Class TeeSinkTokenFilter

  • All Implemented Interfaces:, java.lang.AutoCloseable

    public final class TeeSinkTokenFilter
    extends TokenFilter
    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));
    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));
    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 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();
    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.

    • Constructor Detail

      • TeeSinkTokenFilter

        public TeeSinkTokenFilter​(TokenStream input)
        Instantiates a new TeeSinkTokenFilter.
    • Method Detail

      • consumeAllTokens

        public void 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.
      • incrementToken

        public boolean incrementToken()
        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 appropriate AttributeImpls 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 AttributeImpls 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 class TokenStream
        false for end of stream; true otherwise
      • end

        public final void end()
        Description copied from class: TokenFilter
        This method is called by the consumer after the last token has been consumed, after TokenStream.incrementToken() returned false (using the new 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.

        If you override this method, always call super.end().

        NOTE: The default implementation chains the call to the input TokenStream, so be sure to call super.end() first when overriding this method.

        end in class TokenFilter
        Throws: - If an I/O error occurs