001/*
002 * Copyright (C) 2012 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.collect;
016
017import static com.google.common.base.Preconditions.checkArgument;
018import static com.google.common.base.Preconditions.checkElementIndex;
019import static com.google.common.base.Preconditions.checkNotNull;
020import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_HIGHER;
021import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_LOWER;
022import static com.google.common.collect.SortedLists.KeyPresentBehavior.ANY_PRESENT;
023
024import com.google.common.annotations.Beta;
025import com.google.common.annotations.GwtIncompatible;
026import com.google.common.collect.SortedLists.KeyAbsentBehavior;
027import com.google.common.collect.SortedLists.KeyPresentBehavior;
028import com.google.common.primitives.Ints;
029import com.google.errorprone.annotations.CanIgnoreReturnValue;
030import com.google.errorprone.annotations.concurrent.LazyInit;
031import java.io.Serializable;
032import java.util.Collections;
033import java.util.Iterator;
034import java.util.List;
035import java.util.NoSuchElementException;
036import java.util.Set;
037import java.util.stream.Collector;
038import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
039import org.checkerframework.checker.nullness.qual.Nullable;
040
041/**
042 * A {@link RangeSet} whose contents will never change, with many other important properties
043 * detailed at {@link ImmutableCollection}.
044 *
045 * @author Louis Wasserman
046 * @since 14.0
047 */
048@Beta
049@GwtIncompatible
050public final class ImmutableRangeSet<C extends Comparable> extends AbstractRangeSet<C>
051    implements Serializable {
052
053  private static final ImmutableRangeSet<Comparable<?>> EMPTY =
054      new ImmutableRangeSet<>(ImmutableList.<Range<Comparable<?>>>of());
055
056  private static final ImmutableRangeSet<Comparable<?>> ALL =
057      new ImmutableRangeSet<>(ImmutableList.of(Range.<Comparable<?>>all()));
058
059  /**
060   * Returns a {@code Collector} that accumulates the input elements into a new {@code
061   * ImmutableRangeSet}. As in {@link Builder}, overlapping ranges are not permitted and adjacent
062   * ranges will be merged.
063   *
064   * @since 23.1
065   */
066  @Beta
067  public static <E extends Comparable<? super E>>
068      Collector<Range<E>, ?, ImmutableRangeSet<E>> toImmutableRangeSet() {
069    return CollectCollectors.toImmutableRangeSet();
070  }
071
072  /** Returns an empty immutable range set. */
073  @SuppressWarnings("unchecked")
074  public static <C extends Comparable> ImmutableRangeSet<C> of() {
075    return (ImmutableRangeSet<C>) EMPTY;
076  }
077
078  /**
079   * Returns an immutable range set containing the specified single range. If {@link Range#isEmpty()
080   * range.isEmpty()}, this is equivalent to {@link ImmutableRangeSet#of()}.
081   */
082  public static <C extends Comparable> ImmutableRangeSet<C> of(Range<C> range) {
083    checkNotNull(range);
084    if (range.isEmpty()) {
085      return of();
086    } else if (range.equals(Range.all())) {
087      return all();
088    } else {
089      return new ImmutableRangeSet<C>(ImmutableList.of(range));
090    }
091  }
092
093  /** Returns an immutable range set containing the single range {@link Range#all()}. */
094  @SuppressWarnings("unchecked")
095  static <C extends Comparable> ImmutableRangeSet<C> all() {
096    return (ImmutableRangeSet<C>) ALL;
097  }
098
099  /** Returns an immutable copy of the specified {@code RangeSet}. */
100  public static <C extends Comparable> ImmutableRangeSet<C> copyOf(RangeSet<C> rangeSet) {
101    checkNotNull(rangeSet);
102    if (rangeSet.isEmpty()) {
103      return of();
104    } else if (rangeSet.encloses(Range.<C>all())) {
105      return all();
106    }
107
108    if (rangeSet instanceof ImmutableRangeSet) {
109      ImmutableRangeSet<C> immutableRangeSet = (ImmutableRangeSet<C>) rangeSet;
110      if (!immutableRangeSet.isPartialView()) {
111        return immutableRangeSet;
112      }
113    }
114    return new ImmutableRangeSet<C>(ImmutableList.copyOf(rangeSet.asRanges()));
115  }
116
117  /**
118   * Returns an {@code ImmutableRangeSet} containing each of the specified disjoint ranges.
119   * Overlapping ranges and empty ranges are forbidden, though adjacent ranges are permitted and
120   * will be merged.
121   *
122   * @throws IllegalArgumentException if any ranges overlap or are empty
123   * @since 21.0
124   */
125  public static <C extends Comparable<?>> ImmutableRangeSet<C> copyOf(Iterable<Range<C>> ranges) {
126    return new ImmutableRangeSet.Builder<C>().addAll(ranges).build();
127  }
128
129  /**
130   * Returns an {@code ImmutableRangeSet} representing the union of the specified ranges.
131   *
132   * <p>This is the smallest {@code RangeSet} which encloses each of the specified ranges. Duplicate
133   * or connected ranges are permitted, and will be coalesced in the result.
134   *
135   * @since 21.0
136   */
137  public static <C extends Comparable<?>> ImmutableRangeSet<C> unionOf(Iterable<Range<C>> ranges) {
138    return copyOf(TreeRangeSet.create(ranges));
139  }
140
141  ImmutableRangeSet(ImmutableList<Range<C>> ranges) {
142    this.ranges = ranges;
143  }
144
145  private ImmutableRangeSet(ImmutableList<Range<C>> ranges, ImmutableRangeSet<C> complement) {
146    this.ranges = ranges;
147    this.complement = complement;
148  }
149
150  private final transient ImmutableList<Range<C>> ranges;
151
152  @Override
153  public boolean intersects(Range<C> otherRange) {
154    int ceilingIndex =
155        SortedLists.binarySearch(
156            ranges,
157            Range.<C>lowerBoundFn(),
158            otherRange.lowerBound,
159            Ordering.natural(),
160            ANY_PRESENT,
161            NEXT_HIGHER);
162    if (ceilingIndex < ranges.size()
163        && ranges.get(ceilingIndex).isConnected(otherRange)
164        && !ranges.get(ceilingIndex).intersection(otherRange).isEmpty()) {
165      return true;
166    }
167    return ceilingIndex > 0
168        && ranges.get(ceilingIndex - 1).isConnected(otherRange)
169        && !ranges.get(ceilingIndex - 1).intersection(otherRange).isEmpty();
170  }
171
172  @Override
173  public boolean encloses(Range<C> otherRange) {
174    int index =
175        SortedLists.binarySearch(
176            ranges,
177            Range.<C>lowerBoundFn(),
178            otherRange.lowerBound,
179            Ordering.natural(),
180            ANY_PRESENT,
181            NEXT_LOWER);
182    return index != -1 && ranges.get(index).encloses(otherRange);
183  }
184
185  @Override
186  public Range<C> rangeContaining(C value) {
187    int index =
188        SortedLists.binarySearch(
189            ranges,
190            Range.<C>lowerBoundFn(),
191            Cut.belowValue(value),
192            Ordering.natural(),
193            ANY_PRESENT,
194            NEXT_LOWER);
195    if (index != -1) {
196      Range<C> range = ranges.get(index);
197      return range.contains(value) ? range : null;
198    }
199    return null;
200  }
201
202  @Override
203  public Range<C> span() {
204    if (ranges.isEmpty()) {
205      throw new NoSuchElementException();
206    }
207    return Range.create(ranges.get(0).lowerBound, ranges.get(ranges.size() - 1).upperBound);
208  }
209
210  @Override
211  public boolean isEmpty() {
212    return ranges.isEmpty();
213  }
214
215  /**
216   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
217   *
218   * @throws UnsupportedOperationException always
219   * @deprecated Unsupported operation.
220   */
221  @Deprecated
222  @Override
223  public void add(Range<C> range) {
224    throw new UnsupportedOperationException();
225  }
226
227  /**
228   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
229   *
230   * @throws UnsupportedOperationException always
231   * @deprecated Unsupported operation.
232   */
233  @Deprecated
234  @Override
235  public void addAll(RangeSet<C> other) {
236    throw new UnsupportedOperationException();
237  }
238
239  /**
240   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
241   *
242   * @throws UnsupportedOperationException always
243   * @deprecated Unsupported operation.
244   */
245  @Deprecated
246  @Override
247  public void addAll(Iterable<Range<C>> other) {
248    throw new UnsupportedOperationException();
249  }
250
251  /**
252   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
253   *
254   * @throws UnsupportedOperationException always
255   * @deprecated Unsupported operation.
256   */
257  @Deprecated
258  @Override
259  public void remove(Range<C> range) {
260    throw new UnsupportedOperationException();
261  }
262
263  /**
264   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
265   *
266   * @throws UnsupportedOperationException always
267   * @deprecated Unsupported operation.
268   */
269  @Deprecated
270  @Override
271  public void removeAll(RangeSet<C> other) {
272    throw new UnsupportedOperationException();
273  }
274
275  /**
276   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
277   *
278   * @throws UnsupportedOperationException always
279   * @deprecated Unsupported operation.
280   */
281  @Deprecated
282  @Override
283  public void removeAll(Iterable<Range<C>> other) {
284    throw new UnsupportedOperationException();
285  }
286
287  @Override
288  public ImmutableSet<Range<C>> asRanges() {
289    if (ranges.isEmpty()) {
290      return ImmutableSet.of();
291    }
292    return new RegularImmutableSortedSet<>(ranges, Range.<C>rangeLexOrdering());
293  }
294
295  @Override
296  public ImmutableSet<Range<C>> asDescendingSetOfRanges() {
297    if (ranges.isEmpty()) {
298      return ImmutableSet.of();
299    }
300    return new RegularImmutableSortedSet<>(ranges.reverse(), Range.<C>rangeLexOrdering().reverse());
301  }
302
303  @LazyInit private transient ImmutableRangeSet<C> complement;
304
305  private final class ComplementRanges extends ImmutableList<Range<C>> {
306    // True if the "positive" range set is empty or bounded below.
307    private final boolean positiveBoundedBelow;
308
309    // True if the "positive" range set is empty or bounded above.
310    private final boolean positiveBoundedAbove;
311
312    private final int size;
313
314    ComplementRanges() {
315      this.positiveBoundedBelow = ranges.get(0).hasLowerBound();
316      this.positiveBoundedAbove = Iterables.getLast(ranges).hasUpperBound();
317
318      int size = ranges.size() - 1;
319      if (positiveBoundedBelow) {
320        size++;
321      }
322      if (positiveBoundedAbove) {
323        size++;
324      }
325      this.size = size;
326    }
327
328    @Override
329    public int size() {
330      return size;
331    }
332
333    @Override
334    public Range<C> get(int index) {
335      checkElementIndex(index, size);
336
337      Cut<C> lowerBound;
338      if (positiveBoundedBelow) {
339        lowerBound = (index == 0) ? Cut.<C>belowAll() : ranges.get(index - 1).upperBound;
340      } else {
341        lowerBound = ranges.get(index).upperBound;
342      }
343
344      Cut<C> upperBound;
345      if (positiveBoundedAbove && index == size - 1) {
346        upperBound = Cut.<C>aboveAll();
347      } else {
348        upperBound = ranges.get(index + (positiveBoundedBelow ? 0 : 1)).lowerBound;
349      }
350
351      return Range.create(lowerBound, upperBound);
352    }
353
354    @Override
355    boolean isPartialView() {
356      return true;
357    }
358  }
359
360  @Override
361  public ImmutableRangeSet<C> complement() {
362    ImmutableRangeSet<C> result = complement;
363    if (result != null) {
364      return result;
365    } else if (ranges.isEmpty()) {
366      return complement = all();
367    } else if (ranges.size() == 1 && ranges.get(0).equals(Range.all())) {
368      return complement = of();
369    } else {
370      ImmutableList<Range<C>> complementRanges = new ComplementRanges();
371      result = complement = new ImmutableRangeSet<C>(complementRanges, this);
372    }
373    return result;
374  }
375
376  /**
377   * Returns a new range set consisting of the union of this range set and {@code other}.
378   *
379   * <p>This is essentially the same as {@code TreeRangeSet.create(this).addAll(other)} except it
380   * returns an {@code ImmutableRangeSet}.
381   *
382   * @since 21.0
383   */
384  public ImmutableRangeSet<C> union(RangeSet<C> other) {
385    return unionOf(Iterables.concat(asRanges(), other.asRanges()));
386  }
387
388  /**
389   * Returns a new range set consisting of the intersection of this range set and {@code other}.
390   *
391   * <p>This is essentially the same as {@code
392   * TreeRangeSet.create(this).removeAll(other.complement())} except it returns an {@code
393   * ImmutableRangeSet}.
394   *
395   * @since 21.0
396   */
397  public ImmutableRangeSet<C> intersection(RangeSet<C> other) {
398    RangeSet<C> copy = TreeRangeSet.create(this);
399    copy.removeAll(other.complement());
400    return copyOf(copy);
401  }
402
403  /**
404   * Returns a new range set consisting of the difference of this range set and {@code other}.
405   *
406   * <p>This is essentially the same as {@code TreeRangeSet.create(this).removeAll(other)} except it
407   * returns an {@code ImmutableRangeSet}.
408   *
409   * @since 21.0
410   */
411  public ImmutableRangeSet<C> difference(RangeSet<C> other) {
412    RangeSet<C> copy = TreeRangeSet.create(this);
413    copy.removeAll(other);
414    return copyOf(copy);
415  }
416
417  /**
418   * Returns a list containing the nonempty intersections of {@code range} with the ranges in this
419   * range set.
420   */
421  private ImmutableList<Range<C>> intersectRanges(final Range<C> range) {
422    if (ranges.isEmpty() || range.isEmpty()) {
423      return ImmutableList.of();
424    } else if (range.encloses(span())) {
425      return ranges;
426    }
427
428    final int fromIndex;
429    if (range.hasLowerBound()) {
430      fromIndex =
431          SortedLists.binarySearch(
432              ranges,
433              Range.<C>upperBoundFn(),
434              range.lowerBound,
435              KeyPresentBehavior.FIRST_AFTER,
436              KeyAbsentBehavior.NEXT_HIGHER);
437    } else {
438      fromIndex = 0;
439    }
440
441    int toIndex;
442    if (range.hasUpperBound()) {
443      toIndex =
444          SortedLists.binarySearch(
445              ranges,
446              Range.<C>lowerBoundFn(),
447              range.upperBound,
448              KeyPresentBehavior.FIRST_PRESENT,
449              KeyAbsentBehavior.NEXT_HIGHER);
450    } else {
451      toIndex = ranges.size();
452    }
453    final int length = toIndex - fromIndex;
454    if (length == 0) {
455      return ImmutableList.of();
456    } else {
457      return new ImmutableList<Range<C>>() {
458        @Override
459        public int size() {
460          return length;
461        }
462
463        @Override
464        public Range<C> get(int index) {
465          checkElementIndex(index, length);
466          if (index == 0 || index == length - 1) {
467            return ranges.get(index + fromIndex).intersection(range);
468          } else {
469            return ranges.get(index + fromIndex);
470          }
471        }
472
473        @Override
474        boolean isPartialView() {
475          return true;
476        }
477      };
478    }
479  }
480
481  /** Returns a view of the intersection of this range set with the given range. */
482  @Override
483  public ImmutableRangeSet<C> subRangeSet(Range<C> range) {
484    if (!isEmpty()) {
485      Range<C> span = span();
486      if (range.encloses(span)) {
487        return this;
488      } else if (range.isConnected(span)) {
489        return new ImmutableRangeSet<C>(intersectRanges(range));
490      }
491    }
492    return of();
493  }
494
495  /**
496   * Returns an {@link ImmutableSortedSet} containing the same values in the given domain
497   * {@linkplain RangeSet#contains contained} by this range set.
498   *
499   * <p><b>Note:</b> {@code a.asSet(d).equals(b.asSet(d))} does not imply {@code a.equals(b)}! For
500   * example, {@code a} and {@code b} could be {@code [2..4]} and {@code (1..5)}, or the empty
501   * ranges {@code [3..3)} and {@code [4..4)}.
502   *
503   * <p><b>Warning:</b> Be extremely careful what you do with the {@code asSet} view of a large
504   * range set (such as {@code ImmutableRangeSet.of(Range.greaterThan(0))}). Certain operations on
505   * such a set can be performed efficiently, but others (such as {@link Set#hashCode} or {@link
506   * Collections#frequency}) can cause major performance problems.
507   *
508   * <p>The returned set's {@link Object#toString} method returns a short-hand form of the set's
509   * contents, such as {@code "[1..100]}"}.
510   *
511   * @throws IllegalArgumentException if neither this range nor the domain has a lower bound, or if
512   *     neither has an upper bound
513   */
514  public ImmutableSortedSet<C> asSet(DiscreteDomain<C> domain) {
515    checkNotNull(domain);
516    if (isEmpty()) {
517      return ImmutableSortedSet.of();
518    }
519    Range<C> span = span().canonical(domain);
520    if (!span.hasLowerBound()) {
521      // according to the spec of canonical, neither this ImmutableRangeSet nor
522      // the range have a lower bound
523      throw new IllegalArgumentException(
524          "Neither the DiscreteDomain nor this range set are bounded below");
525    } else if (!span.hasUpperBound()) {
526      try {
527        domain.maxValue();
528      } catch (NoSuchElementException e) {
529        throw new IllegalArgumentException(
530            "Neither the DiscreteDomain nor this range set are bounded above");
531      }
532    }
533
534    return new AsSet(domain);
535  }
536
537  private final class AsSet extends ImmutableSortedSet<C> {
538    private final DiscreteDomain<C> domain;
539
540    AsSet(DiscreteDomain<C> domain) {
541      super(Ordering.natural());
542      this.domain = domain;
543    }
544
545    private transient @MonotonicNonNull Integer size;
546
547    @Override
548    public int size() {
549      // racy single-check idiom
550      Integer result = size;
551      if (result == null) {
552        long total = 0;
553        for (Range<C> range : ranges) {
554          total += ContiguousSet.create(range, domain).size();
555          if (total >= Integer.MAX_VALUE) {
556            break;
557          }
558        }
559        result = size = Ints.saturatedCast(total);
560      }
561      return result.intValue();
562    }
563
564    @Override
565    public UnmodifiableIterator<C> iterator() {
566      return new AbstractIterator<C>() {
567        final Iterator<Range<C>> rangeItr = ranges.iterator();
568        Iterator<C> elemItr = Iterators.emptyIterator();
569
570        @Override
571        protected C computeNext() {
572          while (!elemItr.hasNext()) {
573            if (rangeItr.hasNext()) {
574              elemItr = ContiguousSet.create(rangeItr.next(), domain).iterator();
575            } else {
576              return endOfData();
577            }
578          }
579          return elemItr.next();
580        }
581      };
582    }
583
584    @Override
585    @GwtIncompatible("NavigableSet")
586    public UnmodifiableIterator<C> descendingIterator() {
587      return new AbstractIterator<C>() {
588        final Iterator<Range<C>> rangeItr = ranges.reverse().iterator();
589        Iterator<C> elemItr = Iterators.emptyIterator();
590
591        @Override
592        protected C computeNext() {
593          while (!elemItr.hasNext()) {
594            if (rangeItr.hasNext()) {
595              elemItr = ContiguousSet.create(rangeItr.next(), domain).descendingIterator();
596            } else {
597              return endOfData();
598            }
599          }
600          return elemItr.next();
601        }
602      };
603    }
604
605    ImmutableSortedSet<C> subSet(Range<C> range) {
606      return subRangeSet(range).asSet(domain);
607    }
608
609    @Override
610    ImmutableSortedSet<C> headSetImpl(C toElement, boolean inclusive) {
611      return subSet(Range.upTo(toElement, BoundType.forBoolean(inclusive)));
612    }
613
614    @Override
615    ImmutableSortedSet<C> subSetImpl(
616        C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
617      if (!fromInclusive && !toInclusive && Range.compareOrThrow(fromElement, toElement) == 0) {
618        return ImmutableSortedSet.of();
619      }
620      return subSet(
621          Range.range(
622              fromElement, BoundType.forBoolean(fromInclusive),
623              toElement, BoundType.forBoolean(toInclusive)));
624    }
625
626    @Override
627    ImmutableSortedSet<C> tailSetImpl(C fromElement, boolean inclusive) {
628      return subSet(Range.downTo(fromElement, BoundType.forBoolean(inclusive)));
629    }
630
631    @Override
632    public boolean contains(@Nullable Object o) {
633      if (o == null) {
634        return false;
635      }
636      try {
637        @SuppressWarnings("unchecked") // we catch CCE's
638        C c = (C) o;
639        return ImmutableRangeSet.this.contains(c);
640      } catch (ClassCastException e) {
641        return false;
642      }
643    }
644
645    @Override
646    int indexOf(Object target) {
647      if (contains(target)) {
648        @SuppressWarnings("unchecked") // if it's contained, it's definitely a C
649        C c = (C) target;
650        long total = 0;
651        for (Range<C> range : ranges) {
652          if (range.contains(c)) {
653            return Ints.saturatedCast(total + ContiguousSet.create(range, domain).indexOf(c));
654          } else {
655            total += ContiguousSet.create(range, domain).size();
656          }
657        }
658        throw new AssertionError("impossible");
659      }
660      return -1;
661    }
662
663    @Override
664    ImmutableSortedSet<C> createDescendingSet() {
665      return new DescendingImmutableSortedSet<C>(this);
666    }
667
668    @Override
669    boolean isPartialView() {
670      return ranges.isPartialView();
671    }
672
673    @Override
674    public String toString() {
675      return ranges.toString();
676    }
677
678    @Override
679    Object writeReplace() {
680      return new AsSetSerializedForm<C>(ranges, domain);
681    }
682  }
683
684  private static class AsSetSerializedForm<C extends Comparable> implements Serializable {
685    private final ImmutableList<Range<C>> ranges;
686    private final DiscreteDomain<C> domain;
687
688    AsSetSerializedForm(ImmutableList<Range<C>> ranges, DiscreteDomain<C> domain) {
689      this.ranges = ranges;
690      this.domain = domain;
691    }
692
693    Object readResolve() {
694      return new ImmutableRangeSet<C>(ranges).asSet(domain);
695    }
696  }
697
698  /**
699   * Returns {@code true} if this immutable range set's implementation contains references to
700   * user-created objects that aren't accessible via this range set's methods. This is generally
701   * used to determine whether {@code copyOf} implementations should make an explicit copy to avoid
702   * memory leaks.
703   */
704  boolean isPartialView() {
705    return ranges.isPartialView();
706  }
707
708  /** Returns a new builder for an immutable range set. */
709  public static <C extends Comparable<?>> Builder<C> builder() {
710    return new Builder<C>();
711  }
712
713  /**
714   * A builder for immutable range sets.
715   *
716   * @since 14.0
717   */
718  public static class Builder<C extends Comparable<?>> {
719    private final List<Range<C>> ranges;
720
721    public Builder() {
722      this.ranges = Lists.newArrayList();
723    }
724
725    // TODO(lowasser): consider adding union, in addition to add, that does allow overlap
726
727    /**
728     * Add the specified range to this builder. Adjacent ranges are permitted and will be merged,
729     * but overlapping ranges will cause an exception when {@link #build()} is called.
730     *
731     * @throws IllegalArgumentException if {@code range} is empty
732     */
733    @CanIgnoreReturnValue
734    public Builder<C> add(Range<C> range) {
735      checkArgument(!range.isEmpty(), "range must not be empty, but was %s", range);
736      ranges.add(range);
737      return this;
738    }
739
740    /**
741     * Add all ranges from the specified range set to this builder. Adjacent ranges are permitted
742     * and will be merged, but overlapping ranges will cause an exception when {@link #build()} is
743     * called.
744     */
745    @CanIgnoreReturnValue
746    public Builder<C> addAll(RangeSet<C> ranges) {
747      return addAll(ranges.asRanges());
748    }
749
750    /**
751     * Add all of the specified ranges to this builder. Adjacent ranges are permitted and will be
752     * merged, but overlapping ranges will cause an exception when {@link #build()} is called.
753     *
754     * @throws IllegalArgumentException if any inserted ranges are empty
755     * @since 21.0
756     */
757    @CanIgnoreReturnValue
758    public Builder<C> addAll(Iterable<Range<C>> ranges) {
759      for (Range<C> range : ranges) {
760        add(range);
761      }
762      return this;
763    }
764
765    @CanIgnoreReturnValue
766    Builder<C> combine(Builder<C> builder) {
767      addAll(builder.ranges);
768      return this;
769    }
770
771    /**
772     * Returns an {@code ImmutableRangeSet} containing the ranges added to this builder.
773     *
774     * @throws IllegalArgumentException if any input ranges have nonempty overlap
775     */
776    public ImmutableRangeSet<C> build() {
777      ImmutableList.Builder<Range<C>> mergedRangesBuilder =
778          new ImmutableList.Builder<>(ranges.size());
779      Collections.sort(ranges, Range.<C>rangeLexOrdering());
780      PeekingIterator<Range<C>> peekingItr = Iterators.peekingIterator(ranges.iterator());
781      while (peekingItr.hasNext()) {
782        Range<C> range = peekingItr.next();
783        while (peekingItr.hasNext()) {
784          Range<C> nextRange = peekingItr.peek();
785          if (range.isConnected(nextRange)) {
786            checkArgument(
787                range.intersection(nextRange).isEmpty(),
788                "Overlapping ranges not permitted but found %s overlapping %s",
789                range,
790                nextRange);
791            range = range.span(peekingItr.next());
792          } else {
793            break;
794          }
795        }
796        mergedRangesBuilder.add(range);
797      }
798      ImmutableList<Range<C>> mergedRanges = mergedRangesBuilder.build();
799      if (mergedRanges.isEmpty()) {
800        return of();
801      } else if (mergedRanges.size() == 1
802          && Iterables.getOnlyElement(mergedRanges).equals(Range.all())) {
803        return all();
804      } else {
805        return new ImmutableRangeSet<C>(mergedRanges);
806      }
807    }
808  }
809
810  private static final class SerializedForm<C extends Comparable> implements Serializable {
811    private final ImmutableList<Range<C>> ranges;
812
813    SerializedForm(ImmutableList<Range<C>> ranges) {
814      this.ranges = ranges;
815    }
816
817    Object readResolve() {
818      if (ranges.isEmpty()) {
819        return of();
820      } else if (ranges.equals(ImmutableList.of(Range.all()))) {
821        return all();
822      } else {
823        return new ImmutableRangeSet<C>(ranges);
824      }
825    }
826  }
827
828  Object writeReplace() {
829    return new SerializedForm<C>(ranges);
830  }
831}