// 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. | |
package org.apache.tapestry.internal.util; | |
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<Integer> | |
{ | |
private final int start; | |
private final int finish; | |
private class RangeIterator implements Iterator<Integer> | |
{ | |
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<Integer> 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; | |
} | |
} |