Package org.apache.lucene.analysis.charfilter

# Class BaseCharFilter

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

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`, `Readable`

Direct Known Subclasses:
  `CJKWidthCharFilter`, `HTMLStripCharFilter`, `MappingCharFilter`, `PatternReplaceCharFilter`

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.

## Field Summary

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

`input`

### Fields inherited from class java.io.Reader

`lock`

## Constructor Summary

Constructors
Constructor
Description
`BaseCharFilter(Reader in)`

## Method Summary

Modifier and Type
Method
Description
`protected void`
`addOffCorrectMap(int off, int cumulativeDiff)`
Adds an offset correction mapping at the given output stream offset.
`protected int`
`correct(int currentOff)`
Retrieve the corrected offset.
`protected int`
`getLastCumulativeDiff()`

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

`close, correctOffset`

### 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`

## Constructor Details

### BaseCharFilter

public BaseCharFilter(Reader in)

## Method Details

### correct

protected int correct(int currentOff)
Retrieve the corrected offset.

Specified by:
  `correct` in class `CharFilter`

### getLastCumulativeDiff

protected int getLastCumulativeDiff()

### addOffCorrectMap

protected void addOffCorrectMap(int off, int cumulativeDiff)
Adds an offset correction mapping at the given output stream offset.

Assumption: the offset given with each successive call to this method will not be smaller than the offset given at the previous invocation.

Parameters:
  `off` - The output stream offset at which to apply the correction
  `cumulativeDiff` - The input offset is given by adding this to the output offset