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
CJKBigramFilter(TokenStream, int, boolean).
This can be used for a combined unigram+bigram approach.
In all cases, all non-CJK input is passed thru unmodified.
|Modifier and Type||Field and Description|
when we emit a bigram, its then marked as this type
bigram flag for Han Ideographs
bigram flag for Hangul
bigram flag for Hiragana
bigram flag for Katakana
when we emit a unigram, its then marked as this type
|Constructor and Description|
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|
This method is called by a consumer before it begins consumption using
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, 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 java.lang.String DOUBLE_TYPE
public static final java.lang.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 java.io.IOException
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
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
public void reset() throws java.io.IOException
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
some internal state will not be correctly reset (e.g.,
IllegalStateException on further usage).
The default implementation chains the call to the input TokenStream, so
be sure to call
super.reset() when overriding this method.
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