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; 23 24/** An ordering that tries several comparators in order. */ 25@GwtCompatible(serializable = true) 26final class CompoundOrdering<T> extends Ordering<T> implements Serializable { 27 final ImmutableList<Comparator<? super T>> comparators; 28 29 CompoundOrdering(Comparator<? super T> primary, 30 Comparator<? super T> secondary) { 31 this.comparators 32 = ImmutableList.<Comparator<? super T>>of(primary, secondary); 33 } 34 35 CompoundOrdering(Iterable<? extends Comparator<? super T>> comparators) { 36 this.comparators = ImmutableList.copyOf(comparators); 37 } 38 39 @Override public int compare(T left, T right) { 40 // Avoid using the Iterator to avoid generating garbage (issue 979). 41 int size = comparators.size(); 42 for (int i = 0; i < size; i++) { 43 int result = comparators.get(i).compare(left, right); 44 if (result != 0) { 45 return result; 46 } 47 } 48 return 0; 49 } 50 51 @Override public boolean equals(Object object) { 52 if (object == this) { 53 return true; 54 } 55 if (object instanceof CompoundOrdering) { 56 CompoundOrdering<?> that = (CompoundOrdering<?>) object; 57 return this.comparators.equals(that.comparators); 58 } 59 return false; 60 } 61 62 @Override public int hashCode() { 63 return comparators.hashCode(); 64 } 65 66 @Override public String toString() { 67 return "Ordering.compound(" + comparators + ")"; 68 } 69 70 private static final long serialVersionUID = 0; 71} 72