001 /*
002 * Copyright (C) 2008 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package com.google.common.collect;
018
019 import static com.google.common.base.Preconditions.checkArgument;
020 import static com.google.common.base.Preconditions.checkNotNull;
021
022 import com.google.common.annotations.GwtCompatible;
023 import com.google.common.annotations.GwtIncompatible;
024
025 import java.io.InvalidObjectException;
026 import java.io.ObjectInputStream;
027 import java.io.Serializable;
028 import java.util.ArrayList;
029 import java.util.Arrays;
030 import java.util.Collection;
031 import java.util.Collections;
032 import java.util.Comparator;
033 import java.util.Iterator;
034 import java.util.List;
035 import java.util.NavigableSet;
036 import java.util.SortedSet;
037
038 import javax.annotation.Nullable;
039
040 /**
041 * An immutable {@code SortedSet} that stores its elements in a sorted array.
042 * Some instances are ordered by an explicit comparator, while others follow the
043 * natural sort ordering of their elements. Either way, null elements are not
044 * supported.
045 *
046 * <p>Unlike {@link Collections#unmodifiableSortedSet}, which is a <i>view</i>
047 * of a separate collection that can still change, an instance of {@code
048 * ImmutableSortedSet} contains its own private data and will <i>never</i>
049 * change. This class is convenient for {@code public static final} sets
050 * ("constant sets") and also lets you easily make a "defensive copy" of a set
051 * provided to your class by a caller.
052 *
053 * <p>The sets returned by the {@link #headSet}, {@link #tailSet}, and
054 * {@link #subSet} methods share the same array as the original set, preventing
055 * that array from being garbage collected. If this is a concern, the data may
056 * be copied into a correctly-sized array by calling {@link #copyOfSorted}.
057 *
058 * <p><b>Note on element equivalence:</b> The {@link #contains(Object)},
059 * {@link #containsAll(Collection)}, and {@link #equals(Object)}
060 * implementations must check whether a provided object is equivalent to an
061 * element in the collection. Unlike most collections, an
062 * {@code ImmutableSortedSet} doesn't use {@link Object#equals} to determine if
063 * two elements are equivalent. Instead, with an explicit comparator, the
064 * following relation determines whether elements {@code x} and {@code y} are
065 * equivalent: <pre> {@code
066 *
067 * {(x, y) | comparator.compare(x, y) == 0}}</pre>
068 *
069 * With natural ordering of elements, the following relation determines whether
070 * two elements are equivalent: <pre> {@code
071 *
072 * {(x, y) | x.compareTo(y) == 0}}</pre>
073 *
074 * <b>Warning:</b> Like most sets, an {@code ImmutableSortedSet} will not
075 * function correctly if an element is modified after being placed in the set.
076 * For this reason, and to avoid general confusion, it is strongly recommended
077 * to place only immutable objects into this collection.
078 *
079 * <p><b>Note:</b> Although this class is not final, it cannot be subclassed as
080 * it has no public or protected constructors. Thus, instances of this type are
081 * guaranteed to be immutable.
082 *
083 * <p>See the Guava User Guide article on <a href=
084 * "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained">
085 * immutable collections</a>.
086 *
087 * @see ImmutableSet
088 * @author Jared Levy
089 * @author Louis Wasserman
090 * @since 2.0 (imported from Google Collections Library; implements {@code NavigableSet} since 12.0)
091 */
092 // TODO(benyu): benchmark and optimize all creation paths, which are a mess now
093 @GwtCompatible(serializable = true, emulated = true)
094 @SuppressWarnings("serial") // we're overriding default serialization
095 public abstract class ImmutableSortedSet<E> extends ImmutableSortedSetFauxverideShim<E>
096 implements NavigableSet<E>, SortedIterable<E> {
097
098 private static final Comparator<Comparable> NATURAL_ORDER =
099 Ordering.natural();
100
101 private static final ImmutableSortedSet<Comparable> NATURAL_EMPTY_SET =
102 new EmptyImmutableSortedSet<Comparable>(NATURAL_ORDER);
103
104 @SuppressWarnings("unchecked")
105 private static <E> ImmutableSortedSet<E> emptySet() {
106 return (ImmutableSortedSet<E>) NATURAL_EMPTY_SET;
107 }
108
109 static <E> ImmutableSortedSet<E> emptySet(
110 Comparator<? super E> comparator) {
111 if (NATURAL_ORDER.equals(comparator)) {
112 return emptySet();
113 } else {
114 return new EmptyImmutableSortedSet<E>(comparator);
115 }
116 }
117
118 /**
119 * Returns the empty immutable sorted set.
120 */
121 public static <E> ImmutableSortedSet<E> of() {
122 return emptySet();
123 }
124
125 /**
126 * Returns an immutable sorted set containing a single element.
127 */
128 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(
129 E element) {
130 return new RegularImmutableSortedSet<E>(
131 ImmutableList.of(element), Ordering.natural());
132 }
133
134 /**
135 * Returns an immutable sorted set containing the given elements sorted by
136 * their natural ordering. When multiple elements are equivalent according to
137 * {@link Comparable#compareTo}, only the first one specified is included.
138 *
139 * @throws NullPointerException if any element is null
140 */
141 @SuppressWarnings("unchecked")
142 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(
143 E e1, E e2) {
144 return copyOf(Ordering.natural(), Arrays.asList(e1, e2));
145 }
146
147 /**
148 * Returns an immutable sorted set containing the given elements sorted by
149 * their natural ordering. When multiple elements are equivalent according to
150 * {@link Comparable#compareTo}, only the first one specified is included.
151 *
152 * @throws NullPointerException if any element is null
153 */
154 @SuppressWarnings("unchecked")
155 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(
156 E e1, E e2, E e3) {
157 return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3));
158 }
159
160 /**
161 * Returns an immutable sorted set containing the given elements sorted by
162 * their natural ordering. When multiple elements are equivalent according to
163 * {@link Comparable#compareTo}, only the first one specified is included.
164 *
165 * @throws NullPointerException if any element is null
166 */
167 @SuppressWarnings("unchecked")
168 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(
169 E e1, E e2, E e3, E e4) {
170 return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4));
171 }
172
173 /**
174 * Returns an immutable sorted set containing the given elements sorted by
175 * their natural ordering. When multiple elements are equivalent according to
176 * {@link Comparable#compareTo}, only the first one specified is included.
177 *
178 * @throws NullPointerException if any element is null
179 */
180 @SuppressWarnings("unchecked")
181 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(
182 E e1, E e2, E e3, E e4, E e5) {
183 return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4, e5));
184 }
185
186 /**
187 * Returns an immutable sorted set containing the given elements sorted by
188 * their natural ordering. When multiple elements are equivalent according to
189 * {@link Comparable#compareTo}, only the first one specified is included.
190 *
191 * @throws NullPointerException if any element is null
192 * @since 3.0 (source-compatible since 2.0)
193 */
194 @SuppressWarnings("unchecked")
195 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(
196 E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
197 int size = remaining.length + 6;
198 List<E> all = new ArrayList<E>(size);
199 Collections.addAll(all, e1, e2, e3, e4, e5, e6);
200 Collections.addAll(all, remaining);
201 return copyOf(Ordering.natural(), all);
202 }
203
204 // TODO(kevinb): Consider factory methods that reject duplicates
205
206 /**
207 * Returns an immutable sorted set containing the given elements sorted by
208 * their natural ordering. When multiple elements are equivalent according to
209 * {@link Comparable#compareTo}, only the first one specified is included.
210 *
211 * @throws NullPointerException if any of {@code elements} is null
212 * @since 3.0
213 */
214 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> copyOf(
215 E[] elements) {
216 return copyOf(Ordering.natural(), Arrays.asList(elements));
217 }
218
219 /**
220 * Returns an immutable sorted set containing the given elements sorted by
221 * their natural ordering. When multiple elements are equivalent according to
222 * {@code compareTo()}, only the first one specified is included. To create a
223 * copy of a {@code SortedSet} that preserves the comparator, call {@link
224 * #copyOfSorted} instead. This method iterates over {@code elements} at most
225 * once.
226
227 *
228 * <p>Note that if {@code s} is a {@code Set<String>}, then {@code
229 * ImmutableSortedSet.copyOf(s)} returns an {@code ImmutableSortedSet<String>}
230 * containing each of the strings in {@code s}, while {@code
231 * ImmutableSortedSet.of(s)} returns an {@code
232 * ImmutableSortedSet<Set<String>>} containing one element (the given set
233 * itself).
234 *
235 * <p>Despite the method name, this method attempts to avoid actually copying
236 * the data when it is safe to do so. The exact circumstances under which a
237 * copy will or will not be performed are undocumented and subject to change.
238 *
239 * <p>This method is not type-safe, as it may be called on elements that are
240 * not mutually comparable.
241 *
242 * @throws ClassCastException if the elements are not mutually comparable
243 * @throws NullPointerException if any of {@code elements} is null
244 */
245 public static <E> ImmutableSortedSet<E> copyOf(
246 Iterable<? extends E> elements) {
247 // Hack around E not being a subtype of Comparable.
248 // Unsafe, see ImmutableSortedSetFauxverideShim.
249 @SuppressWarnings("unchecked")
250 Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable>natural();
251 return copyOf(naturalOrder, elements);
252 }
253
254 /**
255 * Returns an immutable sorted set containing the given elements sorted by
256 * their natural ordering. When multiple elements are equivalent according to
257 * {@code compareTo()}, only the first one specified is included. To create a
258 * copy of a {@code SortedSet} that preserves the comparator, call
259 * {@link #copyOfSorted} instead. This method iterates over {@code elements}
260 * at most once.
261 *
262 * <p>Note that if {@code s} is a {@code Set<String>}, then
263 * {@code ImmutableSortedSet.copyOf(s)} returns an
264 * {@code ImmutableSortedSet<String>} containing each of the strings in
265 * {@code s}, while {@code ImmutableSortedSet.of(s)} returns an
266 * {@code ImmutableSortedSet<Set<String>>} containing one element (the given
267 * set itself).
268 *
269 * <p><b>Note:</b> Despite what the method name suggests, if {@code elements}
270 * is an {@code ImmutableSortedSet}, it may be returned instead of a copy.
271 *
272 * <p>This method is not type-safe, as it may be called on elements that are
273 * not mutually comparable.
274 *
275 * <p>This method is safe to use even when {@code elements} is a synchronized
276 * or concurrent collection that is currently being modified by another
277 * thread.
278 *
279 * @throws ClassCastException if the elements are not mutually comparable
280 * @throws NullPointerException if any of {@code elements} is null
281 * @since 7.0 (source-compatible since 2.0)
282 */
283 public static <E> ImmutableSortedSet<E> copyOf(
284 Collection<? extends E> elements) {
285 // Hack around E not being a subtype of Comparable.
286 // Unsafe, see ImmutableSortedSetFauxverideShim.
287 @SuppressWarnings("unchecked")
288 Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable>natural();
289 return copyOf(naturalOrder, elements);
290 }
291
292 /**
293 * Returns an immutable sorted set containing the given elements sorted by
294 * their natural ordering. When multiple elements are equivalent according to
295 * {@code compareTo()}, only the first one specified is included.
296 *
297 * <p>This method is not type-safe, as it may be called on elements that are
298 * not mutually comparable.
299 *
300 * @throws ClassCastException if the elements are not mutually comparable
301 * @throws NullPointerException if any of {@code elements} is null
302 */
303 public static <E> ImmutableSortedSet<E> copyOf(
304 Iterator<? extends E> elements) {
305 // Hack around E not being a subtype of Comparable.
306 // Unsafe, see ImmutableSortedSetFauxverideShim.
307 @SuppressWarnings("unchecked")
308 Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable>natural();
309 return copyOf(naturalOrder, elements);
310 }
311
312 /**
313 * Returns an immutable sorted set containing the given elements sorted by
314 * the given {@code Comparator}. When multiple elements are equivalent
315 * according to {@code compareTo()}, only the first one specified is
316 * included.
317 *
318 * @throws NullPointerException if {@code comparator} or any of
319 * {@code elements} is null
320 */
321 public static <E> ImmutableSortedSet<E> copyOf(
322 Comparator<? super E> comparator, Iterator<? extends E> elements) {
323 return copyOf(comparator, Lists.newArrayList(elements));
324 }
325
326 /**
327 * Returns an immutable sorted set containing the given elements sorted by
328 * the given {@code Comparator}. When multiple elements are equivalent
329 * according to {@code compare()}, only the first one specified is
330 * included. This method iterates over {@code elements} at most once.
331 *
332 * <p>Despite the method name, this method attempts to avoid actually copying
333 * the data when it is safe to do so. The exact circumstances under which a
334 * copy will or will not be performed are undocumented and subject to change.
335 *
336 * @throws NullPointerException if {@code comparator} or any of {@code
337 * elements} is null
338 */
339 public static <E> ImmutableSortedSet<E> copyOf(
340 Comparator<? super E> comparator, Iterable<? extends E> elements) {
341 checkNotNull(comparator);
342 boolean hasSameComparator =
343 SortedIterables.hasSameComparator(comparator, elements);
344
345 if (hasSameComparator && (elements instanceof ImmutableSortedSet)) {
346 @SuppressWarnings("unchecked")
347 ImmutableSortedSet<E> original = (ImmutableSortedSet<E>) elements;
348 if (!original.isPartialView()) {
349 return original;
350 }
351 }
352 @SuppressWarnings("unchecked") // elements only contains E's; it's safe.
353 E[] array = (E[]) Iterables.toArray(elements);
354 return construct(comparator, array.length, array);
355 }
356
357 /**
358 * Returns an immutable sorted set containing the given elements sorted by
359 * the given {@code Comparator}. When multiple elements are equivalent
360 * according to {@code compareTo()}, only the first one specified is
361 * included.
362 *
363 * <p>Despite the method name, this method attempts to avoid actually copying
364 * the data when it is safe to do so. The exact circumstances under which a
365 * copy will or will not be performed are undocumented and subject to change.
366 *
367 * <p>This method is safe to use even when {@code elements} is a synchronized
368 * or concurrent collection that is currently being modified by another
369 * thread.
370 *
371 * @throws NullPointerException if {@code comparator} or any of
372 * {@code elements} is null
373 * @since 7.0 (source-compatible since 2.0)
374 */
375 public static <E> ImmutableSortedSet<E> copyOf(
376 Comparator<? super E> comparator, Collection<? extends E> elements) {
377 return copyOf(comparator, (Iterable<? extends E>) elements);
378 }
379
380 /**
381 * Returns an immutable sorted set containing the elements of a sorted set,
382 * sorted by the same {@code Comparator}. That behavior differs from {@link
383 * #copyOf(Iterable)}, which always uses the natural ordering of the
384 * elements.
385 *
386 * <p>Despite the method name, this method attempts to avoid actually copying
387 * the data when it is safe to do so. The exact circumstances under which a
388 * copy will or will not be performed are undocumented and subject to change.
389 *
390 * <p>This method is safe to use even when {@code sortedSet} is a synchronized
391 * or concurrent collection that is currently being modified by another
392 * thread.
393 *
394 * @throws NullPointerException if {@code sortedSet} or any of its elements
395 * is null
396 */
397 public static <E> ImmutableSortedSet<E> copyOfSorted(SortedSet<E> sortedSet) {
398 Comparator<? super E> comparator = SortedIterables.comparator(sortedSet);
399 E[] elements = (E[]) sortedSet.toArray();
400 if (elements.length == 0) {
401 return emptySet(comparator);
402 } else {
403 return new RegularImmutableSortedSet<E>(
404 ImmutableList.<E>asImmutableList(elements), comparator);
405 }
406 }
407
408 /**
409 * Sorts and eliminates duplicates from the first {@code n} positions in {@code contents}.
410 * Returns the number of unique elements. If this returns {@code k}, then the first {@code k}
411 * elements of {@code contents} will be the sorted, unique elements, and {@code
412 * contents[i] == null} for {@code k <= i < n}.
413 *
414 * @throws NullPointerException if any of the first {@code n} elements of {@code contents} is
415 * null
416 */
417 static <E> int sortAndUnique(
418 Comparator<? super E> comparator, int n, E... contents) {
419 if (n == 0) {
420 return 0;
421 }
422 for (int i = 0; i < n; i++) {
423 ObjectArrays.checkElementNotNull(contents[i], i);
424 }
425 Arrays.sort(contents, 0, n, comparator);
426 int uniques = 1;
427 for (int i = 1; i < n; i++) {
428 E cur = contents[i];
429 E prev = contents[uniques - 1];
430 if (comparator.compare(cur, prev) != 0) {
431 contents[uniques++] = cur;
432 }
433 }
434 Arrays.fill(contents, uniques, n, null);
435 return uniques;
436 }
437
438 /**
439 * Constructs an {@code ImmutableSortedSet} from the first {@code n} elements of
440 * {@code contents}. If {@code k} is the size of the returned {@code ImmutableSortedSet}, then
441 * the sorted unique elements are in the first {@code k} positions of {@code contents}, and
442 * {@code contents[i] == null} for {@code k <= i < n}.
443 *
444 * <p>If {@code k == contents.length}, then {@code contents} may no longer be safe for
445 * modification.
446 *
447 * @throws NullPointerException if any of the first {@code n} elements of {@code contents} is
448 * null
449 */
450 static <E> ImmutableSortedSet<E> construct(
451 Comparator<? super E> comparator, int n, E... contents) {
452 int uniques = sortAndUnique(comparator, n, contents);
453 if (uniques == 0) {
454 return emptySet(comparator);
455 } else if (uniques < contents.length) {
456 contents = ObjectArrays.arraysCopyOf(contents, uniques);
457 }
458 return new RegularImmutableSortedSet<E>(
459 ImmutableList.<E>asImmutableList(contents), comparator);
460 }
461
462 /**
463 * Returns a builder that creates immutable sorted sets with an explicit
464 * comparator. If the comparator has a more general type than the set being
465 * generated, such as creating a {@code SortedSet<Integer>} with a
466 * {@code Comparator<Number>}, use the {@link Builder} constructor instead.
467 *
468 * @throws NullPointerException if {@code comparator} is null
469 */
470 public static <E> Builder<E> orderedBy(Comparator<E> comparator) {
471 return new Builder<E>(comparator);
472 }
473
474 /**
475 * Returns a builder that creates immutable sorted sets whose elements are
476 * ordered by the reverse of their natural ordering.
477 *
478 * <p>Note: the type parameter {@code E} extends {@code Comparable<E>} rather
479 * than {@code Comparable<? super E>} as a workaround for javac <a
480 * href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6468354">bug
481 * 6468354</a>.
482 */
483 public static <E extends Comparable<E>> Builder<E> reverseOrder() {
484 return new Builder<E>(Ordering.natural().reverse());
485 }
486
487 /**
488 * Returns a builder that creates immutable sorted sets whose elements are
489 * ordered by their natural ordering. The sorted sets use {@link
490 * Ordering#natural()} as the comparator. This method provides more
491 * type-safety than {@link #builder}, as it can be called only for classes
492 * that implement {@link Comparable}.
493 *
494 * <p>Note: the type parameter {@code E} extends {@code Comparable<E>} rather
495 * than {@code Comparable<? super E>} as a workaround for javac <a
496 * href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6468354">bug
497 * 6468354</a>.
498 */
499 public static <E extends Comparable<E>> Builder<E> naturalOrder() {
500 return new Builder<E>(Ordering.natural());
501 }
502
503 /**
504 * A builder for creating immutable sorted set instances, especially {@code
505 * public static final} sets ("constant sets"), with a given comparator.
506 * Example: <pre> {@code
507 *
508 * public static final ImmutableSortedSet<Number> LUCKY_NUMBERS =
509 * new ImmutableSortedSet.Builder<Number>(ODDS_FIRST_COMPARATOR)
510 * .addAll(SINGLE_DIGIT_PRIMES)
511 * .add(42)
512 * .build();}</pre>
513 *
514 * Builder instances can be reused; it is safe to call {@link #build} multiple
515 * times to build multiple sets in series. Each set is a superset of the set
516 * created before it.
517 *
518 * @since 2.0 (imported from Google Collections Library)
519 */
520 public static final class Builder<E> extends ImmutableSet.Builder<E> {
521 private final Comparator<? super E> comparator;
522
523 /**
524 * Creates a new builder. The returned builder is equivalent to the builder
525 * generated by {@link ImmutableSortedSet#orderedBy}.
526 */
527 public Builder(Comparator<? super E> comparator) {
528 this.comparator = checkNotNull(comparator);
529 }
530
531 /**
532 * Adds {@code element} to the {@code ImmutableSortedSet}. If the
533 * {@code ImmutableSortedSet} already contains {@code element}, then
534 * {@code add} has no effect. (only the previously added element
535 * is retained).
536 *
537 * @param element the element to add
538 * @return this {@code Builder} object
539 * @throws NullPointerException if {@code element} is null
540 */
541 @Override public Builder<E> add(E element) {
542 super.add(element);
543 return this;
544 }
545
546 /**
547 * Adds each element of {@code elements} to the {@code ImmutableSortedSet},
548 * ignoring duplicate elements (only the first duplicate element is added).
549 *
550 * @param elements the elements to add
551 * @return this {@code Builder} object
552 * @throws NullPointerException if {@code elements} contains a null element
553 */
554 @Override public Builder<E> add(E... elements) {
555 super.add(elements);
556 return this;
557 }
558
559 /**
560 * Adds each element of {@code elements} to the {@code ImmutableSortedSet},
561 * ignoring duplicate elements (only the first duplicate element is added).
562 *
563 * @param elements the elements to add to the {@code ImmutableSortedSet}
564 * @return this {@code Builder} object
565 * @throws NullPointerException if {@code elements} contains a null element
566 */
567 @Override public Builder<E> addAll(Iterable<? extends E> elements) {
568 super.addAll(elements);
569 return this;
570 }
571
572 /**
573 * Adds each element of {@code elements} to the {@code ImmutableSortedSet},
574 * ignoring duplicate elements (only the first duplicate element is added).
575 *
576 * @param elements the elements to add to the {@code ImmutableSortedSet}
577 * @return this {@code Builder} object
578 * @throws NullPointerException if {@code elements} contains a null element
579 */
580 @Override public Builder<E> addAll(Iterator<? extends E> elements) {
581 super.addAll(elements);
582 return this;
583 }
584
585 /**
586 * Returns a newly-created {@code ImmutableSortedSet} based on the contents
587 * of the {@code Builder} and its comparator.
588 */
589 @Override public ImmutableSortedSet<E> build() {
590 @SuppressWarnings("unchecked") // we're careful to put only E's in here
591 E[] contentsArray = (E[]) contents;
592 ImmutableSortedSet<E> result = construct(comparator, size, contentsArray);
593 this.size = result.size(); // we eliminated duplicates in-place in contentsArray
594 return result;
595 }
596 }
597
598 int unsafeCompare(Object a, Object b) {
599 return unsafeCompare(comparator, a, b);
600 }
601
602 static int unsafeCompare(
603 Comparator<?> comparator, Object a, Object b) {
604 // Pretend the comparator can compare anything. If it turns out it can't
605 // compare a and b, we should get a CCE on the subsequent line. Only methods
606 // that are spec'd to throw CCE should call this.
607 @SuppressWarnings("unchecked")
608 Comparator<Object> unsafeComparator = (Comparator<Object>) comparator;
609 return unsafeComparator.compare(a, b);
610 }
611
612 final transient Comparator<? super E> comparator;
613
614 ImmutableSortedSet(Comparator<? super E> comparator) {
615 this.comparator = comparator;
616 }
617
618 /**
619 * Returns the comparator that orders the elements, which is
620 * {@link Ordering#natural()} when the natural ordering of the
621 * elements is used. Note that its behavior is not consistent with
622 * {@link SortedSet#comparator()}, which returns {@code null} to indicate
623 * natural ordering.
624 */
625 @Override
626 public Comparator<? super E> comparator() {
627 return comparator;
628 }
629
630 @Override // needed to unify the iterator() methods in Collection and SortedIterable
631 public abstract UnmodifiableIterator<E> iterator();
632
633 /**
634 * {@inheritDoc}
635 *
636 * <p>This method returns a serializable {@code ImmutableSortedSet}.
637 *
638 * <p>The {@link SortedSet#headSet} documentation states that a subset of a
639 * subset throws an {@link IllegalArgumentException} if passed a
640 * {@code toElement} greater than an earlier {@code toElement}. However, this
641 * method doesn't throw an exception in that situation, but instead keeps the
642 * original {@code toElement}.
643 */
644 @Override
645 public ImmutableSortedSet<E> headSet(E toElement) {
646 return headSet(toElement, false);
647 }
648
649 /**
650 * @since 12.0
651 */
652 @GwtIncompatible("NavigableSet")
653 @Override
654 public ImmutableSortedSet<E> headSet(E toElement, boolean inclusive) {
655 return headSetImpl(checkNotNull(toElement), inclusive);
656 }
657
658 /**
659 * {@inheritDoc}
660 *
661 * <p>This method returns a serializable {@code ImmutableSortedSet}.
662 *
663 * <p>The {@link SortedSet#subSet} documentation states that a subset of a
664 * subset throws an {@link IllegalArgumentException} if passed a
665 * {@code fromElement} smaller than an earlier {@code fromElement}. However,
666 * this method doesn't throw an exception in that situation, but instead keeps
667 * the original {@code fromElement}. Similarly, this method keeps the
668 * original {@code toElement}, instead of throwing an exception, if passed a
669 * {@code toElement} greater than an earlier {@code toElement}.
670 */
671 @Override
672 public ImmutableSortedSet<E> subSet(E fromElement, E toElement) {
673 return subSet(fromElement, true, toElement, false);
674 }
675
676 /**
677 * @since 12.0
678 */
679 @GwtIncompatible("NavigableSet")
680 @Override
681 public ImmutableSortedSet<E> subSet(
682 E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
683 checkNotNull(fromElement);
684 checkNotNull(toElement);
685 checkArgument(comparator.compare(fromElement, toElement) <= 0);
686 return subSetImpl(fromElement, fromInclusive, toElement, toInclusive);
687 }
688
689 /**
690 * {@inheritDoc}
691 *
692 * <p>This method returns a serializable {@code ImmutableSortedSet}.
693 *
694 * <p>The {@link SortedSet#tailSet} documentation states that a subset of a
695 * subset throws an {@link IllegalArgumentException} if passed a
696 * {@code fromElement} smaller than an earlier {@code fromElement}. However,
697 * this method doesn't throw an exception in that situation, but instead keeps
698 * the original {@code fromElement}.
699 */
700 @Override
701 public ImmutableSortedSet<E> tailSet(E fromElement) {
702 return tailSet(fromElement, true);
703 }
704
705 /**
706 * @since 12.0
707 */
708 @GwtIncompatible("NavigableSet")
709 @Override
710 public ImmutableSortedSet<E> tailSet(E fromElement, boolean inclusive) {
711 return tailSetImpl(checkNotNull(fromElement), inclusive);
712 }
713
714 /*
715 * These methods perform most headSet, subSet, and tailSet logic, besides
716 * parameter validation.
717 */
718 abstract ImmutableSortedSet<E> headSetImpl(E toElement, boolean inclusive);
719
720 abstract ImmutableSortedSet<E> subSetImpl(
721 E fromElement, boolean fromInclusive, E toElement, boolean toInclusive);
722
723 abstract ImmutableSortedSet<E> tailSetImpl(E fromElement, boolean inclusive);
724
725 /**
726 * @since 12.0
727 */
728 @GwtIncompatible("NavigableSet")
729 @Override
730 public E lower(E e) {
731 return Iterables.getFirst(headSet(e, false).descendingSet(), null);
732 }
733
734 /**
735 * @since 12.0
736 */
737 @GwtIncompatible("NavigableSet")
738 @Override
739 public E floor(E e) {
740 return Iterables.getFirst(headSet(e, true).descendingSet(), null);
741 }
742
743 /**
744 * @since 12.0
745 */
746 @GwtIncompatible("NavigableSet")
747 @Override
748 public E ceiling(E e) {
749 return Iterables.getFirst(tailSet(e, true), null);
750 }
751
752 /**
753 * @since 12.0
754 */
755 @GwtIncompatible("NavigableSet")
756 @Override
757 public E higher(E e) {
758 return Iterables.getFirst(tailSet(e, false), null);
759 }
760
761 /**
762 * @since 12.0
763 */
764 @GwtIncompatible("NavigableSet")
765 @Override
766 public final E pollFirst() {
767 throw new UnsupportedOperationException();
768 }
769
770 /**
771 * @since 12.0
772 */
773 @GwtIncompatible("NavigableSet")
774 @Override
775 public final E pollLast() {
776 throw new UnsupportedOperationException();
777 }
778
779 @GwtIncompatible("NavigableSet")
780 transient ImmutableSortedSet<E> descendingSet;
781
782 /**
783 * @since 12.0
784 */
785 @GwtIncompatible("NavigableSet")
786 @Override
787 public ImmutableSortedSet<E> descendingSet() {
788 ImmutableSortedSet<E> result = descendingSet;
789 if (result == null) {
790 result = descendingSet = createDescendingSet();
791 result.descendingSet = this;
792 }
793 return result;
794 }
795
796 @GwtIncompatible("NavigableSet")
797 abstract ImmutableSortedSet<E> createDescendingSet();
798
799 /**
800 * @since 12.0
801 */
802 @GwtIncompatible("NavigableSet")
803 @Override
804 public UnmodifiableIterator<E> descendingIterator() {
805 return descendingSet().iterator();
806 }
807
808 /**
809 * Returns the position of an element within the set, or -1 if not present.
810 */
811 abstract int indexOf(@Nullable Object target);
812
813 /*
814 * This class is used to serialize all ImmutableSortedSet instances,
815 * regardless of implementation type. It captures their "logical contents"
816 * only. This is necessary to ensure that the existence of a particular
817 * implementation type is an implementation detail.
818 */
819 private static class SerializedForm<E> implements Serializable {
820 final Comparator<? super E> comparator;
821 final Object[] elements;
822
823 public SerializedForm(Comparator<? super E> comparator, Object[] elements) {
824 this.comparator = comparator;
825 this.elements = elements;
826 }
827
828 @SuppressWarnings("unchecked")
829 Object readResolve() {
830 return new Builder<E>(comparator).add((E[]) elements).build();
831 }
832
833 private static final long serialVersionUID = 0;
834 }
835
836 private void readObject(ObjectInputStream stream)
837 throws InvalidObjectException {
838 throw new InvalidObjectException("Use SerializedForm");
839 }
840
841 @Override Object writeReplace() {
842 return new SerializedForm<E>(comparator, toArray());
843 }
844 }
845