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 and Description
    `BaseCharFilter(Reader in)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and 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, read, read, read, read, ready, reset, skip`

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### BaseCharFilter

          public BaseCharFilter(Reader in)

  - ### Method Detail

    - #### 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

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