Update #0 - First Release

sources/main/java/com/google/common/collect/ReverseOrdering.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2007 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;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.io.Serializable;
+import java.util.Iterator;
+
+import javax.annotation.Nullable;
+
+import com.google.common.annotations.GwtCompatible;
+
+/** An ordering that uses the reverse of a given order. */
+@GwtCompatible(serializable = true)
+final class ReverseOrdering<T> extends Ordering<T> implements Serializable {
+	final Ordering<? super T> forwardOrder;
+
+	ReverseOrdering(Ordering<? super T> forwardOrder) {
+		this.forwardOrder = checkNotNull(forwardOrder);
+	}
+
+	@Override
+	public int compare(T a, T b) {
+		return forwardOrder.compare(b, a);
+	}
+
+	@SuppressWarnings("unchecked") // how to explain?
+	@Override
+	public <S extends T> Ordering<S> reverse() {
+		return (Ordering<S>) forwardOrder;
+	}
+
+	// Override the min/max methods to "hoist" delegation outside loops
+
+	@Override
+	public <E extends T> E min(E a, E b) {
+		return forwardOrder.max(a, b);
+	}
+
+	@Override
+	public <E extends T> E min(E a, E b, E c, E... rest) {
+		return forwardOrder.max(a, b, c, rest);
+	}
+
+	@Override
+	public <E extends T> E min(Iterator<E> iterator) {
+		return forwardOrder.max(iterator);
+	}
+
+	@Override
+	public <E extends T> E min(Iterable<E> iterable) {
+		return forwardOrder.max(iterable);
+	}
+
+	@Override
+	public <E extends T> E max(E a, E b) {
+		return forwardOrder.min(a, b);
+	}
+
+	@Override
+	public <E extends T> E max(E a, E b, E c, E... rest) {
+		return forwardOrder.min(a, b, c, rest);
+	}
+
+	@Override
+	public <E extends T> E max(Iterator<E> iterator) {
+		return forwardOrder.min(iterator);
+	}
+
+	@Override
+	public <E extends T> E max(Iterable<E> iterable) {
+		return forwardOrder.min(iterable);
+	}
+
+	@Override
+	public int hashCode() {
+		return -forwardOrder.hashCode();
+	}
+
+	@Override
+	public boolean equals(@Nullable Object object) {
+		if (object == this) {
+			return true;
+		}
+		if (object instanceof ReverseOrdering) {
+			ReverseOrdering<?> that = (ReverseOrdering<?>) object;
+			return this.forwardOrder.equals(that.forwardOrder);
+		}
+		return false;
+	}
+
+	@Override
+	public String toString() {
+		return forwardOrder + ".reverse()";
+	}
+
+	private static final long serialVersionUID = 0;
+}