public abstract class CharTokenizer extends Tokenizer
You must specify the required Version
compatibility
when creating CharTokenizer
:
CharTokenizer
uses an int based API to normalize and
detect token codepoints. See isTokenChar(int)
and
normalize(int)
for details.
A new CharTokenizer
API has been introduced with Lucene 3.1. This API
moved from UTF-16 code units to UTF-32 codepoints to eventually add support
for supplementary characters. The old char based API has been
deprecated and should be replaced with the int based methods
isTokenChar(int)
and normalize(int)
.
As of Lucene 3.1 each CharTokenizer
- constructor expects a
Version
argument. Based on the given Version
either the new
API or a backwards compatibility layer is used at runtime. For
Version
< 3.1 the backwards compatibility layer ensures correct
behavior even for indexes build with previous versions of Lucene. If a
Version
>= 3.1 is used CharTokenizer
requires the new API to
be implemented by the instantiated class. Yet, the old char based API
is not required anymore even if backwards compatibility must be preserved.
CharTokenizer
subclasses implementing the new API are fully backwards
compatible if instantiated with Version
< 3.1.
Note: If you use a subclass of CharTokenizer
with Version
>=
3.1 on an index build with a version < 3.1, created tokens might not be
compatible with the terms in your index.
AttributeSource.AttributeFactory, AttributeSource.State
Constructor and Description |
---|
CharTokenizer(Version matchVersion,
AttributeSource.AttributeFactory factory,
Reader input)
Creates a new
CharTokenizer instance |
CharTokenizer(Version matchVersion,
Reader input)
Creates a new
CharTokenizer instance |
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 CharTokenizer(Version matchVersion, Reader input)
CharTokenizer
instancematchVersion
- Lucene version to matchinput
- the input to split up into tokenspublic CharTokenizer(Version matchVersion, AttributeSource.AttributeFactory factory, Reader input)
CharTokenizer
instancematchVersion
- Lucene version to matchfactory
- the attribute factory to use for this Tokenizer
input
- the input to split up into tokenspublic final boolean incrementToken() throws 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
IOException
public final 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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