public final class PatternTokenizer extends Tokenizer
group=-1 (the default) is equivalent to "split". In this case, the tokens will
be equivalent to the output from (without empty tokens):
String.split(java.lang.String)
Using group >= 0 selects the matching group as the token. For example, if you have:
pattern = \'([^\']+)\' group = 0 input = aaa 'bbb' 'ccc'the output will be two tokens: 'bbb' and 'ccc' (including the ' marks). With the same input but using group=1, the output would be: bbb and ccc (no ' marks)
NOTE: This Tokenizer does not output tokens that are of zero length.
Pattern
AttributeSource.AttributeFactory, AttributeSource.State
Constructor and Description |
---|
PatternTokenizer(AttributeSource.AttributeFactory factory,
Reader input,
Pattern pattern,
int group)
creates a new PatternTokenizer returning tokens from group (-1 for split functionality)
|
PatternTokenizer(Reader input,
Pattern pattern,
int group)
creates a new PatternTokenizer returning tokens from group (-1 for split functionality)
|
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() . |
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString
public PatternTokenizer(Reader input, Pattern pattern, int group)
public PatternTokenizer(AttributeSource.AttributeFactory factory, Reader input, Pattern pattern, int group)
public boolean incrementToken()
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
public void end() throws IOException
TokenStream
TokenStream.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()
.
end
in class TokenStream
IOException
- If an I/O error occurspublic void reset() throws IOException
TokenStream
TokenStream.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).
reset
in class Tokenizer
IOException
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