Class TeeSinkTokenFilter

  • All Implemented Interfaces:
    Closeable, 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());
     TeeSinkTokenFilter.SinkTokenStream sink1 = source1.newSinkTokenStream();
     TeeSinkTokenFilter.SinkTokenStream sink2 = source1.newSinkTokenStream();
     TokenStream final1 = new LowerCaseFilter(source1);
     TokenStream final2 = new EntityDetect(sink1);
     TokenStream final3 = new URLDetect(sink2);
     d.add(new TextField("f1", final1));
     d.add(new TextField("f2", final2));
     d.add(new TextField("f3", final3));

    In this example, sink1 and sink2 will both get tokens from source1 after whitespace tokenization, and will further do additional token filtering, e.g. detect entities and URLs.

    NOTE: it is important, that tees are consumed before sinks, therefore you should add them to the document before the sinks. In the above example, f1 is added before the other fields, and so by the time they are processed, it has already been consumed, which is the correct way to index the three streams. If for some reason you cannot ensure that, you should call consumeAllTokens() before adding the sinks to document fields.

    • Method Detail

      • consumeAllTokens

        public void consumeAllTokens()
                              throws IOException
        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 method returns, but all sinks are instant available.
      • incrementToken

        public boolean incrementToken()
                               throws IOException
        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()
                       throws IOException
        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
        IOException - If an I/O error occurs
      • reset

        public void reset()
                   throws IOException
        Description copied from class: TokenFilter
        This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

        Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.

        If you override this method, always call super.reset(), otherwise some internal state will not be correctly reset (e.g., Tokenizer will throw IllegalStateException on further usage).

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

        reset in class TokenFilter