Class PositionFilter

  • All Implemented Interfaces:
    Closeable, AutoCloseable

    public final class PositionFilter
    extends TokenFilter
    Set the positionIncrement of all tokens to the "positionIncrement", except the first return token which retains its original positionIncrement value. The default positionIncrement value is zero.
    • Constructor Detail

      • PositionFilter

        public PositionFilter​(TokenStream input)
        Constructs a PositionFilter that assigns a position increment of zero to all but the first token from the given input stream.
        Parameters:
        input - the input stream
      • PositionFilter

        public PositionFilter​(TokenStream input,
                              int positionIncrement)
        Constructs a PositionFilter that assigns the given position increment to all but the first token from the given input stream.
        Parameters:
        input - the input stream
        positionIncrement - position increment to assign to all but the first token from the input stream
    • Method Detail

      • incrementToken

        public final 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
        Returns:
        false for end of stream; true otherwise
        Throws:
        IOException