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