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-rw-r--r--guava/src/com/google/common/collect/LexicographicalOrdering.java78
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diff --git a/guava/src/com/google/common/collect/LexicographicalOrdering.java b/guava/src/com/google/common/collect/LexicographicalOrdering.java
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+/*
+ * 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 com.google.common.annotations.GwtCompatible;
+
+import java.io.Serializable;
+import java.util.Iterator;
+
+import javax.annotation.Nullable;
+
+/**
+ * An ordering which sorts iterables by comparing corresponding elements
+ * pairwise.
+ */
+@GwtCompatible(serializable = true)
+final class LexicographicalOrdering<T>
+ extends Ordering<Iterable<T>> implements Serializable {
+ final Ordering<? super T> elementOrder;
+
+ LexicographicalOrdering(Ordering<? super T> elementOrder) {
+ this.elementOrder = elementOrder;
+ }
+
+ @Override public int compare(
+ Iterable<T> leftIterable, Iterable<T> rightIterable) {
+ Iterator<T> left = leftIterable.iterator();
+ Iterator<T> right = rightIterable.iterator();
+ while (left.hasNext()) {
+ if (!right.hasNext()) {
+ return LEFT_IS_GREATER; // because it's longer
+ }
+ int result = elementOrder.compare(left.next(), right.next());
+ if (result != 0) {
+ return result;
+ }
+ }
+ if (right.hasNext()) {
+ return RIGHT_IS_GREATER; // because it's longer
+ }
+ return 0;
+ }
+
+ @Override public boolean equals(@Nullable Object object) {
+ if (object == this) {
+ return true;
+ }
+ if (object instanceof LexicographicalOrdering) {
+ LexicographicalOrdering<?> that = (LexicographicalOrdering<?>) object;
+ return this.elementOrder.equals(that.elementOrder);
+ }
+ return false;
+ }
+
+ @Override public int hashCode() {
+ return elementOrder.hashCode() ^ 2075626741; // meaningless
+ }
+
+ @Override public String toString() {
+ return elementOrder + ".lexicographical()";
+ }
+
+ private static final long serialVersionUID = 0;
+}