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      1 /*
      2  * Copyright (C) 2007 Google Inc.
      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 import java.util.List;
     24 
     25 /** An ordering that tries several comparators in order. */
     26 @GwtCompatible(serializable = true)
     27 final 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   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