MinimalCollection.java revision 3c77433663281544363151bf284b0240dfd22a42 
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.testing;
18
19import com.google.common.annotations.GwtCompatible;
20
21import java.util.AbstractCollection;
22import java.util.Arrays;
23import java.util.Collection;
24import java.util.Iterator;
25
26/**
27 * A simplistic collection which implements only the bare minimum allowed by the
28 * spec, and throws exceptions whenever it can.
29 *
30 * @author Kevin Bourrillion
31 */
32@GwtCompatible
33public class MinimalCollection<E> extends AbstractCollection<E> {
34  // TODO: expose allow nulls parameter?
35
36  public static <E> MinimalCollection<E> of(E... contents) {
37    return new MinimalCollection<E>(Object.class, true, contents);
38  }
39
40  // TODO: use this
41  public static <E> MinimalCollection<E> ofClassAndContents(
42      Class<? super E> type, E... contents) {
43    return new MinimalCollection<E>(type, true, contents);
44  }
45
46  private final E[] contents;
47  private final Class<? super E> type;
48  private final boolean allowNulls;
49
50  // Package-private so that it can be extended.
51  MinimalCollection(Class<? super E> type, boolean allowNulls, E... contents) {
52    // TODO: consider making it shuffle the contents to test iteration order.
53    this.contents = Platform.clone(contents);
54    this.type = type;
55    this.allowNulls = allowNulls;
56
57    if (!allowNulls) {
58      for (Object element : contents) {
59        if (element == null) {
60          throw new NullPointerException();
61        }
62      }
63    }
64  }
65
66  @Override public int size() {
67    return contents.length;
68  }
69
70  @Override public boolean contains(Object object) {
71    if (!allowNulls) {
72      // behave badly
73      if (object == null) {
74        throw new NullPointerException();
75      }
76    }
77    Platform.checkCast(type, object);  // behave badly
78    return Arrays.asList(contents).contains(object);
79  }
80
81  @Override public boolean containsAll(Collection<?> collection) {
82    if (!allowNulls) {
83      for (Object object : collection) {
84        // behave badly
85        if (object == null) {
86          throw new NullPointerException();
87        }
88      }
89    }
90    return super.containsAll(collection);
91  }
92
93  @Override public Iterator<E> iterator() {
94    return Arrays.asList(contents).iterator();
95  }
96
97  @Override public Object[] toArray() {
98    Object[] result = new Object[contents.length];
99    System.arraycopy(contents, 0, result, 0, contents.length);
100    return result;
101  }
102
103  /*
104   * a "type A" unmodifiable collection freaks out proactively, even if there
105   * wasn't going to be any actual work to do anyway
106   */
107
108  @Override public boolean addAll(Collection<? extends E> elementsToAdd) {
109    throw up();
110  }
111  @Override public boolean removeAll(Collection<?> elementsToRemove) {
112    throw up();
113  }
114  @Override public boolean retainAll(Collection<?> elementsToRetain) {
115    throw up();
116  }
117  @Override public void clear() {
118    throw up();
119  }
120  private static UnsupportedOperationException up() {
121    throw new UnsupportedOperationException();
122  }
123}
124