001/*
002 * Copyright (C) 2012 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.collect;
018
019import com.google.common.annotations.Beta;
020import com.google.common.annotations.GwtIncompatible;
021import com.google.errorprone.annotations.DoNotMock;
022import java.util.Collection;
023import java.util.Map;
024import java.util.Map.Entry;
025import java.util.NoSuchElementException;
026import javax.annotation.CheckForNull;
027
028/**
029 * A mapping from disjoint nonempty ranges to non-null values. Queries look up the value associated
030 * with the range (if any) that contains a specified key.
031 *
032 * <p>In contrast to {@link RangeSet}, no "coalescing" is done of {@linkplain
033 * Range#isConnected(Range) connected} ranges, even if they are mapped to the same value.
034 *
035 * @author Louis Wasserman
036 * @since 14.0
037 */
038@Beta
039@DoNotMock("Use ImmutableRangeMap or TreeRangeMap")
040@GwtIncompatible
041@ElementTypesAreNonnullByDefault
042public interface RangeMap<K extends Comparable, V> {
043  /*
044   * TODO(cpovirk): These docs sometimes say "map" and sometimes say "range map." Pick one, or at
045   * least decide on a policy for when to use which.
046   */
047
048  /**
049   * Returns the value associated with the specified key, or {@code null} if there is no such value.
050   *
051   * <p>Specifically, if any range in this range map contains the specified key, the value
052   * associated with that range is returned.
053   */
054  @CheckForNull
055  V get(K key);
056
057  /**
058   * Returns the range containing this key and its associated value, if such a range is present in
059   * the range map, or {@code null} otherwise.
060   */
061  @CheckForNull
062  Entry<Range<K>, V> getEntry(K key);
063
064  /**
065   * Returns the minimal range {@linkplain Range#encloses(Range) enclosing} the ranges in this
066   * {@code RangeMap}.
067   *
068   * @throws NoSuchElementException if this range map is empty
069   */
070  Range<K> span();
071
072  /**
073   * Maps a range to a specified value (optional operation).
074   *
075   * <p>Specifically, after a call to {@code put(range, value)}, if {@link
076   * Range#contains(Comparable) range.contains(k)}, then {@link #get(Comparable) get(k)} will return
077   * {@code value}.
078   *
079   * <p>If {@code range} {@linkplain Range#isEmpty() is empty}, then this is a no-op.
080   */
081  void put(Range<K> range, V value);
082
083  /**
084   * Maps a range to a specified value, coalescing this range with any existing ranges with the same
085   * value that are {@linkplain Range#isConnected connected} to this range.
086   *
087   * <p>The behavior of {@link #get(Comparable) get(k)} after calling this method is identical to
088   * the behavior described in {@link #put(Range, Object) put(range, value)}, however the ranges
089   * returned from {@link #asMapOfRanges} will be different if there were existing entries which
090   * connect to the given range and value.
091   *
092   * <p>Even if the input range is empty, if it is connected on both sides by ranges mapped to the
093   * same value those two ranges will be coalesced.
094   *
095   * <p><b>Note:</b> coalescing requires calling {@code .equals()} on any connected values, which
096   * may be expensive depending on the value type. Using this method on range maps with large values
097   * such as {@link Collection} types is discouraged.
098   *
099   * @since 22.0
100   */
101  void putCoalescing(Range<K> range, V value);
102
103  /** Puts all the associations from {@code rangeMap} into this range map (optional operation). */
104  void putAll(RangeMap<K, V> rangeMap);
105
106  /** Removes all associations from this range map (optional operation). */
107  void clear();
108
109  /**
110   * Removes all associations from this range map in the specified range (optional operation).
111   *
112   * <p>If {@code !range.contains(k)}, {@link #get(Comparable) get(k)} will return the same result
113   * before and after a call to {@code remove(range)}. If {@code range.contains(k)}, then after a
114   * call to {@code remove(range)}, {@code get(k)} will return {@code null}.
115   */
116  void remove(Range<K> range);
117
118  /**
119   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
120   * this range map are guaranteed to read through to the returned {@code Map}.
121   *
122   * <p>The returned {@code Map} iterates over entries in ascending order of the bounds of the
123   * {@code Range} entries.
124   *
125   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
126   */
127  Map<Range<K>, V> asMapOfRanges();
128
129  /**
130   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
131   * this range map are guaranteed to read through to the returned {@code Map}.
132   *
133   * <p>The returned {@code Map} iterates over entries in descending order of the bounds of the
134   * {@code Range} entries.
135   *
136   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
137   *
138   * @since 19.0
139   */
140  Map<Range<K>, V> asDescendingMapOfRanges();
141
142  /**
143   * Returns a view of the part of this range map that intersects with {@code range}.
144   *
145   * <p>For example, if {@code rangeMap} had the entries {@code [1, 5] => "foo", (6, 8) => "bar",
146   * (10, ∞) => "baz"} then {@code rangeMap.subRangeMap(Range.open(3, 12))} would return a range map
147   * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
148   *
149   * <p>The returned range map supports all optional operations that this range map supports, except
150   * for {@code asMapOfRanges().iterator().remove()}.
151   *
152   * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
153   * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
154   */
155  // TODO(cpovirk): Consider documenting that IAE on the various methods that can throw it.
156  RangeMap<K, V> subRangeMap(Range<K> range);
157
158  /**
159   * Returns {@code true} if {@code obj} is another {@code RangeMap} that has an equivalent {@link
160   * #asMapOfRanges()}.
161   */
162  @Override
163  boolean equals(@CheckForNull Object o);
164
165  /** Returns {@code asMapOfRanges().hashCode()}. */
166  @Override
167  int hashCode();
168
169  /** Returns a readable string representation of this range map. */
170  @Override
171  String toString();
172}