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 javax.annotation.CheckForNull;
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@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, ? extends 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   * Merges a value into a part of the map by applying a remapping function.
120   *
121   * <p>If any parts of the range are already present in this map, those parts are mapped to new
122   * values by applying the remapping function. The remapping function accepts the map's existing
123   * value for that part of the range and the given value. It returns the value to be associated
124   * with that part of the map, or it returns {@code null} to clear that part of the map.
125   *
126   * <p>Any parts of the range not already present in this map are mapped to the specified value,
127   * unless the value is {@code null}.
128   *
129   * <p>Any existing entry spanning either range boundary may be split at the boundary, even if the
130   * merge does not affect its value. For example, if {@code rangeMap} had one entry {@code [1, 5]
131   * => 3} then {@code rangeMap.merge(Range.closed(0,2), 3, Math::max)} could yield a map with the
132   * entries {@code [0, 1) => 3, [1, 2] => 3, (2, 5] => 3}.
133   *
134   * @since 28.1
135   */
136  void merge(
137      Range<K> range,
138      @CheckForNull V value,
139      BiFunction<? super V, ? super @Nullable V, ? extends @Nullable V> remappingFunction);
140
141  /**
142   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
143   * this range map are guaranteed to read through to the returned {@code Map}.
144   *
145   * <p>The returned {@code Map} iterates over entries in ascending order of the bounds of the
146   * {@code Range} entries.
147   *
148   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
149   */
150  Map<Range<K>, V> asMapOfRanges();
151
152  /**
153   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
154   * this range map are guaranteed to read through to the returned {@code Map}.
155   *
156   * <p>The returned {@code Map} iterates over entries in descending order of the bounds of the
157   * {@code Range} entries.
158   *
159   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
160   *
161   * @since 19.0
162   */
163  Map<Range<K>, V> asDescendingMapOfRanges();
164
165  /**
166   * Returns a view of the part of this range map that intersects with {@code range}.
167   *
168   * <p>For example, if {@code rangeMap} had the entries {@code [1, 5] => "foo", (6, 8) => "bar",
169   * (10, ∞) => "baz"} then {@code rangeMap.subRangeMap(Range.open(3, 12))} would return a range map
170   * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
171   *
172   * <p>The returned range map supports all optional operations that this range map supports, except
173   * for {@code asMapOfRanges().iterator().remove()}.
174   *
175   * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
176   * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
177   */
178  // TODO(cpovirk): Consider documenting that IAE on the various methods that can throw it.
179  RangeMap<K, V> subRangeMap(Range<K> range);
180
181  /**
182   * Returns {@code true} if {@code obj} is another {@code RangeMap} that has an equivalent {@link
183   * #asMapOfRanges()}.
184   */
185  @Override
186  boolean equals(@CheckForNull Object o);
187
188  /** Returns {@code asMapOfRanges().hashCode()}. */
189  @Override
190  int hashCode();
191
192  /** Returns a readable string representation of this range map. */
193  @Override
194  String toString();
195}