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.
+ CharFilters modify an input stream via a series of substring + replacements (including deletions and insertions) to produce an output + stream. There are three possible replacement cases: the replacement + string has the same length as the original substring; the replacement + is shorter; and the replacement is longer. In the latter two cases + (when the replacement has a different length than the original), + one or more offset correction mappings are required. +
+
+ When the replacement is shorter than the original (e.g. when the
+ replacement is the empty string), a single offset correction mapping
+ should be added at the replacement's end offset in the output stream.
+ The cumulativeDiff parameter to the
+ addOffCorrectMapping() method will be the sum of all
+ previous replacement offset adjustments, with the addition of the
+ difference between the lengths of the original substring and the
+ replacement string (a positive value).
+
+ When the replacement is longer than the original (e.g. when the
+ original is the empty string), you should add as many offset
+ correction mappings as the difference between the lengths of the
+ replacement string and the original substring, starting at the
+ end offset the original substring would have had in the output stream.
+ The cumulativeDiff parameter to the
+ addOffCorrectMapping() method will be the sum of all
+ previous replacement offset adjustments, with the addition of the
+ difference between the lengths of the original substring and the
+ replacement string so far (a negative value).
+
input| Constructor and Description |
|---|
BaseCharFilter(CharStream in) |
| 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() |
close, correctOffset, mark, markSupported, read, resetpublic BaseCharFilter(CharStream in)
protected int correct(int currentOff)
correct in class CharFiltercurrentOff - current offsetprotected int getLastCumulativeDiff()
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.
off - The output stream offset at which to apply the correctioncumulativeDiff - The input offset is given by adding this
to the output offset