Class LimitTokenOffsetFilter

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable

    public final class LimitTokenOffsetFilter
    extends TokenFilter
    Lets all tokens pass through until it sees one with a start offset <= a configured limit, which won't pass and ends the stream. This can be useful to limit highlighting, for example.

    By default, this filter ignores any tokens in the wrapped TokenStream once the limit has been exceeded, which can result in reset() being called prior to incrementToken() returning false. For most TokenStream implementations this should be acceptable, and faster then consuming the full stream. If you are wrapping a TokenStream which requires that the full stream of tokens be exhausted in order to function properly, use the LimitTokenOffsetFilter(TokenStream, int, boolean) option.

    • Field Detail

      • maxStartOffset

        private int maxStartOffset
      • consumeAllTokens

        private final boolean consumeAllTokens
    • Constructor Detail

      • LimitTokenOffsetFilter

        public LimitTokenOffsetFilter​(TokenStream input,
                                      int maxStartOffset)
        Lets all tokens pass through until it sees one with a start offset <= maxStartOffset which won't pass and ends the stream. It won't consume any tokens afterwards.
        Parameters:
        maxStartOffset - the maximum start offset allowed
      • LimitTokenOffsetFilter

        public LimitTokenOffsetFilter​(TokenStream input,
                                      int maxStartOffset,
                                      boolean consumeAllTokens)
    • Method Detail

      • incrementToken

        public boolean incrementToken()
                               throws java.io.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:
        java.io.IOException