| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.openjpa.meta; |
| |
| import java.io.Serializable; |
| import java.util.Comparator; |
| |
| /** |
| * Comparator that keeps classes in inheritance order. |
| * |
| * @author Abe White |
| */ |
| public class InheritanceComparator |
| implements Comparator, Serializable { |
| |
| |
| private static final long serialVersionUID = 1L; |
| private Class _base = Object.class; |
| |
| /** |
| * Set the least-derived type possible; defaults to <code>null</code>. |
| */ |
| public void setBase(Class base) { |
| _base = base; |
| } |
| |
| public Class getBase() { |
| return _base; |
| } |
| |
| /** |
| * Subclasses can override this method to extract the class to compare |
| * on from the elements of the collection. |
| */ |
| protected Class toClass(Object elem) { |
| return (Class) elem; |
| } |
| |
| @Override |
| public int compare(Object o1, Object o2) { |
| if (o1 == o2) |
| return 0; |
| if (o1 == null) |
| return -1; |
| if (o2 == null) |
| return 1; |
| |
| Class c1 = toClass(o1); |
| Class c2 = toClass(o2); |
| if (c1 == c2) |
| return 0; |
| if (c1 == null) |
| return -1; |
| if (c2 == null) |
| return 1; |
| |
| int i1 = levels(c1); |
| int i2 = levels(c2); |
| if (i1 == i2) { |
| // sort simple interfaces as well as simple order test will fail. |
| if (c1.isAssignableFrom(c2)) |
| return -1; |
| if (c2.isAssignableFrom(c1)) |
| return 1; |
| return c1.getName().compareTo(c2.getName()); |
| } |
| if (i1 < i2) |
| return -1; |
| else if (i1 > i2) |
| return 1; |
| else |
| return 0; |
| } |
| |
| /** |
| * Count the levels of inheritance between this class and our base class. |
| */ |
| private int levels(Class to) { |
| if (to.isInterface()) |
| return to.getInterfaces().length; |
| for (int i = 0; to != null; i++, to = to.getSuperclass()) |
| if (to == _base) |
| return i; |
| return Integer.MAX_VALUE; |
| } |
| } |