1 /*
2 * Copyright (c) 1997, 2013, 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 javany.util;
27
28 import java.util.Objects;
29
30 import javany.util.function.*;
31
32 /**
33 * This class provides a skeletal implementation of the <tt>Collection</tt>
34 * interface, to minimize the effort required to implement this interface. <p>
35 *
36 * To implement an unmodifiable collection, the programmer needs only to
37 * extend this class and provide implementations for the <tt>iterator</tt> and
38 * <tt>size</tt> methods. (The iterator returned by the <tt>iterator</tt>
39 * method must implement <tt>hasNext</tt> and <tt>next</tt>.)<p>
40 *
41 * To implement a modifiable collection, the programmer must additionally
42 * override this class's <tt>add</tt> method (which otherwise throws an
43 * <tt>UnsupportedOperationException</tt>), and the iterator returned by the
44 * <tt>iterator</tt> method must additionally implement its <tt>remove</tt>
45 * method.<p>
46 *
47 * The programmer should generally provide a void (no argument) and
48 * <tt>Collection</tt> constructor, as per the recommendation in the
49 * <tt>Collection</tt> interface specification.<p>
50 *
51 * The documentation for each non-abstract method in this class describes its
52 * implementation in detail. Each of these methods may be overridden if
53 * the collection being implemented admits a more efficient implementation.<p>
54 *
55 * This class is a member of the
56 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
57 * Java Collections Framework</a>.
58 *
59 * @author Josh Bloch
60 * @author Neal Gafter
61 * @see Collection
62 * @since 1.2
63 */
64
65 public abstract class AbstractCollection<any E> implements Collection<E> {
66 /**
67 * Sole constructor. (For invocation by subclass constructors, typically
68 * implicit.)
69 */
70 protected AbstractCollection() {
71 }
72
73 // Query Operations
74
75 /**
76 * Returns an iterator over the elements contained in this collection.
77 *
78 * @return an iterator over the elements contained in this collection
79 */
80 public abstract Iterator<E> iterator();
81
82 public abstract int size();
83
84 /**
85 * {@inheritDoc}
86 *
87 * @implSpec
88 * This implementation returns <tt>size() == 0</tt>.
89 */
90 public boolean isEmpty() {
91 return size() == 0;
92 }
93
94 /**
95 * {@inheritDoc}
96 *
97 * @implSpec
98 * This implementation iterates over the elements in the collection,
99 * checking each element in turn for equality with the specified element.
100 *
101 * @throws ClassCastException {@inheritDoc}
102 * @throws NullPointerException {@inheritDoc}
103 */
104 public boolean contains(Object o) {
105 __WhereVal(E) {
106 Iterator<E> it = iterator();
107 if (o == null) {
108 return false;
109 } else {
110 Function<E, Object> box = Any.converter();
111 while (it.hasNext())
112 if (o.equals(box.apply(it.next())))
113 return true;
114 }
115 return false;
116 }
117 __WhereRef(E) {
118 Iterator<E> it = iterator();
119 if (o == null) {
120 while (it.hasNext())
121 if (it.next() == null)
122 return true;
123 } else {
124 while (it.hasNext())
125 if (o.equals(it.next()))
126 return true;
127 }
128 return false;
129 }
130 }
131
132 /**
133 * {@inheritDoc}
134 *
135 * @implSpec
136 * This implementation returns an array containing all the elements
137 * returned by this collection's iterator, in the same order, stored in
138 * consecutive elements of the array, starting with index {@code 0}.
139 * The length of the returned array is equal to the number of elements
140 * returned by the iterator, even if the size of this collection changes
141 * during iteration, as might happen if the collection permits
142 * concurrent modification during iteration. The {@code size} method is
143 * called only as an optimization hint; the correct result is returned
144 * even if the iterator returns a different number of elements.
145 *
146 * <p>This method is equivalent to:
147 *
148 * <pre> {@code
149 * List<E> list = new ArrayList<E>(size());
150 * for (E e : this)
151 * list.add(e);
152 * return list.toArray();
153 * }</pre>
154 */
155 public Object[] toArray() {
156 // Estimate size of array; be prepared to see more or fewer elements
157 Object[] r = new Object[size()];
158 Iterator<E> it = iterator();
159 Function<E, Object> box = Any.converter();
160 for (int i = 0; i < r.length; i++) {
161 if (! it.hasNext()) // fewer elements than expected
162 return Arrays.copyOf(r, i);
163 r[i] = box.apply(it.next()); // boxing
164 }
165 return it.hasNext() ? finishToArray(r, it, box) : r;
166 }
167
168 /**
169 * {@inheritDoc}
170 *
171 * @implSpec
172 * This implementation returns an array containing all the elements
173 * returned by this collection's iterator in the same order, stored in
174 * consecutive elements of the array, starting with index {@code 0}.
175 * If the number of elements returned by the iterator is too large to
176 * fit into the specified array, then the elements are returned in a
177 * newly allocated array with length equal to the number of elements
178 * returned by the iterator, even if the size of this collection
179 * changes during iteration, as might happen if the collection permits
180 * concurrent modification during iteration. The {@code size} method is
181 * called only as an optimization hint; the correct result is returned
182 * even if the iterator returns a different number of elements.
183 *
184 * <p>This method is equivalent to:
185 *
186 * <pre> {@code
187 * List<E> list = new ArrayList<E>(size());
188 * for (E e : this)
189 * list.add(e);
190 * return list.toArray(a);
191 * }</pre>
192 *
193 * @throws ArrayStoreException {@inheritDoc}
194 * @throws NullPointerException {@inheritDoc}
195 */
196 @SuppressWarnings("unchecked")
197 public <any T> T[] toArray(T[] a) {
198 // Estimate size of array; be prepared to see more or fewer elements
199 int size = size();
200 T[] r = a.length >= size ? a :
201 (T[])java.lang.reflect.Array
202 .newInstance(a.getClass().getComponentType(), size);
203 Iterator<E> it = iterator();
204 Function<E, T> converter = Any.converter();
205
206 for (int i = 0; i < r.length; i++) {
207 if (! it.hasNext()) { // fewer elements than expected
208 if (a == r) {
209 r[i] = Any.defaultValue(); // null/zero-terminate
210 } else if (a.length < i) {
211 return Arrays.copyOf(r, i);
212 } else {
213 Any.arraycopy(r, 0, a, 0, i);
214 if (a.length > i) {
215 a[i] = Any.defaultValue();
216 }
217 }
218 return a;
219 }
220 r[i] = converter.apply(it.next());
221 }
222 // more elements than expected
223 return it.hasNext() ? finishToArray(r, it, converter) : r;
224 }
225
226 /**
227 * The maximum size of array to allocate.
228 * Some VMs reserve some header words in an array.
229 * Attempts to allocate larger arrays may result in
230 * OutOfMemoryError: Requested array size exceeds VM limit
231 */
232 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
233
234 /**
235 * Reallocates the array being used within toArray when the iterator
236 * returned more elements than expected, and finishes filling it from
237 * the iterator.
238 *
239 * @param r the array, replete with previously stored elements
240 * @param it the in-progress iterator over this collection
241 * @return array containing the elements in the given array, plus any
242 * further elements returned by the iterator, trimmed to size
243 */
244 @SuppressWarnings("unchecked")
245 private static <any E, any T> T[] finishToArray(T[] r, Iterator<E> it, Function<E, T> converter) {
246 int i = r.length;
247 while (it.hasNext()) {
248 int cap = r.length;
249 if (i == cap) {
250 int newCap = cap + (cap >> 1) + 1;
251 // overflow-conscious code
252 if (newCap - MAX_ARRAY_SIZE > 0)
253 newCap = hugeCapacity(cap + 1);
254 r = Arrays.copyOf(r, newCap);
255 }
256 r[i++] = converter.apply(it.next());
257 }
258 // trim if overallocated
259 return (i == r.length) ? r : Arrays.copyOf(r, i);
260 }
261
262 private static int hugeCapacity(int minCapacity) {
263 if (minCapacity < 0) // overflow
264 throw new OutOfMemoryError
265 ("Required array size too large");
266 return (minCapacity > MAX_ARRAY_SIZE) ?
267 Integer.MAX_VALUE :
268 MAX_ARRAY_SIZE;
269 }
270
271 // Modification Operations
272
273 /**
274 * {@inheritDoc}
275 *
276 * @implSpec
277 * This implementation always throws an
278 * <tt>UnsupportedOperationException</tt>.
279 *
280 * @throws UnsupportedOperationException {@inheritDoc}
281 * @throws ClassCastException {@inheritDoc}
282 * @throws NullPointerException {@inheritDoc}
283 * @throws IllegalArgumentException {@inheritDoc}
284 * @throws IllegalStateException {@inheritDoc}
285 */
286 public boolean add(E e) {
287 throw new UnsupportedOperationException();
288 }
289
290 /**
291 * {@inheritDoc}
292 *
293 * @implSpec
294 * This implementation iterates over the collection looking for the
295 * specified element. If it finds the element, it removes the element
296 * from the collection using the iterator's remove method.
297 *
298 * <p>Note that this implementation throws an
299 * <tt>UnsupportedOperationException</tt> if the iterator returned by this
300 * collection's iterator method does not implement the <tt>remove</tt>
301 * method and this collection contains the specified object.
302 *
303 * @throws UnsupportedOperationException {@inheritDoc}
304 * @throws ClassCastException {@inheritDoc}
305 * @throws NullPointerException {@inheritDoc}
306 */
307 public boolean remove(Object o) {
308 __WhereVal(E) {
309 if (o == null) {
310 return false;
311 }
312 Iterator<E> it = iterator();
313 Function<E, Object> box = Any.converter();
314 while (it.hasNext()) {
315 if (o.equals(box.apply(it.next()))) {
316 it.remove();
317 return true;
318 }
319 }
320 return false;
321 }
322 __WhereRef(E) {
323 Iterator<E> it = iterator();
324 if (o==null) {
325 while (it.hasNext()) {
326 if (it.next()==null) {
327 it.remove();
328 return true;
329 }
330 }
331 } else {
332 while (it.hasNext()) {
333 if (o.equals(it.next())) {
334 it.remove();
335 return true;
336 }
337 }
338 }
339 return false;
340 }
341 }
342
343 // Bulk Operations
344
345 /**
346 * {@inheritDoc}
347 *
348 * @implSpec
349 * This implementation iterates over the specified collection,
350 * checking each element returned by the iterator in turn to see
351 * if it's contained in this collection. If all elements are so
352 * contained <tt>true</tt> is returned, otherwise <tt>false</tt>.
353 *
354 * @throws ClassCastException {@inheritDoc}
355 * @throws NullPointerException {@inheritDoc}
356 * @see #contains(Object)
357 */
358 public boolean containsAll(Collection<?> c) {
359 Iterator<?> it =c.iterator();
360 while (it.hasNext())
361 if (!contains(it.next()))
362 return false;
363 return true;
364 }
365
366 /**
367 * {@inheritDoc}
368 *
369 * @implSpec
370 * This implementation iterates over the specified collection, and adds
371 * each object returned by the iterator to this collection, in turn.
372 *
373 * <p>Note that this implementation will throw an
374 * <tt>UnsupportedOperationException</tt> unless <tt>add</tt> is
375 * overridden (assuming the specified collection is non-empty).
376 *
377 * @throws UnsupportedOperationException {@inheritDoc}
378 * @throws ClassCastException {@inheritDoc}
379 * @throws NullPointerException {@inheritDoc}
380 * @throws IllegalArgumentException {@inheritDoc}
381 * @throws IllegalStateException {@inheritDoc}
382 *
383 * @see #add(Object)
384 */
385 public boolean addAll(Collection<? extends E> c) {
386 boolean modified = false;
387 Iterator<? extends E> it = c.iterator();
388 while (it.hasNext()) {
389 if (add(it.next())) {
390 modified = true;
391 }
392 }
393 return modified;
394 }
395
396 /**
397 * {@inheritDoc}
398 *
399 * @implSpec
400 * This implementation iterates over this collection, checking each
401 * element returned by the iterator in turn to see if it's contained
402 * in the specified collection. If it's so contained, it's removed from
403 * this collection with the iterator's <tt>remove</tt> method.
404 *
405 * <p>Note that this implementation will throw an
406 * <tt>UnsupportedOperationException</tt> if the iterator returned by the
407 * <tt>iterator</tt> method does not implement the <tt>remove</tt> method
408 * and this collection contains one or more elements in common with the
409 * specified collection.
410 *
411 * @throws UnsupportedOperationException {@inheritDoc}
412 * @throws ClassCastException {@inheritDoc}
413 * @throws NullPointerException {@inheritDoc}
414 *
415 * @see #remove(Object)
416 * @see #contains(Object)
417 */
418 public boolean removeAll(Collection<?> c) {
419 Objects.requireNonNull(c);
420 boolean modified = false;
421 Iterator<E> it = iterator();
422 Function<E, Object> box = Any.converter();
423 while (it.hasNext()) {
424 if (c.contains(box.apply(it.next()))) { // boxing
425 it.remove();
426 modified = true;
427 }
428 }
429 return modified;
430 }
431
432 /**
433 * {@inheritDoc}
434 *
435 * @implSpec
436 * This implementation iterates over this collection, checking each
437 * element returned by the iterator in turn to see if it's contained
438 * in the specified collection. If it's not so contained, it's removed
439 * from this collection with the iterator's <tt>remove</tt> method.
440 *
441 * <p>Note that this implementation will throw an
442 * <tt>UnsupportedOperationException</tt> if the iterator returned by the
443 * <tt>iterator</tt> method does not implement the <tt>remove</tt> method
444 * and this collection contains one or more elements not present in the
445 * specified collection.
446 *
447 * @throws UnsupportedOperationException {@inheritDoc}
448 * @throws ClassCastException {@inheritDoc}
449 * @throws NullPointerException {@inheritDoc}
450 *
451 * @see #remove(Object)
452 * @see #contains(Object)
453 */
454 public boolean retainAll(Collection<?> c) {
455 Objects.requireNonNull(c);
456 boolean modified = false;
457 Iterator<E> it = iterator();
458 Function<E, Object> box = Any.converter();
459 while (it.hasNext()) {
460 if (!c.contains(box.apply(it.next()))) { // boxing
461 it.remove();
462 modified = true;
463 }
464 }
465 return modified;
466 }
467
468 /**
469 * {@inheritDoc}
470 *
471 * @implSpec
472 * This implementation iterates over this collection, removing each
473 * element using the <tt>Iterator.remove</tt> operation. Most
474 * implementations will probably choose to override this method for
475 * efficiency.
476 *
477 * <p>Note that this implementation will throw an
478 * <tt>UnsupportedOperationException</tt> if the iterator returned by this
479 * collection's <tt>iterator</tt> method does not implement the
480 * <tt>remove</tt> method and this collection is non-empty.
481 *
482 * @throws UnsupportedOperationException {@inheritDoc}
483 */
484 public void clear() {
485 Iterator<E> it = iterator();
486 while (it.hasNext()) {
487 it.next();
488 it.remove();
489 }
490 }
491
492
493 // String conversion
494
495 /**
496 * Returns a string representation of this collection. The string
497 * representation consists of a list of the collection's elements in the
498 * order they are returned by its iterator, enclosed in square brackets
499 * (<tt>"[]"</tt>). Adjacent elements are separated by the characters
500 * <tt>", "</tt> (comma and space). Elements are converted to strings as
501 * by {@link String#valueOf(Object)}.
502 *
503 * @return a string representation of this collection
504 */
505 public String toString() {
506 __WhereVal(E) {
507 Iterator<E> it = iterator();
508 if (!it.hasNext())
509 return "[]";
510
511 StringBuilder sb = new StringBuilder();
512 sb.append('[');
513 for (; ; ) {
514 sb.append(Any.toString(it.next()));
515 if (!it.hasNext())
516 return sb.append(']').toString();
517 sb.append(',').append(' ');
518 }
519 }
520 __WhereRef(E) {
521 Iterator<E> it = iterator();
522 if (!it.hasNext())
523 return "[]";
524
525 StringBuilder sb = new StringBuilder();
526 sb.append('[');
527 for (; ; ) {
528 E e = it.next();
529 sb.append(e == this ? "(this Collection)" : e);
530 if (!it.hasNext())
531 return sb.append(']').toString();
532 sb.append(',').append(' ');
533 }
534 }
535 }
536 }