Package org.apache.lucene.analysis

Class CharFilter

java.lang.Object

java.io.Reader

org.apache.lucene.analysis.CharFilter

All Implemented Interfaces:

Closeable, AutoCloseable, Readable

public abstract class CharFilter
extends Reader

Subclasses of CharFilter can be chained to filter a Reader They can be used as Reader with additional offset correction. Tokenizers will automatically use correctOffset(int) if a CharFilter subclass is used.

This class is abstract: at a minimum you must implement Reader.read(char[], int, int), transforming the input in some way from input, and correct(int) to adjust the offsets to match the originals.

You can optionally provide more efficient implementations of additional methods like Reader.read(), Reader.read(char[]), Reader.read(java.nio.CharBuffer), but this is not required.

For examples and integration with Analyzer, see the Analysis package documentation.

Field Summary

Fields

Modifier and Type	Field	Description
protected final Reader	input	The underlying character-input stream.

Fields inherited from class java.io.Reader

lock

Constructor Summary

Constructors

Constructor	Description
CharFilter(Reader input)	Create a new CharFilter wrapping the provided reader.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the underlying input stream.
protected abstract int	correct(int currentOff)	Subclasses override to correct the current offset.
final int	correctOffset(int currentOff)	Chains the corrected offset through the input CharFilter(s).

Methods inherited from class java.io.Reader

mark, markSupported, nullReader, read, read, read, read, ready, reset, skip, transferTo

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

input

protected final Reader input

The underlying character-input stream.

Constructor Details

CharFilter

public CharFilter(Reader input)

Create a new CharFilter wrapping the provided reader.

Parameters:

input - a Reader, can also be a CharFilter for chaining.

Method Details

close

public void close()
           throws IOException

Closes the underlying input stream.

NOTE: The default implementation closes the input Reader, so be sure to call super.close() when overriding this method.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in class Reader

Throws:

IOException

correct

protected abstract int correct(int currentOff)

Subclasses override to correct the current offset.

Parameters:

currentOff - current offset

Returns:

corrected offset

correctOffset

public final int correctOffset(int currentOff)

Chains the corrected offset through the input CharFilter(s).