Class CharTokenizer
- java.lang.Object
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- org.apache.lucene.util.AttributeSource
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- org.apache.lucene.analysis.TokenStream
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- org.apache.lucene.analysis.Tokenizer
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- org.apache.lucene.analysis.CharTokenizer
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- All Implemented Interfaces:
Closeable
,AutoCloseable
- Direct Known Subclasses:
IndicTokenizer
,LetterTokenizer
,RussianLetterTokenizer
,WhitespaceTokenizer
public abstract class CharTokenizer extends Tokenizer
An abstract base class for simple, character-oriented tokenizers.You must specify the required
Version
compatibility when creatingCharTokenizer
:- As of 3.1,
CharTokenizer
uses an int based API to normalize and detect token codepoints. SeeisTokenChar(int)
andnormalize(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 methodsisTokenChar(int)
andnormalize(int)
.As of Lucene 3.1 each
CharTokenizer
- constructor expects aVersion
argument. Based on the givenVersion
either the new API or a backwards compatibility layer is used at runtime. ForVersion
< 3.1 the backwards compatibility layer ensures correct behavior even for indexes build with previous versions of Lucene. If aVersion
>= 3.1 is usedCharTokenizer
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 withVersion
< 3.1.Note: If you use a subclass of
CharTokenizer
withVersion
>= 3.1 on an index build with a version < 3.1, created tokens might not be compatible with the terms in your index.
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.AttributeFactory, AttributeSource.State
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Constructor Summary
Constructors Constructor Description CharTokenizer(Reader input)
Deprecated.useCharTokenizer(Version, Reader)
instead.CharTokenizer(AttributeSource.AttributeFactory factory, Reader input)
Deprecated.CharTokenizer(AttributeSource source, Reader input)
Deprecated.useCharTokenizer(Version, AttributeSource, Reader)
instead.CharTokenizer(Version matchVersion, Reader input)
Creates a newCharTokenizer
instanceCharTokenizer(Version matchVersion, AttributeSource.AttributeFactory factory, Reader input)
Creates a newCharTokenizer
instanceCharTokenizer(Version matchVersion, AttributeSource source, Reader input)
Creates a newCharTokenizer
instance
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Method Summary
All Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description void
end()
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API).boolean
incrementToken()
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token.protected boolean
isTokenChar(char c)
Deprecated.useisTokenChar(int)
instead.protected boolean
isTokenChar(int c)
Returns true iff a codepoint should be included in a token.protected char
normalize(char c)
Deprecated.usenormalize(int)
instead.protected int
normalize(int c)
Called on each token character to normalize it before it is added to the token.void
reset(Reader input)
Expert: Reset the tokenizer to a new reader.-
Methods inherited from class org.apache.lucene.analysis.Tokenizer
close, correctOffset
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Methods inherited from class org.apache.lucene.analysis.TokenStream
reset
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Methods inherited from class org.apache.lucene.util.AttributeSource
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString
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Constructor Detail
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CharTokenizer
public CharTokenizer(Version matchVersion, Reader input)
Creates a newCharTokenizer
instance- Parameters:
matchVersion
- Lucene version to match See {@link above}input
- the input to split up into tokens
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CharTokenizer
public CharTokenizer(Version matchVersion, AttributeSource source, Reader input)
Creates a newCharTokenizer
instance
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CharTokenizer
public CharTokenizer(Version matchVersion, AttributeSource.AttributeFactory factory, Reader input)
Creates a newCharTokenizer
instance
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CharTokenizer
@Deprecated public CharTokenizer(Reader input)
Deprecated.useCharTokenizer(Version, Reader)
instead. This will be removed in Lucene 4.0.Creates a newCharTokenizer
instance- Parameters:
input
- the input to split up into tokens
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CharTokenizer
@Deprecated public CharTokenizer(AttributeSource source, Reader input)
Deprecated.useCharTokenizer(Version, AttributeSource, Reader)
instead. This will be removed in Lucene 4.0.Creates a newCharTokenizer
instance- Parameters:
input
- the input to split up into tokenssource
- the attribute source to use for thisTokenizer
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CharTokenizer
@Deprecated public CharTokenizer(AttributeSource.AttributeFactory factory, Reader input)
Deprecated.useCharTokenizer(Version, AttributeSource.AttributeFactory, Reader)
instead. This will be removed in Lucene 4.0.Creates a newCharTokenizer
instance- Parameters:
input
- the input to split up into tokensfactory
- the attribute factory to use for thisTokenizer
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Method Detail
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isTokenChar
@Deprecated protected boolean isTokenChar(char c)
Deprecated.useisTokenChar(int)
instead. This method will be removed in Lucene 4.0.Returns true iff a UTF-16 code unit should be included in a token. This tokenizer generates as tokens adjacent sequences of characters which satisfy this predicate. Characters for which this isfalse
are used to define token boundaries and are not included in tokens.Note: This method cannot handle supplementary characters. To support all Unicode characters, including supplementary characters, use the
isTokenChar(int)
method.
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normalize
@Deprecated protected char normalize(char c)
Deprecated.usenormalize(int)
instead. This method will be removed in Lucene 4.0.Called on each token UTF-16 code unit to normalize it before it is added to the token. The default implementation does nothing. Subclasses may use this to, e.g., lowercase tokens.Note: This method cannot handle supplementary characters. To support all Unicode characters, including supplementary characters, use the
normalize(int)
method.
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isTokenChar
protected boolean isTokenChar(int c)
Returns true iff a codepoint should be included in a token. This tokenizer generates as tokens adjacent sequences of codepoints which satisfy this predicate. Codepoints for which this is false are used to define token boundaries and are not included in tokens.As of Lucene 3.1 the char based API (
isTokenChar(char)
andnormalize(char)
) has been depreciated in favor of a Unicode 4.0 compatible int based API to support codepoints instead of UTF-16 code units. Subclasses ofCharTokenizer
must not override the char based methods if aVersion
>= 3.1 is passed to the constructor.NOTE: This method will be marked abstract in Lucene 4.0.
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normalize
protected int normalize(int c)
Called on each token character to normalize it before it is added to the token. The default implementation does nothing. Subclasses may use this to, e.g., lowercase tokens.As of Lucene 3.1 the char based API (
isTokenChar(char)
andnormalize(char)
) has been depreciated in favor of a Unicode 4.0 compatible int based API to support codepoints instead of UTF-16 code units. Subclasses ofCharTokenizer
must not override the char based methods if aVersion
>= 3.1 is passed to the constructor.NOTE: This method will be marked abstract in Lucene 4.0.
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incrementToken
public final boolean incrementToken() throws IOException
Description copied from class:TokenStream
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriateAttributeImpl
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)
andAttributeSource.getAttribute(Class)
, references to allAttributeImpl
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()
.- Specified by:
incrementToken
in classTokenStream
- Returns:
- false for end of stream; true otherwise
- Throws:
IOException
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end
public final void end()
Description copied from class:TokenStream
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
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 aWhitespaceTokenizer
was used.- Overrides:
end
in classTokenStream
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reset
public void reset(Reader input) throws IOException
Description copied from class:Tokenizer
Expert: Reset the tokenizer to a new reader. Typically, an analyzer (in its reusableTokenStream method) will use this to re-use a previously created tokenizer.- Overrides:
reset
in classTokenizer
- Throws:
IOException
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