1 files changed, 100 insertions, 0 deletions
diff --git a/guava/src/com/google/common/collect/ReverseOrdering.java b/guava/src/com/google/common/collect/ReverseOrdering.java
new file mode 100644
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+++ b/guava/src/com/google/common/collect/ReverseOrdering.java
@@ -0,0 +1,100 @@
+/*
+ * 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 com.google.common.annotations.GwtCompatible;
+
+import java.io.Serializable;
+import java.util.Iterator;
+
+import javax.annotation.Nullable;
+
+/** 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;
+}