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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.testing;
     18 
     19 import java.util.AbstractCollection;
     20 import java.util.Arrays;
     21 import java.util.Collection;
     22 import java.util.Iterator;
     23 
     24 /**
     25  * A simplistic collection which implements only the bare minimum allowed by the
     26  * spec, and throws exceptions whenever it can.
     27  *
     28  * @author Kevin Bourrillion
     29  */
     30 public class MinimalCollection<E> extends AbstractCollection<E> {
     31   // TODO: expose allow nulls parameter?
     32 
     33   public static <E> MinimalCollection<E> of(E... contents) {
     34     return new MinimalCollection<E>(Object.class, true, contents);
     35   }
     36 
     37   // TODO: use this
     38   public static <E> MinimalCollection<E> ofClassAndContents(
     39       Class<? super E> type, E... contents) {
     40     return new MinimalCollection<E>(type, true, contents);
     41   }
     42 
     43   private final E[] contents;
     44   private final Class<? super E> type;
     45   private final boolean allowNulls;
     46 
     47   // Package-private so that it can be extended.
     48   MinimalCollection(Class<? super E> type, boolean allowNulls, E... contents) {
     49     // TODO: consider making it shuffle the contents to test iteration order.
     50     this.contents = Platform.clone(contents);
     51     this.type = type;
     52     this.allowNulls = allowNulls;
     53 
     54     if (!allowNulls) {
     55       for (Object element : contents) {
     56         if (element == null) {
     57           throw new NullPointerException();
     58         }
     59       }
     60     }
     61   }
     62 
     63   @Override public int size() {
     64     return contents.length;
     65   }
     66 
     67   @Override public boolean contains(Object object) {
     68     if (!allowNulls) {
     69       // behave badly
     70       if (object == null) {
     71         throw new NullPointerException();
     72       }
     73     }
     74     Platform.checkCast(type, object);  // behave badly
     75     return Arrays.asList(contents).contains(object);
     76   }
     77 
     78   @Override public boolean containsAll(Collection<?> collection) {
     79     if (!allowNulls) {
     80       for (Object object : collection) {
     81         // behave badly
     82         if (object == null) {
     83           throw new NullPointerException();
     84         }
     85       }
     86     }
     87     return super.containsAll(collection);
     88   }
     89 
     90   @Override public Iterator<E> iterator() {
     91     return Arrays.asList(contents).iterator();
     92   }
     93 
     94   @Override public Object[] toArray() {
     95     Object[] result = new Object[contents.length];
     96     Platform.unsafeArrayCopy(contents, 0, result, 0, contents.length);
     97     return result;
     98   }
     99 
    100   /*
    101    * a "type A" unmodifiable collection freaks out proactively, even if there
    102    * wasn't going to be any actual work to do anyway
    103    */
    104 
    105   @Override public boolean addAll(Collection<? extends E> elementsToAdd) {
    106     throw up();
    107   }
    108   @Override public boolean removeAll(Collection<?> elementsToRemove) {
    109     throw up();
    110   }
    111   @Override public boolean retainAll(Collection<?> elementsToRetain) {
    112     throw up();
    113   }
    114   @Override public void clear() {
    115     throw up();
    116   }
    117   private static UnsupportedOperationException up() {
    118     throw new UnsupportedOperationException();
    119   }
    120 }
    121