org.apache.lucene.analysis.cjk

Class CJKBigramFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.cjk.CJKBigramFilter

All Implemented Interfaces:

Closeable

public final class CJKBigramFilter
extends TokenFilter

Forms bigrams of CJK terms that are generated from StandardTokenizer or ICUTokenizer.

CJK types are set by these tokenizers, but you can also use CJKBigramFilter(TokenStream, int) to explicitly control which of the CJK scripts are turned into bigrams.

In all cases, all non-CJK input is passed thru unmodified.

Nested Class Summary

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

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
static String	DOUBLE_TYPE when we emit a bigram, its then marked as this type
static int	HAN bigram flag for Han Ideographs
static int	HANGUL bigram flag for Hangul
static int	HIRAGANA bigram flag for Hiragana
static int	KATAKANA bigram flag for Katakana
static String	SINGLE_TYPE when we emit a unigram, its then marked as this type

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

input

Constructor Summary

Constructors

Constructor and Description
CJKBigramFilter(TokenStream in) Calls CJKBigramFilter(HAN | HIRAGANA | KATAKANA | HANGUL)
CJKBigramFilter(TokenStream in, int flags) Create a new CJKBigramFilter, specifying which writing systems should be bigrammed.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	incrementToken() Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.
void	reset() Reset the filter as well as the input TokenStream.

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

close, end

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

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

Methods inherited from class java.lang.Object

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

Field Detail

HAN

public static final int HAN

bigram flag for Han Ideographs

See Also:

Constant Field Values

HIRAGANA

public static final int HIRAGANA

bigram flag for Hiragana

See Also:

Constant Field Values

KATAKANA

public static final int KATAKANA

bigram flag for Katakana

See Also:

Constant Field Values

HANGUL

public static final int HANGUL

bigram flag for Hangul

See Also:

Constant Field Values

DOUBLE_TYPE

public static final String DOUBLE_TYPE

when we emit a bigram, its then marked as this type

See Also:

Constant Field Values

SINGLE_TYPE

public static final String SINGLE_TYPE

when we emit a unigram, its then marked as this type

See Also:

Constant Field Values

Constructor Detail

CJKBigramFilter

public CJKBigramFilter(TokenStream in)

Calls CJKBigramFilter(HAN | HIRAGANA | KATAKANA | HANGUL)

CJKBigramFilter

public CJKBigramFilter(TokenStream in,
               int flags)

Create a new CJKBigramFilter, specifying which writing systems should be bigrammed.

Parameters:

flags - OR'ed set from HAN, HIRAGANA, KATAKANA, HANGUL

Method Detail

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

reset

public void reset()
           throws IOException

Description copied from class: TokenFilter

Reset the filter as well as the input TokenStream.

Overrides:

reset in class TokenFilter

Throws:

IOException