org.snapscript.tree.collection.Sequence Maven / Gradle / Ivy
package org.snapscript.tree.collection;
import java.util.Iterator;
public class Sequence implements Iterable {
private final long first;
private final long last;
public Sequence(long first, long last) {
this.first = first;
this.last = last;
}
@Override
public Iterator iterator() {
if(first > last) {
return new ReverseIterator(first, last);
}
return new ForwardIterator(first, last);
}
private static class ForwardIterator implements Iterator {
private long first;
private long last;
public ForwardIterator(Long first, Long last) {
this.first = first;
this.last = last;
}
@Override
public boolean hasNext() {
return first <= last;
}
@Override
public Number next() {
if(first <= last) {
return first++;
}
return null;
}
@Override
public void remove() {
throw new UnsupportedOperationException("Illegal modification of range");
}
}
private static class ReverseIterator implements Iterator {
private long first;
private long last;
public ReverseIterator(long first, long last) {
this.first = first;
this.last = last;
}
@Override
public boolean hasNext() {
return first >= last;
}
@Override
public Number next() {
if(first >= last) {
return first--;
}
return null;
}
@Override
public void remove() {
throw new UnsupportedOperationException("Illegal modification of range");
}
}
}