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 java.util.function.BiFunction;
027import org.checkerframework.checker.nullness.qual.Nullable;
028
029/**
030 * A mapping from disjoint nonempty ranges to non-null values. Queries look up the value associated
031 * with the range (if any) that contains a specified key.
032 *
033 * <p>In contrast to {@link RangeSet}, no "coalescing" is done of {@linkplain
034 * Range#isConnected(Range) connected} ranges, even if they are mapped to the same value.
035 *
036 * @author Louis Wasserman
037 * @since 14.0
038 */
039@Beta
040@DoNotMock("Use ImmutableRangeMap or TreeRangeMap")
041@GwtIncompatible
042public interface RangeMap<K extends Comparable, V> {
043  /**
044   * Returns the value associated with the specified key, or {@code null} if there is no such value.
045   *
046   * <p>Specifically, if any range in this range map contains the specified key, the value
047   * associated with that range is returned.
048   */
049  @Nullable
050  V get(K key);
051
052  /**
053   * Returns the range containing this key and its associated value, if such a range is present in
054   * the range map, or {@code null} otherwise.
055   */
056  @Nullable
057  Entry<Range<K>, V> getEntry(K key);
058
059  /**
060   * Returns the minimal range {@linkplain Range#encloses(Range) enclosing} the ranges in this
061   * {@code RangeMap}.
062   *
063   * @throws NoSuchElementException if this range map is empty
064   */
065  Range<K> span();
066
067  /**
068   * Maps a range to a specified value (optional operation).
069   *
070   * <p>Specifically, after a call to {@code put(range, value)}, if {@link
071   * Range#contains(Comparable) range.contains(k)}, then {@link #get(Comparable) get(k)} will return
072   * {@code value}.
073   *
074   * <p>If {@code range} {@linkplain Range#isEmpty() is empty}, then this is a no-op.
075   */
076  void put(Range<K> range, V value);
077
078  /**
079   * Maps a range to a specified value, coalescing this range with any existing ranges with the same
080   * value that are {@linkplain Range#isConnected connected} to this range.
081   *
082   * <p>The behavior of {@link #get(Comparable) get(k)} after calling this method is identical to
083   * the behavior described in {@link #put(Range, Object) put(range, value)}, however the ranges
084   * returned from {@link #asMapOfRanges} will be different if there were existing entries which
085   * connect to the given range and value.
086   *
087   * <p>Even if the input range is empty, if it is connected on both sides by ranges mapped to the
088   * same value those two ranges will be coalesced.
089   *
090   * <p><b>Note:</b> coalescing requires calling {@code .equals()} on any connected values, which
091   * may be expensive depending on the value type. Using this method on range maps with large values
092   * such as {@link Collection} types is discouraged.
093   *
094   * @since 22.0
095   */
096  void putCoalescing(Range<K> range, V value);
097
098  /** Puts all the associations from {@code rangeMap} into this range map (optional operation). */
099  void putAll(RangeMap<K, V> rangeMap);
100
101  /** Removes all associations from this range map (optional operation). */
102  void clear();
103
104  /**
105   * Removes all associations from this range map in the specified range (optional operation).
106   *
107   * <p>If {@code !range.contains(k)}, {@link #get(Comparable) get(k)} will return the same result
108   * before and after a call to {@code remove(range)}. If {@code range.contains(k)}, then after a
109   * call to {@code remove(range)}, {@code get(k)} will return {@code null}.
110   */
111  void remove(Range<K> range);
112
113  /**
114   * Merges a value into the map over a range by applying a remapping function.
115   *
116   * <p>If any parts of the range are already present in this range map, those parts are mapped to
117   * new values by applying the remapping function. Any parts of the range not already present in
118   * this range map are mapped to the specified value, unless the value is {@code null}.
119   *
120   * <p>Any existing map entry spanning either range boundary may be split at the boundary, even if
121   * the merge does not affect its value.
122   *
123   * <p>For example, if {@code rangeMap} had one entry {@code [1, 5] => 3} then {@code
124   * rangeMap.merge(Range.closed(0,2), 3, Math::max)} could yield a range map with the entries
125   * {@code [0, 1) => 3, [1, 2] => 3, (2, 5] => 3}.
126   *
127   * @since 28.1
128   */
129  void merge(
130      Range<K> range,
131      @Nullable V value,
132      BiFunction<? super V, ? super V, ? extends V> remappingFunction);
133
134  /**
135   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
136   * this range map are guaranteed to read through to the returned {@code Map}.
137   *
138   * <p>The returned {@code Map} iterates over entries in ascending order of the bounds of the
139   * {@code Range} entries.
140   *
141   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
142   */
143  Map<Range<K>, V> asMapOfRanges();
144
145  /**
146   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
147   * this range map are guaranteed to read through to the returned {@code Map}.
148   *
149   * <p>The returned {@code Map} iterates over entries in descending order of the bounds of the
150   * {@code Range} entries.
151   *
152   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
153   *
154   * @since 19.0
155   */
156  Map<Range<K>, V> asDescendingMapOfRanges();
157
158  /**
159   * Returns a view of the part of this range map that intersects with {@code range}.
160   *
161   * <p>For example, if {@code rangeMap} had the entries {@code [1, 5] => "foo", (6, 8) => "bar",
162   * (10, ∞) => "baz"} then {@code rangeMap.subRangeMap(Range.open(3, 12))} would return a range map
163   * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
164   *
165   * <p>The returned range map supports all optional operations that this range map supports, except
166   * for {@code asMapOfRanges().iterator().remove()}.
167   *
168   * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
169   * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
170   */
171  RangeMap<K, V> subRangeMap(Range<K> range);
172
173  /**
174   * Returns {@code true} if {@code obj} is another {@code RangeMap} that has an equivalent {@link
175   * #asMapOfRanges()}.
176   */
177  @Override
178  boolean equals(@Nullable Object o);
179
180  /** Returns {@code asMapOfRanges().hashCode()}. */
181  @Override
182  int hashCode();
183
184  /** Returns a readable string representation of this range map. */
185  @Override
186  String toString();
187}