https://github.com/google/guava/guava: Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. 
/*
 * Copyright (C) 2012 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_HIGHER;
import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_LOWER;
import static com.google.common.collect.SortedLists.KeyPresentBehavior.ANY_PRESENT;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.SortedLists.KeyAbsentBehavior;
import com.google.common.collect.SortedLists.KeyPresentBehavior;
import com.google.common.primitives.Ints;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.LazyInit;
import java.io.Serializable;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.stream.Collector;
import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import org.checkerframework.checker.nullness.qual.Nullable;


A RangeSet whose contents will never change, with many other important properties detailed at ImmutableCollection. 
Author:Louis Wasserman
Since:14.0
/**
 * A {@link RangeSet} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *
 * @author Louis Wasserman
 * @since 14.0
 */
@Beta
@GwtIncompatible
public final class ImmutableRangeSet<C extends Comparable> extends AbstractRangeSet<C>
    implements Serializable {

  private static final ImmutableRangeSet<Comparable<?>> EMPTY =
      new ImmutableRangeSet<>(ImmutableList.<Range<Comparable<?>>>of());

  private static final ImmutableRangeSet<Comparable<?>> ALL =
      new ImmutableRangeSet<>(ImmutableList.of(Range.<Comparable<?>>all()));

  
Returns a Collector that accumulates the input elements into a new 
ImmutableRangeSet. As in Builder, overlapping ranges are not permitted and adjacent ranges will be merged. 
Since:23.1
/**
   * Returns a {@code Collector} that accumulates the input elements into a new {@code
   * ImmutableRangeSet}. As in {@link Builder}, overlapping ranges are not permitted and adjacent
   * ranges will be merged.
   *
   * @since 23.1
   */
  public static <E extends Comparable<? super E>>
      Collector<Range<E>, ?, ImmutableRangeSet<E>> toImmutableRangeSet() {
    return CollectCollectors.toImmutableRangeSet();
  }

  
Returns an empty immutable range set. 
/** Returns an empty immutable range set. */
  @SuppressWarnings("unchecked")
  public static <C extends Comparable> ImmutableRangeSet<C> of() {
    return (ImmutableRangeSet<C>) EMPTY;
  }

  
Returns an immutable range set containing the specified single range. If 
range.isEmpty(), this is equivalent to of(). 
/**
   * Returns an immutable range set containing the specified single range. If {@link Range#isEmpty()
   * range.isEmpty()}, this is equivalent to {@link ImmutableRangeSet#of()}.
   */
  public static <C extends Comparable> ImmutableRangeSet<C> of(Range<C> range) {
    checkNotNull(range);
    if (range.isEmpty()) {
      return of();
    } else if (range.equals(Range.all())) {
      return all();
    } else {
      return new ImmutableRangeSet<C>(ImmutableList.of(range));
    }
  }

  
Returns an immutable range set containing the single range Range.all(). 
/** Returns an immutable range set containing the single range {@link Range#all()}. */
  @SuppressWarnings("unchecked")
  static <C extends Comparable> ImmutableRangeSet<C> all() {
    return (ImmutableRangeSet<C>) ALL;
  }

  
Returns an immutable copy of the specified RangeSet. 
/** Returns an immutable copy of the specified {@code RangeSet}. */
  public static <C extends Comparable> ImmutableRangeSet<C> copyOf(RangeSet<C> rangeSet) {
    checkNotNull(rangeSet);
    if (rangeSet.isEmpty()) {
      return of();
    } else if (rangeSet.encloses(Range.<C>all())) {
      return all();
    }

    if (rangeSet instanceof ImmutableRangeSet) {
      ImmutableRangeSet<C> immutableRangeSet = (ImmutableRangeSet<C>) rangeSet;
      if (!immutableRangeSet.isPartialView()) {
        return immutableRangeSet;
      }
    }
    return new ImmutableRangeSet<C>(ImmutableList.copyOf(rangeSet.asRanges()));
  }

  
Returns an ImmutableRangeSet containing each of the specified disjoint ranges. Overlapping ranges and empty ranges are forbidden, though adjacent ranges are permitted and will be merged. 
Throws:
Since:21.0
/**
   * Returns an {@code ImmutableRangeSet} containing each of the specified disjoint ranges.
   * Overlapping ranges and empty ranges are forbidden, though adjacent ranges are permitted and
   * will be merged.
   *
   * @throws IllegalArgumentException if any ranges overlap or are empty
   * @since 21.0
   */
  public static <C extends Comparable<?>> ImmutableRangeSet<C> copyOf(Iterable<Range<C>> ranges) {
    return new ImmutableRangeSet.Builder<C>().addAll(ranges).build();
  }

  
Returns an ImmutableRangeSet representing the union of the specified ranges. 
This is the smallest RangeSet which encloses each of the specified ranges. Duplicate or connected ranges are permitted, and will be coalesced in the result. 
Since:21.0
/**
   * Returns an {@code ImmutableRangeSet} representing the union of the specified ranges.
   *
   * <p>This is the smallest {@code RangeSet} which encloses each of the specified ranges. Duplicate
   * or connected ranges are permitted, and will be coalesced in the result.
   *
   * @since 21.0
   */
  public static <C extends Comparable<?>> ImmutableRangeSet<C> unionOf(Iterable<Range<C>> ranges) {
    return copyOf(TreeRangeSet.create(ranges));
  }

  ImmutableRangeSet(ImmutableList<Range<C>> ranges) {
    this.ranges = ranges;
  }

  private ImmutableRangeSet(ImmutableList<Range<C>> ranges, ImmutableRangeSet<C> complement) {
    this.ranges = ranges;
    this.complement = complement;
  }

  private final transient ImmutableList<Range<C>> ranges;

  @Override
  public boolean intersects(Range<C> otherRange) {
    int ceilingIndex =
        SortedLists.binarySearch(
            ranges,
            Range.<C>lowerBoundFn(),
            otherRange.lowerBound,
            Ordering.natural(),
            ANY_PRESENT,
            NEXT_HIGHER);
    if (ceilingIndex < ranges.size()
        && ranges.get(ceilingIndex).isConnected(otherRange)
        && !ranges.get(ceilingIndex).intersection(otherRange).isEmpty()) {
      return true;
    }
    return ceilingIndex > 0
        && ranges.get(ceilingIndex - 1).isConnected(otherRange)
        && !ranges.get(ceilingIndex - 1).intersection(otherRange).isEmpty();
  }

  @Override
  public boolean encloses(Range<C> otherRange) {
    int index =
        SortedLists.binarySearch(
            ranges,
            Range.<C>lowerBoundFn(),
            otherRange.lowerBound,
            Ordering.natural(),
            ANY_PRESENT,
            NEXT_LOWER);
    return index != -1 && ranges.get(index).encloses(otherRange);
  }

  @Override
  public Range<C> rangeContaining(C value) {
    int index =
        SortedLists.binarySearch(
            ranges,
            Range.<C>lowerBoundFn(),
            Cut.belowValue(value),
            Ordering.natural(),
            ANY_PRESENT,
            NEXT_LOWER);
    if (index != -1) {
      Range<C> range = ranges.get(index);
      return range.contains(value) ? range : null;
    }
    return null;
  }

  @Override
  public Range<C> span() {
    if (ranges.isEmpty()) {
      throw new NoSuchElementException();
    }
    return Range.create(ranges.get(0).lowerBound, ranges.get(ranges.size() - 1).upperBound);
  }

  @Override
  public boolean isEmpty() {
    return ranges.isEmpty();
  }

  
Guaranteed to throw an exception and leave the RangeSet unmodified. 
Throws:
Deprecated:Unsupported operation.
/**
   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  public void add(Range<C> range) {
    throw new UnsupportedOperationException();
  }

  
Guaranteed to throw an exception and leave the RangeSet unmodified. 
Throws:
Deprecated:Unsupported operation.
/**
   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  public void addAll(RangeSet<C> other) {
    throw new UnsupportedOperationException();
  }

  
Guaranteed to throw an exception and leave the RangeSet unmodified. 
Throws:
Deprecated:Unsupported operation.
/**
   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  public void addAll(Iterable<Range<C>> other) {
    throw new UnsupportedOperationException();
  }

  
Guaranteed to throw an exception and leave the RangeSet unmodified. 
Throws:
Deprecated:Unsupported operation.
/**
   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  public void remove(Range<C> range) {
    throw new UnsupportedOperationException();
  }

  
Guaranteed to throw an exception and leave the RangeSet unmodified. 
Throws:
Deprecated:Unsupported operation.
/**
   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  public void removeAll(RangeSet<C> other) {
    throw new UnsupportedOperationException();
  }

  
Guaranteed to throw an exception and leave the RangeSet unmodified. 
Throws:
Deprecated:Unsupported operation.
/**
   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  public void removeAll(Iterable<Range<C>> other) {
    throw new UnsupportedOperationException();
  }

  @Override
  public ImmutableSet<Range<C>> asRanges() {
    if (ranges.isEmpty()) {
      return ImmutableSet.of();
    }
    return new RegularImmutableSortedSet<>(ranges, Range.<C>rangeLexOrdering());
  }

  @Override
  public ImmutableSet<Range<C>> asDescendingSetOfRanges() {
    if (ranges.isEmpty()) {
      return ImmutableSet.of();
    }
    return new RegularImmutableSortedSet<>(ranges.reverse(), Range.<C>rangeLexOrdering().reverse());
  }

  @LazyInit private transient ImmutableRangeSet<C> complement;

  private final class ComplementRanges extends ImmutableList<Range<C>> {
    // True if the "positive" range set is empty or bounded below.
    private final boolean positiveBoundedBelow;

    // True if the "positive" range set is empty or bounded above.
    private final boolean positiveBoundedAbove;

    private final int size;

    ComplementRanges() {
      this.positiveBoundedBelow = ranges.get(0).hasLowerBound();
      this.positiveBoundedAbove = Iterables.getLast(ranges).hasUpperBound();

      int size = ranges.size() - 1;
      if (positiveBoundedBelow) {
        size++;
      }
      if (positiveBoundedAbove) {
        size++;
      }
      this.size = size;
    }

    @Override
    public int size() {
      return size;
    }

    @Override
    public Range<C> get(int index) {
      checkElementIndex(index, size);

      Cut<C> lowerBound;
      if (positiveBoundedBelow) {
        lowerBound = (index == 0) ? Cut.<C>belowAll() : ranges.get(index - 1).upperBound;
      } else {
        lowerBound = ranges.get(index).upperBound;
      }

      Cut<C> upperBound;
      if (positiveBoundedAbove && index == size - 1) {
        upperBound = Cut.<C>aboveAll();
      } else {
        upperBound = ranges.get(index + (positiveBoundedBelow ? 0 : 1)).lowerBound;
      }

      return Range.create(lowerBound, upperBound);
    }

    @Override
    boolean isPartialView() {
      return true;
    }
  }

  @Override
  public ImmutableRangeSet<C> complement() {
    ImmutableRangeSet<C> result = complement;
    if (result != null) {
      return result;
    } else if (ranges.isEmpty()) {
      return complement = all();
    } else if (ranges.size() == 1 && ranges.get(0).equals(Range.all())) {
      return complement = of();
    } else {
      ImmutableList<Range<C>> complementRanges = new ComplementRanges();
      result = complement = new ImmutableRangeSet<C>(complementRanges, this);
    }
    return result;
  }

  
Returns a new range set consisting of the union of this range set and other. 
This is essentially the same as TreeRangeSet.create(this).addAll(other) except it returns an ImmutableRangeSet. 
Since:21.0
/**
   * Returns a new range set consisting of the union of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code TreeRangeSet.create(this).addAll(other)} except it
   * returns an {@code ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> union(RangeSet<C> other) {
    return unionOf(Iterables.concat(asRanges(), other.asRanges()));
  }

  
Returns a new range set consisting of the intersection of this range set and other. 
This is essentially the same as 
TreeRangeSet.create(this).removeAll(other.complement()) except it returns an 
ImmutableRangeSet. 
Since:21.0
/**
   * Returns a new range set consisting of the intersection of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code
   * TreeRangeSet.create(this).removeAll(other.complement())} except it returns an {@code
   * ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> intersection(RangeSet<C> other) {
    RangeSet<C> copy = TreeRangeSet.create(this);
    copy.removeAll(other.complement());
    return copyOf(copy);
  }

  
Returns a new range set consisting of the difference of this range set and other. 
This is essentially the same as TreeRangeSet.create(this).removeAll(other) except it returns an ImmutableRangeSet. 
Since:21.0
/**
   * Returns a new range set consisting of the difference of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code TreeRangeSet.create(this).removeAll(other)} except it
   * returns an {@code ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> difference(RangeSet<C> other) {
    RangeSet<C> copy = TreeRangeSet.create(this);
    copy.removeAll(other);
    return copyOf(copy);
  }

  
Returns a list containing the nonempty intersections of range with the ranges in this range set. 
/**
   * Returns a list containing the nonempty intersections of {@code range} with the ranges in this
   * range set.
   */
  private ImmutableList<Range<C>> intersectRanges(final Range<C> range) {
    if (ranges.isEmpty() || range.isEmpty()) {
      return ImmutableList.of();
    } else if (range.encloses(span())) {
      return ranges;
    }

    final int fromIndex;
    if (range.hasLowerBound()) {
      fromIndex =
          SortedLists.binarySearch(
              ranges,
              Range.<C>upperBoundFn(),
              range.lowerBound,
              KeyPresentBehavior.FIRST_AFTER,
              KeyAbsentBehavior.NEXT_HIGHER);
    } else {
      fromIndex = 0;
    }

    int toIndex;
    if (range.hasUpperBound()) {
      toIndex =
          SortedLists.binarySearch(
              ranges,
              Range.<C>lowerBoundFn(),
              range.upperBound,
              KeyPresentBehavior.FIRST_PRESENT,
              KeyAbsentBehavior.NEXT_HIGHER);
    } else {
      toIndex = ranges.size();
    }
    final int length = toIndex - fromIndex;
    if (length == 0) {
      return ImmutableList.of();
    } else {
      return new ImmutableList<Range<C>>() {
        @Override
        public int size() {
          return length;
        }

        @Override
        public Range<C> get(int index) {
          checkElementIndex(index, length);
          if (index == 0 || index == length - 1) {
            return ranges.get(index + fromIndex).intersection(range);
          } else {
            return ranges.get(index + fromIndex);
          }
        }

        @Override
        boolean isPartialView() {
          return true;
        }
      };
    }
  }

  
Returns a view of the intersection of this range set with the given range. 
/** Returns a view of the intersection of this range set with the given range. */
  @Override
  public ImmutableRangeSet<C> subRangeSet(Range<C> range) {
    if (!isEmpty()) {
      Range<C> span = span();
      if (range.encloses(span)) {
        return this;
      } else if (range.isConnected(span)) {
        return new ImmutableRangeSet<C>(intersectRanges(range));
      }
    }
    return of();
  }

  
Returns an ImmutableSortedSet containing the same values in the given domain contained by this range set. 
Note: a.asSet(d).equals(b.asSet(d)) does not imply a.equals(b)! For example, a and b could be [2..4] and (1..5), or the empty ranges [3..3) and [4..4). 
Warning: Be extremely careful what you do with the asSet view of a large range set (such as ImmutableRangeSet.of(Range.greaterThan(0))). Certain operations on such a set can be performed efficiently, but others (such as Set.hashCode or Collections.frequency) can cause major performance problems. 
The returned set's Object.toString method returns a short-hand form of the set's contents, such as "[1..100]"}. 
Throws:
/**
   * Returns an {@link ImmutableSortedSet} containing the same values in the given domain
   * {@linkplain RangeSet#contains contained} by this range set.
   *
   * <p><b>Note:</b> {@code a.asSet(d).equals(b.asSet(d))} does not imply {@code a.equals(b)}! For
   * example, {@code a} and {@code b} could be {@code [2..4]} and {@code (1..5)}, or the empty
   * ranges {@code [3..3)} and {@code [4..4)}.
   *
   * <p><b>Warning:</b> Be extremely careful what you do with the {@code asSet} view of a large
   * range set (such as {@code ImmutableRangeSet.of(Range.greaterThan(0))}). Certain operations on
   * such a set can be performed efficiently, but others (such as {@link Set#hashCode} or {@link
   * Collections#frequency}) can cause major performance problems.
   *
   * <p>The returned set's {@link Object#toString} method returns a short-hand form of the set's
   * contents, such as {@code "[1..100]}"}.
   *
   * @throws IllegalArgumentException if neither this range nor the domain has a lower bound, or if
   *     neither has an upper bound
   */
  public ImmutableSortedSet<C> asSet(DiscreteDomain<C> domain) {
    checkNotNull(domain);
    if (isEmpty()) {
      return ImmutableSortedSet.of();
    }
    Range<C> span = span().canonical(domain);
    if (!span.hasLowerBound()) {
      // according to the spec of canonical, neither this ImmutableRangeSet nor
      // the range have a lower bound
      throw new IllegalArgumentException(
          "Neither the DiscreteDomain nor this range set are bounded below");
    } else if (!span.hasUpperBound()) {
      try {
        domain.maxValue();
      } catch (NoSuchElementException e) {
        throw new IllegalArgumentException(
            "Neither the DiscreteDomain nor this range set are bounded above");
      }
    }

    return new AsSet(domain);
  }

  private final class AsSet extends ImmutableSortedSet<C> {
    private final DiscreteDomain<C> domain;

    AsSet(DiscreteDomain<C> domain) {
      super(Ordering.natural());
      this.domain = domain;
    }

    private transient @MonotonicNonNull Integer size;

    @Override
    public int size() {
      // racy single-check idiom
      Integer result = size;
      if (result == null) {
        long total = 0;
        for (Range<C> range : ranges) {
          total += ContiguousSet.create(range, domain).size();
          if (total >= Integer.MAX_VALUE) {
            break;
          }
        }
        result = size = Ints.saturatedCast(total);
      }
      return result.intValue();
    }

    @Override
    public UnmodifiableIterator<C> iterator() {
      return new AbstractIterator<C>() {
        final Iterator<Range<C>> rangeItr = ranges.iterator();
        Iterator<C> elemItr = Iterators.emptyIterator();

        @Override
        protected C computeNext() {
          while (!elemItr.hasNext()) {
            if (rangeItr.hasNext()) {
              elemItr = ContiguousSet.create(rangeItr.next(), domain).iterator();
            } else {
              return endOfData();
            }
          }
          return elemItr.next();
        }
      };
    }

    @Override
    @GwtIncompatible("NavigableSet")
    public UnmodifiableIterator<C> descendingIterator() {
      return new AbstractIterator<C>() {
        final Iterator<Range<C>> rangeItr = ranges.reverse().iterator();
        Iterator<C> elemItr = Iterators.emptyIterator();

        @Override
        protected C computeNext() {
          while (!elemItr.hasNext()) {
            if (rangeItr.hasNext()) {
              elemItr = ContiguousSet.create(rangeItr.next(), domain).descendingIterator();
            } else {
              return endOfData();
            }
          }
          return elemItr.next();
        }
      };
    }

    ImmutableSortedSet<C> subSet(Range<C> range) {
      return subRangeSet(range).asSet(domain);
    }

    @Override
    ImmutableSortedSet<C> headSetImpl(C toElement, boolean inclusive) {
      return subSet(Range.upTo(toElement, BoundType.forBoolean(inclusive)));
    }

    @Override
    ImmutableSortedSet<C> subSetImpl(
        C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
      if (!fromInclusive && !toInclusive && Range.compareOrThrow(fromElement, toElement) == 0) {
        return ImmutableSortedSet.of();
      }
      return subSet(
          Range.range(
              fromElement, BoundType.forBoolean(fromInclusive),
              toElement, BoundType.forBoolean(toInclusive)));
    }

    @Override
    ImmutableSortedSet<C> tailSetImpl(C fromElement, boolean inclusive) {
      return subSet(Range.downTo(fromElement, BoundType.forBoolean(inclusive)));
    }

    @Override
    public boolean contains(@Nullable Object o) {
      if (o == null) {
        return false;
      }
      try {
        @SuppressWarnings("unchecked") // we catch CCE's
        C c = (C) o;
        return ImmutableRangeSet.this.contains(c);
      } catch (ClassCastException e) {
        return false;
      }
    }

    @Override
    int indexOf(Object target) {
      if (contains(target)) {
        @SuppressWarnings("unchecked") // if it's contained, it's definitely a C
        C c = (C) target;
        long total = 0;
        for (Range<C> range : ranges) {
          if (range.contains(c)) {
            return Ints.saturatedCast(total + ContiguousSet.create(range, domain).indexOf(c));
          } else {
            total += ContiguousSet.create(range, domain).size();
          }
        }
        throw new AssertionError("impossible");
      }
      return -1;
    }

    @Override
    ImmutableSortedSet<C> createDescendingSet() {
      return new DescendingImmutableSortedSet<C>(this);
    }

    @Override
    boolean isPartialView() {
      return ranges.isPartialView();
    }

    @Override
    public String toString() {
      return ranges.toString();
    }

    @Override
    Object writeReplace() {
      return new AsSetSerializedForm<C>(ranges, domain);
    }
  }

  private static class AsSetSerializedForm<C extends Comparable> implements Serializable {
    private final ImmutableList<Range<C>> ranges;
    private final DiscreteDomain<C> domain;

    AsSetSerializedForm(ImmutableList<Range<C>> ranges, DiscreteDomain<C> domain) {
      this.ranges = ranges;
      this.domain = domain;
    }

    Object readResolve() {
      return new ImmutableRangeSet<C>(ranges).asSet(domain);
    }
  }

  
Returns true if this immutable range set's implementation contains references to user-created objects that aren't accessible via this range set's methods. This is generally used to determine whether copyOf implementations should make an explicit copy to avoid memory leaks. 
/**
   * Returns {@code true} if this immutable range set's implementation contains references to
   * user-created objects that aren't accessible via this range set's methods. This is generally
   * used to determine whether {@code copyOf} implementations should make an explicit copy to avoid
   * memory leaks.
   */
  boolean isPartialView() {
    return ranges.isPartialView();
  }

  
Returns a new builder for an immutable range set. 
/** Returns a new builder for an immutable range set. */
  public static <C extends Comparable<?>> Builder<C> builder() {
    return new Builder<C>();
  }

  
A builder for immutable range sets.

Since:14.0
/**
   * A builder for immutable range sets.
   *
   * @since 14.0
   */
  public static class Builder<C extends Comparable<?>> {
    private final List<Range<C>> ranges;

    public Builder() {
      this.ranges = Lists.newArrayList();
    }

    // TODO(lowasser): consider adding union, in addition to add, that does allow overlap

    
Add the specified range to this builder. Adjacent ranges are permitted and will be merged, but overlapping ranges will cause an exception when build() is called. 
Throws:
/**
     * Add the specified range to this builder. Adjacent ranges are permitted and will be merged,
     * but overlapping ranges will cause an exception when {@link #build()} is called.
     *
     * @throws IllegalArgumentException if {@code range} is empty
     */
    @CanIgnoreReturnValue
    public Builder<C> add(Range<C> range) {
      checkArgument(!range.isEmpty(), "range must not be empty, but was %s", range);
      ranges.add(range);
      return this;
    }

    
Add all ranges from the specified range set to this builder. Adjacent ranges are permitted and will be merged, but overlapping ranges will cause an exception when build() is called. 
/**
     * Add all ranges from the specified range set to this builder. Adjacent ranges are permitted
     * and will be merged, but overlapping ranges will cause an exception when {@link #build()} is
     * called.
     */
    @CanIgnoreReturnValue
    public Builder<C> addAll(RangeSet<C> ranges) {
      return addAll(ranges.asRanges());
    }

    
Add all of the specified ranges to this builder. Adjacent ranges are permitted and will be merged, but overlapping ranges will cause an exception when build() is called. 
Throws:
Since:21.0
/**
     * Add all of the specified ranges to this builder. Adjacent ranges are permitted and will be
     * merged, but overlapping ranges will cause an exception when {@link #build()} is called.
     *
     * @throws IllegalArgumentException if any inserted ranges are empty
     * @since 21.0
     */
    @CanIgnoreReturnValue
    public Builder<C> addAll(Iterable<Range<C>> ranges) {
      for (Range<C> range : ranges) {
        add(range);
      }
      return this;
    }

    @CanIgnoreReturnValue
    Builder<C> combine(Builder<C> builder) {
      addAll(builder.ranges);
      return this;
    }

    
Returns an ImmutableRangeSet containing the ranges added to this builder. 
Throws:
/**
     * Returns an {@code ImmutableRangeSet} containing the ranges added to this builder.
     *
     * @throws IllegalArgumentException if any input ranges have nonempty overlap
     */
    public ImmutableRangeSet<C> build() {
      ImmutableList.Builder<Range<C>> mergedRangesBuilder =
          new ImmutableList.Builder<>(ranges.size());
      Collections.sort(ranges, Range.<C>rangeLexOrdering());
      PeekingIterator<Range<C>> peekingItr = Iterators.peekingIterator(ranges.iterator());
      while (peekingItr.hasNext()) {
        Range<C> range = peekingItr.next();
        while (peekingItr.hasNext()) {
          Range<C> nextRange = peekingItr.peek();
          if (range.isConnected(nextRange)) {
            checkArgument(
                range.intersection(nextRange).isEmpty(),
                "Overlapping ranges not permitted but found %s overlapping %s",
                range,
                nextRange);
            range = range.span(peekingItr.next());
          } else {
            break;
          }
        }
        mergedRangesBuilder.add(range);
      }
      ImmutableList<Range<C>> mergedRanges = mergedRangesBuilder.build();
      if (mergedRanges.isEmpty()) {
        return of();
      } else if (mergedRanges.size() == 1
          && Iterables.getOnlyElement(mergedRanges).equals(Range.all())) {
        return all();
      } else {
        return new ImmutableRangeSet<C>(mergedRanges);
      }
    }
  }

  private static final class SerializedForm<C extends Comparable> implements Serializable {
    private final ImmutableList<Range<C>> ranges;

    SerializedForm(ImmutableList<Range<C>> ranges) {
      this.ranges = ranges;
    }

    Object readResolve() {
      if (ranges.isEmpty()) {
        return of();
      } else if (ranges.equals(ImmutableList.of(Range.all()))) {
        return all();
      } else {
        return new ImmutableRangeSet<C>(ranges);
      }
    }
  }

  Object writeReplace() {
    return new SerializedForm<C>(ranges);
  }
}