public final class CJKBigramFilter extends TokenFilter
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.
By default, when a CJK character has no adjacent characters to form
a bigram, it is output in unigram form. If you want to always output
both unigrams and bigrams, set the outputUnigrams
flag in CJKBigramFilter(TokenStream, int, boolean)
.
This can be used for a combined unigram+bigram approach.
Unlike ICUTokenizer, StandardTokenizer does not split at script boundaries.
Korean Hangul characters are treated the same as many other scripts'
letters, and as a result, StandardTokenizer can produce tokens that mix
Hangul and non-Hangul characters, e.g. "한국abc". Such mixed-script tokens
are typed as <ALPHANUM>
rather than
<HANGUL>
, and as a result, will not be converted to
bigrams by CJKBigramFilter.
In all cases, all non-CJK input is passed thru unmodified.
AttributeSource.State
Modifier and Type | Field and Description |
---|---|
static String |
DOUBLE_TYPE
when we emit a bigram, it's 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, it's then marked as this type
|
input
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
Constructor and Description |
---|
CJKBigramFilter(TokenStream in)
|
CJKBigramFilter(TokenStream in,
int flags)
|
CJKBigramFilter(TokenStream in,
int flags,
boolean outputUnigrams)
Create a new CJKBigramFilter, specifying which writing systems should be bigrammed,
and whether or not unigrams should also be output.
|
Modifier and Type | Method and Description |
---|---|
boolean |
incrementToken() |
void |
reset() |
close, end
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString
public static final int HAN
public static final int HIRAGANA
public static final int KATAKANA
public static final int HANGUL
public static final String DOUBLE_TYPE
public static final String SINGLE_TYPE
public CJKBigramFilter(TokenStream in)
public CJKBigramFilter(TokenStream in, int flags)
public CJKBigramFilter(TokenStream in, int flags, boolean outputUnigrams)
public boolean incrementToken() throws IOException
incrementToken
in class TokenStream
IOException
public void reset() throws IOException
reset
in class TokenFilter
IOException
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