/*
* Copyright (C) 2010 The Guava Authors
*
* 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 com.google.common.collect.testing;
import java.io.Serializable;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.SortedSet;
import java.util.TreeSet;
/**
* A wrapper around {@code TreeSet} that aggressively checks to see if elements
* are mutually comparable. This implementation passes the navigable set test
* suites.
*
* @author Louis Wasserman
*/
public final class SafeTreeSet<E> implements Serializable, SortedSet<E> {
@SuppressWarnings("unchecked")
private static final Comparator<Object> NATURAL_ORDER = new Comparator<Object>() {
@Override public int compare(Object o1, Object o2) {
return ((Comparable<Object>) o1).compareTo(o2);
}
};
private final SortedSet<E> delegate;
public SafeTreeSet() {
this(new TreeSet<E>());
}
public SafeTreeSet(Collection<? extends E> collection) {
this(new TreeSet<E>(collection));
}
public SafeTreeSet(Comparator<? super E> comparator) {
this(new TreeSet<E>(comparator));
}
private SafeTreeSet(SortedSet<E> delegate) {
this.delegate = delegate;
for (E e : this) {
checkValid(e);
}
}
@Override public boolean add(E element) {
return delegate.add(checkValid(element));
}
@Override public boolean addAll(Collection<? extends E> collection) {
for (E e : collection) {
checkValid(e);
}
return delegate.addAll(collection);
}
@Override public void clear() {
delegate.clear();
}
@SuppressWarnings("unchecked")
@Override public Comparator<? super E> comparator() {
Comparator<? super E> comparator = delegate.comparator();
if (comparator == null) {
comparator = (Comparator<? super E>) NATURAL_ORDER;
}
return comparator;
}
@Override public boolean contains(Object object) {
return delegate.contains(checkValid(object));
}
@Override public boolean containsAll(Collection<?> c) {
return delegate.containsAll(c);
}
@Override public E first() {
return delegate.first();
}
@Override public SortedSet<E> headSet(E toElement) {
return new SafeTreeSet<E>(delegate.headSet(checkValid(toElement)));
}
@Override public boolean isEmpty() {
return delegate.isEmpty();
}
@Override public Iterator<E> iterator() {
return delegate.iterator();
}
@Override public E last() {
return delegate.last();
}
@Override public boolean remove(Object object) {
return delegate.remove(checkValid(object));
}
@Override public boolean removeAll(Collection<?> c) {
return delegate.removeAll(c);
}
@Override public boolean retainAll(Collection<?> c) {
return delegate.retainAll(c);
}
@Override public int size() {
return delegate.size();
}
@Override public SortedSet<E> subSet(E fromElement, E toElement) {
return new SafeTreeSet<E>(delegate.subSet(checkValid(fromElement), checkValid(toElement)));
}
@Override public SortedSet<E> tailSet(E fromElement) {
return new SafeTreeSet<E>(delegate.tailSet(checkValid(fromElement)));
}
@Override public Object[] toArray() {
return delegate.toArray();
}
@Override public <T> T[] toArray(T[] a) {
return delegate.toArray(a);
}
private <T> T checkValid(T t) {
// a ClassCastException is what's supposed to happen!
@SuppressWarnings("unchecked")
E e = (E) t;
comparator().compare(e, e);
return t;
}
@Override public boolean equals(Object obj) {
return delegate.equals(obj);
}
@Override public int hashCode() {
return delegate.hashCode();
}
@Override public String toString() {
return delegate.toString();
}
private static final long serialVersionUID = 0L;
}