// Copyright 2006 The Apache Software Foundation
//
// Licensed 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.
import java.util.Iterator;
/**
* Represents a sequence of integer values, either ascending or descending. The sequence is always inclusive (of the
* finish value).
*/
public final class IntegerRange implements Iterable
{
private final int start;
private final int finish;
private class RangeIterator implements Iterator
{
private final int increment;
private int value = start;
private boolean hasNext = true;
RangeIterator()
{
increment = start < finish ? +1 : -1;
}
public boolean hasNext()
{
return hasNext;
}
public Integer next()
{
if (!hasNext) throw new IllegalStateException();
int result = value;
hasNext = value != finish;
value += increment;
return result;
}
public void remove()
{
throw new UnsupportedOperationException();
}
}
public IntegerRange(final int start, final int finish)
{
this.start = start;
this.finish = finish;
}
public int getFinish()
{
return finish;
}
public int getStart()
{
return start;
}
@Override
public String toString()
{
return String.format("%d..%d", start, finish);
}
/**
* The main puprose of a range object is to produce an Iterator. Since IntegerRange is iterable, it is useful with
* the Tapestry Loop component, but also with the Java for loop!
*/
public Iterator iterator()
{
return new RangeIterator();
}
@Override
public int hashCode()
{
final int PRIME = 31;
int result = PRIME + finish;
result = PRIME * result + start;
return result;
}
/**
* Returns true if the other object is an IntegerRange with the same start and finish values.
*/
@Override
public boolean equals(Object obj)
{
if (this == obj) return true;
if (obj == null) return false;
if (getClass() != obj.getClass()) return false;
final IntegerRange other = (IntegerRange) obj;
if (finish != other.finish) return false;
return start == other.start;
}
}