public final class FixedShingleFilter extends TokenFilter
Unlike the ShingleFilter, FixedShingleFilter only emits shingles of a
fixed size, and never emits unigrams, even at the end of a TokenStream. In
addition, if the filter encounters stacked tokens (eg synonyms), then it will
output stacked shingles
For example, the sentence "please divide this sentence into shingles" might be tokenized into shingles "please divide", "divide this", "this sentence", "sentence into", and "into shingles".
This filter handles position increments > 1 by inserting filler tokens (tokens with termtext "_").
AttributeSource.StateinputDEFAULT_TOKEN_ATTRIBUTE_FACTORY| Constructor and Description |
|---|
FixedShingleFilter(TokenStream input,
int shingleSize)
Creates a FixedShingleFilter over an input token stream
|
FixedShingleFilter(TokenStream input,
int shingleSize,
java.lang.String tokenSeparator,
java.lang.String fillerToken)
Creates a FixedShingleFilter over an input token stream
|
| Modifier and Type | Method and Description |
|---|---|
void |
end()
This method is called by the consumer after the last token has been
consumed, after
TokenStream.incrementToken() returned false
(using the new TokenStream API). |
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter) use this method to advance the stream to
the next token. |
void |
reset()
This method is called by a consumer before it begins consumption using
TokenStream.incrementToken(). |
closeaddAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toStringpublic FixedShingleFilter(TokenStream input, int shingleSize)
input - the input streamshingleSize - the shingle sizepublic FixedShingleFilter(TokenStream input, int shingleSize, java.lang.String tokenSeparator, java.lang.String fillerToken)
input - the input tokenstreamshingleSize - the shingle sizetokenSeparator - a String to use as a token separatorfillerToken - a String to use to represent gaps in the input stream (due to eg stopwords)public boolean incrementToken()
throws java.io.IOException
TokenStreamIndexWriter) 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().
incrementToken in class TokenStreamjava.io.IOExceptionpublic void reset()
throws java.io.IOException
TokenFilterTokenStream.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
throw IllegalStateException on further usage).
NOTE:
The default implementation chains the call to the input TokenStream, so
be sure to call super.reset() when overriding this method.
reset in class TokenFilterjava.io.IOExceptionpublic void end()
throws java.io.IOException
TokenFilterTokenStream.incrementToken() returned false
(using the new TokenStream 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().
NOTE:
The default implementation chains the call to the input TokenStream, so
be sure to call super.end() first when overriding this method.
end in class TokenFilterjava.io.IOException - If an I/O error occursCopyright © 2000–2025 The Apache Software Foundation. All rights reserved.