Class DelimitedTermFrequencyTokenFilter

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

public final class DelimitedTermFrequencyTokenFilter extends TokenFilter
Characters before the delimiter are the "token", the textual integer after is the term frequency. To use this TokenFilter the field must be indexed with IndexOptions.DOCS_AND_FREQS but no positions or offsets.

For example, if the delimiter is '|', then for the string "foo|5", "foo" is the token and "5" is a term frequency. If there is no delimiter, the TokenFilter does not modify the term frequency.

Note make sure your Tokenizer doesn't split on the delimiter, or this won't work

  • Field Details

  • Constructor Details

    • DelimitedTermFrequencyTokenFilter

      public DelimitedTermFrequencyTokenFilter(TokenStream input)
    • DelimitedTermFrequencyTokenFilter

      public DelimitedTermFrequencyTokenFilter(TokenStream input, char delimiter)
  • 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