org.apache.lucene.analysis
Class BaseCharFilter

java.lang.Object
  java.io.Reader
      org.apache.lucene.analysis.CharStream
          org.apache.lucene.analysis.CharFilter
              org.apache.lucene.analysis.BaseCharFilter

All Implemented Interfaces:

Closeable, Readable

Direct Known Subclasses:

MappingCharFilter

public abstract class BaseCharFilter
extends CharFilter

Base utility class for implementing a CharFilter. You subclass this, and then record mappings by calling addOffCorrectMap(int, int), and then invoke the correct method to correct an offset.

NOTE: This class is not particularly efficient. For example, a new class instance is created for every call to addOffCorrectMap(int, int), which is then appended to a private list.

Field Summary

Fields inherited from class org.apache.lucene.analysis.CharFilter

input

Fields inherited from class java.io.Reader

lock

Constructor Summary

BaseCharFilter(CharStream in)

Method Summary

protected void	addOffCorrectMap(int off, int cumulativeDiff)
protected int	correct(int currentOff) Retrieve the corrected offset.
protected int	getLastCumulativeDiff()

Methods inherited from class org.apache.lucene.analysis.CharFilter

close, correctOffset, mark, markSupported, read, reset

Methods inherited from class java.io.Reader

read, read, read, ready, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

BaseCharFilter

public BaseCharFilter(CharStream in)

Method Detail

correct

protected int correct(int currentOff)

Retrieve the corrected offset. Note that this method is slow, if you correct positions far before the most recently added position, as it's a simple linear search backwards through all offset corrections added by addOffCorrectMap(int, int).

Overrides:

correct in class CharFilter

Parameters:

currentOff - current offset

Returns:

corrected offset

getLastCumulativeDiff

protected int getLastCumulativeDiff()

addOffCorrectMap

protected void addOffCorrectMap(int off,
                                int cumulativeDiff)