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.GwtIncompatible;
020import com.google.errorprone.annotations.DoNotMock;
021import java.util.Collection;
022import java.util.Map;
023import java.util.Map.Entry;
024import java.util.NoSuchElementException;
025import java.util.function.BiFunction;
026import org.jspecify.annotations.Nullable;
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@SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
039@DoNotMock("Use ImmutableRangeMap or TreeRangeMap")
040@GwtIncompatible
041public interface RangeMap<K extends Comparable, V> {
042  /*
043   * TODO(cpovirk): These docs sometimes say "map" and sometimes say "range map." Pick one, or at
044   * least decide on a policy for when to use which.
045   */
046
047  /**
048   * Returns the value associated with the specified key, or {@code null} if there is no such value.
049   *
050   * <p>Specifically, if any range in this range map contains the specified key, the value
051   * associated with that range is returned.
052   */
053  @Nullable V get(K key);
054
055  /**
056   * Returns the range containing this key and its associated value, if such a range is present in
057   * the range map, or {@code null} otherwise.
058   */
059  @Nullable Entry<Range<K>, V> getEntry(K key);
060
061  /**
062   * Returns the minimal range {@linkplain Range#encloses(Range) enclosing} the ranges in this
063   * {@code RangeMap}.
064   *
065   * @throws NoSuchElementException if this range map is empty
066   */
067  Range<K> span();
068
069  /**
070   * Maps a range to a specified value (optional operation).
071   *
072   * <p>Specifically, after a call to {@code put(range, value)}, if {@link
073   * Range#contains(Comparable) range.contains(k)}, then {@link #get(Comparable) get(k)} will return
074   * {@code value}.
075   *
076   * <p>If {@code range} {@linkplain Range#isEmpty() is empty}, then this is a no-op.
077   */
078  void put(Range<K> range, V value);
079
080  /**
081   * Maps a range to a specified value, coalescing this range with any existing ranges with the same
082   * value that are {@linkplain Range#isConnected connected} to this range.
083   *
084   * <p>The behavior of {@link #get(Comparable) get(k)} after calling this method is identical to
085   * the behavior described in {@link #put(Range, Object) put(range, value)}, however the ranges
086   * returned from {@link #asMapOfRanges} will be different if there were existing entries which
087   * connect to the given range and value.
088   *
089   * <p>Even if the input range is empty, if it is connected on both sides by ranges mapped to the
090   * same value those two ranges will be coalesced.
091   *
092   * <p><b>Note:</b> coalescing requires calling {@code .equals()} on any connected values, which
093   * may be expensive depending on the value type. Using this method on range maps with large values
094   * such as {@link Collection} types is discouraged.
095   *
096   * @since 22.0
097   */
098  void putCoalescing(Range<K> range, V value);
099
100  /** Puts all the associations from {@code rangeMap} into this range map (optional operation). */
101  void putAll(RangeMap<K, ? extends V> rangeMap);
102
103  /** Removes all associations from this range map (optional operation). */
104  void clear();
105
106  /**
107   * Removes all associations from this range map in the specified range (optional operation).
108   *
109   * <p>If {@code !range.contains(k)}, {@link #get(Comparable) get(k)} will return the same result
110   * before and after a call to {@code remove(range)}. If {@code range.contains(k)}, then after a
111   * call to {@code remove(range)}, {@code get(k)} will return {@code null}.
112   */
113  void remove(Range<K> range);
114
115  /**
116   * Merges a value into a part of the map by applying a remapping function.
117   *
118   * <p>If any parts of the range are already present in this map, those parts are mapped to new
119   * values by applying the remapping function. The remapping function accepts the map's existing
120   * value for that part of the range and the given value. It returns the value to be associated
121   * with that part of the map, or it returns {@code null} to clear that part of the map.
122   *
123   * <p>Any parts of the range not already present in this map are mapped to the specified value,
124   * unless the value is {@code null}.
125   *
126   * <p>Any existing entry spanning either range boundary may be split at the boundary, even if the
127   * merge does not affect its value. For example, if {@code rangeMap} had one entry {@code [1, 5]
128   * => 3} then {@code rangeMap.merge(Range.closed(0,2), 3, Math::max)} could yield a map with the
129   * entries {@code [0, 1) => 3, [1, 2] => 3, (2, 5] => 3}.
130   *
131   * @since 28.1
132   */
133  void merge(
134      Range<K> range,
135      @Nullable V value,
136      BiFunction<? super V, ? super @Nullable V, ? extends @Nullable V> remappingFunction);
137
138  /**
139   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
140   * this range map are guaranteed to read through to the returned {@code Map}.
141   *
142   * <p>The returned {@code Map} iterates over entries in ascending order of the bounds of the
143   * {@code Range} entries.
144   *
145   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
146   */
147  Map<Range<K>, V> asMapOfRanges();
148
149  /**
150   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
151   * this range map are guaranteed to read through to the returned {@code Map}.
152   *
153   * <p>The returned {@code Map} iterates over entries in descending order of the bounds of the
154   * {@code Range} entries.
155   *
156   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
157   *
158   * @since 19.0
159   */
160  Map<Range<K>, V> asDescendingMapOfRanges();
161
162  /**
163   * Returns a view of the part of this range map that intersects with {@code range}.
164   *
165   * <p>For example, if {@code rangeMap} had the entries {@code [1, 5] => "foo", (6, 8) => "bar",
166   * (10, ∞) => "baz"} then {@code rangeMap.subRangeMap(Range.open(3, 12))} would return a range map
167   * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
168   *
169   * <p>The returned range map supports all optional operations that this range map supports, except
170   * for {@code asMapOfRanges().iterator().remove()}.
171   *
172   * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
173   * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
174   */
175  // TODO(cpovirk): Consider documenting that IAE on the various methods that can throw it.
176  RangeMap<K, V> subRangeMap(Range<K> range);
177
178  /**
179   * Returns {@code true} if {@code obj} is another {@code RangeMap} that has an equivalent {@link
180   * #asMapOfRanges()}.
181   */
182  @Override
183  boolean equals(@Nullable Object o);
184
185  /** Returns {@code asMapOfRanges().hashCode()}. */
186  @Override
187  int hashCode();
188
189  /** Returns a readable string representation of this range map. */
190  @Override
191  String toString();
192}