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:

java.io.Closeable, java.lang.AutoCloseable

public final class KoreanTokenizer
extends Tokenizer

Tokenizer for Korean that uses morphological analysis.

This tokenizer sets a number of additional attributes:

• PartOfSpeechAttribute containing part-of-speech.
• ReadingAttribute containing reading.

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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	KoreanTokenizer.DecompoundMode Decompound mode: this determines how the tokenizer handles POS.Type.COMPOUND, POS.Type.INFLECT and POS.Type.PREANALYSIS tokens.
static class	KoreanTokenizer.Type Token type reflecting the original source of this token

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
static KoreanTokenizer.DecompoundMode	DEFAULT_DECOMPOUND Default mode for the decompound of tokens (KoreanTokenizer.DecompoundMode.DISCARD.

Fields inherited from class org.apache.lucene.analysis.Tokenizer

input

Fields inherited from class org.apache.lucene.analysis.TokenStream

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor and Description
KoreanTokenizer() Creates a new KoreanTokenizer with default parameters.
KoreanTokenizer(AttributeFactory factory, UserDictionary userDictionary, KoreanTokenizer.DecompoundMode mode, boolean outputUnknownUnigrams) Create a new KoreanTokenizer.

Method Summary

Modifier and Type	Method and Description
void	close() Releases resources associated with this stream.
void	end() This method is called by the consumer after the last token has been consumed, after TokenStream.incrementToken() returned false (using the new TokenStream API).
boolean	incrementToken() Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.
void	reset() This method is called by a consumer before it begins consumption using TokenStream.incrementToken().
void	setGraphvizFormatter(GraphvizFormatter dotOut) Expert: set this to produce graphviz (dot) output of the Viterbi lattice

Methods inherited from class org.apache.lucene.analysis.Tokenizer

correctOffset, setReader

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT_DECOMPOUND

public static final KoreanTokenizer.DecompoundMode DEFAULT_DECOMPOUND

Default mode for the decompound of tokens (KoreanTokenizer.DecompoundMode.DISCARD.

Constructor Detail

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.

Parameters:

factory - the AttributeFactory to use

userDictionary - Optional: if non-null, user dictionary.

mode - Decompound mode.

outputUnknownUnigrams - If true outputs unigrams for unknown words.

Method Detail

setGraphvizFormatter

public void setGraphvizFormatter(GraphvizFormatter dotOut)

Expert: set this to produce graphviz (dot) output of the Viterbi lattice

close

public void close()
           throws java.io.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 java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class Tokenizer

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

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