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) 2011 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 com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import java.util.NoSuchElementException;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.Nullable;


A set comprising zero or more nonempty, disconnected ranges of type C. 
Implementations that choose to support the add(Range) operation are required to ignore empty ranges and coalesce connected ranges. For example: 

RangeSet<Integer> rangeSet = TreeRangeSet.create();
rangeSet.add(Range.closed(1, 10)); // {[1, 10]}
rangeSet.add(Range.closedOpen(11, 15)); // disconnected range; {[1, 10], [11, 15)}
rangeSet.add(Range.closedOpen(15, 20)); // connected range; {[1, 10], [11, 20)}
rangeSet.add(Range.openClosed(0, 0)); // empty range; {[1, 10], [11, 20)}
rangeSet.remove(Range.open(5, 10)); // splits [1, 10]; {[1, 5], [10, 10], [11, 20)}



Note that the behavior of Range.isEmpty() and Range.isConnected(Range) may not be as expected on discrete ranges. See the Javadoc of those methods for details. 
For a Set whose contents are specified by a Range, see ContiguousSet. 
See the Guava User Guide article on  RangeSets.

Author:Kevin Bourrillion, Louis Wasserman
Since:14.0
/**
 * A set comprising zero or more {@linkplain Range#isEmpty nonempty}, {@linkplain
 * Range#isConnected(Range) disconnected} ranges of type {@code C}.
 *
 * <p>Implementations that choose to support the {@link #add(Range)} operation are required to
 * ignore empty ranges and coalesce connected ranges. For example:
 *
 * <pre>{@code
 * RangeSet<Integer> rangeSet = TreeRangeSet.create();
 * rangeSet.add(Range.closed(1, 10)); // {[1, 10]}
 * rangeSet.add(Range.closedOpen(11, 15)); // disconnected range; {[1, 10], [11, 15)}
 * rangeSet.add(Range.closedOpen(15, 20)); // connected range; {[1, 10], [11, 20)}
 * rangeSet.add(Range.openClosed(0, 0)); // empty range; {[1, 10], [11, 20)}
 * rangeSet.remove(Range.open(5, 10)); // splits [1, 10]; {[1, 5], [10, 10], [11, 20)}
 * }</pre>
 *
 * <p>Note that the behavior of {@link Range#isEmpty()} and {@link Range#isConnected(Range)} may not
 * be as expected on discrete ranges. See the Javadoc of those methods for details.
 *
 * <p>For a {@link Set} whose contents are specified by a {@link Range}, see {@link ContiguousSet}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#rangeset"> RangeSets</a>.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 * @since 14.0
 */
@Beta
@GwtIncompatible
public interface RangeSet<C extends Comparable> {
  // TODO(lowasser): consider adding default implementations of some of these methods

  // Query methods

  
Determines whether any of this range set's member ranges contains value. 
/** Determines whether any of this range set's member ranges contains {@code value}. */
  boolean contains(C value);

  
Returns the unique range from this range set that contains 
value, or null if this range set does not contain value. 
/**
   * Returns the unique range from this range set that {@linkplain Range#contains contains} {@code
   * value}, or {@code null} if this range set does not contain {@code value}.
   */
  Range<C> rangeContaining(C value);

  
Returns true if there exists a non-empty range enclosed by both a member range in this range set and the specified range. This is equivalent to calling 
subRangeSet(otherRange) and testing whether the resulting range set is non-empty. 
Since:20.0
/**
   * Returns {@code true} if there exists a non-empty range enclosed by both a member range in this
   * range set and the specified range. This is equivalent to calling {@code
   * subRangeSet(otherRange)} and testing whether the resulting range set is non-empty.
   *
   * @since 20.0
   */
  boolean intersects(Range<C> otherRange);

  
Returns true if there exists a member range in this range set which encloses the specified range. 
/**
   * Returns {@code true} if there exists a member range in this range set which {@linkplain
   * Range#encloses encloses} the specified range.
   */
  boolean encloses(Range<C> otherRange);

  
Returns true if for each member range in other there exists a member range in this range set which encloses it. It follows that 
this.contains(value) whenever other.contains(value). Returns true if 
other is empty. 
This is equivalent to checking if this range set encloses each of the ranges in other. 
/**
   * Returns {@code true} if for each member range in {@code other} there exists a member range in
   * this range set which {@linkplain Range#encloses encloses} it. It follows that {@code
   * this.contains(value)} whenever {@code other.contains(value)}. Returns {@code true} if {@code
   * other} is empty.
   *
   * <p>This is equivalent to checking if this range set {@link #encloses} each of the ranges in
   * {@code other}.
   */
  boolean enclosesAll(RangeSet<C> other);

  
Returns true if for each range in other there exists a member range in this range set which encloses it. Returns true if other is empty. 
This is equivalent to checking if this range set encloses each range in 
other. 
Since:21.0
/**
   * Returns {@code true} if for each range in {@code other} there exists a member range in this
   * range set which {@linkplain Range#encloses encloses} it. Returns {@code true} if {@code other}
   * is empty.
   *
   * <p>This is equivalent to checking if this range set {@link #encloses} each range in {@code
   * other}.
   *
   * @since 21.0
   */
  default boolean enclosesAll(Iterable<Range<C>> other) {
    for (Range<C> range : other) {
      if (!encloses(range)) {
        return false;
      }
    }
    return true;
  }

  
Returns true if this range set contains no ranges. 
/** Returns {@code true} if this range set contains no ranges. */
  boolean isEmpty();

  
Returns the minimal range which encloses all ranges in this range set. 
Throws:
/**
   * Returns the minimal range which {@linkplain Range#encloses(Range) encloses} all ranges in this
   * range set.
   *
   * @throws NoSuchElementException if this range set is {@linkplain #isEmpty() empty}
   */
  Range<C> span();

  // Views

  
Returns a view of the disconnected ranges that make up this range set. The returned set may be empty. The iterators returned by its Iterable.iterator method return the ranges in increasing order of lower bound (equivalently, of upper bound). 
/**
   * Returns a view of the {@linkplain Range#isConnected disconnected} ranges that make up this
   * range set. The returned set may be empty. The iterators returned by its {@link
   * Iterable#iterator} method return the ranges in increasing order of lower bound (equivalently,
   * of upper bound).
   */
  Set<Range<C>> asRanges();

  
Returns a descending view of the disconnected ranges that make up this range set. The returned set may be empty. The iterators returned by its Iterable.iterator method return the ranges in decreasing order of lower bound (equivalently, of upper bound). 
Since:19.0
/**
   * Returns a descending view of the {@linkplain Range#isConnected disconnected} ranges that make
   * up this range set. The returned set may be empty. The iterators returned by its {@link
   * Iterable#iterator} method return the ranges in decreasing order of lower bound (equivalently,
   * of upper bound).
   *
   * @since 19.0
   */
  Set<Range<C>> asDescendingSetOfRanges();

  
Returns a view of the complement of this RangeSet. 
The returned view supports the add operation if this RangeSet supports remove, and vice versa. 
/**
   * Returns a view of the complement of this {@code RangeSet}.
   *
   * <p>The returned view supports the {@link #add} operation if this {@code RangeSet} supports
   * {@link #remove}, and vice versa.
   */
  RangeSet<C> complement();

  
Returns a view of the intersection of this RangeSet with the specified range. 
The returned view supports all optional operations supported by this RangeSet, with the caveat that an IllegalArgumentException is thrown on an attempt to add any range not enclosed by view. 
/**
   * Returns a view of the intersection of this {@code RangeSet} with the specified range.
   *
   * <p>The returned view supports all optional operations supported by this {@code RangeSet}, with
   * the caveat that an {@link IllegalArgumentException} is thrown on an attempt to {@linkplain
   * #add(Range) add} any range not {@linkplain Range#encloses(Range) enclosed} by {@code view}.
   */
  RangeSet<C> subRangeSet(Range<C> view);

  // Modification

  
Adds the specified range to this RangeSet (optional operation). That is, for equal range sets a and b, the result of a.add(range) is that a will be the minimal range set for which both a.enclosesAll(b) and a.encloses(range). 
Note that range will be coalesced with any ranges in the range set that are connected with it. Moreover, if range is empty, this is a no-op. 
Throws:
/**
   * Adds the specified range to this {@code RangeSet} (optional operation). That is, for equal
   * range sets a and b, the result of {@code a.add(range)} is that {@code a} will be the minimal
   * range set for which both {@code a.enclosesAll(b)} and {@code a.encloses(range)}.
   *
   * <p>Note that {@code range} will be {@linkplain Range#span(Range) coalesced} with any ranges in
   * the range set that are {@linkplain Range#isConnected(Range) connected} with it. Moreover, if
   * {@code range} is empty, this is a no-op.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code add}
   *     operation
   */
  void add(Range<C> range);

  
Removes the specified range from this RangeSet (optional operation). After this operation, if range.contains(c), this.contains(c) will return false. 
If range is empty, this is a no-op. 
Throws:
/**
   * Removes the specified range from this {@code RangeSet} (optional operation). After this
   * operation, if {@code range.contains(c)}, {@code this.contains(c)} will return {@code false}.
   *
   * <p>If {@code range} is empty, this is a no-op.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code remove}
   *     operation
   */
  void remove(Range<C> range);

  
Removes all ranges from this RangeSet (optional operation). After this operation, this.contains(c) will return false for all c. 
This is equivalent to remove(Range.all()). 
Throws:
/**
   * Removes all ranges from this {@code RangeSet} (optional operation). After this operation,
   * {@code this.contains(c)} will return false for all {@code c}.
   *
   * <p>This is equivalent to {@code remove(Range.all())}.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code clear}
   *     operation
   */
  void clear();

  
Adds all of the ranges from the specified range set to this range set (optional operation). After this operation, this range set is the minimal range set that encloses both the original range set and other. 
This is equivalent to calling add on each of the ranges in other in turn. 
Throws:
/**
   * Adds all of the ranges from the specified range set to this range set (optional operation).
   * After this operation, this range set is the minimal range set that {@linkplain
   * #enclosesAll(RangeSet) encloses} both the original range set and {@code other}.
   *
   * <p>This is equivalent to calling {@link #add} on each of the ranges in {@code other} in turn.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code addAll}
   *     operation
   */
  void addAll(RangeSet<C> other);

  
Adds all of the specified ranges to this range set (optional operation). After this operation, this range set is the minimal range set that encloses both the original range set and each range in other. 
This is equivalent to calling add on each of the ranges in other in turn. 
Throws:
Since:21.0
/**
   * Adds all of the specified ranges to this range set (optional operation). After this operation,
   * this range set is the minimal range set that {@linkplain #enclosesAll(RangeSet) encloses} both
   * the original range set and each range in {@code other}.
   *
   * <p>This is equivalent to calling {@link #add} on each of the ranges in {@code other} in turn.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code addAll}
   *     operation
   * @since 21.0
   */
  default void addAll(Iterable<Range<C>> ranges) {
    for (Range<C> range : ranges) {
      add(range);
    }
  }

  
Removes all of the ranges from the specified range set from this range set (optional operation). After this operation, if other.contains(c), this.contains(c) will return false. 
This is equivalent to calling remove on each of the ranges in other in turn. 
Throws:
/**
   * Removes all of the ranges from the specified range set from this range set (optional
   * operation). After this operation, if {@code other.contains(c)}, {@code this.contains(c)} will
   * return {@code false}.
   *
   * <p>This is equivalent to calling {@link #remove} on each of the ranges in {@code other} in
   * turn.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code removeAll}
   *     operation
   */
  void removeAll(RangeSet<C> other);

  
Removes all of the specified ranges from this range set (optional operation).

This is equivalent to calling remove on each of the ranges in other in turn. 
Throws:
Since:21.0
/**
   * Removes all of the specified ranges from this range set (optional operation).
   *
   * <p>This is equivalent to calling {@link #remove} on each of the ranges in {@code other} in
   * turn.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code removeAll}
   *     operation
   * @since 21.0
   */
  default void removeAll(Iterable<Range<C>> ranges) {
    for (Range<C> range : ranges) {
      remove(range);
    }
  }

  // Object methods

  
Returns true if obj is another RangeSet that contains the same ranges according to Range.equals(Object). 
/**
   * Returns {@code true} if {@code obj} is another {@code RangeSet} that contains the same ranges
   * according to {@link Range#equals(Object)}.
   */
  @Override
  boolean equals(@Nullable Object obj);

  
Returns asRanges().hashCode(). 
/** Returns {@code asRanges().hashCode()}. */
  @Override
  int hashCode();

  
Returns a readable string representation of this range set. For example, if this 
RangeSet consisted of Range.closed(1, 3) and Range.greaterThan(4), this might return " [1..3](4..+∞)"}. 
/**
   * Returns a readable string representation of this range set. For example, if this {@code
   * RangeSet} consisted of {@code Range.closed(1, 3)} and {@code Range.greaterThan(4)}, this might
   * return {@code " [1..3](4..+∞)}"}.
   */
  @Override
  String toString();
}