Module org.apache.lucene.analysis.kuromoji
Package org.apache.lucene.analysis.ja

Class JapaneseCompletionFilter

java.lang.Object
org.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.TokenFilter
org.apache.lucene.analysis.ja.JapaneseCompletionFilter
All Implemented Interfaces:
Closeable, AutoCloseable, Unwrappable<TokenStream>
public final class JapaneseCompletionFilter extends TokenFilter
A TokenFilter that adds Japanese romanized tokens to the term attribute. Also, this keeps original tokens (surface forms). Main usage of this filter is Query Auto-Completion.

Supported romanization systems: (modified) Hepburn-shiki, Kunrei-shiki (Nihon-shiki) and Wāpuro shiki.

This does not strictly comply with the romanization systems listed above, but tries to cover possible keystroke supported by various Input Methods. e.g.: Circumflex / Macron representing Chōonpu (長音符) are not supported.

The romanization behaviour changes according to its JapaneseCompletionFilter.Mode. The default mode is JapaneseCompletionFilter.Mode.INDEX.

Note: This filter must be applied AFTER half-width and full-width normalization. Please ensure that a width normalizer such as CJKWidthCharFilter or CJKWidthFilter is included in your analysis chain. IF THE WIDTH NORMALIZATION IS NOT PERFORMED, THIS DOES NOT WORK AS EXPECTED. See also: JapaneseCompletionAnalyzer.

  • Field Details

  • Constructor Details

    • JapaneseCompletionFilter

      public JapaneseCompletionFilter(TokenStream input)
      Creates a new JapaneseCompletionFilter with default configurations

    • JapaneseCompletionFilter

      public JapaneseCompletionFilter(TokenStream input, JapaneseCompletionFilter.Mode mode)
      Creates a new JapaneseCompletionFilter

  • Method Details

    • reset

      public void reset() throws IOException
      Description copied from class: TokenFilter
      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).

      NOTE: The default implementation chains the call to the input TokenStream, so be sure to call super.reset() when overriding this method.

      Overrides:
      reset in class TokenFilter
      Throws:
      IOException

    • 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

    • mayIncrementToken

      private void mayIncrementToken() throws IOException
      Throws:
      IOException