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