Class JapaneseTokenizer
- java.lang.Object
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- org.apache.lucene.util.AttributeSource
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- org.apache.lucene.analysis.TokenStream
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- org.apache.lucene.analysis.Tokenizer
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- org.apache.lucene.analysis.ja.JapaneseTokenizer
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
public final class JapaneseTokenizer extends Tokenizer
Tokenizer for Japanese that uses morphological analysis.This tokenizer sets a number of additional attributes:
BaseFormAttribute
containing base form for inflected adjectives and verbs.PartOfSpeechAttribute
containing part-of-speech.ReadingAttribute
containing reading and pronunciation.InflectionAttribute
containing additional part-of-speech information for inflected forms.
This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is
JapaneseTokenizer.Mode.SEARCH
, we output the alternate segmentation as well.
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Nested Class Summary
Nested Classes Modifier and Type Class Description private static class
JapaneseTokenizer.Lattice
static class
JapaneseTokenizer.Mode
Tokenization mode: this determines how the tokenizer handles compound and unknown words.(package private) static class
JapaneseTokenizer.Position
static class
JapaneseTokenizer.Type
Token type reflecting the original source of this token(package private) static class
JapaneseTokenizer.WrappedPositionArray
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
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Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
Constructors Constructor Description JapaneseTokenizer(UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer.JapaneseTokenizer(AttributeFactory factory, TokenInfoDictionary systemDictionary, UnknownDictionary unkDictionary, ConnectionCosts connectionCosts, UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer, supplying a custom system dictionary and unknown dictionary.JapaneseTokenizer(AttributeFactory factory, UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer using the system and unknown dictionaries shipped with Lucene.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description private void
add(Dictionary dict, JapaneseTokenizer.Position fromPosData, int endPos, int wordID, JapaneseTokenizer.Type type, boolean addPenalty)
private void
backtrace(JapaneseTokenizer.Position endPosData, int fromIDX)
private void
backtraceNBest(JapaneseTokenizer.Position endPosData, boolean useEOS)
int
calcNBestCost(java.lang.String examples)
void
close()
Releases resources associated with this stream.private int
computePenalty(int pos, int length)
private int
computeSecondBestThreshold(int pos, int length)
void
end()
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API).private void
fixupPendingList()
(package private) Dictionary
getDict(JapaneseTokenizer.Type type)
boolean
incrementToken()
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token.private static boolean
isPunctuation(char ch)
private void
parse()
private int
probeDelta(java.lang.String inText, java.lang.String requiredToken)
private void
pruneAndRescore(int startPos, int endPos, int bestStartIDX)
private void
registerNode(int node, char[] fragment)
void
reset()
This method is called by a consumer before it begins consumption usingTokenStream.incrementToken()
.private void
resetState()
void
setGraphvizFormatter(GraphvizFormatter dotOut)
Expert: set this to produce graphviz (dot) output of the Viterbi latticevoid
setNBestCost(int value)
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Methods inherited from class org.apache.lucene.analysis.Tokenizer
correctOffset, setReader
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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
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Field Detail
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DEFAULT_MODE
public static final JapaneseTokenizer.Mode DEFAULT_MODE
Default tokenization mode. Currently this isJapaneseTokenizer.Mode.SEARCH
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VERBOSE
private static final boolean VERBOSE
- See Also:
- Constant Field Values
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SEARCH_MODE_KANJI_LENGTH
private static final int SEARCH_MODE_KANJI_LENGTH
- See Also:
- Constant Field Values
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SEARCH_MODE_OTHER_LENGTH
private static final int SEARCH_MODE_OTHER_LENGTH
- See Also:
- Constant Field Values
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SEARCH_MODE_KANJI_PENALTY
private static final int SEARCH_MODE_KANJI_PENALTY
- See Also:
- Constant Field Values
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SEARCH_MODE_OTHER_PENALTY
private static final int SEARCH_MODE_OTHER_PENALTY
- See Also:
- Constant Field Values
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MAX_UNKNOWN_WORD_LENGTH
private static final int MAX_UNKNOWN_WORD_LENGTH
- See Also:
- Constant Field Values
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MAX_BACKTRACE_GAP
private static final int MAX_BACKTRACE_GAP
- See Also:
- Constant Field Values
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dictionaryMap
private final java.util.EnumMap<JapaneseTokenizer.Type,Dictionary> dictionaryMap
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fst
private final TokenInfoFST fst
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dictionary
private final TokenInfoDictionary dictionary
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unkDictionary
private final UnknownDictionary unkDictionary
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costs
private final ConnectionCosts costs
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userDictionary
private final UserDictionary userDictionary
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characterDefinition
private final CharacterDefinition characterDefinition
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arc
private final FST.Arc<java.lang.Long> arc
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fstReader
private final FST.BytesReader fstReader
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wordIdRef
private final IntsRef wordIdRef
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userFSTReader
private final FST.BytesReader userFSTReader
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userFST
private final TokenInfoFST userFST
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buffer
private final RollingCharBuffer buffer
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positions
private final JapaneseTokenizer.WrappedPositionArray positions
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discardPunctuation
private final boolean discardPunctuation
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searchMode
private final boolean searchMode
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extendedMode
private final boolean extendedMode
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outputCompounds
private final boolean outputCompounds
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outputNBest
private boolean outputNBest
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nBestCost
private int nBestCost
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end
private boolean end
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lastBackTracePos
private int lastBackTracePos
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lastTokenPos
private int lastTokenPos
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pos
private int pos
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pending
private final java.util.List<Token> pending
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termAtt
private final CharTermAttribute termAtt
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offsetAtt
private final OffsetAttribute offsetAtt
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posIncAtt
private final PositionIncrementAttribute posIncAtt
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posLengthAtt
private final PositionLengthAttribute posLengthAtt
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basicFormAtt
private final BaseFormAttribute basicFormAtt
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posAtt
private final PartOfSpeechAttribute posAtt
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readingAtt
private final ReadingAttribute readingAtt
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inflectionAtt
private final InflectionAttribute inflectionAtt
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dotOut
private GraphvizFormatter dotOut
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lattice
private JapaneseTokenizer.Lattice lattice
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Constructor Detail
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JapaneseTokenizer
public JapaneseTokenizer(UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer.Uses the default AttributeFactory.
- Parameters:
userDictionary
- Optional: if non-null, user dictionary.discardPunctuation
- true if punctuation tokens should be dropped from the output.mode
- tokenization mode.
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JapaneseTokenizer
public JapaneseTokenizer(AttributeFactory factory, UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer using the system and unknown dictionaries shipped with Lucene.- Parameters:
factory
- the AttributeFactory to useuserDictionary
- Optional: if non-null, user dictionary.discardPunctuation
- true if punctuation tokens should be dropped from the output.mode
- tokenization mode.
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JapaneseTokenizer
public JapaneseTokenizer(AttributeFactory factory, TokenInfoDictionary systemDictionary, UnknownDictionary unkDictionary, ConnectionCosts connectionCosts, UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer, 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 usesystemDictionary
- a custom known token dictionaryunkDictionary
- a custom unknown token dictionaryconnectionCosts
- custom token transition costsuserDictionary
- Optional: if non-null, user dictionary.discardPunctuation
- true if punctuation tokens should be dropped from the output.mode
- tokenization mode.
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Method Detail
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setGraphvizFormatter
public void setGraphvizFormatter(GraphvizFormatter dotOut)
Expert: set this to produce graphviz (dot) output of the Viterbi lattice
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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 throwIllegalStateException
on reuse).NOTE: The default implementation closes the input Reader, so be sure to call
super.close()
when overriding this method.
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reset
public void reset() throws java.io.IOException
Description copied from class:TokenStream
This method is called by a consumer before it begins consumption usingTokenStream.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 throwIllegalStateException
on further usage).
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resetState
private void resetState()
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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, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
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 classTokenStream
- Throws:
java.io.IOException
- If an I/O error occurs
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computeSecondBestThreshold
private int computeSecondBestThreshold(int pos, int length) throws java.io.IOException
- Throws:
java.io.IOException
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computePenalty
private int computePenalty(int pos, int length) throws java.io.IOException
- Throws:
java.io.IOException
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add
private void add(Dictionary dict, JapaneseTokenizer.Position fromPosData, int endPos, int wordID, JapaneseTokenizer.Type type, boolean addPenalty) throws java.io.IOException
- Throws:
java.io.IOException
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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 appropriateAttributeImpl
s 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)
andAttributeSource.getAttribute(Class)
, references to allAttributeImpl
s 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 classTokenStream
- Returns:
- false for end of stream; true otherwise
- Throws:
java.io.IOException
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parse
private void parse() throws java.io.IOException
- Throws:
java.io.IOException
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pruneAndRescore
private void pruneAndRescore(int startPos, int endPos, int bestStartIDX) throws java.io.IOException
- Throws:
java.io.IOException
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registerNode
private void registerNode(int node, char[] fragment)
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fixupPendingList
private void fixupPendingList()
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probeDelta
private int probeDelta(java.lang.String inText, java.lang.String requiredToken) throws java.io.IOException
- Throws:
java.io.IOException
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calcNBestCost
public int calcNBestCost(java.lang.String examples)
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setNBestCost
public void setNBestCost(int value)
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backtraceNBest
private void backtraceNBest(JapaneseTokenizer.Position endPosData, boolean useEOS) throws java.io.IOException
- Throws:
java.io.IOException
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backtrace
private void backtrace(JapaneseTokenizer.Position endPosData, int fromIDX) throws java.io.IOException
- Throws:
java.io.IOException
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getDict
Dictionary getDict(JapaneseTokenizer.Type type)
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isPunctuation
private static boolean isPunctuation(char ch)
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