the example and do not currently exist in Lucene.

TeeSinkTokenFilter.SinkFilter

A filter that decides which Lucene.Net.Util.AttributeSource states to store in the sink.

TeeSinkTokenFilter.SinkTokenStream

Lucene.Net.Analysis.TokenStream output from a tee with optional filtering.

TokenRangeSinkFilter

Counts the tokens as they go by and saves to the internal list those between the range of lower and upper, exclusive of upper

TokenTypeSinkFilter

Adds a token to the sink if it has a specific type.