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 017package com.google.common.collect; 018 019import static com.google.common.base.Preconditions.checkArgument; 020import static com.google.common.base.Preconditions.checkNotNull; 021import static com.google.common.collect.ObjectArrays.checkElementsNotNull; 022 023import com.google.common.annotations.GwtCompatible; 024import com.google.common.annotations.GwtIncompatible; 025import com.google.errorprone.annotations.CanIgnoreReturnValue; 026import com.google.errorprone.annotations.DoNotCall; 027import com.google.errorprone.annotations.concurrent.LazyInit; 028import java.io.InvalidObjectException; 029import java.io.ObjectInputStream; 030import java.io.Serializable; 031import java.util.Arrays; 032import java.util.Collection; 033import java.util.Collections; 034import java.util.Comparator; 035import java.util.Iterator; 036import java.util.NavigableSet; 037import java.util.SortedSet; 038import javax.annotation.CheckForNull; 039import org.checkerframework.checker.nullness.qual.Nullable; 040 041/** 042 * A {@link NavigableSet} whose contents will never change, with many other important properties 043 * detailed at {@link ImmutableCollection}. 044 * 045 * <p><b>Warning:</b> as with any sorted collection, you are strongly advised not to use a {@link 046 * Comparator} or {@link Comparable} type whose comparison behavior is <i>inconsistent with 047 * equals</i>. That is, {@code a.compareTo(b)} or {@code comparator.compare(a, b)} should equal zero 048 * <i>if and only if</i> {@code a.equals(b)}. If this advice is not followed, the resulting 049 * collection will not correctly obey its specification. 050 * 051 * <p>See the Guava User Guide article on <a href= 052 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>. 053 * 054 * @author Jared Levy 055 * @author Louis Wasserman 056 * @since 2.0 (implements {@code NavigableSet} since 12.0) 057 */ 058// TODO(benyu): benchmark and optimize all creation paths, which are a mess now 059@GwtCompatible(serializable = true, emulated = true) 060@SuppressWarnings("serial") // we're overriding default serialization 061@ElementTypesAreNonnullByDefault 062public abstract class ImmutableSortedSet<E> extends ImmutableSortedSetFauxverideShim<E> 063 implements NavigableSet<E>, SortedIterable<E> { 064 static <E> RegularImmutableSortedSet<E> emptySet(Comparator<? super E> comparator) { 065 if (Ordering.natural().equals(comparator)) { 066 return (RegularImmutableSortedSet<E>) RegularImmutableSortedSet.NATURAL_EMPTY_SET; 067 } else { 068 return new RegularImmutableSortedSet<E>(ImmutableList.<E>of(), comparator); 069 } 070 } 071 072 /** 073 * Returns the empty immutable sorted set. 074 * 075 * <p><b>Performance note:</b> the instance returned is a singleton. 076 */ 077 public static <E> ImmutableSortedSet<E> of() { 078 return (ImmutableSortedSet<E>) RegularImmutableSortedSet.NATURAL_EMPTY_SET; 079 } 080 081 /** Returns an immutable sorted set containing a single element. */ 082 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(E element) { 083 return new RegularImmutableSortedSet<E>(ImmutableList.of(element), Ordering.natural()); 084 } 085 086 /** 087 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 088 * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first 089 * one specified is included. 090 * 091 * @throws NullPointerException if any element is null 092 */ 093 @SuppressWarnings("unchecked") 094 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(E e1, E e2) { 095 return construct(Ordering.natural(), 2, e1, e2); 096 } 097 098 /** 099 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 100 * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first 101 * one specified is included. 102 * 103 * @throws NullPointerException if any element is null 104 */ 105 @SuppressWarnings("unchecked") 106 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(E e1, E e2, E e3) { 107 return construct(Ordering.natural(), 3, e1, e2, e3); 108 } 109 110 /** 111 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 112 * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first 113 * one specified is included. 114 * 115 * @throws NullPointerException if any element is null 116 */ 117 @SuppressWarnings("unchecked") 118 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4) { 119 return construct(Ordering.natural(), 4, e1, e2, e3, e4); 120 } 121 122 /** 123 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 124 * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first 125 * one specified is included. 126 * 127 * @throws NullPointerException if any element is null 128 */ 129 @SuppressWarnings("unchecked") 130 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of( 131 E e1, E e2, E e3, E e4, E e5) { 132 return construct(Ordering.natural(), 5, e1, e2, e3, e4, e5); 133 } 134 135 /** 136 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 137 * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first 138 * one specified is included. 139 * 140 * @throws NullPointerException if any element is null 141 * @since 3.0 (source-compatible since 2.0) 142 */ 143 @SuppressWarnings("unchecked") 144 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> of( 145 E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) { 146 Comparable[] contents = new Comparable[6 + remaining.length]; 147 contents[0] = e1; 148 contents[1] = e2; 149 contents[2] = e3; 150 contents[3] = e4; 151 contents[4] = e5; 152 contents[5] = e6; 153 System.arraycopy(remaining, 0, contents, 6, remaining.length); 154 return construct(Ordering.natural(), contents.length, (E[]) contents); 155 } 156 157 // TODO(kevinb): Consider factory methods that reject duplicates 158 159 /** 160 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 161 * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first 162 * one specified is included. 163 * 164 * @throws NullPointerException if any of {@code elements} is null 165 * @since 3.0 166 */ 167 public static <E extends Comparable<? super E>> ImmutableSortedSet<E> copyOf(E[] elements) { 168 return construct(Ordering.natural(), elements.length, elements.clone()); 169 } 170 171 /** 172 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 173 * When multiple elements are equivalent according to {@code compareTo()}, only the first one 174 * specified is included. To create a copy of a {@code SortedSet} that preserves the comparator, 175 * call {@link #copyOfSorted} instead. This method iterates over {@code elements} at most once. 176 * 177 * <p>Note that if {@code s} is a {@code Set<String>}, then {@code ImmutableSortedSet.copyOf(s)} 178 * returns an {@code ImmutableSortedSet<String>} containing each of the strings in {@code s}, 179 * while {@code ImmutableSortedSet.of(s)} returns an {@code ImmutableSortedSet<Set<String>>} 180 * containing one element (the given set itself). 181 * 182 * <p>Despite the method name, this method attempts to avoid actually copying the data when it is 183 * safe to do so. The exact circumstances under which a copy will or will not be performed are 184 * undocumented and subject to change. 185 * 186 * <p>This method is not type-safe, as it may be called on elements that are not mutually 187 * comparable. 188 * 189 * @throws ClassCastException if the elements are not mutually comparable 190 * @throws NullPointerException if any of {@code elements} is null 191 */ 192 public static <E> ImmutableSortedSet<E> copyOf(Iterable<? extends E> elements) { 193 // Hack around E not being a subtype of Comparable. 194 // Unsafe, see ImmutableSortedSetFauxverideShim. 195 @SuppressWarnings("unchecked") 196 Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable>natural(); 197 return copyOf(naturalOrder, elements); 198 } 199 200 /** 201 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 202 * When multiple elements are equivalent according to {@code compareTo()}, only the first one 203 * specified is included. To create a copy of a {@code SortedSet} that preserves the comparator, 204 * call {@link #copyOfSorted} instead. This method iterates over {@code elements} at most once. 205 * 206 * <p>Note that if {@code s} is a {@code Set<String>}, then {@code ImmutableSortedSet.copyOf(s)} 207 * returns an {@code ImmutableSortedSet<String>} containing each of the strings in {@code s}, 208 * while {@code ImmutableSortedSet.of(s)} returns an {@code ImmutableSortedSet<Set<String>>} 209 * containing one element (the given set itself). 210 * 211 * <p><b>Note:</b> Despite what the method name suggests, if {@code elements} is an {@code 212 * ImmutableSortedSet}, it may be returned instead of a copy. 213 * 214 * <p>This method is not type-safe, as it may be called on elements that are not mutually 215 * comparable. 216 * 217 * <p>This method is safe to use even when {@code elements} is a synchronized or concurrent 218 * collection that is currently being modified by another thread. 219 * 220 * @throws ClassCastException if the elements are not mutually comparable 221 * @throws NullPointerException if any of {@code elements} is null 222 * @since 7.0 (source-compatible since 2.0) 223 */ 224 public static <E> ImmutableSortedSet<E> copyOf(Collection<? extends E> elements) { 225 // Hack around E not being a subtype of Comparable. 226 // Unsafe, see ImmutableSortedSetFauxverideShim. 227 @SuppressWarnings("unchecked") 228 Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable>natural(); 229 return copyOf(naturalOrder, elements); 230 } 231 232 /** 233 * Returns an immutable sorted set containing the given elements sorted by their natural ordering. 234 * When multiple elements are equivalent according to {@code compareTo()}, only the first one 235 * specified is included. 236 * 237 * <p>This method is not type-safe, as it may be called on elements that are not mutually 238 * comparable. 239 * 240 * @throws ClassCastException if the elements are not mutually comparable 241 * @throws NullPointerException if any of {@code elements} is null 242 */ 243 public static <E> ImmutableSortedSet<E> copyOf(Iterator<? extends E> elements) { 244 // Hack around E not being a subtype of Comparable. 245 // Unsafe, see ImmutableSortedSetFauxverideShim. 246 @SuppressWarnings("unchecked") 247 Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable>natural(); 248 return copyOf(naturalOrder, elements); 249 } 250 251 /** 252 * Returns an immutable sorted set containing the given elements sorted by the given {@code 253 * Comparator}. When multiple elements are equivalent according to {@code compareTo()}, only the 254 * first one specified is included. 255 * 256 * @throws NullPointerException if {@code comparator} or any of {@code elements} is null 257 */ 258 public static <E> ImmutableSortedSet<E> copyOf( 259 Comparator<? super E> comparator, Iterator<? extends E> elements) { 260 return new Builder<E>(comparator).addAll(elements).build(); 261 } 262 263 /** 264 * Returns an immutable sorted set containing the given elements sorted by the given {@code 265 * Comparator}. When multiple elements are equivalent according to {@code compare()}, only the 266 * first one specified is included. This method iterates over {@code elements} at most once. 267 * 268 * <p>Despite the method name, this method attempts to avoid actually copying the data when it is 269 * safe to do so. The exact circumstances under which a copy will or will not be performed are 270 * undocumented and subject to change. 271 * 272 * @throws NullPointerException if {@code comparator} or any of {@code elements} is null 273 */ 274 public static <E> ImmutableSortedSet<E> copyOf( 275 Comparator<? super E> comparator, Iterable<? extends E> elements) { 276 checkNotNull(comparator); 277 boolean hasSameComparator = SortedIterables.hasSameComparator(comparator, elements); 278 279 if (hasSameComparator && (elements instanceof ImmutableSortedSet)) { 280 @SuppressWarnings("unchecked") 281 ImmutableSortedSet<E> original = (ImmutableSortedSet<E>) elements; 282 if (!original.isPartialView()) { 283 return original; 284 } 285 } 286 @SuppressWarnings("unchecked") // elements only contains E's; it's safe. 287 E[] array = (E[]) Iterables.toArray(elements); 288 return construct(comparator, array.length, array); 289 } 290 291 /** 292 * Returns an immutable sorted set containing the given elements sorted by the given {@code 293 * Comparator}. When multiple elements are equivalent according to {@code compareTo()}, only the 294 * first one specified is included. 295 * 296 * <p>Despite the method name, this method attempts to avoid actually copying the data when it is 297 * safe to do so. The exact circumstances under which a copy will or will not be performed are 298 * undocumented and subject to change. 299 * 300 * <p>This method is safe to use even when {@code elements} is a synchronized or concurrent 301 * collection that is currently being modified by another thread. 302 * 303 * @throws NullPointerException if {@code comparator} or any of {@code elements} is null 304 * @since 7.0 (source-compatible since 2.0) 305 */ 306 public static <E> ImmutableSortedSet<E> copyOf( 307 Comparator<? super E> comparator, Collection<? extends E> elements) { 308 return copyOf(comparator, (Iterable<? extends E>) elements); 309 } 310 311 /** 312 * Returns an immutable sorted set containing the elements of a sorted set, sorted by the same 313 * {@code Comparator}. That behavior differs from {@link #copyOf(Iterable)}, which always uses the 314 * natural ordering of the elements. 315 * 316 * <p>Despite the method name, this method attempts to avoid actually copying the data when it is 317 * safe to do so. The exact circumstances under which a copy will or will not be performed are 318 * undocumented and subject to change. 319 * 320 * <p>This method is safe to use even when {@code sortedSet} is a synchronized or concurrent 321 * collection that is currently being modified by another thread. 322 * 323 * @throws NullPointerException if {@code sortedSet} or any of its elements is null 324 */ 325 public static <E> ImmutableSortedSet<E> copyOfSorted(SortedSet<E> sortedSet) { 326 Comparator<? super E> comparator = SortedIterables.comparator(sortedSet); 327 ImmutableList<E> list = ImmutableList.copyOf(sortedSet); 328 if (list.isEmpty()) { 329 return emptySet(comparator); 330 } else { 331 return new RegularImmutableSortedSet<E>(list, comparator); 332 } 333 } 334 335 /** 336 * Constructs an {@code ImmutableSortedSet} from the first {@code n} elements of {@code contents}. 337 * If {@code k} is the size of the returned {@code ImmutableSortedSet}, then the sorted unique 338 * elements are in the first {@code k} positions of {@code contents}, and {@code contents[i] == 339 * null} for {@code k <= i < n}. 340 * 341 * <p>This method takes ownership of {@code contents}; do not modify {@code contents} after this 342 * returns. 343 * 344 * @throws NullPointerException if any of the first {@code n} elements of {@code contents} is null 345 */ 346 static <E> ImmutableSortedSet<E> construct( 347 Comparator<? super E> comparator, int n, E... contents) { 348 if (n == 0) { 349 return emptySet(comparator); 350 } 351 checkElementsNotNull(contents, n); 352 Arrays.sort(contents, 0, n, comparator); 353 int uniques = 1; 354 for (int i = 1; i < n; i++) { 355 E cur = contents[i]; 356 E prev = contents[uniques - 1]; 357 if (comparator.compare(cur, prev) != 0) { 358 contents[uniques++] = cur; 359 } 360 } 361 Arrays.fill(contents, uniques, n, null); 362 if (uniques < contents.length / 2) { 363 // Deduplication eliminated many of the elements. We don't want to retain an arbitrarily 364 // large array relative to the number of elements, so we cap the ratio. 365 contents = Arrays.copyOf(contents, uniques); 366 } 367 return new RegularImmutableSortedSet<E>( 368 ImmutableList.<E>asImmutableList(contents, uniques), comparator); 369 } 370 371 /** 372 * Returns a builder that creates immutable sorted sets with an explicit comparator. If the 373 * comparator has a more general type than the set being generated, such as creating a {@code 374 * SortedSet<Integer>} with a {@code Comparator<Number>}, use the {@link Builder} constructor 375 * instead. 376 * 377 * @throws NullPointerException if {@code comparator} is null 378 */ 379 public static <E> Builder<E> orderedBy(Comparator<E> comparator) { 380 return new Builder<E>(comparator); 381 } 382 383 /** 384 * Returns a builder that creates immutable sorted sets whose elements are ordered by the reverse 385 * of their natural ordering. 386 */ 387 public static <E extends Comparable<?>> Builder<E> reverseOrder() { 388 return new Builder<E>(Collections.reverseOrder()); 389 } 390 391 /** 392 * Returns a builder that creates immutable sorted sets whose elements are ordered by their 393 * natural ordering. The sorted sets use {@link Ordering#natural()} as the comparator. This method 394 * provides more type-safety than {@link #builder}, as it can be called only for classes that 395 * implement {@link Comparable}. 396 */ 397 public static <E extends Comparable<?>> Builder<E> naturalOrder() { 398 return new Builder<E>(Ordering.natural()); 399 } 400 401 /** 402 * A builder for creating immutable sorted set instances, especially {@code public static final} 403 * sets ("constant sets"), with a given comparator. Example: 404 * 405 * <pre>{@code 406 * public static final ImmutableSortedSet<Number> LUCKY_NUMBERS = 407 * new ImmutableSortedSet.Builder<Number>(ODDS_FIRST_COMPARATOR) 408 * .addAll(SINGLE_DIGIT_PRIMES) 409 * .add(42) 410 * .build(); 411 * }</pre> 412 * 413 * <p>Builder instances can be reused; it is safe to call {@link #build} multiple times to build 414 * multiple sets in series. Each set is a superset of the set created before it. 415 * 416 * @since 2.0 417 */ 418 public static final class Builder<E> extends ImmutableSet.Builder<E> { 419 private final Comparator<? super E> comparator; 420 421 /** 422 * Creates a new builder. The returned builder is equivalent to the builder generated by {@link 423 * ImmutableSortedSet#orderedBy}. 424 */ 425 public Builder(Comparator<? super E> comparator) { 426 this.comparator = checkNotNull(comparator); 427 } 428 429 /** 430 * Adds {@code element} to the {@code ImmutableSortedSet}. If the {@code ImmutableSortedSet} 431 * already contains {@code element}, then {@code add} has no effect. (only the previously added 432 * element is retained). 433 * 434 * @param element the element to add 435 * @return this {@code Builder} object 436 * @throws NullPointerException if {@code element} is null 437 */ 438 @CanIgnoreReturnValue 439 @Override 440 public Builder<E> add(E element) { 441 super.add(element); 442 return this; 443 } 444 445 /** 446 * Adds each element of {@code elements} to the {@code ImmutableSortedSet}, ignoring duplicate 447 * elements (only the first duplicate element is added). 448 * 449 * @param elements the elements to add 450 * @return this {@code Builder} object 451 * @throws NullPointerException if {@code elements} contains a null element 452 */ 453 @CanIgnoreReturnValue 454 @Override 455 public Builder<E> add(E... elements) { 456 super.add(elements); 457 return this; 458 } 459 460 /** 461 * Adds each element of {@code elements} to the {@code ImmutableSortedSet}, ignoring duplicate 462 * elements (only the first duplicate element is added). 463 * 464 * @param elements the elements to add to the {@code ImmutableSortedSet} 465 * @return this {@code Builder} object 466 * @throws NullPointerException if {@code elements} contains a null element 467 */ 468 @CanIgnoreReturnValue 469 @Override 470 public Builder<E> addAll(Iterable<? extends E> elements) { 471 super.addAll(elements); 472 return this; 473 } 474 475 /** 476 * Adds each element of {@code elements} to the {@code ImmutableSortedSet}, ignoring duplicate 477 * elements (only the first duplicate element is added). 478 * 479 * @param elements the elements to add to the {@code ImmutableSortedSet} 480 * @return this {@code Builder} object 481 * @throws NullPointerException if {@code elements} contains a null element 482 */ 483 @CanIgnoreReturnValue 484 @Override 485 public Builder<E> addAll(Iterator<? extends E> elements) { 486 super.addAll(elements); 487 return this; 488 } 489 490 @CanIgnoreReturnValue 491 @Override 492 Builder<E> combine(ImmutableSet.Builder<E> builder) { 493 super.combine(builder); 494 return this; 495 } 496 497 /** 498 * Returns a newly-created {@code ImmutableSortedSet} based on the contents of the {@code 499 * Builder} and its comparator. 500 */ 501 @Override 502 public ImmutableSortedSet<E> build() { 503 @SuppressWarnings("unchecked") // we're careful to put only E's in here 504 E[] contentsArray = (E[]) contents; 505 ImmutableSortedSet<E> result = construct(comparator, size, contentsArray); 506 this.size = result.size(); // we eliminated duplicates in-place in contentsArray 507 this.forceCopy = true; 508 return result; 509 } 510 } 511 512 int unsafeCompare(Object a, @CheckForNull Object b) { 513 return unsafeCompare(comparator, a, b); 514 } 515 516 static int unsafeCompare(Comparator<?> comparator, Object a, @CheckForNull Object b) { 517 // Pretend the comparator can compare anything. If it turns out it can't 518 // compare a and b, we should get a CCE or NPE on the subsequent line. Only methods 519 // that are spec'd to throw CCE and NPE should call this. 520 @SuppressWarnings({"unchecked", "nullness"}) 521 Comparator<@Nullable Object> unsafeComparator = (Comparator<@Nullable Object>) comparator; 522 return unsafeComparator.compare(a, b); 523 } 524 525 final transient Comparator<? super E> comparator; 526 527 ImmutableSortedSet(Comparator<? super E> comparator) { 528 this.comparator = comparator; 529 } 530 531 /** 532 * Returns the comparator that orders the elements, which is {@link Ordering#natural()} when the 533 * natural ordering of the elements is used. Note that its behavior is not consistent with {@link 534 * SortedSet#comparator()}, which returns {@code null} to indicate natural ordering. 535 */ 536 @Override 537 public Comparator<? super E> comparator() { 538 return comparator; 539 } 540 541 @Override // needed to unify the iterator() methods in Collection and SortedIterable 542 public abstract UnmodifiableIterator<E> iterator(); 543 544 /** 545 * {@inheritDoc} 546 * 547 * <p>This method returns a serializable {@code ImmutableSortedSet}. 548 * 549 * <p>The {@link SortedSet#headSet} documentation states that a subset of a subset throws an 550 * {@link IllegalArgumentException} if passed a {@code toElement} greater than an earlier {@code 551 * toElement}. However, this method doesn't throw an exception in that situation, but instead 552 * keeps the original {@code toElement}. 553 */ 554 @Override 555 public ImmutableSortedSet<E> headSet(E toElement) { 556 return headSet(toElement, false); 557 } 558 559 /** @since 12.0 */ 560 @Override 561 public ImmutableSortedSet<E> headSet(E toElement, boolean inclusive) { 562 return headSetImpl(checkNotNull(toElement), inclusive); 563 } 564 565 /** 566 * {@inheritDoc} 567 * 568 * <p>This method returns a serializable {@code ImmutableSortedSet}. 569 * 570 * <p>The {@link SortedSet#subSet} documentation states that a subset of a subset throws an {@link 571 * IllegalArgumentException} if passed a {@code fromElement} smaller than an earlier {@code 572 * fromElement}. However, this method doesn't throw an exception in that situation, but instead 573 * keeps the original {@code fromElement}. Similarly, this method keeps the original {@code 574 * toElement}, instead of throwing an exception, if passed a {@code toElement} greater than an 575 * earlier {@code toElement}. 576 */ 577 @Override 578 public ImmutableSortedSet<E> subSet(E fromElement, E toElement) { 579 return subSet(fromElement, true, toElement, false); 580 } 581 582 /** @since 12.0 */ 583 @GwtIncompatible // NavigableSet 584 @Override 585 public ImmutableSortedSet<E> subSet( 586 E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) { 587 checkNotNull(fromElement); 588 checkNotNull(toElement); 589 checkArgument(comparator.compare(fromElement, toElement) <= 0); 590 return subSetImpl(fromElement, fromInclusive, toElement, toInclusive); 591 } 592 593 /** 594 * {@inheritDoc} 595 * 596 * <p>This method returns a serializable {@code ImmutableSortedSet}. 597 * 598 * <p>The {@link SortedSet#tailSet} documentation states that a subset of a subset throws an 599 * {@link IllegalArgumentException} if passed a {@code fromElement} smaller than an earlier {@code 600 * fromElement}. However, this method doesn't throw an exception in that situation, but instead 601 * keeps the original {@code fromElement}. 602 */ 603 @Override 604 public ImmutableSortedSet<E> tailSet(E fromElement) { 605 return tailSet(fromElement, true); 606 } 607 608 /** @since 12.0 */ 609 @Override 610 public ImmutableSortedSet<E> tailSet(E fromElement, boolean inclusive) { 611 return tailSetImpl(checkNotNull(fromElement), inclusive); 612 } 613 614 /* 615 * These methods perform most headSet, subSet, and tailSet logic, besides 616 * parameter validation. 617 */ 618 abstract ImmutableSortedSet<E> headSetImpl(E toElement, boolean inclusive); 619 620 abstract ImmutableSortedSet<E> subSetImpl( 621 E fromElement, boolean fromInclusive, E toElement, boolean toInclusive); 622 623 abstract ImmutableSortedSet<E> tailSetImpl(E fromElement, boolean inclusive); 624 625 /** @since 12.0 */ 626 @GwtIncompatible // NavigableSet 627 @Override 628 @CheckForNull 629 public E lower(E e) { 630 return Iterators.getNext(headSet(e, false).descendingIterator(), null); 631 } 632 633 /** @since 12.0 */ 634 @Override 635 @CheckForNull 636 public E floor(E e) { 637 return Iterators.getNext(headSet(e, true).descendingIterator(), null); 638 } 639 640 /** @since 12.0 */ 641 @Override 642 @CheckForNull 643 public E ceiling(E e) { 644 return Iterables.getFirst(tailSet(e, true), null); 645 } 646 647 /** @since 12.0 */ 648 @GwtIncompatible // NavigableSet 649 @Override 650 @CheckForNull 651 public E higher(E e) { 652 return Iterables.getFirst(tailSet(e, false), null); 653 } 654 655 @Override 656 public E first() { 657 return iterator().next(); 658 } 659 660 @Override 661 public E last() { 662 return descendingIterator().next(); 663 } 664 665 /** 666 * Guaranteed to throw an exception and leave the set unmodified. 667 * 668 * @since 12.0 669 * @throws UnsupportedOperationException always 670 * @deprecated Unsupported operation. 671 */ 672 @CanIgnoreReturnValue 673 @Deprecated 674 @GwtIncompatible // NavigableSet 675 @Override 676 @DoNotCall("Always throws UnsupportedOperationException") 677 @CheckForNull 678 public final E pollFirst() { 679 throw new UnsupportedOperationException(); 680 } 681 682 /** 683 * Guaranteed to throw an exception and leave the set unmodified. 684 * 685 * @since 12.0 686 * @throws UnsupportedOperationException always 687 * @deprecated Unsupported operation. 688 */ 689 @CanIgnoreReturnValue 690 @Deprecated 691 @GwtIncompatible // NavigableSet 692 @Override 693 @DoNotCall("Always throws UnsupportedOperationException") 694 @CheckForNull 695 public final E pollLast() { 696 throw new UnsupportedOperationException(); 697 } 698 699 @GwtIncompatible // NavigableSet 700 @LazyInit 701 @CheckForNull 702 transient ImmutableSortedSet<E> descendingSet; 703 704 /** @since 12.0 */ 705 @GwtIncompatible // NavigableSet 706 @Override 707 public ImmutableSortedSet<E> descendingSet() { 708 // racy single-check idiom 709 ImmutableSortedSet<E> result = descendingSet; 710 if (result == null) { 711 result = descendingSet = createDescendingSet(); 712 result.descendingSet = this; 713 } 714 return result; 715 } 716 717 // Most classes should implement this as new DescendingImmutableSortedSet<E>(this), 718 // but we push down that implementation because ProGuard can't eliminate it even when it's always 719 // overridden. 720 @GwtIncompatible // NavigableSet 721 abstract ImmutableSortedSet<E> createDescendingSet(); 722 723 /** @since 12.0 */ 724 @GwtIncompatible // NavigableSet 725 @Override 726 public abstract UnmodifiableIterator<E> descendingIterator(); 727 728 /** Returns the position of an element within the set, or -1 if not present. */ 729 abstract int indexOf(@CheckForNull Object target); 730 731 /* 732 * This class is used to serialize all ImmutableSortedSet instances, 733 * regardless of implementation type. It captures their "logical contents" 734 * only. This is necessary to ensure that the existence of a particular 735 * implementation type is an implementation detail. 736 */ 737 private static class SerializedForm<E> implements Serializable { 738 final Comparator<? super E> comparator; 739 final Object[] elements; 740 741 public SerializedForm(Comparator<? super E> comparator, Object[] elements) { 742 this.comparator = comparator; 743 this.elements = elements; 744 } 745 746 @SuppressWarnings("unchecked") 747 Object readResolve() { 748 return new Builder<E>(comparator).add((E[]) elements).build(); 749 } 750 751 private static final long serialVersionUID = 0; 752 } 753 754 private void readObject(ObjectInputStream unused) throws InvalidObjectException { 755 throw new InvalidObjectException("Use SerializedForm"); 756 } 757 758 @Override 759 Object writeReplace() { 760 return new SerializedForm<E>(comparator, toArray()); 761 } 762}