Source code

001/*
002 * Copyright (C) 2011 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.checkNotNull;
019
020import com.google.common.annotations.Beta;
021import com.google.common.annotations.GwtIncompatible;
022import com.google.common.annotations.VisibleForTesting;
023import com.google.common.base.MoreObjects;
024import java.io.Serializable;
025import java.util.Collection;
026import java.util.Comparator;
027import java.util.Iterator;
028import java.util.Map.Entry;
029import java.util.NavigableMap;
030import java.util.NoSuchElementException;
031import java.util.Set;
032import java.util.TreeMap;
033import javax.annotation.CheckForNull;
034
035/**
036 * An implementation of {@link RangeSet} backed by a {@link TreeMap}.
037 *
038 * @author Louis Wasserman
039 * @since 14.0
040 */
041@Beta
042@GwtIncompatible // uses NavigableMap
043@ElementTypesAreNonnullByDefault
044public class TreeRangeSet<C extends Comparable<?>> extends AbstractRangeSet<C>
045    implements Serializable {
046
047  @VisibleForTesting final NavigableMap<Cut<C>, Range<C>> rangesByLowerBound;
048
049  /** Creates an empty {@code TreeRangeSet} instance. */
050  public static <C extends Comparable<?>> TreeRangeSet<C> create() {
051    return new TreeRangeSet<>(new TreeMap<Cut<C>, Range<C>>());
052  }
053
054  /** Returns a {@code TreeRangeSet} initialized with the ranges in the specified range set. */
055  public static <C extends Comparable<?>> TreeRangeSet<C> create(RangeSet<C> rangeSet) {
056    TreeRangeSet<C> result = create();
057    result.addAll(rangeSet);
058    return result;
059  }
060
061  /**
062   * Returns a {@code TreeRangeSet} representing the union of the specified ranges.
063   *
064   * <p>This is the smallest {@code RangeSet} which encloses each of the specified ranges. An
065   * element will be contained in this {@code RangeSet} if and only if it is contained in at least
066   * one {@code Range} in {@code ranges}.
067   *
068   * @since 21.0
069   */
070  public static <C extends Comparable<?>> TreeRangeSet<C> create(Iterable<Range<C>> ranges) {
071    TreeRangeSet<C> result = create();
072    result.addAll(ranges);
073    return result;
074  }
075
076  private TreeRangeSet(NavigableMap<Cut<C>, Range<C>> rangesByLowerCut) {
077    this.rangesByLowerBound = rangesByLowerCut;
078  }
079
080  @CheckForNull private transient Set<Range<C>> asRanges;
081  @CheckForNull private transient Set<Range<C>> asDescendingSetOfRanges;
082
083  @Override
084  public Set<Range<C>> asRanges() {
085    Set<Range<C>> result = asRanges;
086    return (result == null) ? asRanges = new AsRanges(rangesByLowerBound.values()) : result;
087  }
088
089  @Override
090  public Set<Range<C>> asDescendingSetOfRanges() {
091    Set<Range<C>> result = asDescendingSetOfRanges;
092    return (result == null)
093        ? asDescendingSetOfRanges = new AsRanges(rangesByLowerBound.descendingMap().values())
094        : result;
095  }
096
097  final class AsRanges extends ForwardingCollection<Range<C>> implements Set<Range<C>> {
098
099    final Collection<Range<C>> delegate;
100
101    AsRanges(Collection<Range<C>> delegate) {
102      this.delegate = delegate;
103    }
104
105    @Override
106    protected Collection<Range<C>> delegate() {
107      return delegate;
108    }
109
110    @Override
111    public int hashCode() {
112      return Sets.hashCodeImpl(this);
113    }
114
115    @Override
116    public boolean equals(@CheckForNull Object o) {
117      return Sets.equalsImpl(this, o);
118    }
119  }
120
121  @Override
122  @CheckForNull
123  public Range<C> rangeContaining(C value) {
124    checkNotNull(value);
125    Entry<Cut<C>, Range<C>> floorEntry = rangesByLowerBound.floorEntry(Cut.belowValue(value));
126    if (floorEntry != null && floorEntry.getValue().contains(value)) {
127      return floorEntry.getValue();
128    } else {
129      // TODO(kevinb): revisit this design choice
130      return null;
131    }
132  }
133
134  @Override
135  public boolean intersects(Range<C> range) {
136    checkNotNull(range);
137    Entry<Cut<C>, Range<C>> ceilingEntry = rangesByLowerBound.ceilingEntry(range.lowerBound);
138    if (ceilingEntry != null
139        && ceilingEntry.getValue().isConnected(range)
140        && !ceilingEntry.getValue().intersection(range).isEmpty()) {
141      return true;
142    }
143    Entry<Cut<C>, Range<C>> priorEntry = rangesByLowerBound.lowerEntry(range.lowerBound);
144    return priorEntry != null
145        && priorEntry.getValue().isConnected(range)
146        && !priorEntry.getValue().intersection(range).isEmpty();
147  }
148
149  @Override
150  public boolean encloses(Range<C> range) {
151    checkNotNull(range);
152    Entry<Cut<C>, Range<C>> floorEntry = rangesByLowerBound.floorEntry(range.lowerBound);
153    return floorEntry != null && floorEntry.getValue().encloses(range);
154  }
155
156  @CheckForNull
157  private Range<C> rangeEnclosing(Range<C> range) {
158    checkNotNull(range);
159    Entry<Cut<C>, Range<C>> floorEntry = rangesByLowerBound.floorEntry(range.lowerBound);
160    return (floorEntry != null && floorEntry.getValue().encloses(range))
161        ? floorEntry.getValue()
162        : null;
163  }
164
165  @Override
166  public Range<C> span() {
167    Entry<Cut<C>, Range<C>> firstEntry = rangesByLowerBound.firstEntry();
168    Entry<Cut<C>, Range<C>> lastEntry = rangesByLowerBound.lastEntry();
169    if (firstEntry == null || lastEntry == null) {
170      /*
171       * Either both are null or neither is: Either the set is empty, or it's not. But we check both
172       * to make the nullness checker happy.
173       */
174      throw new NoSuchElementException();
175    }
176    return Range.create(firstEntry.getValue().lowerBound, lastEntry.getValue().upperBound);
177  }
178
179  @Override
180  public void add(Range<C> rangeToAdd) {
181    checkNotNull(rangeToAdd);
182
183    if (rangeToAdd.isEmpty()) {
184      return;
185    }
186
187    // We will use { } to illustrate ranges currently in the range set, and < >
188    // to illustrate rangeToAdd.
189    Cut<C> lbToAdd = rangeToAdd.lowerBound;
190    Cut<C> ubToAdd = rangeToAdd.upperBound;
191
192    Entry<Cut<C>, Range<C>> entryBelowLB = rangesByLowerBound.lowerEntry(lbToAdd);
193    if (entryBelowLB != null) {
194      // { <
195      Range<C> rangeBelowLB = entryBelowLB.getValue();
196      if (rangeBelowLB.upperBound.compareTo(lbToAdd) >= 0) {
197        // { < }, and we will need to coalesce
198        if (rangeBelowLB.upperBound.compareTo(ubToAdd) >= 0) {
199          // { < > }
200          ubToAdd = rangeBelowLB.upperBound;
201          /*
202           * TODO(cpovirk): can we just "return;" here? Or, can we remove this if() entirely? If
203           * not, add tests to demonstrate the problem with each approach
204           */
205        }
206        lbToAdd = rangeBelowLB.lowerBound;
207      }
208    }
209
210    Entry<Cut<C>, Range<C>> entryBelowUB = rangesByLowerBound.floorEntry(ubToAdd);
211    if (entryBelowUB != null) {
212      // { >
213      Range<C> rangeBelowUB = entryBelowUB.getValue();
214      if (rangeBelowUB.upperBound.compareTo(ubToAdd) >= 0) {
215        // { > }, and we need to coalesce
216        ubToAdd = rangeBelowUB.upperBound;
217      }
218    }
219
220    // Remove ranges which are strictly enclosed.
221    rangesByLowerBound.subMap(lbToAdd, ubToAdd).clear();
222
223    replaceRangeWithSameLowerBound(Range.create(lbToAdd, ubToAdd));
224  }
225
226  @Override
227  public void remove(Range<C> rangeToRemove) {
228    checkNotNull(rangeToRemove);
229
230    if (rangeToRemove.isEmpty()) {
231      return;
232    }
233
234    // We will use { } to illustrate ranges currently in the range set, and < >
235    // to illustrate rangeToRemove.
236
237    Entry<Cut<C>, Range<C>> entryBelowLB = rangesByLowerBound.lowerEntry(rangeToRemove.lowerBound);
238    if (entryBelowLB != null) {
239      // { <
240      Range<C> rangeBelowLB = entryBelowLB.getValue();
241      if (rangeBelowLB.upperBound.compareTo(rangeToRemove.lowerBound) >= 0) {
242        // { < }, and we will need to subdivide
243        if (rangeToRemove.hasUpperBound()
244            && rangeBelowLB.upperBound.compareTo(rangeToRemove.upperBound) >= 0) {
245          // { < > }
246          replaceRangeWithSameLowerBound(
247              Range.create(rangeToRemove.upperBound, rangeBelowLB.upperBound));
248        }
249        replaceRangeWithSameLowerBound(
250            Range.create(rangeBelowLB.lowerBound, rangeToRemove.lowerBound));
251      }
252    }
253
254    Entry<Cut<C>, Range<C>> entryBelowUB = rangesByLowerBound.floorEntry(rangeToRemove.upperBound);
255    if (entryBelowUB != null) {
256      // { >
257      Range<C> rangeBelowUB = entryBelowUB.getValue();
258      if (rangeToRemove.hasUpperBound()
259          && rangeBelowUB.upperBound.compareTo(rangeToRemove.upperBound) >= 0) {
260        // { > }
261        replaceRangeWithSameLowerBound(
262            Range.create(rangeToRemove.upperBound, rangeBelowUB.upperBound));
263      }
264    }
265
266    rangesByLowerBound.subMap(rangeToRemove.lowerBound, rangeToRemove.upperBound).clear();
267  }
268
269  private void replaceRangeWithSameLowerBound(Range<C> range) {
270    if (range.isEmpty()) {
271      rangesByLowerBound.remove(range.lowerBound);
272    } else {
273      rangesByLowerBound.put(range.lowerBound, range);
274    }
275  }
276
277  @CheckForNull private transient RangeSet<C> complement;
278
279  @Override
280  public RangeSet<C> complement() {
281    RangeSet<C> result = complement;
282    return (result == null) ? complement = new Complement() : result;
283  }
284
285  @VisibleForTesting
286  static final class RangesByUpperBound<C extends Comparable<?>>
287      extends AbstractNavigableMap<Cut<C>, Range<C>> {
288    private final NavigableMap<Cut<C>, Range<C>> rangesByLowerBound;
289
290    /**
291     * upperBoundWindow represents the headMap/subMap/tailMap view of the entire "ranges by upper
292     * bound" map; it's a constraint on the *keys*, and does not affect the values.
293     */
294    private final Range<Cut<C>> upperBoundWindow;
295
296    RangesByUpperBound(NavigableMap<Cut<C>, Range<C>> rangesByLowerBound) {
297      this.rangesByLowerBound = rangesByLowerBound;
298      this.upperBoundWindow = Range.all();
299    }
300
301    private RangesByUpperBound(
302        NavigableMap<Cut<C>, Range<C>> rangesByLowerBound, Range<Cut<C>> upperBoundWindow) {
303      this.rangesByLowerBound = rangesByLowerBound;
304      this.upperBoundWindow = upperBoundWindow;
305    }
306
307    private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> window) {
308      if (window.isConnected(upperBoundWindow)) {
309        return new RangesByUpperBound<>(rangesByLowerBound, window.intersection(upperBoundWindow));
310      } else {
311        return ImmutableSortedMap.of();
312      }
313    }
314
315    @Override
316    public NavigableMap<Cut<C>, Range<C>> subMap(
317        Cut<C> fromKey, boolean fromInclusive, Cut<C> toKey, boolean toInclusive) {
318      return subMap(
319          Range.range(
320              fromKey, BoundType.forBoolean(fromInclusive),
321              toKey, BoundType.forBoolean(toInclusive)));
322    }
323
324    @Override
325    public NavigableMap<Cut<C>, Range<C>> headMap(Cut<C> toKey, boolean inclusive) {
326      return subMap(Range.upTo(toKey, BoundType.forBoolean(inclusive)));
327    }
328
329    @Override
330    public NavigableMap<Cut<C>, Range<C>> tailMap(Cut<C> fromKey, boolean inclusive) {
331      return subMap(Range.downTo(fromKey, BoundType.forBoolean(inclusive)));
332    }
333
334    @Override
335    public Comparator<? super Cut<C>> comparator() {
336      return Ordering.<Cut<C>>natural();
337    }
338
339    @Override
340    public boolean containsKey(@CheckForNull Object key) {
341      return get(key) != null;
342    }
343
344    @Override
345    @CheckForNull
346    public Range<C> get(@CheckForNull Object key) {
347      if (key instanceof Cut) {
348        try {
349          @SuppressWarnings("unchecked") // we catch CCEs
350          Cut<C> cut = (Cut<C>) key;
351          if (!upperBoundWindow.contains(cut)) {
352            return null;
353          }
354          Entry<Cut<C>, Range<C>> candidate = rangesByLowerBound.lowerEntry(cut);
355          if (candidate != null && candidate.getValue().upperBound.equals(cut)) {
356            return candidate.getValue();
357          }
358        } catch (ClassCastException e) {
359          return null;
360        }
361      }
362      return null;
363    }
364
365    @Override
366    Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
367      /*
368       * We want to start the iteration at the first range where the upper bound is in
369       * upperBoundWindow.
370       */
371      Iterator<Range<C>> backingItr;
372      if (!upperBoundWindow.hasLowerBound()) {
373        backingItr = rangesByLowerBound.values().iterator();
374      } else {
375        Entry<Cut<C>, Range<C>> lowerEntry =
376            rangesByLowerBound.lowerEntry(upperBoundWindow.lowerEndpoint());
377        if (lowerEntry == null) {
378          backingItr = rangesByLowerBound.values().iterator();
379        } else if (upperBoundWindow.lowerBound.isLessThan(lowerEntry.getValue().upperBound)) {
380          backingItr = rangesByLowerBound.tailMap(lowerEntry.getKey(), true).values().iterator();
381        } else {
382          backingItr =
383              rangesByLowerBound
384                  .tailMap(upperBoundWindow.lowerEndpoint(), true)
385                  .values()
386                  .iterator();
387        }
388      }
389      return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
390        @Override
391        @CheckForNull
392        protected Entry<Cut<C>, Range<C>> computeNext() {
393          if (!backingItr.hasNext()) {
394            return endOfData();
395          }
396          Range<C> range = backingItr.next();
397          if (upperBoundWindow.upperBound.isLessThan(range.upperBound)) {
398            return endOfData();
399          } else {
400            return Maps.immutableEntry(range.upperBound, range);
401          }
402        }
403      };
404    }
405
406    @Override
407    Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
408      Collection<Range<C>> candidates;
409      if (upperBoundWindow.hasUpperBound()) {
410        candidates =
411            rangesByLowerBound
412                .headMap(upperBoundWindow.upperEndpoint(), false)
413                .descendingMap()
414                .values();
415      } else {
416        candidates = rangesByLowerBound.descendingMap().values();
417      }
418      PeekingIterator<Range<C>> backingItr = Iterators.peekingIterator(candidates.iterator());
419      if (backingItr.hasNext()
420          && upperBoundWindow.upperBound.isLessThan(backingItr.peek().upperBound)) {
421        backingItr.next();
422      }
423      return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
424        @Override
425        @CheckForNull
426        protected Entry<Cut<C>, Range<C>> computeNext() {
427          if (!backingItr.hasNext()) {
428            return endOfData();
429          }
430          Range<C> range = backingItr.next();
431          return upperBoundWindow.lowerBound.isLessThan(range.upperBound)
432              ? Maps.immutableEntry(range.upperBound, range)
433              : endOfData();
434        }
435      };
436    }
437
438    @Override
439    public int size() {
440      if (upperBoundWindow.equals(Range.all())) {
441        return rangesByLowerBound.size();
442      }
443      return Iterators.size(entryIterator());
444    }
445
446    @Override
447    public boolean isEmpty() {
448      return upperBoundWindow.equals(Range.all())
449          ? rangesByLowerBound.isEmpty()
450          : !entryIterator().hasNext();
451    }
452  }
453
454  private static final class ComplementRangesByLowerBound<C extends Comparable<?>>
455      extends AbstractNavigableMap<Cut<C>, Range<C>> {
456    private final NavigableMap<Cut<C>, Range<C>> positiveRangesByLowerBound;
457    private final NavigableMap<Cut<C>, Range<C>> positiveRangesByUpperBound;
458
459    /**
460     * complementLowerBoundWindow represents the headMap/subMap/tailMap view of the entire
461     * "complement ranges by lower bound" map; it's a constraint on the *keys*, and does not affect
462     * the values.
463     */
464    private final Range<Cut<C>> complementLowerBoundWindow;
465
466    ComplementRangesByLowerBound(NavigableMap<Cut<C>, Range<C>> positiveRangesByLowerBound) {
467      this(positiveRangesByLowerBound, Range.<Cut<C>>all());
468    }
469
470    private ComplementRangesByLowerBound(
471        NavigableMap<Cut<C>, Range<C>> positiveRangesByLowerBound, Range<Cut<C>> window) {
472      this.positiveRangesByLowerBound = positiveRangesByLowerBound;
473      this.positiveRangesByUpperBound = new RangesByUpperBound<>(positiveRangesByLowerBound);
474      this.complementLowerBoundWindow = window;
475    }
476
477    private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> subWindow) {
478      if (!complementLowerBoundWindow.isConnected(subWindow)) {
479        return ImmutableSortedMap.of();
480      } else {
481        subWindow = subWindow.intersection(complementLowerBoundWindow);
482        return new ComplementRangesByLowerBound<>(positiveRangesByLowerBound, subWindow);
483      }
484    }
485
486    @Override
487    public NavigableMap<Cut<C>, Range<C>> subMap(
488        Cut<C> fromKey, boolean fromInclusive, Cut<C> toKey, boolean toInclusive) {
489      return subMap(
490          Range.range(
491              fromKey, BoundType.forBoolean(fromInclusive),
492              toKey, BoundType.forBoolean(toInclusive)));
493    }
494
495    @Override
496    public NavigableMap<Cut<C>, Range<C>> headMap(Cut<C> toKey, boolean inclusive) {
497      return subMap(Range.upTo(toKey, BoundType.forBoolean(inclusive)));
498    }
499
500    @Override
501    public NavigableMap<Cut<C>, Range<C>> tailMap(Cut<C> fromKey, boolean inclusive) {
502      return subMap(Range.downTo(fromKey, BoundType.forBoolean(inclusive)));
503    }
504
505    @Override
506    public Comparator<? super Cut<C>> comparator() {
507      return Ordering.<Cut<C>>natural();
508    }
509
510    @Override
511    Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
512      /*
513       * firstComplementRangeLowerBound is the first complement range lower bound inside
514       * complementLowerBoundWindow. Complement range lower bounds are either positive range upper
515       * bounds, or Cut.belowAll().
516       *
517       * positiveItr starts at the first positive range with lower bound greater than
518       * firstComplementRangeLowerBound. (Positive range lower bounds correspond to complement range
519       * upper bounds.)
520       */
521      Collection<Range<C>> positiveRanges;
522      if (complementLowerBoundWindow.hasLowerBound()) {
523        positiveRanges =
524            positiveRangesByUpperBound
525                .tailMap(
526                    complementLowerBoundWindow.lowerEndpoint(),
527                    complementLowerBoundWindow.lowerBoundType() == BoundType.CLOSED)
528                .values();
529      } else {
530        positiveRanges = positiveRangesByUpperBound.values();
531      }
532      PeekingIterator<Range<C>> positiveItr = Iterators.peekingIterator(positiveRanges.iterator());
533      Cut<C> firstComplementRangeLowerBound;
534      if (complementLowerBoundWindow.contains(Cut.<C>belowAll())
535          && (!positiveItr.hasNext() || positiveItr.peek().lowerBound != Cut.<C>belowAll())) {
536        firstComplementRangeLowerBound = Cut.belowAll();
537      } else if (positiveItr.hasNext()) {
538        firstComplementRangeLowerBound = positiveItr.next().upperBound;
539      } else {
540        return Iterators.emptyIterator();
541      }
542      return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
543        Cut<C> nextComplementRangeLowerBound = firstComplementRangeLowerBound;
544
545        @Override
546        @CheckForNull
547        protected Entry<Cut<C>, Range<C>> computeNext() {
548          if (complementLowerBoundWindow.upperBound.isLessThan(nextComplementRangeLowerBound)
549              || nextComplementRangeLowerBound == Cut.<C>aboveAll()) {
550            return endOfData();
551          }
552          Range<C> negativeRange;
553          if (positiveItr.hasNext()) {
554            Range<C> positiveRange = positiveItr.next();
555            negativeRange = Range.create(nextComplementRangeLowerBound, positiveRange.lowerBound);
556            nextComplementRangeLowerBound = positiveRange.upperBound;
557          } else {
558            negativeRange = Range.create(nextComplementRangeLowerBound, Cut.<C>aboveAll());
559            nextComplementRangeLowerBound = Cut.aboveAll();
560          }
561          return Maps.immutableEntry(negativeRange.lowerBound, negativeRange);
562        }
563      };
564    }
565
566    @Override
567    Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
568      /*
569       * firstComplementRangeUpperBound is the upper bound of the last complement range with lower
570       * bound inside complementLowerBoundWindow.
571       *
572       * positiveItr starts at the first positive range with upper bound less than
573       * firstComplementRangeUpperBound. (Positive range upper bounds correspond to complement range
574       * lower bounds.)
575       */
576      Cut<C> startingPoint =
577          complementLowerBoundWindow.hasUpperBound()
578              ? complementLowerBoundWindow.upperEndpoint()
579              : Cut.<C>aboveAll();
580      boolean inclusive =
581          complementLowerBoundWindow.hasUpperBound()
582              && complementLowerBoundWindow.upperBoundType() == BoundType.CLOSED;
583      PeekingIterator<Range<C>> positiveItr =
584          Iterators.peekingIterator(
585              positiveRangesByUpperBound
586                  .headMap(startingPoint, inclusive)
587                  .descendingMap()
588                  .values()
589                  .iterator());
590      Cut<C> cut;
591      if (positiveItr.hasNext()) {
592        cut =
593            (positiveItr.peek().upperBound == Cut.<C>aboveAll())
594                ? positiveItr.next().lowerBound
595                : positiveRangesByLowerBound.higherKey(positiveItr.peek().upperBound);
596      } else if (!complementLowerBoundWindow.contains(Cut.<C>belowAll())
597          || positiveRangesByLowerBound.containsKey(Cut.belowAll())) {
598        return Iterators.emptyIterator();
599      } else {
600        cut = positiveRangesByLowerBound.higherKey(Cut.<C>belowAll());
601      }
602      Cut<C> firstComplementRangeUpperBound = MoreObjects.firstNonNull(cut, Cut.<C>aboveAll());
603      return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
604        Cut<C> nextComplementRangeUpperBound = firstComplementRangeUpperBound;
605
606        @Override
607        @CheckForNull
608        protected Entry<Cut<C>, Range<C>> computeNext() {
609          if (nextComplementRangeUpperBound == Cut.<C>belowAll()) {
610            return endOfData();
611          } else if (positiveItr.hasNext()) {
612            Range<C> positiveRange = positiveItr.next();
613            Range<C> negativeRange =
614                Range.create(positiveRange.upperBound, nextComplementRangeUpperBound);
615            nextComplementRangeUpperBound = positiveRange.lowerBound;
616            if (complementLowerBoundWindow.lowerBound.isLessThan(negativeRange.lowerBound)) {
617              return Maps.immutableEntry(negativeRange.lowerBound, negativeRange);
618            }
619          } else if (complementLowerBoundWindow.lowerBound.isLessThan(Cut.<C>belowAll())) {
620            Range<C> negativeRange = Range.create(Cut.<C>belowAll(), nextComplementRangeUpperBound);
621            nextComplementRangeUpperBound = Cut.belowAll();
622            return Maps.immutableEntry(Cut.<C>belowAll(), negativeRange);
623          }
624          return endOfData();
625        }
626      };
627    }
628
629    @Override
630    public int size() {
631      return Iterators.size(entryIterator());
632    }
633
634    @Override
635    @CheckForNull
636    public Range<C> get(@CheckForNull Object key) {
637      if (key instanceof Cut) {
638        try {
639          @SuppressWarnings("unchecked")
640          Cut<C> cut = (Cut<C>) key;
641          // tailMap respects the current window
642          Entry<Cut<C>, Range<C>> firstEntry = tailMap(cut, true).firstEntry();
643          if (firstEntry != null && firstEntry.getKey().equals(cut)) {
644            return firstEntry.getValue();
645          }
646        } catch (ClassCastException e) {
647          return null;
648        }
649      }
650      return null;
651    }
652
653    @Override
654    public boolean containsKey(@CheckForNull Object key) {
655      return get(key) != null;
656    }
657  }
658
659  private final class Complement extends TreeRangeSet<C> {
660    Complement() {
661      super(new ComplementRangesByLowerBound<C>(TreeRangeSet.this.rangesByLowerBound));
662    }
663
664    @Override
665    public void add(Range<C> rangeToAdd) {
666      TreeRangeSet.this.remove(rangeToAdd);
667    }
668
669    @Override
670    public void remove(Range<C> rangeToRemove) {
671      TreeRangeSet.this.add(rangeToRemove);
672    }
673
674    @Override
675    public boolean contains(C value) {
676      return !TreeRangeSet.this.contains(value);
677    }
678
679    @Override
680    public RangeSet<C> complement() {
681      return TreeRangeSet.this;
682    }
683  }
684
685  private static final class SubRangeSetRangesByLowerBound<C extends Comparable<?>>
686      extends AbstractNavigableMap<Cut<C>, Range<C>> {
687    /**
688     * lowerBoundWindow is the headMap/subMap/tailMap view; it only restricts the keys, and does not
689     * affect the values.
690     */
691    private final Range<Cut<C>> lowerBoundWindow;
692
693    /**
694     * restriction is the subRangeSet view; ranges are truncated to their intersection with
695     * restriction.
696     */
697    private final Range<C> restriction;
698
699    private final NavigableMap<Cut<C>, Range<C>> rangesByLowerBound;
700    private final NavigableMap<Cut<C>, Range<C>> rangesByUpperBound;
701
702    private SubRangeSetRangesByLowerBound(
703        Range<Cut<C>> lowerBoundWindow,
704        Range<C> restriction,
705        NavigableMap<Cut<C>, Range<C>> rangesByLowerBound) {
706      this.lowerBoundWindow = checkNotNull(lowerBoundWindow);
707      this.restriction = checkNotNull(restriction);
708      this.rangesByLowerBound = checkNotNull(rangesByLowerBound);
709      this.rangesByUpperBound = new RangesByUpperBound<>(rangesByLowerBound);
710    }
711
712    private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> window) {
713      if (!window.isConnected(lowerBoundWindow)) {
714        return ImmutableSortedMap.of();
715      } else {
716        return new SubRangeSetRangesByLowerBound<>(
717            lowerBoundWindow.intersection(window), restriction, rangesByLowerBound);
718      }
719    }
720
721    @Override
722    public NavigableMap<Cut<C>, Range<C>> subMap(
723        Cut<C> fromKey, boolean fromInclusive, Cut<C> toKey, boolean toInclusive) {
724      return subMap(
725          Range.range(
726              fromKey,
727              BoundType.forBoolean(fromInclusive),
728              toKey,
729              BoundType.forBoolean(toInclusive)));
730    }
731
732    @Override
733    public NavigableMap<Cut<C>, Range<C>> headMap(Cut<C> toKey, boolean inclusive) {
734      return subMap(Range.upTo(toKey, BoundType.forBoolean(inclusive)));
735    }
736
737    @Override
738    public NavigableMap<Cut<C>, Range<C>> tailMap(Cut<C> fromKey, boolean inclusive) {
739      return subMap(Range.downTo(fromKey, BoundType.forBoolean(inclusive)));
740    }
741
742    @Override
743    public Comparator<? super Cut<C>> comparator() {
744      return Ordering.<Cut<C>>natural();
745    }
746
747    @Override
748    public boolean containsKey(@CheckForNull Object key) {
749      return get(key) != null;
750    }
751
752    @Override
753    @CheckForNull
754    public Range<C> get(@CheckForNull Object key) {
755      if (key instanceof Cut) {
756        try {
757          @SuppressWarnings("unchecked") // we catch CCE's
758          Cut<C> cut = (Cut<C>) key;
759          if (!lowerBoundWindow.contains(cut)
760              || cut.compareTo(restriction.lowerBound) < 0
761              || cut.compareTo(restriction.upperBound) >= 0) {
762            return null;
763          } else if (cut.equals(restriction.lowerBound)) {
764            // it might be present, truncated on the left
765            Range<C> candidate = Maps.valueOrNull(rangesByLowerBound.floorEntry(cut));
766            if (candidate != null && candidate.upperBound.compareTo(restriction.lowerBound) > 0) {
767              return candidate.intersection(restriction);
768            }
769          } else {
770            Range<C> result = rangesByLowerBound.get(cut);
771            if (result != null) {
772              return result.intersection(restriction);
773            }
774          }
775        } catch (ClassCastException e) {
776          return null;
777        }
778      }
779      return null;
780    }
781
782    @Override
783    Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
784      if (restriction.isEmpty()) {
785        return Iterators.emptyIterator();
786      }
787      Iterator<Range<C>> completeRangeItr;
788      if (lowerBoundWindow.upperBound.isLessThan(restriction.lowerBound)) {
789        return Iterators.emptyIterator();
790      } else if (lowerBoundWindow.lowerBound.isLessThan(restriction.lowerBound)) {
791        // starts at the first range with upper bound strictly greater than restriction.lowerBound
792        completeRangeItr =
793            rangesByUpperBound.tailMap(restriction.lowerBound, false).values().iterator();
794      } else {
795        // starts at the first range with lower bound above lowerBoundWindow.lowerBound
796        completeRangeItr =
797            rangesByLowerBound
798                .tailMap(
799                    lowerBoundWindow.lowerBound.endpoint(),
800                    lowerBoundWindow.lowerBoundType() == BoundType.CLOSED)
801                .values()
802                .iterator();
803      }
804      Cut<Cut<C>> upperBoundOnLowerBounds =
805          Ordering.natural()
806              .min(lowerBoundWindow.upperBound, Cut.belowValue(restriction.upperBound));
807      return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
808        @Override
809        @CheckForNull
810        protected Entry<Cut<C>, Range<C>> computeNext() {
811          if (!completeRangeItr.hasNext()) {
812            return endOfData();
813          }
814          Range<C> nextRange = completeRangeItr.next();
815          if (upperBoundOnLowerBounds.isLessThan(nextRange.lowerBound)) {
816            return endOfData();
817          } else {
818            nextRange = nextRange.intersection(restriction);
819            return Maps.immutableEntry(nextRange.lowerBound, nextRange);
820          }
821        }
822      };
823    }
824
825    @Override
826    Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
827      if (restriction.isEmpty()) {
828        return Iterators.emptyIterator();
829      }
830      Cut<Cut<C>> upperBoundOnLowerBounds =
831          Ordering.natural()
832              .min(lowerBoundWindow.upperBound, Cut.belowValue(restriction.upperBound));
833      Iterator<Range<C>> completeRangeItr =
834          rangesByLowerBound
835              .headMap(
836                  upperBoundOnLowerBounds.endpoint(),
837                  upperBoundOnLowerBounds.typeAsUpperBound() == BoundType.CLOSED)
838              .descendingMap()
839              .values()
840              .iterator();
841      return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
842        @Override
843        @CheckForNull
844        protected Entry<Cut<C>, Range<C>> computeNext() {
845          if (!completeRangeItr.hasNext()) {
846            return endOfData();
847          }
848          Range<C> nextRange = completeRangeItr.next();
849          if (restriction.lowerBound.compareTo(nextRange.upperBound) >= 0) {
850            return endOfData();
851          }
852          nextRange = nextRange.intersection(restriction);
853          if (lowerBoundWindow.contains(nextRange.lowerBound)) {
854            return Maps.immutableEntry(nextRange.lowerBound, nextRange);
855          } else {
856            return endOfData();
857          }
858        }
859      };
860    }
861
862    @Override
863    public int size() {
864      return Iterators.size(entryIterator());
865    }
866  }
867
868  @Override
869  public RangeSet<C> subRangeSet(Range<C> view) {
870    return view.equals(Range.<C>all()) ? this : new SubRangeSet(view);
871  }
872
873  private final class SubRangeSet extends TreeRangeSet<C> {
874    private final Range<C> restriction;
875
876    SubRangeSet(Range<C> restriction) {
877      super(
878          new SubRangeSetRangesByLowerBound<C>(
879              Range.<Cut<C>>all(), restriction, TreeRangeSet.this.rangesByLowerBound));
880      this.restriction = restriction;
881    }
882
883    @Override
884    public boolean encloses(Range<C> range) {
885      if (!restriction.isEmpty() && restriction.encloses(range)) {
886        Range<C> enclosing = TreeRangeSet.this.rangeEnclosing(range);
887        return enclosing != null && !enclosing.intersection(restriction).isEmpty();
888      }
889      return false;
890    }
891
892    @Override
893    @CheckForNull
894    public Range<C> rangeContaining(C value) {
895      if (!restriction.contains(value)) {
896        return null;
897      }
898      Range<C> result = TreeRangeSet.this.rangeContaining(value);
899      return (result == null) ? null : result.intersection(restriction);
900    }
901
902    @Override
903    public void add(Range<C> rangeToAdd) {
904      checkArgument(
905          restriction.encloses(rangeToAdd),
906          "Cannot add range %s to subRangeSet(%s)",
907          rangeToAdd,
908          restriction);
909      TreeRangeSet.this.add(rangeToAdd);
910    }
911
912    @Override
913    public void remove(Range<C> rangeToRemove) {
914      if (rangeToRemove.isConnected(restriction)) {
915        TreeRangeSet.this.remove(rangeToRemove.intersection(restriction));
916      }
917    }
918
919    @Override
920    public boolean contains(C value) {
921      return restriction.contains(value) && TreeRangeSet.this.contains(value);
922    }
923
924    @Override
925    public void clear() {
926      TreeRangeSet.this.remove(restriction);
927    }
928
929    @Override
930    public RangeSet<C> subRangeSet(Range<C> view) {
931      if (view.encloses(restriction)) {
932        return this;
933      } else if (view.isConnected(restriction)) {
934        return new SubRangeSet(restriction.intersection(view));
935      } else {
936        return ImmutableRangeSet.of();
937      }
938    }
939  }
940}