/*
* This file is part of LibrePlan
*
* Copyright (C) 2009-2010 Fundación para o Fomento da Calidade Industrial e
* Desenvolvemento Tecnolóxico de Galicia
* Copyright (C) 2010-2011 Igalia, S.L.
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* 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 <http://www.gnu.org/licenses/>.
*/
package org.libreplan.web.limitingresources;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import org.apache.commons.collections.comparators.BooleanComparator;
import org.libreplan.business.planner.limiting.entities.Gap.GapOnQueue;
/**
* Utility class for doing a merge sort of several ordered list of Gaps <br />
* @author Óscar González Fernández <ogonzalez@igalia.com>
*/
public class GapsMergeSort {
private GapsMergeSort() {
}
/**
* Note: this class has a natural ordering that is inconsistent with equals.
*
*/
private static class CurrentGap implements Comparable<CurrentGap> {
static List<CurrentGap> convert(
Collection<? extends Iterator<GapOnQueue>> iterators) {
List<CurrentGap> result = new ArrayList<CurrentGap>();
for (Iterator<GapOnQueue> iterator : iterators) {
result.add(new CurrentGap(iterator));
}
return result;
}
private Iterator<GapOnQueue> iterator;
private GapOnQueue current;
private CurrentGap(Iterator<GapOnQueue> iterator) {
this.iterator = iterator;
}
public GapOnQueue consume() {
GapOnQueue result = getCurrent();
current = null;
return result;
}
boolean hasFinished() {
return current == null && !iterator.hasNext();
}
private GapOnQueue getCurrent() {
if (hasFinished()) {
throw new IllegalStateException("already finished");
}
if (current != null) {
return current;
}
return current = iterator.next();
}
/**
* Ordering by hasFinished and the gap. An already finished is
* considered bigger than a not finished
*/
@Override
public int compareTo(CurrentGap other) {
int finishComparison = BooleanComparator.getFalseFirstComparator()
.compare(hasFinished(), other.hasFinished());
if (finishComparison != 0) {
return finishComparison;
} else if (hasFinished()) {
assert other.hasFinished();
return 0;
} else {
assert !hasFinished() && !other.hasFinished();
return getCurrent().getGap().compareTo(
other.getCurrent().getGap());
}
}
}
public static List<GapOnQueue> sort(
List<List<GapOnQueue>> orderedListsOfGaps) {
List<GapOnQueue> result = new ArrayList<GapOnQueue>();
if (orderedListsOfGaps.isEmpty()) {
return result;
}
if (orderedListsOfGaps.size() == 1) {
return orderedListsOfGaps.get(0);
}
List<CurrentGap> currentGaps = CurrentGap.convert(iteratorsFor(orderedListsOfGaps));
CurrentGap min = Collections.min(currentGaps);
while (!currentGaps.isEmpty() && !min.hasFinished()) {
result.add(min.consume());
if (min.hasFinished()) {
currentGaps.remove(min);
if (!currentGaps.isEmpty()) {
min = Collections.min(currentGaps);
}
}
}
return result;
}
private static List<Iterator<GapOnQueue>> iteratorsFor(
List<List<GapOnQueue>> orderedListsOfGaps) {
List<Iterator<GapOnQueue>> result = new ArrayList<Iterator<GapOnQueue>>();
for (List<GapOnQueue> each : orderedListsOfGaps) {
result.add(each.iterator());
}
return result;
}
}