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      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 
     17 package com.google.common.collect;
     18 
     19 import com.google.common.annotations.GwtCompatible;
     20 
     21 import java.io.Serializable;
     22 import java.util.Comparator;
     23 
     24 /** An ordering that tries several comparators in order. */
     25 @GwtCompatible(serializable = true)
     26 final 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