Coverage Summary for Class: SortedIterables (com.google.common.collect)

1 /*
2  * Copyright (C) 2011 The Guava Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5  * in compliance with the License. You may obtain a copy of the License at
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software distributed under the
10  * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
11  * express or implied. See the License for the specific language governing permissions and
12  * limitations under the License.
13  */
14 
15 package com.google.common.collect;
16 
17 import static com.google.common.base.Preconditions.checkNotNull;
18 
19 import com.google.common.annotations.GwtCompatible;
20 import java.util.Comparator;
21 import java.util.SortedSet;
22 
23 /**
24  * Utilities for dealing with sorted collections of all types.
25  *
26  * @author Louis Wasserman
27  */
28 @GwtCompatible
29 final class SortedIterables {
30   private SortedIterables() {}
31 
32   /**
33    * Returns {@code true} if {@code elements} is a sorted collection using an ordering equivalent to
34    * {@code comparator}.
35    */
36   public static boolean hasSameComparator(Comparator<?> comparator, Iterable<?> elements) {
37     checkNotNull(comparator);
38     checkNotNull(elements);
39     Comparator<?> comparator2;
40     if (elements instanceof SortedSet) {
41       comparator2 = comparator((SortedSet<?>) elements);
42     } else if (elements instanceof SortedIterable) {
43       comparator2 = ((SortedIterable<?>) elements).comparator();
44     } else {
45       return false;
46     }
47     return comparator.equals(comparator2);
48   }
49 
50   @SuppressWarnings("unchecked")
51   // if sortedSet.comparator() is null, the set must be naturally ordered
52   public static <E> Comparator<? super E> comparator(SortedSet<E> sortedSet) {
53     Comparator<? super E> result = sortedSet.comparator();
54     if (result == null) {
55       result = (Comparator<? super E>) Ordering.natural();
56     }
57     return result;
58   }
59 }