Class LimitTokenOffsetFilter

All Implemented Interfaces:
Closeable, AutoCloseable, Unwrappable<TokenStream>

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 Details

    • offsetAttrib

      private final OffsetAttribute offsetAttrib
    • maxStartOffset

      private int maxStartOffset
    • consumeAllTokens

      private final boolean consumeAllTokens
  • Constructor Details

    • 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 Details

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