Class StandardTokenizer

  • All Implemented Interfaces:
    Closeable, AutoCloseable

    public final class StandardTokenizer
    extends Tokenizer
    A grammar-based tokenizer constructed with JFlex.

    As of Lucene version 3.1, this class implements the Word Break rules from the Unicode Text Segmentation algorithm, as specified in Unicode Standard Annex #29.

    Many applications have specific tokenizer needs. If this tokenizer does not suit your application, please consider copying this source code directory to your project and maintaining your own grammar-based tokenizer.

    You must specify the required Version compatibility when creating StandardTokenizer:

    • As of 3.4, Hiragana and Han characters are no longer wrongly split from their combining characters. If you use a previous version number, you get the exact broken behavior for backwards compatibility.
    • As of 3.1, StandardTokenizer implements Unicode text segmentation. If you use a previous version number, you get the exact behavior of ClassicTokenizer for backwards compatibility.
    • Method Detail

      • setMaxTokenLength

        public void setMaxTokenLength​(int length)
        Set the max allowed token length. Any token longer than this is skipped.
      • 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
      • end

        public final void end()
        Description copied from class: TokenStream
        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.

        Overrides:
        end in class TokenStream
      • reset

        public void reset​(Reader reader)
                   throws IOException
        Description copied from class: Tokenizer
        Expert: Reset the tokenizer to a new reader. Typically, an analyzer (in its reusableTokenStream method) will use this to re-use a previously created tokenizer.
        Overrides:
        reset in class Tokenizer
        Throws:
        IOException
      • isReplaceInvalidAcronym

        @Deprecated
        public boolean isReplaceInvalidAcronym()
        Deprecated.
        Remove in 3.X and make true the only valid value
        Prior to https://issues.apache.org/jira/browse/LUCENE-1068, StandardTokenizer mischaracterized as acronyms tokens like www.abc.com when they should have been labeled as hosts instead.
        Returns:
        true if StandardTokenizer now returns these tokens as Hosts, otherwise false
      • setReplaceInvalidAcronym

        @Deprecated
        public void setReplaceInvalidAcronym​(boolean replaceInvalidAcronym)
        Deprecated.
        Remove in 3.X and make true the only valid value See https://issues.apache.org/jira/browse/LUCENE-1068
        Parameters:
        replaceInvalidAcronym - Set to true to replace mischaracterized acronyms as HOST.