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 javax.annotation.Nullable;
026
027/**
028 * A mapping from disjoint nonempty ranges to non-null values. Queries look up the value
029 * associated 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
042   * 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
052   * in 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
059   * in this {@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
069   * {@link Range#contains(Comparable) range.contains(k)}, then {@link #get(Comparable) get(k)}
070   * will return {@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  /**
097   * Puts all the associations from {@code rangeMap} into this range map (optional operation).
098   */
099  void putAll(RangeMap<K, V> rangeMap);
100
101  /**
102   * Removes all associations from this range map (optional operation).
103   */
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
111   * after a call to {@code remove(range)}, {@code get(k)} will return {@code null}.
112   */
113  void remove(Range<K> range);
114
115  /**
116   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}.
117   * Modifications to this range map are guaranteed to read through to the returned {@code Map}.
118   *
119   * <p>The returned {@code Map} iterates over entries in ascending order of the bounds of the
120   * {@code Range} entries.
121   *
122   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
123   */
124  Map<Range<K>, V> asMapOfRanges();
125
126  /**
127   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}.
128   * Modifications to this range map are guaranteed to read through to the returned {@code Map}.
129   *
130   * <p>The returned {@code Map} iterates over entries in descending order of the bounds of the
131   * {@code Range} entries.
132   *
133   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
134   *
135   * @since 19.0
136   */
137  Map<Range<K>, V> asDescendingMapOfRanges();
138
139  /**
140   * Returns a view of the part of this range map that intersects with {@code range}.
141   *
142   * <p>For example, if {@code rangeMap} had the entries
143   * {@code [1, 5] => "foo", (6, 8) => "bar", (10, ∞) => "baz"}
144   * then {@code rangeMap.subRangeMap(Range.open(3, 12))} would return a range map
145   * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
146   *
147   * <p>The returned range map supports all optional operations that this range map supports,
148   * except for {@code asMapOfRanges().iterator().remove()}.
149   *
150   * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
151   * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
152   */
153  RangeMap<K, V> subRangeMap(Range<K> range);
154
155  /**
156   * Returns {@code true} if {@code obj} is another {@code RangeMap} that has an equivalent
157   * {@link #asMapOfRanges()}.
158   */
159  @Override
160  boolean equals(@Nullable Object o);
161
162  /**
163   * Returns {@code asMapOfRanges().hashCode()}.
164   */
165  @Override
166  int hashCode();
167
168  /**
169   * Returns a readable string representation of this range map.
170   */
171  @Override
172  String toString();
173}