QuestionRegexpComparator.java
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* Copyright (C) 2000 - 2024 Silverpeas
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* As a special exception to the terms and conditions of version 3.0 of
* the GPL, you may redistribute this Program in connection with Free/Libre
* Open Source Software ("FLOSS") applications as described in Silverpeas's
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*
* This program is distributed in the hope that it will be useful,
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
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package org.silverpeas.components.questionreply.service;
import org.silverpeas.components.questionreply.model.Question;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* @author ehugonnet
*/
public class QuestionRegexpComparator implements Comparator<Question> {
private static QuestionRegexpComparator instance;
private Pattern pattern = Pattern.compile("([0-9\\.]*)\\s?-\\s?.*");
private Pattern numberPattern = Pattern.compile("[0-9]+");
private QuestionRegexpComparator() {
}
public static QuestionRegexpComparator getInstance() {
synchronized (QuestionRegexpComparator.class) {
if (instance == null) {
instance = new QuestionRegexpComparator();
}
return instance;
}
}
@Override
public int compare(Question question1, Question question2) {
int result = -1;
if (question1 == question2) {
result = 0;
} else {
if (question1 == null || question1.getTitle() == null) {
result = -1;
} else if (question2 == null || question2.getTitle() == null) {
result = 1;
} else {
List<Integer> numbersQuestion1 = extractNumber(question1.getTitle());
List<Integer> numbersQuestion2 = extractNumber(question2.getTitle());
if (numbersQuestion1.isEmpty() || numbersQuestion2.isEmpty()) {
result = question1.getTitle().compareTo(question2.getTitle());
} else {
if (numbersQuestion1.size() > numbersQuestion2.size()) {
result = compareNumbers(numbersQuestion1, numbersQuestion2);
} else {
result = -1 * compareNumbers(numbersQuestion2, numbersQuestion1);
}
}
}
}
return result;
}
protected List<Integer> extractNumber(final String label) {
Matcher matcher = pattern.matcher(label);
List<Integer> result = new ArrayList<>();
String prefix = null;
if (matcher.matches()) {
prefix = matcher.group(1);
}
if (prefix != null) {
matcher = numberPattern.matcher(prefix);
while (matcher.find()) {
String number = prefix.substring(matcher.start(), matcher.end());
result.add(Integer.valueOf(number));
}
}
return result;
}
protected int compareNumbers(List<Integer> bigList, List<Integer> smallList) {
for (int i = 0; i < smallList.size(); i++) {
int value1 = bigList.get(i);
int value2 = smallList.get(i);
if (value1 != value2) {
return value1 - value2;
}
}
return bigList.size() - smallList.size();
}
}