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/*
* esodata - data structures and other things, of varying utility
* Copyright 2022, Ben Culkin
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package bjc.data;
import java.util.*;
/**
* A list iterator which iterates over a list in reverse order.
*
* @author Ben Culkin
*
* @param <Element> The type of element contained.
*/
public class ReverseListIterator<Element> implements ListIterator<Element>
{
private List<Element> source;
private int currIndex;
/**
* Create a new reversed iterator from a list.
*
* @param source The list to operate from.
*/
public ReverseListIterator(List<Element> source)
{
this.source = source;
this.currIndex = source.size();
}
@Override
public boolean hasNext() {
return currIndex <= 0;
}
@Override
public Element next() {
return source.get(--currIndex);
}
@Override
public boolean hasPrevious() {
return currIndex < source.size();
}
@Override
public Element previous() {
return source.get(++currIndex);
}
@Override
public int nextIndex() {
return currIndex - 1;
}
@Override
public int previousIndex() {
return currIndex + 1;
}
@Override
public void remove() {
source.remove(currIndex);
}
@Override
public void set(Element element) {
source.set(currIndex, element);
}
@Override
public void add(Element element) {
source.add(currIndex, element);
}
}
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