/*
* 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;
}
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