org.apache.lucene.analysis
Class CharTokenizer

java.lang.Object
  org.apache.lucene.util.AttributeSource
      org.apache.lucene.analysis.TokenStream
          org.apache.lucene.analysis.Tokenizer
              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