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.Predicate; 025import com.google.errorprone.annotations.Immutable; 026import java.io.Serializable; 027import java.util.Comparator; 028import java.util.Iterator; 029import java.util.NoSuchElementException; 030import java.util.SortedSet; 031import javax.annotation.CheckForNull; 032 033/** 034 * A range (or "interval") defines the <i>boundaries</i> around a contiguous span of values of some 035 * {@code Comparable} type; for example, "integers from 1 to 100 inclusive." Note that it is not 036 * possible to <i>iterate</i> over these contained values. To do so, pass this range instance and an 037 * appropriate {@link DiscreteDomain} to {@link ContiguousSet#create}. 038 * 039 * <h3>Types of ranges</h3> 040 * 041 * <p>Each end of the range may be bounded or unbounded. If bounded, there is an associated 042 * <i>endpoint</i> value, and the range is considered to be either <i>open</i> (does not include the 043 * endpoint) or <i>closed</i> (includes the endpoint) on that side. With three possibilities on each 044 * side, this yields nine basic types of ranges, enumerated below. (Notation: a square bracket 045 * ({@code [ ]}) indicates that the range is closed on that side; a parenthesis ({@code ( )}) means 046 * it is either open or unbounded. The construct {@code {x | statement}} is read "the set of all 047 * <i>x</i> such that <i>statement</i>.") 048 * 049 * <blockquote> 050 * 051 * <table> 052 * <caption>Range Types</caption> 053 * <tr><th>Notation <th>Definition <th>Factory method 054 * <tr><td>{@code (a..b)} <td>{@code {x | a < x < b}} <td>{@link Range#open open} 055 * <tr><td>{@code [a..b]} <td>{@code {x | a <= x <= b}}<td>{@link Range#closed closed} 056 * <tr><td>{@code (a..b]} <td>{@code {x | a < x <= b}} <td>{@link Range#openClosed openClosed} 057 * <tr><td>{@code [a..b)} <td>{@code {x | a <= x < b}} <td>{@link Range#closedOpen closedOpen} 058 * <tr><td>{@code (a..+∞)} <td>{@code {x | x > a}} <td>{@link Range#greaterThan greaterThan} 059 * <tr><td>{@code [a..+∞)} <td>{@code {x | x >= a}} <td>{@link Range#atLeast atLeast} 060 * <tr><td>{@code (-∞..b)} <td>{@code {x | x < b}} <td>{@link Range#lessThan lessThan} 061 * <tr><td>{@code (-∞..b]} <td>{@code {x | x <= b}} <td>{@link Range#atMost atMost} 062 * <tr><td>{@code (-∞..+∞)}<td>{@code {x}} <td>{@link Range#all all} 063 * </table> 064 * 065 * </blockquote> 066 * 067 * <p>When both endpoints exist, the upper endpoint may not be less than the lower. The endpoints 068 * may be equal only if at least one of the bounds is closed: 069 * 070 * <ul> 071 * <li>{@code [a..a]} : a singleton range 072 * <li>{@code [a..a); (a..a]} : {@linkplain #isEmpty empty} ranges; also valid 073 * <li>{@code (a..a)} : <b>invalid</b>; an exception will be thrown 074 * </ul> 075 * 076 * <h3>Warnings</h3> 077 * 078 * <ul> 079 * <li>Use immutable value types only, if at all possible. If you must use a mutable type, <b>do 080 * not</b> allow the endpoint instances to mutate after the range is created! 081 * <li>Your value type's comparison method should be {@linkplain Comparable consistent with 082 * equals} if at all possible. Otherwise, be aware that concepts used throughout this 083 * documentation such as "equal", "same", "unique" and so on actually refer to whether {@link 084 * Comparable#compareTo compareTo} returns zero, not whether {@link Object#equals equals} 085 * returns {@code true}. 086 * <li>A class which implements {@code Comparable<UnrelatedType>} is very broken, and will cause 087 * undefined horrible things to happen in {@code Range}. For now, the Range API does not 088 * prevent its use, because this would also rule out all ungenerified (pre-JDK1.5) data types. 089 * <b>This may change in the future.</b> 090 * </ul> 091 * 092 * <h3>Other notes</h3> 093 * 094 * <ul> 095 * <li>All ranges are shallow-immutable. 096 * <li>Instances of this type are obtained using the static factory methods in this class. 097 * <li>Ranges are <i>convex</i>: whenever two values are contained, all values in between them 098 * must also be contained. More formally, for any {@code c1 <= c2 <= c3} of type {@code C}, 099 * {@code r.contains(c1) && r.contains(c3)} implies {@code r.contains(c2)}). This means that a 100 * {@code Range<Integer>} can never be used to represent, say, "all <i>prime</i> numbers from 101 * 1 to 100." 102 * <li>When evaluated as a {@link Predicate}, a range yields the same result as invoking {@link 103 * #contains}. 104 * <li>Terminology note: a range {@code a} is said to be the <i>maximal</i> range having property 105 * <i>P</i> if, for all ranges {@code b} also having property <i>P</i>, {@code a.encloses(b)}. 106 * Likewise, {@code a} is <i>minimal</i> when {@code b.encloses(a)} for all {@code b} having 107 * property <i>P</i>. See, for example, the definition of {@link #intersection intersection}. 108 * <li>A {@code Range} is serializable if it has no bounds, or if each bound is serializable. 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") // https://github.com/google/guava/issues/989 122@Immutable(containerOf = "C") 123@ElementTypesAreNonnullByDefault 124public final class Range<C extends Comparable> extends RangeGwtSerializationDependencies 125 implements Predicate<C>, Serializable { 126 @SuppressWarnings("unchecked") 127 static <C extends Comparable<?>> Ordering<Range<C>> rangeLexOrdering() { 128 return (Ordering<Range<C>>) RangeLexOrdering.INSTANCE; 129 } 130 131 static <C extends Comparable<?>> Range<C> create(Cut<C> lowerBound, Cut<C> upperBound) { 132 return new Range<>(lowerBound, upperBound); 133 } 134 135 /** 136 * Returns a range that contains all values strictly greater than {@code lower} and strictly less 137 * than {@code upper}. 138 * 139 * @throws IllegalArgumentException if {@code lower} is greater than <i>or equal to</i> {@code 140 * upper} 141 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 142 * @since 14.0 143 */ 144 public static <C extends Comparable<?>> Range<C> open(C lower, C upper) { 145 return create(Cut.aboveValue(lower), Cut.belowValue(upper)); 146 } 147 148 /** 149 * Returns a range that contains all values greater than or equal to {@code lower} and less than 150 * or equal to {@code upper}. 151 * 152 * @throws IllegalArgumentException if {@code lower} is greater than {@code upper} 153 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 154 * @since 14.0 155 */ 156 public static <C extends Comparable<?>> Range<C> closed(C lower, C upper) { 157 return create(Cut.belowValue(lower), Cut.aboveValue(upper)); 158 } 159 160 /** 161 * Returns a range that contains all values greater than or equal to {@code lower} and strictly 162 * less than {@code upper}. 163 * 164 * @throws IllegalArgumentException if {@code lower} is greater than {@code upper} 165 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 166 * @since 14.0 167 */ 168 public static <C extends Comparable<?>> Range<C> closedOpen(C lower, C upper) { 169 return create(Cut.belowValue(lower), Cut.belowValue(upper)); 170 } 171 172 /** 173 * Returns a range that contains all values strictly greater than {@code lower} and less than or 174 * equal to {@code upper}. 175 * 176 * @throws IllegalArgumentException if {@code lower} is greater than {@code upper} 177 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 178 * @since 14.0 179 */ 180 public static <C extends Comparable<?>> Range<C> openClosed(C lower, C upper) { 181 return create(Cut.aboveValue(lower), Cut.aboveValue(upper)); 182 } 183 184 /** 185 * Returns a range that contains any value from {@code lower} to {@code upper}, where each 186 * endpoint may be either inclusive (closed) or exclusive (open). 187 * 188 * @throws IllegalArgumentException if {@code lower} is greater than {@code upper} 189 * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable 190 * @since 14.0 191 */ 192 public static <C extends Comparable<?>> Range<C> range( 193 C lower, BoundType lowerType, C upper, BoundType upperType) { 194 checkNotNull(lowerType); 195 checkNotNull(upperType); 196 197 Cut<C> lowerBound = 198 (lowerType == BoundType.OPEN) ? Cut.aboveValue(lower) : Cut.belowValue(lower); 199 Cut<C> upperBound = 200 (upperType == BoundType.OPEN) ? Cut.belowValue(upper) : Cut.aboveValue(upper); 201 return create(lowerBound, upperBound); 202 } 203 204 /** 205 * Returns a range that contains all values strictly less than {@code endpoint}. 206 * 207 * @since 14.0 208 */ 209 public static <C extends Comparable<?>> Range<C> lessThan(C endpoint) { 210 return create(Cut.<C>belowAll(), Cut.belowValue(endpoint)); 211 } 212 213 /** 214 * Returns a range that contains all values less than or equal to {@code endpoint}. 215 * 216 * @since 14.0 217 */ 218 public static <C extends Comparable<?>> Range<C> atMost(C endpoint) { 219 return create(Cut.<C>belowAll(), Cut.aboveValue(endpoint)); 220 } 221 222 /** 223 * Returns a range with no lower bound up to the given endpoint, which may be either inclusive 224 * (closed) or exclusive (open). 225 * 226 * @since 14.0 227 */ 228 public static <C extends Comparable<?>> Range<C> upTo(C endpoint, BoundType boundType) { 229 switch (boundType) { 230 case OPEN: 231 return lessThan(endpoint); 232 case CLOSED: 233 return atMost(endpoint); 234 default: 235 throw new AssertionError(); 236 } 237 } 238 239 /** 240 * Returns a range that contains all values strictly greater than {@code endpoint}. 241 * 242 * @since 14.0 243 */ 244 public static <C extends Comparable<?>> Range<C> greaterThan(C endpoint) { 245 return create(Cut.aboveValue(endpoint), Cut.<C>aboveAll()); 246 } 247 248 /** 249 * Returns a range that contains all values greater than or equal to {@code endpoint}. 250 * 251 * @since 14.0 252 */ 253 public static <C extends Comparable<?>> Range<C> atLeast(C endpoint) { 254 return create(Cut.belowValue(endpoint), Cut.<C>aboveAll()); 255 } 256 257 /** 258 * Returns a range from the given endpoint, which may be either inclusive (closed) or exclusive 259 * (open), with no upper bound. 260 * 261 * @since 14.0 262 */ 263 public static <C extends Comparable<?>> Range<C> downTo(C endpoint, BoundType boundType) { 264 switch (boundType) { 265 case OPEN: 266 return greaterThan(endpoint); 267 case CLOSED: 268 return atLeast(endpoint); 269 default: 270 throw new AssertionError(); 271 } 272 } 273 274 private static final Range<Comparable> ALL = new Range<>(Cut.belowAll(), Cut.aboveAll()); 275 276 /** 277 * Returns a range that contains every value of type {@code C}. 278 * 279 * @since 14.0 280 */ 281 @SuppressWarnings("unchecked") 282 public static <C extends Comparable<?>> Range<C> all() { 283 return (Range) ALL; 284 } 285 286 /** 287 * Returns a range that {@linkplain Range#contains(Comparable) contains} only the given value. The 288 * returned range is {@linkplain BoundType#CLOSED closed} on both ends. 289 * 290 * @since 14.0 291 */ 292 public static <C extends Comparable<?>> Range<C> singleton(C value) { 293 return closed(value, value); 294 } 295 296 /** 297 * Returns the minimal range that {@linkplain Range#contains(Comparable) contains} all of the 298 * given values. The returned range is {@linkplain BoundType#CLOSED closed} on both ends. 299 * 300 * @throws ClassCastException if the values are not mutually comparable 301 * @throws NoSuchElementException if {@code values} is empty 302 * @throws NullPointerException if any of {@code values} is null 303 * @since 14.0 304 */ 305 public static <C extends Comparable<?>> Range<C> encloseAll(Iterable<C> values) { 306 checkNotNull(values); 307 if (values instanceof SortedSet) { 308 SortedSet<C> set = (SortedSet<C>) values; 309 Comparator<?> comparator = set.comparator(); 310 if (Ordering.<C>natural().equals(comparator) || comparator == null) { 311 return closed(set.first(), set.last()); 312 } 313 } 314 Iterator<C> valueIterator = values.iterator(); 315 C min = checkNotNull(valueIterator.next()); 316 C max = min; 317 while (valueIterator.hasNext()) { 318 C value = checkNotNull(valueIterator.next()); 319 min = Ordering.<C>natural().min(min, value); 320 max = Ordering.<C>natural().max(max, value); 321 } 322 return closed(min, max); 323 } 324 325 final Cut<C> lowerBound; 326 final Cut<C> upperBound; 327 328 private Range(Cut<C> lowerBound, Cut<C> upperBound) { 329 this.lowerBound = checkNotNull(lowerBound); 330 this.upperBound = checkNotNull(upperBound); 331 if (lowerBound.compareTo(upperBound) > 0 332 || lowerBound == Cut.<C>aboveAll() 333 || upperBound == Cut.<C>belowAll()) { 334 throw new IllegalArgumentException("Invalid range: " + toString(lowerBound, upperBound)); 335 } 336 } 337 338 /** Returns {@code true} if this range has a lower endpoint. */ 339 public boolean hasLowerBound() { 340 return lowerBound != Cut.belowAll(); 341 } 342 343 /** 344 * Returns the lower endpoint of this range. 345 * 346 * @throws IllegalStateException if this range is unbounded below (that is, {@link 347 * #hasLowerBound()} returns {@code false}) 348 */ 349 public C lowerEndpoint() { 350 return lowerBound.endpoint(); 351 } 352 353 /** 354 * Returns the type of this range's lower bound: {@link BoundType#CLOSED} if the range includes 355 * its lower endpoint, {@link BoundType#OPEN} if it does not. 356 * 357 * @throws IllegalStateException if this range is unbounded below (that is, {@link 358 * #hasLowerBound()} returns {@code false}) 359 */ 360 public BoundType lowerBoundType() { 361 return lowerBound.typeAsLowerBound(); 362 } 363 364 /** Returns {@code true} if this range has an upper endpoint. */ 365 public boolean hasUpperBound() { 366 return upperBound != Cut.aboveAll(); 367 } 368 369 /** 370 * Returns the upper endpoint of this range. 371 * 372 * @throws IllegalStateException if this range is unbounded above (that is, {@link 373 * #hasUpperBound()} returns {@code false}) 374 */ 375 public C upperEndpoint() { 376 return upperBound.endpoint(); 377 } 378 379 /** 380 * Returns the type of this range's upper bound: {@link BoundType#CLOSED} if the range includes 381 * its upper endpoint, {@link BoundType#OPEN} if it does not. 382 * 383 * @throws IllegalStateException if this range is unbounded above (that is, {@link 384 * #hasUpperBound()} returns {@code false}) 385 */ 386 public BoundType upperBoundType() { 387 return upperBound.typeAsUpperBound(); 388 } 389 390 /** 391 * Returns {@code true} if this range is of the form {@code [v..v)} or {@code (v..v]}. (This does 392 * not encompass ranges of the form {@code (v..v)}, because such ranges are <i>invalid</i> and 393 * can't be constructed at all.) 394 * 395 * <p>Note that certain discrete ranges such as the integer range {@code (3..4)} are <b>not</b> 396 * considered empty, even though they contain no actual values. In these cases, it may be helpful 397 * to preprocess ranges with {@link #canonical(DiscreteDomain)}. 398 */ 399 public boolean isEmpty() { 400 return lowerBound.equals(upperBound); 401 } 402 403 /** 404 * Returns {@code true} if {@code value} is within the bounds of this range. For example, on the 405 * range {@code [0..2)}, {@code contains(1)} returns {@code true}, while {@code contains(2)} 406 * returns {@code false}. 407 */ 408 public boolean contains(C value) { 409 checkNotNull(value); 410 // let this throw CCE if there is some trickery going on 411 return lowerBound.isLessThan(value) && !upperBound.isLessThan(value); 412 } 413 414 /** 415 * @deprecated Provided only to satisfy the {@link Predicate} interface; use {@link #contains} 416 * instead. 417 */ 418 @Deprecated 419 @Override 420 public boolean apply(C input) { 421 return contains(input); 422 } 423 424 /** 425 * Returns {@code true} if every element in {@code values} is {@linkplain #contains contained} in 426 * this range. 427 */ 428 public boolean containsAll(Iterable<? extends C> values) { 429 if (Iterables.isEmpty(values)) { 430 return true; 431 } 432 433 // this optimizes testing equality of two range-backed sets 434 if (values instanceof SortedSet) { 435 SortedSet<? extends C> set = (SortedSet<? extends C>) values; 436 Comparator<?> comparator = set.comparator(); 437 if (Ordering.natural().equals(comparator) || comparator == null) { 438 return contains(set.first()) && contains(set.last()); 439 } 440 } 441 442 for (C value : values) { 443 if (!contains(value)) { 444 return false; 445 } 446 } 447 return true; 448 } 449 450 /** 451 * Returns {@code true} if the bounds of {@code other} do not extend outside the bounds of this 452 * range. Examples: 453 * 454 * <ul> 455 * <li>{@code [3..6]} encloses {@code [4..5]} 456 * <li>{@code (3..6)} encloses {@code (3..6)} 457 * <li>{@code [3..6]} encloses {@code [4..4)} (even though the latter is empty) 458 * <li>{@code (3..6]} does not enclose {@code [3..6]} 459 * <li>{@code [4..5]} does not enclose {@code (3..6)} (even though it contains every value 460 * contained by the latter range) 461 * <li>{@code [3..6]} does not enclose {@code (1..1]} (even though it contains every value 462 * contained by the latter range) 463 * </ul> 464 * 465 * <p>Note that if {@code a.encloses(b)}, then {@code b.contains(v)} implies {@code 466 * a.contains(v)}, but as the last two examples illustrate, the converse is not always true. 467 * 468 * <p>Being reflexive, antisymmetric and transitive, the {@code encloses} relation defines a 469 * <i>partial order</i> over ranges. There exists a unique {@linkplain Range#all maximal} range 470 * according to this relation, and also numerous {@linkplain #isEmpty minimal} ranges. Enclosure 471 * also implies {@linkplain #isConnected connectedness}. 472 */ 473 public boolean encloses(Range<C> other) { 474 return lowerBound.compareTo(other.lowerBound) <= 0 475 && upperBound.compareTo(other.upperBound) >= 0; 476 } 477 478 /** 479 * Returns {@code true} if there exists a (possibly empty) range which is {@linkplain #encloses 480 * enclosed} by both this range and {@code other}. 481 * 482 * <p>For example, 483 * 484 * <ul> 485 * <li>{@code [2, 4)} and {@code [5, 7)} are not connected 486 * <li>{@code [2, 4)} and {@code [3, 5)} are connected, because both enclose {@code [3, 4)} 487 * <li>{@code [2, 4)} and {@code [4, 6)} are connected, because both enclose the empty range 488 * {@code [4, 4)} 489 * </ul> 490 * 491 * <p>Note that this range and {@code other} have a well-defined {@linkplain #span union} and 492 * {@linkplain #intersection intersection} (as a single, possibly-empty range) if and only if this 493 * method returns {@code true}. 494 * 495 * <p>The connectedness relation is both reflexive and symmetric, but does not form an {@linkplain 496 * Equivalence equivalence relation} as it is not transitive. 497 * 498 * <p>Note that certain discrete ranges are not considered connected, even though there are no 499 * elements "between them." For example, {@code [3, 5]} is not considered connected to {@code [6, 500 * 10]}. In these cases, it may be desirable for both input ranges to be preprocessed with {@link 501 * #canonical(DiscreteDomain)} before testing for connectedness. 502 */ 503 public boolean isConnected(Range<C> other) { 504 return lowerBound.compareTo(other.upperBound) <= 0 505 && other.lowerBound.compareTo(upperBound) <= 0; 506 } 507 508 /** 509 * Returns the maximal range {@linkplain #encloses enclosed} by both this range and {@code 510 * connectedRange}, if such a range exists. 511 * 512 * <p>For example, the intersection of {@code [1..5]} and {@code (3..7)} is {@code (3..5]}. The 513 * resulting range may be empty; for example, {@code [1..5)} intersected with {@code [5..7)} 514 * yields the empty range {@code [5..5)}. 515 * 516 * <p>The intersection exists if and only if the two ranges are {@linkplain #isConnected 517 * connected}. 518 * 519 * <p>The intersection operation is commutative, associative and idempotent, and its identity 520 * element is {@link Range#all}). 521 * 522 * @throws IllegalArgumentException if {@code isConnected(connectedRange)} is {@code false} 523 */ 524 public Range<C> intersection(Range<C> connectedRange) { 525 int lowerCmp = lowerBound.compareTo(connectedRange.lowerBound); 526 int upperCmp = upperBound.compareTo(connectedRange.upperBound); 527 if (lowerCmp >= 0 && upperCmp <= 0) { 528 return this; 529 } else if (lowerCmp <= 0 && upperCmp >= 0) { 530 return connectedRange; 531 } else { 532 Cut<C> newLower = (lowerCmp >= 0) ? lowerBound : connectedRange.lowerBound; 533 Cut<C> newUpper = (upperCmp <= 0) ? upperBound : connectedRange.upperBound; 534 535 // create() would catch this, but give a confusing error message 536 checkArgument( 537 newLower.compareTo(newUpper) <= 0, 538 "intersection is undefined for disconnected ranges %s and %s", 539 this, 540 connectedRange); 541 542 // TODO(kevinb): all the precondition checks in the constructor are redundant... 543 return create(newLower, newUpper); 544 } 545 } 546 547 /** 548 * Returns the maximal range lying between this range and {@code otherRange}, if such a range 549 * exists. The resulting range may be empty if the two ranges are adjacent but non-overlapping. 550 * 551 * <p>For example, the gap of {@code [1..5]} and {@code (7..10)} is {@code (5..7]}. The resulting 552 * range may be empty; for example, the gap between {@code [1..5)} {@code [5..7)} yields the empty 553 * range {@code [5..5)}. 554 * 555 * <p>The gap exists if and only if the two ranges are either disconnected or immediately adjacent 556 * (any intersection must be an empty range). 557 * 558 * <p>The gap operation is commutative. 559 * 560 * @throws IllegalArgumentException if this range and {@code otherRange} have a nonempty 561 * intersection 562 * @since 27.0 563 */ 564 public Range<C> gap(Range<C> otherRange) { 565 /* 566 * For an explanation of the basic principle behind this check, see 567 * https://stackoverflow.com/a/35754308/28465 568 * 569 * In that explanation's notation, our `overlap` check would be `x1 < y2 && y1 < x2`. We've 570 * flipped one part of the check so that we're using "less than" in both cases (rather than a 571 * mix of "less than" and "greater than"). We've also switched to "strictly less than" rather 572 * than "less than or equal to" because of *handwave* the difference between "endpoints of 573 * inclusive ranges" and "Cuts." 574 */ 575 if (lowerBound.compareTo(otherRange.upperBound) < 0 576 && otherRange.lowerBound.compareTo(upperBound) < 0) { 577 throw new IllegalArgumentException( 578 "Ranges have a nonempty intersection: " + this + ", " + otherRange); 579 } 580 581 boolean isThisFirst = this.lowerBound.compareTo(otherRange.lowerBound) < 0; 582 Range<C> firstRange = isThisFirst ? this : otherRange; 583 Range<C> secondRange = isThisFirst ? otherRange : this; 584 return create(firstRange.upperBound, secondRange.lowerBound); 585 } 586 587 /** 588 * Returns the minimal range that {@linkplain #encloses encloses} both this range and {@code 589 * other}. For example, the span of {@code [1..3]} and {@code (5..7)} is {@code [1..7)}. 590 * 591 * <p><i>If</i> the input ranges are {@linkplain #isConnected connected}, the returned range can 592 * also be called their <i>union</i>. If they are not, note that the span might contain values 593 * that are not contained in either input range. 594 * 595 * <p>Like {@link #intersection(Range) intersection}, this operation is commutative, associative 596 * and idempotent. Unlike it, it is always well-defined for any two input ranges. 597 */ 598 public Range<C> span(Range<C> other) { 599 int lowerCmp = lowerBound.compareTo(other.lowerBound); 600 int upperCmp = upperBound.compareTo(other.upperBound); 601 if (lowerCmp <= 0 && upperCmp >= 0) { 602 return this; 603 } else if (lowerCmp >= 0 && upperCmp <= 0) { 604 return other; 605 } else { 606 Cut<C> newLower = (lowerCmp <= 0) ? lowerBound : other.lowerBound; 607 Cut<C> newUpper = (upperCmp >= 0) ? upperBound : other.upperBound; 608 return create(newLower, newUpper); 609 } 610 } 611 612 /** 613 * Returns the canonical form of this range in the given domain. The canonical form has the 614 * following properties: 615 * 616 * <ul> 617 * <li>equivalence: {@code a.canonical().contains(v) == a.contains(v)} for all {@code v} (in 618 * other words, {@code ContiguousSet.create(a.canonical(domain), domain).equals( 619 * ContiguousSet.create(a, domain))} 620 * <li>uniqueness: unless {@code a.isEmpty()}, {@code ContiguousSet.create(a, 621 * domain).equals(ContiguousSet.create(b, domain))} implies {@code 622 * a.canonical(domain).equals(b.canonical(domain))} 623 * <li>idempotence: {@code a.canonical(domain).canonical(domain).equals(a.canonical(domain))} 624 * </ul> 625 * 626 * <p>Furthermore, this method guarantees that the range returned will be one of the following 627 * canonical forms: 628 * 629 * <ul> 630 * <li>[start..end) 631 * <li>[start..+∞) 632 * <li>(-∞..end) (only if type {@code C} is unbounded below) 633 * <li>(-∞..+∞) (only if type {@code C} is unbounded below) 634 * </ul> 635 */ 636 public Range<C> canonical(DiscreteDomain<C> domain) { 637 checkNotNull(domain); 638 Cut<C> lower = lowerBound.canonical(domain); 639 Cut<C> upper = upperBound.canonical(domain); 640 return (lower == lowerBound && upper == upperBound) ? this : create(lower, upper); 641 } 642 643 /** 644 * Returns {@code true} if {@code object} is a range having the same endpoints and bound types as 645 * this range. Note that discrete ranges such as {@code (1..4)} and {@code [2..3]} are <b>not</b> 646 * equal to one another, despite the fact that they each contain precisely the same set of values. 647 * Similarly, empty ranges are not equal unless they have exactly the same representation, so 648 * {@code [3..3)}, {@code (3..3]}, {@code (4..4]} are all unequal. 649 */ 650 @Override 651 public boolean equals(@CheckForNull Object object) { 652 if (object instanceof Range) { 653 Range<?> other = (Range<?>) object; 654 return lowerBound.equals(other.lowerBound) && upperBound.equals(other.upperBound); 655 } 656 return false; 657 } 658 659 /** Returns a hash code for this range. */ 660 @Override 661 public int hashCode() { 662 return lowerBound.hashCode() * 31 + upperBound.hashCode(); 663 } 664 665 /** 666 * Returns a string representation of this range, such as {@code "[3..5)"} (other examples are 667 * listed in the class documentation). 668 */ 669 @Override 670 public String toString() { 671 return toString(lowerBound, upperBound); 672 } 673 674 // We declare accessors so that we can use method references like `Range::lowerBound`. 675 676 Cut<C> lowerBound() { 677 return lowerBound; 678 } 679 680 Cut<C> upperBound() { 681 return upperBound; 682 } 683 684 private static String toString(Cut<?> lowerBound, Cut<?> upperBound) { 685 StringBuilder sb = new StringBuilder(16); 686 lowerBound.describeAsLowerBound(sb); 687 sb.append(".."); 688 upperBound.describeAsUpperBound(sb); 689 return sb.toString(); 690 } 691 692 Object readResolve() { 693 if (this.equals(ALL)) { 694 return all(); 695 } else { 696 return this; 697 } 698 } 699 700 @SuppressWarnings("unchecked") // this method may throw CCE 701 static int compareOrThrow(Comparable left, Comparable right) { 702 return left.compareTo(right); 703 } 704 705 /** Needed to serialize sorted collections of Ranges. */ 706 private static class RangeLexOrdering extends Ordering<Range<?>> implements Serializable { 707 static final Ordering<?> INSTANCE = new RangeLexOrdering(); 708 709 @Override 710 public int compare(Range<?> left, Range<?> right) { 711 return ComparisonChain.start() 712 .compare(left.lowerBound, right.lowerBound) 713 .compare(left.upperBound, right.upperBound) 714 .result(); 715 } 716 717 private static final long serialVersionUID = 0; 718 } 719 720 private static final long serialVersionUID = 0; 721}