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 copyOfInternal(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 checkNotNull(comparator);
324 return copyOfInternal(comparator, elements);
325 }
326
327 /**
328 * Returns an immutable sorted set containing the given elements sorted by
329 * the given {@code Comparator}. When multiple elements are equivalent
330 * according to {@code compare()}, only the first one specified is
331 * included. This method iterates over {@code elements} at most once.
332 *
333 * <p>Despite the method name, this method attempts to avoid actually copying
334 * the data when it is safe to do so. The exact circumstances under which a
335 * copy will or will not be performed are undocumented and subject to change.
336 *
337 * @throws NullPointerException if {@code comparator} or any of {@code
338 * elements} is null
339 */
340 public static <E> ImmutableSortedSet<E> copyOf(
341 Comparator<? super E> comparator, Iterable<? extends E> elements) {
342 checkNotNull(comparator);
343 return copyOfInternal(comparator, elements);
344 }
345
346 /**
347 * Returns an immutable sorted set containing the given elements sorted by
348 * the given {@code Comparator}. When multiple elements are equivalent
349 * according to {@code compareTo()}, only the first one specified is
350 * included.
351 *
352 * <p>Despite the method name, this method attempts to avoid actually copying
353 * the data when it is safe to do so. The exact circumstances under which a
354 * copy will or will not be performed are undocumented and subject to change.
355 *
356 * <p>This method is safe to use even when {@code elements} is a synchronized
357 * or concurrent collection that is currently being modified by another
358 * thread.
359 *
360 * @throws NullPointerException if {@code comparator} or any of
361 * {@code elements} is null
362 * @since 7.0 (source-compatible since 2.0)
363 */
364 public static <E> ImmutableSortedSet<E> copyOf(
365 Comparator<? super E> comparator, Collection<? extends E> elements) {
366 checkNotNull(comparator);
367 return copyOfInternal(comparator, elements);
368 }
369
370 /**
371 * Returns an immutable sorted set containing the elements of a sorted set,
372 * sorted by the same {@code Comparator}. That behavior differs from {@link
373 * #copyOf(Iterable)}, which always uses the natural ordering of the
374 * elements.
375 *
376 * <p>Despite the method name, this method attempts to avoid actually copying
377 * the data when it is safe to do so. The exact circumstances under which a
378 * copy will or will not be performed are undocumented and subject to change.
379 *
380 * <p>This method is safe to use even when {@code sortedSet} is a synchronized
381 * or concurrent collection that is currently being modified by another
382 * thread.
383 *
384 * @throws NullPointerException if {@code sortedSet} or any of its elements
385 * is null
386 */
387 @SuppressWarnings("unchecked")
388 public static <E> ImmutableSortedSet<E> copyOfSorted(SortedSet<E> sortedSet) {
389 Comparator<? super E> comparator = sortedSet.comparator();
390 if (comparator == null) {
391 comparator = (Comparator<? super E>) NATURAL_ORDER;
392 }
393 return copyOfInternal(comparator, sortedSet);
394 }
395
396 private static <E> ImmutableSortedSet<E> copyOfInternal(
397 Comparator<? super E> comparator, Iterable<? extends E> elements) {
398 boolean hasSameComparator =
399 SortedIterables.hasSameComparator(comparator, elements);
400
401 if (hasSameComparator && (elements instanceof ImmutableSortedSet)) {
402 @SuppressWarnings("unchecked")
403 ImmutableSortedSet<E> original = (ImmutableSortedSet<E>) elements;
404 if (!original.isPartialView()) {
405 return original;
406 }
407 }
408 ImmutableList<E> list = ImmutableList.copyOf(
409 SortedIterables.sortedUnique(comparator, elements));
410 return list.isEmpty()
411 ? ImmutableSortedSet.<E>emptySet(comparator)
412 : new RegularImmutableSortedSet<E>(list, comparator);
413 }
414
415 private static <E> ImmutableSortedSet<E> copyOfInternal(
416 Comparator<? super E> comparator, Iterator<? extends E> elements) {
417 ImmutableList<E> list =
418 ImmutableList.copyOf(SortedIterables.sortedUnique(comparator, elements));
419 return list.isEmpty()
420 ? ImmutableSortedSet.<E>emptySet(comparator)
421 : new RegularImmutableSortedSet<E>(list, comparator);
422 }
423
424 /**
425 * Returns a builder that creates immutable sorted sets with an explicit
426 * comparator. If the comparator has a more general type than the set being
427 * generated, such as creating a {@code SortedSet<Integer>} with a
428 * {@code Comparator<Number>}, use the {@link Builder} constructor instead.
429 *
430 * @throws NullPointerException if {@code comparator} is null
431 */
432 public static <E> Builder<E> orderedBy(Comparator<E> comparator) {
433 return new Builder<E>(comparator);
434 }
435
436 /**
437 * Returns a builder that creates immutable sorted sets whose elements are
438 * ordered by the reverse of their natural ordering.
439 *
440 * <p>Note: the type parameter {@code E} extends {@code Comparable<E>} rather
441 * than {@code Comparable<? super E>} as a workaround for javac <a
442 * href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6468354">bug
443 * 6468354</a>.
444 */
445 public static <E extends Comparable<E>> Builder<E> reverseOrder() {
446 return new Builder<E>(Ordering.natural().reverse());
447 }
448
449 /**
450 * Returns a builder that creates immutable sorted sets whose elements are
451 * ordered by their natural ordering. The sorted sets use {@link
452 * Ordering#natural()} as the comparator. This method provides more
453 * type-safety than {@link #builder}, as it can be called only for classes
454 * that implement {@link Comparable}.
455 *
456 * <p>Note: the type parameter {@code E} extends {@code Comparable<E>} rather
457 * than {@code Comparable<? super E>} as a workaround for javac <a
458 * href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6468354">bug
459 * 6468354</a>.
460 */
461 public static <E extends Comparable<E>> Builder<E> naturalOrder() {
462 return new Builder<E>(Ordering.natural());
463 }
464
465 /**
466 * A builder for creating immutable sorted set instances, especially {@code
467 * public static final} sets ("constant sets"), with a given comparator.
468 * Example: <pre> {@code
469 *
470 * public static final ImmutableSortedSet<Number> LUCKY_NUMBERS =
471 * new ImmutableSortedSet.Builder<Number>(ODDS_FIRST_COMPARATOR)
472 * .addAll(SINGLE_DIGIT_PRIMES)
473 * .add(42)
474 * .build();}</pre>
475 *
476 * Builder instances can be reused; it is safe to call {@link #build} multiple
477 * times to build multiple sets in series. Each set is a superset of the set
478 * created before it.
479 *
480 * @since 2.0 (imported from Google Collections Library)
481 */
482 public static final class Builder<E> extends ImmutableSet.Builder<E> {
483 private final Comparator<? super E> comparator;
484
485 /**
486 * Creates a new builder. The returned builder is equivalent to the builder
487 * generated by {@link ImmutableSortedSet#orderedBy}.
488 */
489 public Builder(Comparator<? super E> comparator) {
490 this.comparator = checkNotNull(comparator);
491 }
492
493 /**
494 * Adds {@code element} to the {@code ImmutableSortedSet}. If the
495 * {@code ImmutableSortedSet} already contains {@code element}, then
496 * {@code add} has no effect. (only the previously added element
497 * is retained).
498 *
499 * @param element the element to add
500 * @return this {@code Builder} object
501 * @throws NullPointerException if {@code element} is null
502 */
503 @Override public Builder<E> add(E element) {
504 super.add(element);
505 return this;
506 }
507
508 /**
509 * Adds each element of {@code elements} to the {@code ImmutableSortedSet},
510 * ignoring duplicate elements (only the first duplicate element is added).
511 *
512 * @param elements the elements to add
513 * @return this {@code Builder} object
514 * @throws NullPointerException if {@code elements} contains a null element
515 */
516 @Override public Builder<E> add(E... elements) {
517 super.add(elements);
518 return this;
519 }
520
521 /**
522 * Adds each element of {@code elements} to the {@code ImmutableSortedSet},
523 * ignoring duplicate elements (only the first duplicate element is added).
524 *
525 * @param elements the elements to add to the {@code ImmutableSortedSet}
526 * @return this {@code Builder} object
527 * @throws NullPointerException if {@code elements} contains a null element
528 */
529 @Override public Builder<E> addAll(Iterable<? extends E> elements) {
530 super.addAll(elements);
531 return this;
532 }
533
534 /**
535 * Adds each element of {@code elements} to the {@code ImmutableSortedSet},
536 * ignoring duplicate elements (only the first duplicate element is added).
537 *
538 * @param elements the elements to add to the {@code ImmutableSortedSet}
539 * @return this {@code Builder} object
540 * @throws NullPointerException if {@code elements} contains a null element
541 */
542 @Override public Builder<E> addAll(Iterator<? extends E> elements) {
543 super.addAll(elements);
544 return this;
545 }
546
547 /**
548 * Returns a newly-created {@code ImmutableSortedSet} based on the contents
549 * of the {@code Builder} and its comparator.
550 */
551 @Override public ImmutableSortedSet<E> build() {
552 return copyOfInternal(comparator, contents.iterator());
553 }
554 }
555
556 int unsafeCompare(Object a, Object b) {
557 return unsafeCompare(comparator, a, b);
558 }
559
560 static int unsafeCompare(
561 Comparator<?> comparator, Object a, Object b) {
562 // Pretend the comparator can compare anything. If it turns out it can't
563 // compare a and b, we should get a CCE on the subsequent line. Only methods
564 // that are spec'd to throw CCE should call this.
565 @SuppressWarnings("unchecked")
566 Comparator<Object> unsafeComparator = (Comparator<Object>) comparator;
567 return unsafeComparator.compare(a, b);
568 }
569
570 final transient Comparator<? super E> comparator;
571
572 ImmutableSortedSet(Comparator<? super E> comparator) {
573 this.comparator = comparator;
574 }
575
576 /**
577 * Returns the comparator that orders the elements, which is
578 * {@link Ordering#natural()} when the natural ordering of the
579 * elements is used. Note that its behavior is not consistent with
580 * {@link SortedSet#comparator()}, which returns {@code null} to indicate
581 * natural ordering.
582 */
583 @Override
584 public Comparator<? super E> comparator() {
585 return comparator;
586 }
587
588 @Override // needed to unify the iterator() methods in Collection and SortedIterable
589 public abstract UnmodifiableIterator<E> iterator();
590
591 /**
592 * {@inheritDoc}
593 *
594 * <p>This method returns a serializable {@code ImmutableSortedSet}.
595 *
596 * <p>The {@link SortedSet#headSet} documentation states that a subset of a
597 * subset throws an {@link IllegalArgumentException} if passed a
598 * {@code toElement} greater than an earlier {@code toElement}. However, this
599 * method doesn't throw an exception in that situation, but instead keeps the
600 * original {@code toElement}.
601 */
602 @Override
603 public ImmutableSortedSet<E> headSet(E toElement) {
604 return headSet(toElement, false);
605 }
606
607 /**
608 * @since 12.0
609 */
610 @GwtIncompatible("NavigableSet")
611 @Override
612 public ImmutableSortedSet<E> headSet(E toElement, boolean inclusive) {
613 return headSetImpl(checkNotNull(toElement), inclusive);
614 }
615
616 /**
617 * {@inheritDoc}
618 *
619 * <p>This method returns a serializable {@code ImmutableSortedSet}.
620 *
621 * <p>The {@link SortedSet#subSet} documentation states that a subset of a
622 * subset throws an {@link IllegalArgumentException} if passed a
623 * {@code fromElement} smaller than an earlier {@code fromElement}. However,
624 * this method doesn't throw an exception in that situation, but instead keeps
625 * the original {@code fromElement}. Similarly, this method keeps the
626 * original {@code toElement}, instead of throwing an exception, if passed a
627 * {@code toElement} greater than an earlier {@code toElement}.
628 */
629 @Override
630 public ImmutableSortedSet<E> subSet(E fromElement, E toElement) {
631 return subSet(fromElement, true, toElement, false);
632 }
633
634 /**
635 * @since 12.0
636 */
637 @GwtIncompatible("NavigableSet")
638 @Override
639 public ImmutableSortedSet<E> subSet(
640 E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
641 checkNotNull(fromElement);
642 checkNotNull(toElement);
643 checkArgument(comparator.compare(fromElement, toElement) <= 0);
644 return subSetImpl(fromElement, fromInclusive, toElement, toInclusive);
645 }
646
647 /**
648 * {@inheritDoc}
649 *
650 * <p>This method returns a serializable {@code ImmutableSortedSet}.
651 *
652 * <p>The {@link SortedSet#tailSet} documentation states that a subset of a
653 * subset throws an {@link IllegalArgumentException} if passed a
654 * {@code fromElement} smaller than an earlier {@code fromElement}. However,
655 * this method doesn't throw an exception in that situation, but instead keeps
656 * the original {@code fromElement}.
657 */
658 @Override
659 public ImmutableSortedSet<E> tailSet(E fromElement) {
660 return tailSet(fromElement, true);
661 }
662
663 /**
664 * @since 12.0
665 */
666 @GwtIncompatible("NavigableSet")
667 @Override
668 public ImmutableSortedSet<E> tailSet(E fromElement, boolean inclusive) {
669 return tailSetImpl(checkNotNull(fromElement), inclusive);
670 }
671
672 /*
673 * These methods perform most headSet, subSet, and tailSet logic, besides
674 * parameter validation.
675 */
676 abstract ImmutableSortedSet<E> headSetImpl(E toElement, boolean inclusive);
677
678 abstract ImmutableSortedSet<E> subSetImpl(
679 E fromElement, boolean fromInclusive, E toElement, boolean toInclusive);
680
681 abstract ImmutableSortedSet<E> tailSetImpl(E fromElement, boolean inclusive);
682
683 /**
684 * @since 12.0
685 */
686 @GwtIncompatible("NavigableSet")
687 @Override
688 public E lower(E e) {
689 return Iterables.getFirst(headSet(e, false).descendingSet(), null);
690 }
691
692 /**
693 * @since 12.0
694 */
695 @GwtIncompatible("NavigableSet")
696 @Override
697 public E floor(E e) {
698 return Iterables.getFirst(headSet(e, true).descendingSet(), null);
699 }
700
701 /**
702 * @since 12.0
703 */
704 @GwtIncompatible("NavigableSet")
705 @Override
706 public E ceiling(E e) {
707 return Iterables.getFirst(tailSet(e, true), null);
708 }
709
710 /**
711 * @since 12.0
712 */
713 @GwtIncompatible("NavigableSet")
714 @Override
715 public E higher(E e) {
716 return Iterables.getFirst(tailSet(e, false), null);
717 }
718
719 /**
720 * @since 12.0
721 */
722 @GwtIncompatible("NavigableSet")
723 @Override
724 public final E pollFirst() {
725 throw new UnsupportedOperationException();
726 }
727
728 /**
729 * @since 12.0
730 */
731 @GwtIncompatible("NavigableSet")
732 @Override
733 public final E pollLast() {
734 throw new UnsupportedOperationException();
735 }
736
737 @GwtIncompatible("NavigableSet")
738 transient ImmutableSortedSet<E> descendingSet;
739
740 /**
741 * @since 12.0
742 */
743 @GwtIncompatible("NavigableSet")
744 @Override
745 public ImmutableSortedSet<E> descendingSet() {
746 ImmutableSortedSet<E> result = descendingSet;
747 if (result == null) {
748 result = descendingSet = createDescendingSet();
749 result.descendingSet = this;
750 }
751 return result;
752 }
753
754 @GwtIncompatible("NavigableSet")
755 abstract ImmutableSortedSet<E> createDescendingSet();
756
757 /**
758 * @since 12.0
759 */
760 @GwtIncompatible("NavigableSet")
761 @Override
762 public UnmodifiableIterator<E> descendingIterator() {
763 return descendingSet().iterator();
764 }
765
766 /**
767 * Returns the position of an element within the set, or -1 if not present.
768 */
769 abstract int indexOf(@Nullable Object target);
770
771 /*
772 * This class is used to serialize all ImmutableSortedSet instances,
773 * regardless of implementation type. It captures their "logical contents"
774 * only. This is necessary to ensure that the existence of a particular
775 * implementation type is an implementation detail.
776 */
777 private static class SerializedForm<E> implements Serializable {
778 final Comparator<? super E> comparator;
779 final Object[] elements;
780
781 public SerializedForm(Comparator<? super E> comparator, Object[] elements) {
782 this.comparator = comparator;
783 this.elements = elements;
784 }
785
786 @SuppressWarnings("unchecked")
787 Object readResolve() {
788 return new Builder<E>(comparator).add((E[]) elements).build();
789 }
790
791 private static final long serialVersionUID = 0;
792 }
793
794 private void readObject(ObjectInputStream stream)
795 throws InvalidObjectException {
796 throw new InvalidObjectException("Use SerializedForm");
797 }
798
799 @Override Object writeReplace() {
800 return new SerializedForm<E>(comparator, toArray());
801 }
802 }
803