1 /*
2 * Copyright (c) 2003, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.util;
27
28 import jdk.internal.misc.SharedSecrets;
29
30 /**
31 * A specialized {@link Set} implementation for use with enum types. All of
32 * the elements in an enum set must come from a single enum type that is
33 * specified, explicitly or implicitly, when the set is created. Enum sets
34 * are represented internally as bit vectors. This representation is
35 * extremely compact and efficient. The space and time performance of this
36 * class should be good enough to allow its use as a high-quality, typesafe
37 * alternative to traditional {@code int}-based "bit flags." Even bulk
38 * operations (such as {@code containsAll} and {@code retainAll}) should
39 * run very quickly if their argument is also an enum set.
40 *
41 * <p>The iterator returned by the {@code iterator} method traverses the
42 * elements in their <i>natural order</i> (the order in which the enum
43 * constants are declared). The returned iterator is <i>weakly
44 * consistent</i>: it will never throw {@link ConcurrentModificationException}
45 * and it may or may not show the effects of any modifications to the set that
46 * occur while the iteration is in progress.
47 *
48 * <p>Null elements are not permitted. Attempts to insert a null element
49 * will throw {@link NullPointerException}. Attempts to test for the
50 * presence of a null element or to remove one will, however, function
51 * properly.
52 *
53 * <P>Like most collection implementations, {@code EnumSet} is not
54 * synchronized. If multiple threads access an enum set concurrently, and at
55 * least one of the threads modifies the set, it should be synchronized
56 * externally. This is typically accomplished by synchronizing on some
57 * object that naturally encapsulates the enum set. If no such object exists,
58 * the set should be "wrapped" using the {@link Collections#synchronizedSet}
59 * method. This is best done at creation time, to prevent accidental
60 * unsynchronized access:
61 *
62 * <pre>
63 * Set<MyEnum> s = Collections.synchronizedSet(EnumSet.noneOf(MyEnum.class));
64 * </pre>
65 *
66 * <p>Implementation note: All basic operations execute in constant time.
67 * They are likely (though not guaranteed) to be much faster than their
68 * {@link HashSet} counterparts. Even bulk operations execute in
69 * constant time if their argument is also an enum set.
70 *
71 * <p>This class is a member of the
72 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
73 * Java Collections Framework</a>.
74 *
75 * @author Josh Bloch
76 * @since 1.5
77 * @see EnumMap
78 * @serial exclude
79 */
80 @SuppressWarnings("serial") // No serialVersionUID due to usage of
81 // serial proxy pattern
82 public abstract class EnumSet<E extends Enum<E>> extends AbstractSet<E>
83 implements Cloneable, java.io.Serializable
84 {
85 /**
86 * The class of all the elements of this set.
87 */
88 final Class<E> elementType;
89
90 /**
91 * All of the values comprising T. (Cached for performance.)
92 */
93 final Enum<?>[] universe;
94
95 private static Enum<?>[] ZERO_LENGTH_ENUM_ARRAY = new Enum<?>[0];
96
97 EnumSet(Class<E>elementType, Enum<?>[] universe) {
98 this.elementType = elementType;
99 this.universe = universe;
100 }
101
102 /**
103 * Creates an empty enum set with the specified element type.
104 *
105 * @param <E> The class of the elements in the set
106 * @param elementType the class object of the element type for this enum
107 * set
108 * @return An empty enum set of the specified type.
109 * @throws NullPointerException if {@code elementType} is null
110 */
111 public static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> elementType) {
112 Enum<?>[] universe = getUniverse(elementType);
113 if (universe == null)
114 throw new ClassCastException(elementType + " not an enum");
115
116 if (universe.length <= 64)
117 return new RegularEnumSet<>(elementType, universe);
118 else
119 return new JumboEnumSet<>(elementType, universe);
120 }
121
122 /**
123 * Creates an enum set containing all of the elements in the specified
124 * element type.
125 *
126 * @param <E> The class of the elements in the set
127 * @param elementType the class object of the element type for this enum
128 * set
129 * @return An enum set containing all the elements in the specified type.
130 * @throws NullPointerException if {@code elementType} is null
131 */
132 public static <E extends Enum<E>> EnumSet<E> allOf(Class<E> elementType) {
133 EnumSet<E> result = noneOf(elementType);
134 result.addAll();
135 return result;
136 }
137
138 /**
139 * Adds all of the elements from the appropriate enum type to this enum
140 * set, which is empty prior to the call.
141 */
142 abstract void addAll();
143
144 /**
145 * Creates an enum set with the same element type as the specified enum
146 * set, initially containing the same elements (if any).
147 *
148 * @param <E> The class of the elements in the set
149 * @param s the enum set from which to initialize this enum set
150 * @return A copy of the specified enum set.
151 * @throws NullPointerException if {@code s} is null
152 */
153 public static <E extends Enum<E>> EnumSet<E> copyOf(EnumSet<E> s) {
154 return s.clone();
155 }
156
157 /**
158 * Creates an enum set initialized from the specified collection. If
159 * the specified collection is an {@code EnumSet} instance, this static
160 * factory method behaves identically to {@link #copyOf(EnumSet)}.
161 * Otherwise, the specified collection must contain at least one element
162 * (in order to determine the new enum set's element type).
163 *
164 * @param <E> The class of the elements in the collection
165 * @param c the collection from which to initialize this enum set
166 * @return An enum set initialized from the given collection.
167 * @throws IllegalArgumentException if {@code c} is not an
168 * {@code EnumSet} instance and contains no elements
169 * @throws NullPointerException if {@code c} is null
170 */
171 public static <E extends Enum<E>> EnumSet<E> copyOf(Collection<E> c) {
172 if (c instanceof EnumSet) {
173 return ((EnumSet<E>)c).clone();
174 } else {
175 if (c.isEmpty())
176 throw new IllegalArgumentException("Collection is empty");
177 Iterator<E> i = c.iterator();
178 E first = i.next();
179 EnumSet<E> result = EnumSet.of(first);
180 while (i.hasNext())
181 result.add(i.next());
182 return result;
183 }
184 }
185
186 /**
187 * Creates an enum set with the same element type as the specified enum
188 * set, initially containing all the elements of this type that are
189 * <i>not</i> contained in the specified set.
190 *
191 * @param <E> The class of the elements in the enum set
192 * @param s the enum set from whose complement to initialize this enum set
193 * @return The complement of the specified set in this set
194 * @throws NullPointerException if {@code s} is null
195 */
196 public static <E extends Enum<E>> EnumSet<E> complementOf(EnumSet<E> s) {
197 EnumSet<E> result = copyOf(s);
198 result.complement();
199 return result;
200 }
201
202 /**
203 * Creates an enum set initially containing the specified element.
204 *
205 * Overloadings of this method exist to initialize an enum set with
206 * one through five elements. A sixth overloading is provided that
207 * uses the varargs feature. This overloading may be used to create
208 * an enum set initially containing an arbitrary number of elements, but
209 * is likely to run slower than the overloadings that do not use varargs.
210 *
211 * @param <E> The class of the specified element and of the set
212 * @param e the element that this set is to contain initially
213 * @throws NullPointerException if {@code e} is null
214 * @return an enum set initially containing the specified element
215 */
216 public static <E extends Enum<E>> EnumSet<E> of(E e) {
217 EnumSet<E> result = noneOf(e.getDeclaringClass());
218 result.add(e);
219 return result;
220 }
221
222 /**
223 * Creates an enum set initially containing the specified elements.
224 *
225 * Overloadings of this method exist to initialize an enum set with
226 * one through five elements. A sixth overloading is provided that
227 * uses the varargs feature. This overloading may be used to create
228 * an enum set initially containing an arbitrary number of elements, but
229 * is likely to run slower than the overloadings that do not use varargs.
230 *
231 * @param <E> The class of the parameter elements and of the set
232 * @param e1 an element that this set is to contain initially
233 * @param e2 another element that this set is to contain initially
234 * @throws NullPointerException if any parameters are null
235 * @return an enum set initially containing the specified elements
236 */
237 public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2) {
238 EnumSet<E> result = noneOf(e1.getDeclaringClass());
239 result.add(e1);
240 result.add(e2);
241 return result;
242 }
243
244 /**
245 * Creates an enum set initially containing the specified elements.
246 *
247 * Overloadings of this method exist to initialize an enum set with
248 * one through five elements. A sixth overloading is provided that
249 * uses the varargs feature. This overloading may be used to create
250 * an enum set initially containing an arbitrary number of elements, but
251 * is likely to run slower than the overloadings that do not use varargs.
252 *
253 * @param <E> The class of the parameter elements and of the set
254 * @param e1 an element that this set is to contain initially
255 * @param e2 another element that this set is to contain initially
256 * @param e3 another element that this set is to contain initially
257 * @throws NullPointerException if any parameters are null
258 * @return an enum set initially containing the specified elements
259 */
260 public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3) {
261 EnumSet<E> result = noneOf(e1.getDeclaringClass());
262 result.add(e1);
263 result.add(e2);
264 result.add(e3);
265 return result;
266 }
267
268 /**
269 * Creates an enum set initially containing the specified elements.
270 *
271 * Overloadings of this method exist to initialize an enum set with
272 * one through five elements. A sixth overloading is provided that
273 * uses the varargs feature. This overloading may be used to create
274 * an enum set initially containing an arbitrary number of elements, but
275 * is likely to run slower than the overloadings that do not use varargs.
276 *
277 * @param <E> The class of the parameter elements and of the set
278 * @param e1 an element that this set is to contain initially
279 * @param e2 another element that this set is to contain initially
280 * @param e3 another element that this set is to contain initially
281 * @param e4 another element that this set is to contain initially
282 * @throws NullPointerException if any parameters are null
283 * @return an enum set initially containing the specified elements
284 */
285 public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4) {
286 EnumSet<E> result = noneOf(e1.getDeclaringClass());
287 result.add(e1);
288 result.add(e2);
289 result.add(e3);
290 result.add(e4);
291 return result;
292 }
293
294 /**
295 * Creates an enum set initially containing the specified elements.
296 *
297 * Overloadings of this method exist to initialize an enum set with
298 * one through five elements. A sixth overloading is provided that
299 * uses the varargs feature. This overloading may be used to create
300 * an enum set initially containing an arbitrary number of elements, but
301 * is likely to run slower than the overloadings that do not use varargs.
302 *
303 * @param <E> The class of the parameter elements and of the set
304 * @param e1 an element that this set is to contain initially
305 * @param e2 another element that this set is to contain initially
306 * @param e3 another element that this set is to contain initially
307 * @param e4 another element that this set is to contain initially
308 * @param e5 another element that this set is to contain initially
309 * @throws NullPointerException if any parameters are null
310 * @return an enum set initially containing the specified elements
311 */
312 public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4,
313 E e5)
314 {
315 EnumSet<E> result = noneOf(e1.getDeclaringClass());
316 result.add(e1);
317 result.add(e2);
318 result.add(e3);
319 result.add(e4);
320 result.add(e5);
321 return result;
322 }
323
324 /**
325 * Creates an enum set initially containing the specified elements.
326 * This factory, whose parameter list uses the varargs feature, may
327 * be used to create an enum set initially containing an arbitrary
328 * number of elements, but it is likely to run slower than the overloadings
329 * that do not use varargs.
330 *
331 * @param <E> The class of the parameter elements and of the set
332 * @param first an element that the set is to contain initially
333 * @param rest the remaining elements the set is to contain initially
334 * @throws NullPointerException if any of the specified elements are null,
335 * or if {@code rest} is null
336 * @return an enum set initially containing the specified elements
337 */
338 @SafeVarargs
339 public static <E extends Enum<E>> EnumSet<E> of(E first, E... rest) {
340 EnumSet<E> result = noneOf(first.getDeclaringClass());
341 result.add(first);
342 for (E e : rest)
343 result.add(e);
344 return result;
345 }
346
347 /**
348 * Creates an enum set initially containing all of the elements in the
349 * range defined by the two specified endpoints. The returned set will
350 * contain the endpoints themselves, which may be identical but must not
351 * be out of order.
352 *
353 * @param <E> The class of the parameter elements and of the set
354 * @param from the first element in the range
355 * @param to the last element in the range
356 * @throws NullPointerException if {@code from} or {@code to} are null
357 * @throws IllegalArgumentException if {@code from.compareTo(to) > 0}
358 * @return an enum set initially containing all of the elements in the
359 * range defined by the two specified endpoints
360 */
361 public static <E extends Enum<E>> EnumSet<E> range(E from, E to) {
362 if (from.compareTo(to) > 0)
363 throw new IllegalArgumentException(from + " > " + to);
364 EnumSet<E> result = noneOf(from.getDeclaringClass());
365 result.addRange(from, to);
366 return result;
367 }
368
369 /**
370 * Adds the specified range to this enum set, which is empty prior
371 * to the call.
372 */
373 abstract void addRange(E from, E to);
374
375 /**
376 * Returns a copy of this set.
377 *
378 * @return a copy of this set
379 */
380 @SuppressWarnings("unchecked")
381 public EnumSet<E> clone() {
382 try {
383 return (EnumSet<E>) super.clone();
384 } catch(CloneNotSupportedException e) {
385 throw new AssertionError(e);
386 }
387 }
388
389 /**
390 * Complements the contents of this enum set.
391 */
392 abstract void complement();
393
394 /**
395 * Throws an exception if e is not of the correct type for this enum set.
396 */
397 final void typeCheck(E e) {
398 Class<?> eClass = e.getClass();
399 if (eClass != elementType && eClass.getSuperclass() != elementType)
400 throw new ClassCastException(eClass + " != " + elementType);
401 }
402
403 /**
404 * Returns all of the values comprising E.
405 * The result is uncloned, cached, and shared by all callers.
406 */
407 private static <E extends Enum<E>> E[] getUniverse(Class<E> elementType) {
408 return SharedSecrets.getJavaLangAccess()
409 .getEnumConstantsShared(elementType);
410 }
411
412 /**
413 * This class is used to serialize all EnumSet instances, regardless of
414 * implementation type. It captures their "logical contents" and they
415 * are reconstructed using public static factories. This is necessary
416 * to ensure that the existence of a particular implementation type is
417 * an implementation detail.
418 *
419 * @serial include
420 */
421 private static class SerializationProxy <E extends Enum<E>>
422 implements java.io.Serializable
423 {
424 /**
425 * The element type of this enum set.
426 *
427 * @serial
428 */
429 private final Class<E> elementType;
430
431 /**
432 * The elements contained in this enum set.
433 *
434 * @serial
435 */
436 private final Enum<?>[] elements;
437
438 SerializationProxy(EnumSet<E> set) {
439 elementType = set.elementType;
440 elements = set.toArray(ZERO_LENGTH_ENUM_ARRAY);
441 }
442
443 // instead of cast to E, we should perhaps use elementType.cast()
444 // to avoid injection of forged stream, but it will slow the implementation
445 @SuppressWarnings("unchecked")
446 private Object readResolve() {
447 EnumSet<E> result = EnumSet.noneOf(elementType);
448 for (Enum<?> e : elements)
449 result.add((E)e);
450 return result;
451 }
452
453 private static final long serialVersionUID = 362491234563181265L;
454 }
455
456 Object writeReplace() {
457 return new SerializationProxy<>(this);
458 }
459
460 // readObject method for the serialization proxy pattern
461 // See Effective Java, Second Ed., Item 78.
462 private void readObject(java.io.ObjectInputStream stream)
463 throws java.io.InvalidObjectException {
464 throw new java.io.InvalidObjectException("Proxy required");
465 }
466 }