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 org.checkerframework.checker.nullness.compatqual.NullableDecl;
026
027/**
028 * A mapping from disjoint nonempty ranges to non-null values. Queries look up the value associated
029 * with the range (if any) that contains a specified key.
030 *
031 * <p>In contrast to {@link RangeSet}, no "coalescing" is done of {@linkplain
032 * Range#isConnected(Range) connected} ranges, even if they are mapped to the same value.
033 *
034 * @author Louis Wasserman
035 * @since 14.0
036 */
037@Beta
038@GwtIncompatible
039public interface RangeMap<K extends Comparable, V> {
040  /**
041   * Returns the value associated with the specified key, or {@code null} if there is no such value.
042   *
043   * <p>Specifically, if any range in this range map contains the specified key, the value
044   * associated with that range is returned.
045   */
046  @NullableDecl
047  V get(K key);
048
049  /**
050   * Returns the range containing this key and its associated value, if such a range is present in
051   * the range map, or {@code null} otherwise.
052   */
053  @NullableDecl
054  Entry<Range<K>, V> getEntry(K key);
055
056  /**
057   * Returns the minimal range {@linkplain Range#encloses(Range) enclosing} the ranges in this
058   * {@code RangeMap}.
059   *
060   * @throws NoSuchElementException if this range map is empty
061   */
062  Range<K> span();
063
064  /**
065   * Maps a range to a specified value (optional operation).
066   *
067   * <p>Specifically, after a call to {@code put(range, value)}, if {@link
068   * Range#contains(Comparable) range.contains(k)}, then {@link #get(Comparable) get(k)} will return
069   * {@code value}.
070   *
071   * <p>If {@code range} {@linkplain Range#isEmpty() is empty}, then this is a no-op.
072   */
073  void put(Range<K> range, V value);
074
075  /**
076   * Maps a range to a specified value, coalescing this range with any existing ranges with the same
077   * value that are {@linkplain Range#isConnected connected} to this range.
078   *
079   * <p>The behavior of {@link #get(Comparable) get(k)} after calling this method is identical to
080   * the behavior described in {@link #put(Range, Object) put(range, value)}, however the ranges
081   * returned from {@link #asMapOfRanges} will be different if there were existing entries which
082   * connect to the given range and value.
083   *
084   * <p>Even if the input range is empty, if it is connected on both sides by ranges mapped to the
085   * same value those two ranges will be coalesced.
086   *
087   * <p><b>Note:</b> coalescing requires calling {@code .equals()} on any connected values, which
088   * may be expensive depending on the value type. Using this method on range maps with large values
089   * such as {@link Collection} types is discouraged.
090   *
091   * @since 22.0
092   */
093  void putCoalescing(Range<K> range, V value);
094
095  /** Puts all the associations from {@code rangeMap} into this range map (optional operation). */
096  void putAll(RangeMap<K, V> rangeMap);
097
098  /** Removes all associations from this range map (optional operation). */
099  void clear();
100
101  /**
102   * Removes all associations from this range map in the specified range (optional operation).
103   *
104   * <p>If {@code !range.contains(k)}, {@link #get(Comparable) get(k)} will return the same result
105   * before and after a call to {@code remove(range)}. If {@code range.contains(k)}, then after a
106   * call to {@code remove(range)}, {@code get(k)} will return {@code null}.
107   */
108  void remove(Range<K> range);
109
110  /**
111   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
112   * this range map are guaranteed to read through to the returned {@code Map}.
113   *
114   * <p>The returned {@code Map} iterates over entries in ascending order of the bounds of the
115   * {@code Range} entries.
116   *
117   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
118   */
119  Map<Range<K>, V> asMapOfRanges();
120
121  /**
122   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
123   * this range map are guaranteed to read through to the returned {@code Map}.
124   *
125   * <p>The returned {@code Map} iterates over entries in descending order of the bounds of the
126   * {@code Range} entries.
127   *
128   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
129   *
130   * @since 19.0
131   */
132  Map<Range<K>, V> asDescendingMapOfRanges();
133
134  /**
135   * Returns a view of the part of this range map that intersects with {@code range}.
136   *
137   * <p>For example, if {@code rangeMap} had the entries {@code [1, 5] => "foo", (6, 8) => "bar",
138   * (10, ∞) => "baz"} then {@code rangeMap.subRangeMap(Range.open(3, 12))} would return a range map
139   * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
140   *
141   * <p>The returned range map supports all optional operations that this range map supports, except
142   * for {@code asMapOfRanges().iterator().remove()}.
143   *
144   * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
145   * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
146   */
147  RangeMap<K, V> subRangeMap(Range<K> range);
148
149  /**
150   * Returns {@code true} if {@code obj} is another {@code RangeMap} that has an equivalent {@link
151   * #asMapOfRanges()}.
152   */
153  @Override
154  boolean equals(@NullableDecl Object o);
155
156  /** Returns {@code asMapOfRanges().hashCode()}. */
157  @Override
158  int hashCode();
159
160  /** Returns a readable string representation of this range map. */
161  @Override
162  String toString();
163}