/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.analysis;
import java.util.ArrayList;
import java.util.List;
/**
* Base utility class for implementing a {@link CharFilter}.
* You subclass this, and then record mappings by calling
* {@link #addOffCorrectMap}, and then invoke the correct
* method to correct an offset.
*
* <p><b>NOTE</b>: This class is not particularly efficient.
* For example, a new class instance is created for every
* call to {@link #addOffCorrectMap}, which is then appended
* to a private list.
*/
public abstract class BaseCharFilter extends CharFilter {
private List<OffCorrectMap> pcmList;
public BaseCharFilter(CharStream in) {
super(in);
}
/** 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 {@link #addOffCorrectMap}. */
@Override
protected int correct(int currentOff) {
if (pcmList == null || pcmList.isEmpty()) {
return currentOff;
}
for (int i = pcmList.size() - 1; i >= 0; i--) {
if (currentOff >= pcmList.get(i).off) {
return currentOff + pcmList.get(i).cumulativeDiff;
}
}
return currentOff;
}
protected int getLastCumulativeDiff() {
return pcmList == null || pcmList.isEmpty() ?
0 : pcmList.get(pcmList.size() - 1).cumulativeDiff;
}
protected void addOffCorrectMap(int off, int cumulativeDiff) {
if (pcmList == null) {
pcmList = new ArrayList<OffCorrectMap>();
}
pcmList.add(new OffCorrectMap(off, cumulativeDiff));
}
static class OffCorrectMap {
int off;
int cumulativeDiff;
OffCorrectMap(int off, int cumulativeDiff) {
this.off = off;
this.cumulativeDiff = cumulativeDiff;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append('(');
sb.append(off);
sb.append(',');
sb.append(cumulativeDiff);
sb.append(')');
return sb.toString();
}
}
}
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