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 javax.annotation.CheckForNull;
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@DoNotMock("Use ImmutableRangeMap or TreeRangeMap")
038@GwtIncompatible
039@ElementTypesAreNonnullByDefault
040public interface RangeMap<K extends Comparable, V> {
041  /*
042   * TODO(cpovirk): These docs sometimes say "map" and sometimes say "range map." Pick one, or at
043   * least decide on a policy for when to use which.
044   */
045
046  /**
047   * Returns the value associated with the specified key, or {@code null} if there is no such value.
048   *
049   * <p>Specifically, if any range in this range map contains the specified key, the value
050   * associated with that range is returned.
051   */
052  @CheckForNull
053  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  @CheckForNull
060  Entry<Range<K>, V> getEntry(K key);
061
062  /**
063   * Returns the minimal range {@linkplain Range#encloses(Range) enclosing} the ranges in this
064   * {@code RangeMap}.
065   *
066   * @throws NoSuchElementException if this range map is empty
067   */
068  Range<K> span();
069
070  /**
071   * Maps a range to a specified value (optional operation).
072   *
073   * <p>Specifically, after a call to {@code put(range, value)}, if {@link
074   * Range#contains(Comparable) range.contains(k)}, then {@link #get(Comparable) get(k)} will return
075   * {@code value}.
076   *
077   * <p>If {@code range} {@linkplain Range#isEmpty() is empty}, then this is a no-op.
078   */
079  void put(Range<K> range, V value);
080
081  /**
082   * Maps a range to a specified value, coalescing this range with any existing ranges with the same
083   * value that are {@linkplain Range#isConnected connected} to this range.
084   *
085   * <p>The behavior of {@link #get(Comparable) get(k)} after calling this method is identical to
086   * the behavior described in {@link #put(Range, Object) put(range, value)}, however the ranges
087   * returned from {@link #asMapOfRanges} will be different if there were existing entries which
088   * connect to the given range and value.
089   *
090   * <p>Even if the input range is empty, if it is connected on both sides by ranges mapped to the
091   * same value those two ranges will be coalesced.
092   *
093   * <p><b>Note:</b> coalescing requires calling {@code .equals()} on any connected values, which
094   * may be expensive depending on the value type. Using this method on range maps with large values
095   * such as {@link Collection} types is discouraged.
096   *
097   * @since 22.0
098   */
099  void putCoalescing(Range<K> range, V value);
100
101  /** Puts all the associations from {@code rangeMap} into this range map (optional operation). */
102  void putAll(RangeMap<K, ? extends V> rangeMap);
103
104  /** Removes all associations from this range map (optional operation). */
105  void clear();
106
107  /**
108   * Removes all associations from this range map in the specified range (optional operation).
109   *
110   * <p>If {@code !range.contains(k)}, {@link #get(Comparable) get(k)} will return the same result
111   * before and after a call to {@code remove(range)}. If {@code range.contains(k)}, then after a
112   * call to {@code remove(range)}, {@code get(k)} will return {@code null}.
113   */
114  void remove(Range<K> range);
115
116  /**
117   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
118   * this range map are guaranteed to read through to the returned {@code Map}.
119   *
120   * <p>The returned {@code Map} iterates over entries in ascending order of the bounds of the
121   * {@code Range} entries.
122   *
123   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
124   */
125  Map<Range<K>, V> asMapOfRanges();
126
127  /**
128   * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
129   * this range map are guaranteed to read through to the returned {@code Map}.
130   *
131   * <p>The returned {@code Map} iterates over entries in descending order of the bounds of the
132   * {@code Range} entries.
133   *
134   * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
135   *
136   * @since 19.0
137   */
138  Map<Range<K>, V> asDescendingMapOfRanges();
139
140  /**
141   * Returns a view of the part of this range map that intersects with {@code range}.
142   *
143   * <p>For example, if {@code rangeMap} had the entries {@code [1, 5] => "foo", (6, 8) => "bar",
144   * (10, ∞) => "baz"} 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, except
148   * 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  // TODO(cpovirk): Consider documenting that IAE on the various methods that can throw it.
154  RangeMap<K, V> subRangeMap(Range<K> range);
155
156  /**
157   * Returns {@code true} if {@code obj} is another {@code RangeMap} that has an equivalent {@link
158   * #asMapOfRanges()}.
159   */
160  @Override
161  boolean equals(@CheckForNull Object o);
162
163  /** Returns {@code asMapOfRanges().hashCode()}. */
164  @Override
165  int hashCode();
166
167  /** Returns a readable string representation of this range map. */
168  @Override
169  String toString();
170}