1/*
2 * Copyright (C) 2007 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.collect;
18
19import com.google.common.annotations.GwtCompatible;
20
21import java.io.Serializable;
22import java.util.Comparator;
23import java.util.List;
24
25/** An ordering that tries several comparators in order. */
26@GwtCompatible(serializable = true)
27final class CompoundOrdering<T> extends Ordering<T> implements Serializable {
28  final ImmutableList<Comparator<? super T>> comparators;
29
30  CompoundOrdering(Comparator<? super T> primary,
31      Comparator<? super T> secondary) {
32    this.comparators
33        = ImmutableList.<Comparator<? super T>>of(primary, secondary);
34  }
35
36  CompoundOrdering(Iterable<? extends Comparator<? super T>> comparators) {
37    this.comparators = ImmutableList.copyOf(comparators);
38  }
39
40  CompoundOrdering(List<? extends Comparator<? super T>> comparators,
41      Comparator<? super T> lastComparator) {
42    this.comparators = new ImmutableList.Builder<Comparator<? super T>>()
43        .addAll(comparators).add(lastComparator).build();
44  }
45
46  @Override public int compare(T left, T right) {
47    for (Comparator<? super T> comparator : comparators) {
48      int result = comparator.compare(left, right);
49      if (result != 0) {
50        return result;
51      }
52    }
53    return 0;
54  }
55
56  @Override public boolean equals(Object object) {
57    if (object == this) {
58      return true;
59    }
60    if (object instanceof CompoundOrdering) {
61      CompoundOrdering<?> that = (CompoundOrdering<?>) object;
62      return this.comparators.equals(that.comparators);
63    }
64    return false;
65  }
66
67  @Override public int hashCode() {
68    return comparators.hashCode();
69  }
70
71  @Override public String toString() {
72    return "Ordering.compound(" + comparators + ")";
73  }
74
75  private static final long serialVersionUID = 0;
76}
77