org.apache.lucene.analysis
Class CharTokenizer

java.lang.Object
  extended by org.apache.lucene.util.AttributeSource
      extended by org.apache.lucene.analysis.TokenStream
          extended by org.apache.lucene.analysis.Tokenizer
              extended by org.apache.lucene.analysis.CharTokenizer
All Implemented Interfaces:
Closeable
Direct Known Subclasses:
LetterTokenizer, WhitespaceTokenizer

public abstract class CharTokenizer
extends Tokenizer

An abstract base class for simple, character-oriented tokenizers.


Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.AttributeFactory, AttributeSource.State
 
Field Summary
 
Fields inherited from class org.apache.lucene.analysis.Tokenizer
input
 
Constructor Summary
CharTokenizer(AttributeSource.AttributeFactory factory, Reader input)
           
CharTokenizer(AttributeSource source, Reader input)
           
CharTokenizer(Reader input)
           
 
Method Summary
 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.
protected abstract  boolean isTokenChar(char c)
          Returns true iff a character should be included in a token.
protected  char normalize(char 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
 
Methods inherited from class org.apache.lucene.analysis.TokenStream
reset
 
Methods inherited from class org.apache.lucene.util.AttributeSource
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, restoreState, toString
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

CharTokenizer

public CharTokenizer(Reader input)

CharTokenizer

public CharTokenizer(AttributeSource source,
                     Reader input)

CharTokenizer

public CharTokenizer(AttributeSource.AttributeFactory factory,
                     Reader input)
Method Detail

isTokenChar

protected abstract boolean isTokenChar(char c)
Returns true iff a character should be included in a token. This tokenizer generates as tokens adjacent sequences of characters which satisfy this predicate. Characters for which this is false are used to define token boundaries and are not included in tokens.


normalize

protected char normalize(char 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.


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 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().

Specified by:
incrementToken in class TokenStream
Returns:
false for end of stream; true otherwise
Throws:
IOException

end

public final void end()
Description copied from class: TokenStream
This method is called by the consumer after the last token has been consumed, after 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.

Overrides:
end in class TokenStream

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 class Tokenizer
Throws:
IOException


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