Module org.apache.lucene.analysis.nori
Package org.apache.lucene.analysis.ko

Class KoreanTokenizer

java.lang.Object
org.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.Tokenizer
org.apache.lucene.analysis.ko.KoreanTokenizer
All Implemented Interfaces:
Closeable, AutoCloseable
public final class KoreanTokenizer extends Tokenizer
Tokenizer for Korean that uses morphological analysis.

This tokenizer sets a number of additional attributes:

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters.

  • Field Details

  • Constructor Details

    • KoreanTokenizer

      public KoreanTokenizer()
      Creates a new KoreanTokenizer with default parameters.

      Uses the default AttributeFactory.

    • KoreanTokenizer

      public KoreanTokenizer(AttributeFactory factory, UserDictionary userDictionary, KoreanTokenizer.DecompoundMode mode, boolean outputUnknownUnigrams)
      Create a new KoreanTokenizer using the system and unknown dictionaries shipped with Lucene.
      Parameters:
      factory - the AttributeFactory to use
      userDictionary - Optional: if non-null, user dictionary.
      mode - Decompound mode.
      outputUnknownUnigrams - if true outputs unigrams for unknown words.

    • KoreanTokenizer

      public KoreanTokenizer(AttributeFactory factory, UserDictionary userDictionary, KoreanTokenizer.DecompoundMode mode, boolean outputUnknownUnigrams, boolean discardPunctuation)
      Create a new KoreanTokenizer using the system and unknown dictionaries shipped with Lucene.
      Parameters:
      factory - the AttributeFactory to use
      userDictionary - Optional: if non-null, user dictionary.
      mode - Decompound mode.
      outputUnknownUnigrams - if true outputs unigrams for unknown words.
      discardPunctuation - true if punctuation tokens should be dropped from the output.

    • KoreanTokenizer

      public KoreanTokenizer(AttributeFactory factory, TokenInfoDictionary systemDictionary, UnknownDictionary unkDictionary, ConnectionCosts connectionCosts, UserDictionary userDictionary, KoreanTokenizer.DecompoundMode mode, boolean outputUnknownUnigrams, boolean discardPunctuation)
      Create a new KoreanTokenizer supplying a custom system dictionary and unknown dictionary. This constructor provides an entry point for users that want to construct custom language models that can be used as input to DictionaryBuilder.
      Parameters:
      factory - the AttributeFactory to use
      systemDictionary - a custom known token dictionary
      unkDictionary - a custom unknown token dictionary
      connectionCosts - custom token transition costs
      userDictionary - Optional: if non-null, user dictionary.
      mode - Decompound mode.
      outputUnknownUnigrams - if true outputs unigrams for unknown words.
      discardPunctuation - true if punctuation tokens should be dropped from the output.

  • Method Details

    • setGraphvizFormatter

      public void setGraphvizFormatter(GraphvizFormatter dotOut)
      Expert: set this to produce graphviz (dot) output of the Viterbi lattice

    • close

      public void close() throws IOException
      Description copied from class: Tokenizer
      Releases resources associated with this stream.

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

      NOTE: The default implementation closes the input Reader, so be sure to call super.close() when overriding this method.

      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class Tokenizer
      Throws:
      IOException

    • reset

      public void reset() throws 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:
      IOException

    • resetState

      private void resetState()

    • end

      public void end() throws 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:
      IOException - If an I/O error occurs

    • computeSpacePenalty

      private int computeSpacePenalty(POS.Tag leftPOS, int numSpaces)
      Returns the space penalty associated with the provided POS.Tag.
      Parameters:
      leftPOS - the left part of speech of the current token.
      numSpaces - the number of spaces before the current token.

    • add

      private void add(Dictionary dict, KoreanTokenizer.Position fromPosData, int wordPos, int endPos, int wordID, KoreanTokenizer.Type type)

    • 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

    • parse

      private void parse() throws IOException
      Throws:
      IOException

    • backtrace

      private void backtrace(KoreanTokenizer.Position endPosData, int fromIDX)

    • getDict

      Dictionary getDict(KoreanTokenizer.Type type)

    • shouldFilterToken

      private boolean shouldFilterToken(Token token)

    • isPunctuation

      private static boolean isPunctuation(char ch)

    • isPunctuation

      private static boolean isPunctuation(char ch, int cid)

    • isCommonOrInherited

      private static boolean isCommonOrInherited(Character.UnicodeScript script)

    • isSameScript

      private static boolean isSameScript(Character.UnicodeScript scriptOne, Character.UnicodeScript scriptTwo)
      Determine if two scripts are compatible.