Package org.apache.lucene.analysis.icu.segmentation

Class ICUTokenizer

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable
    public final class ICUTokenizer
extends Tokenizer
    Breaks text into words according to UAX #29: Unicode Text Segmentation (http://www.unicode.org/reports/tr29/)

    Words are broken across script boundaries, then segmented according to the BreakIterator and typing provided by the ICUTokenizerConfig

    See Also:
    ICUTokenizerConfig

    • Field Detail

      • buffer

        private final char[] buffer

      • length

        private int length
        true length of text in the buffer

      • usableLength

        private int usableLength
        length in buffer that can be evaluated safely, up to a safe end point

      • offset

        private int offset
        accumulated offset of previous buffers for this reader, for offsetAtt

    • Constructor Detail

      • ICUTokenizer

        public ICUTokenizer()
        Construct a new ICUTokenizer that breaks text into words from the given Reader.

        The default script-specific handling is used.

        The default attribute factory is used.

        See Also:
        DefaultICUTokenizerConfig

      • ICUTokenizer

        public ICUTokenizer​(ICUTokenizerConfig config)
        Construct a new ICUTokenizer that breaks text into words from the given Reader, using a tailored BreakIterator configuration.

        The default attribute factory is used.

        Parameters:
        config - Tailored BreakIterator configuration

      • ICUTokenizer

        public ICUTokenizer​(AttributeFactory factory,
                    ICUTokenizerConfig config)
        Construct a new ICUTokenizer that breaks text into words from the given Reader, using a tailored BreakIterator configuration.
        Parameters:
        factory - AttributeFactory to use
        config - Tailored BreakIterator configuration

    • 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

      • reset

        public void reset()
           throws java.io.IOException
        Description copied from class: TokenStream
        This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

        Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.

        If you override this method, always call super.reset(), otherwise some internal state will not be correctly reset (e.g., Tokenizer will throw IllegalStateException on further usage).

        Overrides:
        reset in class Tokenizer
        Throws:
        java.io.IOException

      • end

        public void end()
         throws java.io.IOException
        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.

        Additionally any skipped positions (such as those removed by a stopfilter) can be applied to the position increment, or any adjustment of other attributes where the end-of-stream value may be important.

        If you override this method, always call super.end().

        Overrides:
        end in class TokenStream
        Throws:
        java.io.IOException - If an I/O error occurs

      • findSafeEnd

        private int findSafeEnd()
        Returns the last unambiguous break position in the text.
        Returns:
        position of character, or -1 if one does not exist

      • refill

        private void refill()
             throws java.io.IOException
        Refill the buffer, accumulating the offset and setting usableLength to the last unambiguous break position
        Throws:
        java.io.IOException - If there is a low-level I/O error.

      • read

        private static int read​(java.io.Reader input,
                        char[] buffer,
                        int offset,
                        int length)
                 throws java.io.IOException
        commons-io's readFully, but without bugs if offset != 0
        Throws:
        java.io.IOException

      • incrementTokenBuffer

        private boolean incrementTokenBuffer()