Class TeeSinkTokenFilter

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.
Inheritance
object
AttributeSource
TokenStream
TokenFilter
TeeSinkTokenFilter
Implements
Inherited Members
TokenFilter.Reset()
TokenStream.Dispose()
AttributeSource.GetAttributeFactory()
AttributeSource.GetAttributeClassesEnumerator()
AttributeSource.GetAttributeImplsEnumerator()
AttributeSource.AddAttributeImpl(Attribute)
AttributeSource.AddAttribute<T>()
AttributeSource.HasAttributes
AttributeSource.HasAttribute<T>()
AttributeSource.GetAttribute<T>()
AttributeSource.ClearAttributes()
AttributeSource.CaptureState()
AttributeSource.RestoreState(AttributeSource.State)
AttributeSource.GetHashCode()
AttributeSource.ReflectWith(IAttributeReflector)
AttributeSource.CloneAttributes()
AttributeSource.CopyTo(AttributeSource)
AttributeSource.ToString()
Namespace: Lucene.Net.Analysis.Sinks
Assembly: Lucene.Net.Analysis.Common.dll
Syntax
public sealed class TeeSinkTokenFilter : TokenFilter, IDisposable

Constructors

TeeSinkTokenFilter(TokenStream)

Instantiates a new TeeSinkTokenFilter.

Declaration
public TeeSinkTokenFilter(TokenStream input)
Parameters
Type Name Description
TokenStream input

Methods

AddSinkTokenStream(SinkTokenStream)

Adds a TeeSinkTokenFilter.SinkTokenStream created by another TeeSinkTokenFilter to this one. The supplied stream will also receive all consumed tokens. This method can be used to pass tokens from two different tees to one sink.

Declaration
public void AddSinkTokenStream(TeeSinkTokenFilter.SinkTokenStream sink)
Parameters
Type Name Description
TeeSinkTokenFilter.SinkTokenStream sink

ConsumeAllTokens()

TeeSinkTokenFilter passes all tokens to the added sinks when itself is consumed. To be sure, that all tokens from the input stream are passed to the sinks, you can call this methods. This instance is exhausted after this, but all sinks are instant available.

Declaration
public void ConsumeAllTokens()

End()

This method is called by the consumer after the last token has been consumed, after Lucene.Net.Analysis.TokenStream.IncrementToken() returned false (using the new Lucene.Net.Analysis.TokenStream 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.

NOTE: The default implementation chains the call to the input TokenStream, so be sure to call base.End() first when overriding this method.
Declaration
public override sealed void End()
Overrides
Lucene.Net.Analysis.TokenFilter.End()
Exceptions
Type Condition
IOException

If an I/O error occurs

IncrementToken()

Consumers (i.e., Lucene.Net.Index.IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate Lucene.Net.Util.IAttributes 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 Lucene.Net.Util.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 Lucene.Net.Util.AttributeSource.AddAttribute<T>() and Lucene.Net.Util.AttributeSource.GetAttribute<T>(), references to all Lucene.Net.Util.IAttributes 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 Lucene.Net.Analysis.TokenStream.IncrementToken().
Declaration
public override bool IncrementToken()
Returns
Type Description
bool

false for end of stream; true otherwise
Overrides
Lucene.Net.Analysis.TokenStream.IncrementToken()

NewSinkTokenStream()

Returns a new TeeSinkTokenFilter.SinkTokenStream that receives all tokens consumed by this stream.

Declaration
public TeeSinkTokenFilter.SinkTokenStream NewSinkTokenStream()
Returns
Type Description
TeeSinkTokenFilter.SinkTokenStream

NewSinkTokenStream(SinkFilter)

Returns a new TeeSinkTokenFilter.SinkTokenStream that receives all tokens consumed by this stream that pass the supplied filter.

Declaration
public TeeSinkTokenFilter.SinkTokenStream NewSinkTokenStream(TeeSinkTokenFilter.SinkFilter filter)
Parameters
Type Name Description
TeeSinkTokenFilter.SinkFilter filter
Returns
Type Description
TeeSinkTokenFilter.SinkTokenStream
See Also

Implements