public final class CJKWidthFilter extends TokenFilter
TokenFilter
that normalizes CJK width differences:
NOTE: this filter can be viewed as a (practical) subset of NFKC/NFKD Unicode normalization. See the normalization support in the ICU package for full normalization.
AttributeSource.State
Modifier and Type | Field and Description |
---|---|
private static byte[] |
KANA_COMBINE_HALF_VOICED |
private static byte[] |
KANA_COMBINE_VOICED |
private static char[] |
KANA_NORM |
private CharTermAttribute |
termAtt |
input
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
Constructor and Description |
---|
CJKWidthFilter(TokenStream input) |
Modifier and Type | Method and Description |
---|---|
private static boolean |
combine(char[] text,
int pos,
char ch)
returns true if we successfully combined the voice mark
|
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter ) use this method to advance the stream to
the next token. |
close, end, reset
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString
private CharTermAttribute termAtt
private static final char[] KANA_NORM
private static final byte[] KANA_COMBINE_VOICED
private static final byte[] KANA_COMBINE_HALF_VOICED
public CJKWidthFilter(TokenStream input)
public boolean incrementToken() throws java.io.IOException
TokenStream
IndexWriter
) use this method to advance the stream to
the next token. Implementing classes must implement this method and update
the appropriate AttributeImpl
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)
and AttributeSource.getAttribute(Class)
,
references to all AttributeImpl
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()
.
incrementToken
in class TokenStream
java.io.IOException
private static boolean combine(char[] text, int pos, char ch)