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; 021 022import com.google.common.annotations.GwtCompatible; 023import com.google.common.base.Equivalence; 024import com.google.common.base.Function; 025import com.google.common.base.Predicate; 026import com.google.errorprone.annotations.Immutable; 027import java.io.Serializable; 028import java.util.Comparator; 029import java.util.Iterator; 030import java.util.NoSuchElementException; 031import java.util.SortedSet; 032import javax.annotation.CheckForNull; 033 034/** 035 * A range (or "interval") defines the <i>boundaries</i> around a contiguous span of values of some 036 * {@code Comparable} type; for example, "integers from 1 to 100 inclusive." Note that it is not 037 * possible to <i>iterate</i> over these contained values. To do so, pass this range instance and an 038 * appropriate {@link DiscreteDomain} to {@link ContiguousSet#create}. 039 * 040 * <h3>Types of ranges</h3> 041 * 042 * <p>Each end of the range may be bounded or unbounded. If bounded, there is an associated 043 * <i>endpoint</i> value, and the range is considered to be either <i>open</i> (does not include the 044 * endpoint) or <i>closed</i> (includes the endpoint) on that side. With three possibilities on each 045 * side, this yields nine basic types of ranges, enumerated below. (Notation: a square bracket 046 * ({@code [ ]}) indicates that the range is closed on that side; a parenthesis ({@code ( )}) means 047 * it is either open or unbounded. The construct {@code {x | statement}} is read "the set of all 048 * <i>x</i> such that <i>statement</i>.") 049 * 050 * <blockquote> 051 * 052 * <table> 053 * <caption>Range Types</caption> 054 * <tr><th>Notation <th>Definition <th>Factory method 055 * <tr><td>{@code (a..b)} <td>{@code {x | a < x < b}} <td>{@link Range#open open} 056 * <tr><td>{@code [a..b]} <td>{@code {x | a <= x <= b}}<td>{@link Range#closed closed} 057 * <tr><td>{@code (a..b]} <td>{@code {x | a < x <= b}} <td>{@link Range#openClosed openClosed} 058 * <tr><td>{@code [a..b)} <td>{@code {x | a <= x < b}} <td>{@link Range#closedOpen closedOpen} 059 * <tr><td>{@code (a..+∞)} <td>{@code {x | x > a}} <td>{@link Range#greaterThan greaterThan} 060 * <tr><td>{@code [a..+∞)} <td>{@code {x | x >= a}} <td>{@link Range#atLeast atLeast} 061 * <tr><td>{@code (-∞..b)} <td>{@code {x | x < b}} <td>{@link Range#lessThan lessThan} 062 * <tr><td>{@code (-∞..b]} <td>{@code {x | x <= b}} <td>{@link Range#atMost atMost} 063 * <tr><td>{@code (-∞..+∞)}<td>{@code {x}} <td>{@link Range#all all} 064 * </table> 065 * 066 * </blockquote> 067 * 068 * <p>When both endpoints exist, the upper endpoint may not be less than the lower. The endpoints 069 * may be equal only if at least one of the bounds is closed: 070 * 071 * <ul> 072 * <li>{@code [a..a]} : a singleton range 073 * <li>{@code [a..a); (a..a]} : {@linkplain #isEmpty empty} ranges; also valid 074 * <li>{@code (a..a)} : <b>invalid</b>; an exception will be thrown 075 * </ul> 076 * 077 * <h3>Warnings</h3> 078 * 079 * <ul> 080 * <li>Use immutable value types only, if at all possible. If you must use a mutable type, <b>do 081 * not</b> allow the endpoint instances to mutate after the range is created! 082 * <li>Your value type's comparison method should be {@linkplain Comparable consistent with 083 * equals} if at all possible. Otherwise, be aware that concepts used throughout this 084 * documentation such as "equal", "same", "unique" and so on actually refer to whether {@link 085 * Comparable#compareTo compareTo} returns zero, not whether {@link Object#equals equals} 086 * returns {@code true}. 087 * <li>A class which implements {@code Comparable<UnrelatedType>} is very broken, and will cause 088 * undefined horrible things to happen in {@code Range}. For now, the Range API does not 089 * prevent its use, because this would also rule out all ungenerified (pre-JDK1.5) data types. 090 * <b>This may change in the future.</b> 091 * </ul> 092 * 093 * <h3>Other notes</h3> 094 * 095 * <ul> 096 * <li>All ranges are shallow-immutable. 097 * <li>Instances of this type are obtained using the static factory methods in this class. 098 * <li>Ranges are <i>convex</i>: whenever two values are contained, all values in between them 099 * must also be contained. More formally, for any {@code c1 <= c2 <= c3} of type {@code C}, 100 * {@code r.contains(c1) && r.contains(c3)} implies {@code r.contains(c2)}). This means that a 101 * {@code Range<Integer>} can never be used to represent, say, "all <i>prime</i> numbers from 102 * 1 to 100." 103 * <li>When evaluated as a {@link Predicate}, a range yields the same result as invoking {@link 104 * #contains}. 105 * <li>Terminology note: a range {@code a} is said to be the <i>maximal</i> range having property 106 * <i>P</i> if, for all ranges {@code b} also having property <i>P</i>, {@code a.encloses(b)}. 107 * Likewise, {@code a} is <i>minimal</i> when {@code b.encloses(a)} for all {@code b} having 108 * property <i>P</i>. See, for example, the definition of {@link #intersection intersection}. 109 * <li>A {@code Range} is serializable if it has no bounds, or if each bound is serializable. 110 * </ul> 111 * 112 * <h3>Further reading</h3> 113 * 114 * <p>See the Guava User Guide article on <a 115 * href="https://github.com/google/guava/wiki/RangesExplained">{@code Range}</a>. 116 * 117 * @author Kevin Bourrillion 118 * @author Gregory Kick 119 * @since 10.0 120 */ 121@GwtCompatible 122@SuppressWarnings("rawtypes") 123@Immutable(containerOf = "C") 124@ElementTypesAreNonnullByDefault 125public final class Range<C extends Comparable> extends RangeGwtSerializationDependencies 126 implements Predicate<C>, Serializable { 127 128 static class LowerBoundFn implements Function<Range, Cut> { 129 static final LowerBoundFn INSTANCE = new LowerBoundFn(); 130 131 @Override 132 public Cut apply(Range range) { 133 return range.lowerBound; 134 } 135 } 136 137 static class UpperBoundFn implements Function<Range, Cut> { 138 static final UpperBoundFn INSTANCE = new UpperBoundFn(); 139 140 @Override 141 public Cut apply(Range range) { 142 return range.upperBound; 143 } 144 } 145 146 @SuppressWarnings("unchecked") 147 static <C extends Comparable<?>> Function<Range<C>, Cut<C>> lowerBoundFn() { 148 return (Function) LowerBoundFn.INSTANCE; 149 } 150 151 @SuppressWarnings("unchecked") 152 static <C extends Comparable<?>> Function<Range<C>, Cut<C>> upperBoundFn() { 153 return (Function) UpperBoundFn.INSTANCE; 154 } 155 156 static <C extends Comparable<?>> Ordering<Range<C>> rangeLexOrdering() { 157 return (Ordering<Range<C>>) (Ordering) RangeLexOrdering.INSTANCE; 158 } 159 160 static <C extends Comparable<?>> Range<C> create(Cut<C> lowerBound, Cut<C> upperBound) { 161 return new Range<>(lowerBound, upperBound); 162 } 163 164 /** 165 * Returns a range that contains all values strictly greater than {@code lower} and strictly less 166 * than {@code upper}. 167 * 168 * @throws IllegalArgumentException if {@code lower} is greater than <i>or equal to</i> {@code 169 * upper} 170 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 171 * @since 14.0 172 */ 173 public static <C extends Comparable<?>> Range<C> open(C lower, C upper) { 174 return create(Cut.aboveValue(lower), Cut.belowValue(upper)); 175 } 176 177 /** 178 * Returns a range that contains all values greater than or equal to {@code lower} and less than 179 * or equal to {@code upper}. 180 * 181 * @throws IllegalArgumentException if {@code lower} is greater than {@code upper} 182 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 183 * @since 14.0 184 */ 185 public static <C extends Comparable<?>> Range<C> closed(C lower, C upper) { 186 return create(Cut.belowValue(lower), Cut.aboveValue(upper)); 187 } 188 189 /** 190 * Returns a range that contains all values greater than or equal to {@code lower} and strictly 191 * less than {@code upper}. 192 * 193 * @throws IllegalArgumentException if {@code lower} is greater than {@code upper} 194 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 195 * @since 14.0 196 */ 197 public static <C extends Comparable<?>> Range<C> closedOpen(C lower, C upper) { 198 return create(Cut.belowValue(lower), Cut.belowValue(upper)); 199 } 200 201 /** 202 * Returns a range that contains all values strictly greater than {@code lower} and less than or 203 * equal to {@code upper}. 204 * 205 * @throws IllegalArgumentException if {@code lower} is greater than {@code upper} 206 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 207 * @since 14.0 208 */ 209 public static <C extends Comparable<?>> Range<C> openClosed(C lower, C upper) { 210 return create(Cut.aboveValue(lower), Cut.aboveValue(upper)); 211 } 212 213 /** 214 * Returns a range that contains any value from {@code lower} to {@code upper}, where each 215 * endpoint may be either inclusive (closed) or exclusive (open). 216 * 217 * @throws IllegalArgumentException if {@code lower} is greater than {@code upper} 218 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 219 * @since 14.0 220 */ 221 public static <C extends Comparable<?>> Range<C> range( 222 C lower, BoundType lowerType, C upper, BoundType upperType) { 223 checkNotNull(lowerType); 224 checkNotNull(upperType); 225 226 Cut<C> lowerBound = 227 (lowerType == BoundType.OPEN) ? Cut.aboveValue(lower) : Cut.belowValue(lower); 228 Cut<C> upperBound = 229 (upperType == BoundType.OPEN) ? Cut.belowValue(upper) : Cut.aboveValue(upper); 230 return create(lowerBound, upperBound); 231 } 232 233 /** 234 * Returns a range that contains all values strictly less than {@code endpoint}. 235 * 236 * @since 14.0 237 */ 238 public static <C extends Comparable<?>> Range<C> lessThan(C endpoint) { 239 return create(Cut.<C>belowAll(), Cut.belowValue(endpoint)); 240 } 241 242 /** 243 * Returns a range that contains all values less than or equal to {@code endpoint}. 244 * 245 * @since 14.0 246 */ 247 public static <C extends Comparable<?>> Range<C> atMost(C endpoint) { 248 return create(Cut.<C>belowAll(), Cut.aboveValue(endpoint)); 249 } 250 251 /** 252 * Returns a range with no lower bound up to the given endpoint, which may be either inclusive 253 * (closed) or exclusive (open). 254 * 255 * @since 14.0 256 */ 257 public static <C extends Comparable<?>> Range<C> upTo(C endpoint, BoundType boundType) { 258 switch (boundType) { 259 case OPEN: 260 return lessThan(endpoint); 261 case CLOSED: 262 return atMost(endpoint); 263 default: 264 throw new AssertionError(); 265 } 266 } 267 268 /** 269 * Returns a range that contains all values strictly greater than {@code endpoint}. 270 * 271 * @since 14.0 272 */ 273 public static <C extends Comparable<?>> Range<C> greaterThan(C endpoint) { 274 return create(Cut.aboveValue(endpoint), Cut.<C>aboveAll()); 275 } 276 277 /** 278 * Returns a range that contains all values greater than or equal to {@code endpoint}. 279 * 280 * @since 14.0 281 */ 282 public static <C extends Comparable<?>> Range<C> atLeast(C endpoint) { 283 return create(Cut.belowValue(endpoint), Cut.<C>aboveAll()); 284 } 285 286 /** 287 * Returns a range from the given endpoint, which may be either inclusive (closed) or exclusive 288 * (open), with no upper bound. 289 * 290 * @since 14.0 291 */ 292 public static <C extends Comparable<?>> Range<C> downTo(C endpoint, BoundType boundType) { 293 switch (boundType) { 294 case OPEN: 295 return greaterThan(endpoint); 296 case CLOSED: 297 return atLeast(endpoint); 298 default: 299 throw new AssertionError(); 300 } 301 } 302 303 private static final Range<Comparable> ALL = new Range<>(Cut.belowAll(), Cut.aboveAll()); 304 305 /** 306 * Returns a range that contains every value of type {@code C}. 307 * 308 * @since 14.0 309 */ 310 @SuppressWarnings("unchecked") 311 public static <C extends Comparable<?>> Range<C> all() { 312 return (Range) ALL; 313 } 314 315 /** 316 * Returns a range that {@linkplain Range#contains(Comparable) contains} only the given value. The 317 * returned range is {@linkplain BoundType#CLOSED closed} on both ends. 318 * 319 * @since 14.0 320 */ 321 public static <C extends Comparable<?>> Range<C> singleton(C value) { 322 return closed(value, value); 323 } 324 325 /** 326 * Returns the minimal range that {@linkplain Range#contains(Comparable) contains} all of the 327 * given values. The returned range is {@linkplain BoundType#CLOSED closed} on both ends. 328 * 329 * @throws ClassCastException if the values are not mutually comparable 330 * @throws NoSuchElementException if {@code values} is empty 331 * @throws NullPointerException if any of {@code values} is null 332 * @since 14.0 333 */ 334 public static <C extends Comparable<?>> Range<C> encloseAll(Iterable<C> values) { 335 checkNotNull(values); 336 if (values instanceof SortedSet) { 337 SortedSet<C> set = (SortedSet<C>) values; 338 Comparator<?> comparator = set.comparator(); 339 if (Ordering.<C>natural().equals(comparator) || comparator == null) { 340 return closed(set.first(), set.last()); 341 } 342 } 343 Iterator<C> valueIterator = values.iterator(); 344 C min = checkNotNull(valueIterator.next()); 345 C max = min; 346 while (valueIterator.hasNext()) { 347 C value = checkNotNull(valueIterator.next()); 348 min = Ordering.<C>natural().min(min, value); 349 max = Ordering.<C>natural().max(max, value); 350 } 351 return closed(min, max); 352 } 353 354 final Cut<C> lowerBound; 355 final Cut<C> upperBound; 356 357 private Range(Cut<C> lowerBound, Cut<C> upperBound) { 358 this.lowerBound = checkNotNull(lowerBound); 359 this.upperBound = checkNotNull(upperBound); 360 if (lowerBound.compareTo(upperBound) > 0 361 || lowerBound == Cut.<C>aboveAll() 362 || upperBound == Cut.<C>belowAll()) { 363 throw new IllegalArgumentException("Invalid range: " + toString(lowerBound, upperBound)); 364 } 365 } 366 367 /** Returns {@code true} if this range has a lower endpoint. */ 368 public boolean hasLowerBound() { 369 return lowerBound != Cut.belowAll(); 370 } 371 372 /** 373 * Returns the lower endpoint of this range. 374 * 375 * @throws IllegalStateException if this range is unbounded below (that is, {@link 376 * #hasLowerBound()} returns {@code false}) 377 */ 378 public C lowerEndpoint() { 379 return lowerBound.endpoint(); 380 } 381 382 /** 383 * Returns the type of this range's lower bound: {@link BoundType#CLOSED} if the range includes 384 * its lower endpoint, {@link BoundType#OPEN} if it does not. 385 * 386 * @throws IllegalStateException if this range is unbounded below (that is, {@link 387 * #hasLowerBound()} returns {@code false}) 388 */ 389 public BoundType lowerBoundType() { 390 return lowerBound.typeAsLowerBound(); 391 } 392 393 /** Returns {@code true} if this range has an upper endpoint. */ 394 public boolean hasUpperBound() { 395 return upperBound != Cut.aboveAll(); 396 } 397 398 /** 399 * Returns the upper endpoint of this range. 400 * 401 * @throws IllegalStateException if this range is unbounded above (that is, {@link 402 * #hasUpperBound()} returns {@code false}) 403 */ 404 public C upperEndpoint() { 405 return upperBound.endpoint(); 406 } 407 408 /** 409 * Returns the type of this range's upper bound: {@link BoundType#CLOSED} if the range includes 410 * its upper endpoint, {@link BoundType#OPEN} if it does not. 411 * 412 * @throws IllegalStateException if this range is unbounded above (that is, {@link 413 * #hasUpperBound()} returns {@code false}) 414 */ 415 public BoundType upperBoundType() { 416 return upperBound.typeAsUpperBound(); 417 } 418 419 /** 420 * Returns {@code true} if this range is of the form {@code [v..v)} or {@code (v..v]}. (This does 421 * not encompass ranges of the form {@code (v..v)}, because such ranges are <i>invalid</i> and 422 * can't be constructed at all.) 423 * 424 * <p>Note that certain discrete ranges such as the integer range {@code (3..4)} are <b>not</b> 425 * considered empty, even though they contain no actual values. In these cases, it may be helpful 426 * to preprocess ranges with {@link #canonical(DiscreteDomain)}. 427 */ 428 public boolean isEmpty() { 429 return lowerBound.equals(upperBound); 430 } 431 432 /** 433 * Returns {@code true} if {@code value} is within the bounds of this range. For example, on the 434 * range {@code [0..2)}, {@code contains(1)} returns {@code true}, while {@code contains(2)} 435 * returns {@code false}. 436 */ 437 public boolean contains(C value) { 438 checkNotNull(value); 439 // let this throw CCE if there is some trickery going on 440 return lowerBound.isLessThan(value) && !upperBound.isLessThan(value); 441 } 442 443 /** 444 * @deprecated Provided only to satisfy the {@link Predicate} interface; use {@link #contains} 445 * instead. 446 */ 447 @Deprecated 448 @Override 449 public boolean apply(C input) { 450 return contains(input); 451 } 452 453 /** 454 * Returns {@code true} if every element in {@code values} is {@linkplain #contains contained} in 455 * this range. 456 */ 457 public boolean containsAll(Iterable<? extends C> values) { 458 if (Iterables.isEmpty(values)) { 459 return true; 460 } 461 462 // this optimizes testing equality of two range-backed sets 463 if (values instanceof SortedSet) { 464 SortedSet<? extends C> set = (SortedSet<? extends C>) values; 465 Comparator<?> comparator = set.comparator(); 466 if (Ordering.natural().equals(comparator) || comparator == null) { 467 return contains(set.first()) && contains(set.last()); 468 } 469 } 470 471 for (C value : values) { 472 if (!contains(value)) { 473 return false; 474 } 475 } 476 return true; 477 } 478 479 /** 480 * Returns {@code true} if the bounds of {@code other} do not extend outside the bounds of this 481 * range. Examples: 482 * 483 * <ul> 484 * <li>{@code [3..6]} encloses {@code [4..5]} 485 * <li>{@code (3..6)} encloses {@code (3..6)} 486 * <li>{@code [3..6]} encloses {@code [4..4)} (even though the latter is empty) 487 * <li>{@code (3..6]} does not enclose {@code [3..6]} 488 * <li>{@code [4..5]} does not enclose {@code (3..6)} (even though it contains every value 489 * contained by the latter range) 490 * <li>{@code [3..6]} does not enclose {@code (1..1]} (even though it contains every value 491 * contained by the latter range) 492 * </ul> 493 * 494 * <p>Note that if {@code a.encloses(b)}, then {@code b.contains(v)} implies {@code 495 * a.contains(v)}, but as the last two examples illustrate, the converse is not always true. 496 * 497 * <p>Being reflexive, antisymmetric and transitive, the {@code encloses} relation defines a 498 * <i>partial order</i> over ranges. There exists a unique {@linkplain Range#all maximal} range 499 * according to this relation, and also numerous {@linkplain #isEmpty minimal} ranges. Enclosure 500 * also implies {@linkplain #isConnected connectedness}. 501 */ 502 public boolean encloses(Range<C> other) { 503 return lowerBound.compareTo(other.lowerBound) <= 0 504 && upperBound.compareTo(other.upperBound) >= 0; 505 } 506 507 /** 508 * Returns {@code true} if there exists a (possibly empty) range which is {@linkplain #encloses 509 * enclosed} by both this range and {@code other}. 510 * 511 * <p>For example, 512 * 513 * <ul> 514 * <li>{@code [2, 4)} and {@code [5, 7)} are not connected 515 * <li>{@code [2, 4)} and {@code [3, 5)} are connected, because both enclose {@code [3, 4)} 516 * <li>{@code [2, 4)} and {@code [4, 6)} are connected, because both enclose the empty range 517 * {@code [4, 4)} 518 * </ul> 519 * 520 * <p>Note that this range and {@code other} have a well-defined {@linkplain #span union} and 521 * {@linkplain #intersection intersection} (as a single, possibly-empty range) if and only if this 522 * method returns {@code true}. 523 * 524 * <p>The connectedness relation is both reflexive and symmetric, but does not form an {@linkplain 525 * Equivalence equivalence relation} as it is not transitive. 526 * 527 * <p>Note that certain discrete ranges are not considered connected, even though there are no 528 * elements "between them." For example, {@code [3, 5]} is not considered connected to {@code [6, 529 * 10]}. In these cases, it may be desirable for both input ranges to be preprocessed with {@link 530 * #canonical(DiscreteDomain)} before testing for connectedness. 531 */ 532 public boolean isConnected(Range<C> other) { 533 return lowerBound.compareTo(other.upperBound) <= 0 534 && other.lowerBound.compareTo(upperBound) <= 0; 535 } 536 537 /** 538 * Returns the maximal range {@linkplain #encloses enclosed} by both this range and {@code 539 * connectedRange}, if such a range exists. 540 * 541 * <p>For example, the intersection of {@code [1..5]} and {@code (3..7)} is {@code (3..5]}. The 542 * resulting range may be empty; for example, {@code [1..5)} intersected with {@code [5..7)} 543 * yields the empty range {@code [5..5)}. 544 * 545 * <p>The intersection exists if and only if the two ranges are {@linkplain #isConnected 546 * connected}. 547 * 548 * <p>The intersection operation is commutative, associative and idempotent, and its identity 549 * element is {@link Range#all}). 550 * 551 * @throws IllegalArgumentException if {@code isConnected(connectedRange)} is {@code false} 552 */ 553 public Range<C> intersection(Range<C> connectedRange) { 554 int lowerCmp = lowerBound.compareTo(connectedRange.lowerBound); 555 int upperCmp = upperBound.compareTo(connectedRange.upperBound); 556 if (lowerCmp >= 0 && upperCmp <= 0) { 557 return this; 558 } else if (lowerCmp <= 0 && upperCmp >= 0) { 559 return connectedRange; 560 } else { 561 Cut<C> newLower = (lowerCmp >= 0) ? lowerBound : connectedRange.lowerBound; 562 Cut<C> newUpper = (upperCmp <= 0) ? upperBound : connectedRange.upperBound; 563 564 // create() would catch this, but give a confusing error message 565 checkArgument( 566 newLower.compareTo(newUpper) <= 0, 567 "intersection is undefined for disconnected ranges %s and %s", 568 this, 569 connectedRange); 570 571 // TODO(kevinb): all the precondition checks in the constructor are redundant... 572 return create(newLower, newUpper); 573 } 574 } 575 576 /** 577 * Returns the maximal range lying between this range and {@code otherRange}, if such a range 578 * exists. The resulting range may be empty if the two ranges are adjacent but non-overlapping. 579 * 580 * <p>For example, the gap of {@code [1..5]} and {@code (7..10)} is {@code (5..7]}. The resulting 581 * range may be empty; for example, the gap between {@code [1..5)} {@code [5..7)} yields the empty 582 * range {@code [5..5)}. 583 * 584 * <p>The gap exists if and only if the two ranges are either disconnected or immediately adjacent 585 * (any intersection must be an empty range). 586 * 587 * <p>The gap operation is commutative. 588 * 589 * @throws IllegalArgumentException if this range and {@code otherRange} have a nonempty 590 * intersection 591 * @since 27.0 592 */ 593 public Range<C> gap(Range<C> otherRange) { 594 /* 595 * For an explanation of the basic principle behind this check, see 596 * https://stackoverflow.com/a/35754308/28465 597 * 598 * In that explanation's notation, our `overlap` check would be `x1 < y2 && y1 < x2`. We've 599 * flipped one part of the check so that we're using "less than" in both cases (rather than a 600 * mix of "less than" and "greater than"). We've also switched to "strictly less than" rather 601 * than "less than or equal to" because of *handwave* the difference between "endpoints of 602 * inclusive ranges" and "Cuts." 603 */ 604 if (lowerBound.compareTo(otherRange.upperBound) < 0 605 && otherRange.lowerBound.compareTo(upperBound) < 0) { 606 throw new IllegalArgumentException( 607 "Ranges have a nonempty intersection: " + this + ", " + otherRange); 608 } 609 610 boolean isThisFirst = this.lowerBound.compareTo(otherRange.lowerBound) < 0; 611 Range<C> firstRange = isThisFirst ? this : otherRange; 612 Range<C> secondRange = isThisFirst ? otherRange : this; 613 return create(firstRange.upperBound, secondRange.lowerBound); 614 } 615 616 /** 617 * Returns the minimal range that {@linkplain #encloses encloses} both this range and {@code 618 * other}. For example, the span of {@code [1..3]} and {@code (5..7)} is {@code [1..7)}. 619 * 620 * <p><i>If</i> the input ranges are {@linkplain #isConnected connected}, the returned range can 621 * also be called their <i>union</i>. If they are not, note that the span might contain values 622 * that are not contained in either input range. 623 * 624 * <p>Like {@link #intersection(Range) intersection}, this operation is commutative, associative 625 * and idempotent. Unlike it, it is always well-defined for any two input ranges. 626 */ 627 public Range<C> span(Range<C> other) { 628 int lowerCmp = lowerBound.compareTo(other.lowerBound); 629 int upperCmp = upperBound.compareTo(other.upperBound); 630 if (lowerCmp <= 0 && upperCmp >= 0) { 631 return this; 632 } else if (lowerCmp >= 0 && upperCmp <= 0) { 633 return other; 634 } else { 635 Cut<C> newLower = (lowerCmp <= 0) ? lowerBound : other.lowerBound; 636 Cut<C> newUpper = (upperCmp >= 0) ? upperBound : other.upperBound; 637 return create(newLower, newUpper); 638 } 639 } 640 641 /** 642 * Returns the canonical form of this range in the given domain. The canonical form has the 643 * following properties: 644 * 645 * <ul> 646 * <li>equivalence: {@code a.canonical().contains(v) == a.contains(v)} for all {@code v} (in 647 * other words, {@code ContiguousSet.create(a.canonical(domain), domain).equals( 648 * ContiguousSet.create(a, domain))} 649 * <li>uniqueness: unless {@code a.isEmpty()}, {@code ContiguousSet.create(a, 650 * domain).equals(ContiguousSet.create(b, domain))} implies {@code 651 * a.canonical(domain).equals(b.canonical(domain))} 652 * <li>idempotence: {@code a.canonical(domain).canonical(domain).equals(a.canonical(domain))} 653 * </ul> 654 * 655 * <p>Furthermore, this method guarantees that the range returned will be one of the following 656 * canonical forms: 657 * 658 * <ul> 659 * <li>[start..end) 660 * <li>[start..+∞) 661 * <li>(-∞..end) (only if type {@code C} is unbounded below) 662 * <li>(-∞..+∞) (only if type {@code C} is unbounded below) 663 * </ul> 664 */ 665 public Range<C> canonical(DiscreteDomain<C> domain) { 666 checkNotNull(domain); 667 Cut<C> lower = lowerBound.canonical(domain); 668 Cut<C> upper = upperBound.canonical(domain); 669 return (lower == lowerBound && upper == upperBound) ? this : create(lower, upper); 670 } 671 672 /** 673 * Returns {@code true} if {@code object} is a range having the same endpoints and bound types as 674 * this range. Note that discrete ranges such as {@code (1..4)} and {@code [2..3]} are <b>not</b> 675 * equal to one another, despite the fact that they each contain precisely the same set of values. 676 * Similarly, empty ranges are not equal unless they have exactly the same representation, so 677 * {@code [3..3)}, {@code (3..3]}, {@code (4..4]} are all unequal. 678 */ 679 @Override 680 public boolean equals(@CheckForNull Object object) { 681 if (object instanceof Range) { 682 Range<?> other = (Range<?>) object; 683 return lowerBound.equals(other.lowerBound) && upperBound.equals(other.upperBound); 684 } 685 return false; 686 } 687 688 /** Returns a hash code for this range. */ 689 @Override 690 public int hashCode() { 691 return lowerBound.hashCode() * 31 + upperBound.hashCode(); 692 } 693 694 /** 695 * Returns a string representation of this range, such as {@code "[3..5)"} (other examples are 696 * listed in the class documentation). 697 */ 698 @Override 699 public String toString() { 700 return toString(lowerBound, upperBound); 701 } 702 703 private static String toString(Cut<?> lowerBound, Cut<?> upperBound) { 704 StringBuilder sb = new StringBuilder(16); 705 lowerBound.describeAsLowerBound(sb); 706 sb.append(".."); 707 upperBound.describeAsUpperBound(sb); 708 return sb.toString(); 709 } 710 711 Object readResolve() { 712 if (this.equals(ALL)) { 713 return all(); 714 } else { 715 return this; 716 } 717 } 718 719 @SuppressWarnings("unchecked") // this method may throw CCE 720 static int compareOrThrow(Comparable left, Comparable right) { 721 return left.compareTo(right); 722 } 723 724 /** Needed to serialize sorted collections of Ranges. */ 725 private static class RangeLexOrdering extends Ordering<Range<?>> implements Serializable { 726 static final Ordering<Range<?>> INSTANCE = new RangeLexOrdering(); 727 728 @Override 729 public int compare(Range<?> left, Range<?> right) { 730 return ComparisonChain.start() 731 .compare(left.lowerBound, right.lowerBound) 732 .compare(left.upperBound, right.upperBound) 733 .result(); 734 } 735 736 private static final long serialVersionUID = 0; 737 } 738 739 private static final long serialVersionUID = 0; 740}