1/*
2 * Copyright (C) 2010 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14
15package com.google.common.collect;
16
17import static com.google.common.base.Preconditions.checkArgument;
18import static com.google.common.base.Preconditions.checkNotNull;
19
20import com.google.common.annotations.Beta;
21import com.google.common.annotations.GwtCompatible;
22
23import java.util.NoSuchElementException;
24
25/**
26 * A sorted set of contiguous values in a given {@link DiscreteDomain}.
27 *
28 * <p><b>Warning:</b> Be extremely careful what you do with conceptually large instances (such as
29 * {@code ContiguousSet.create(Range.greaterThan(0), DiscreteDomain.integers()}). Certain
30 * operations on such a set can be performed efficiently, but others (such as {@link Set#hashCode}
31 * or {@link Collections#frequency}) can cause major performance problems.
32 *
33 * @author Gregory Kick
34 * @since 10.0
35 */
36@Beta
37@GwtCompatible(emulated = true)
38@SuppressWarnings("rawtypes") // allow ungenerified Comparable types
39public abstract class ContiguousSet<C extends Comparable> extends ImmutableSortedSet<C> {
40  /**
41   * Returns a {@code ContiguousSet} containing the same values in the given domain
42   * {@linkplain Range#contains contained} by the range.
43   *
44   * @throws IllegalArgumentException if neither range nor the domain has a lower bound, or if
45   *     neither has an upper bound
46   *
47   * @since 13.0
48   */
49  public static <C extends Comparable> ContiguousSet<C> create(
50      Range<C> range, DiscreteDomain<C> domain) {
51    checkNotNull(range);
52    checkNotNull(domain);
53    Range<C> effectiveRange = range;
54    try {
55      if (!range.hasLowerBound()) {
56        effectiveRange = effectiveRange.intersection(Range.atLeast(domain.minValue()));
57      }
58      if (!range.hasUpperBound()) {
59        effectiveRange = effectiveRange.intersection(Range.atMost(domain.maxValue()));
60      }
61    } catch (NoSuchElementException e) {
62      throw new IllegalArgumentException(e);
63    }
64
65    // Per class spec, we are allowed to throw CCE if necessary
66    boolean empty = effectiveRange.isEmpty()
67        || Range.compareOrThrow(
68            range.lowerBound.leastValueAbove(domain),
69            range.upperBound.greatestValueBelow(domain)) > 0;
70
71    return empty
72        ? new EmptyContiguousSet<C>(domain)
73        : new RegularContiguousSet<C>(effectiveRange, domain);
74  }
75
76  final DiscreteDomain<C> domain;
77
78  ContiguousSet(DiscreteDomain<C> domain) {
79    super(Ordering.natural());
80    this.domain = domain;
81  }
82
83  @Override public ContiguousSet<C> headSet(C toElement) {
84    return headSetImpl(checkNotNull(toElement), false);
85  }
86
87  @Override public ContiguousSet<C> subSet(C fromElement, C toElement) {
88    checkNotNull(fromElement);
89    checkNotNull(toElement);
90    checkArgument(comparator().compare(fromElement, toElement) <= 0);
91    return subSetImpl(fromElement, true, toElement, false);
92  }
93
94  @Override public ContiguousSet<C> tailSet(C fromElement) {
95    return tailSetImpl(checkNotNull(fromElement), true);
96  }
97
98  /*
99   * These methods perform most headSet, subSet, and tailSet logic, besides parameter validation.
100   */
101  /*@Override*/ abstract ContiguousSet<C> headSetImpl(C toElement, boolean inclusive);
102
103  /*@Override*/ abstract ContiguousSet<C> subSetImpl(C fromElement, boolean fromInclusive,
104      C toElement, boolean toInclusive);
105
106  /*@Override*/ abstract ContiguousSet<C> tailSetImpl(C fromElement, boolean inclusive);
107
108  /**
109   * Returns the set of values that are contained in both this set and the other.
110   *
111   * <p>This method should always be used instead of
112   * {@link Sets#intersection} for {@link ContiguousSet} instances.
113   */
114  public abstract ContiguousSet<C> intersection(ContiguousSet<C> other);
115
116  /**
117   * Returns a range, closed on both ends, whose endpoints are the minimum and maximum values
118   * contained in this set.  This is equivalent to {@code range(CLOSED, CLOSED)}.
119   *
120   * @throws NoSuchElementException if this set is empty
121   */
122  public abstract Range<C> range();
123
124  /**
125   * Returns the minimal range with the given boundary types for which all values in this set are
126   * {@linkplain Range#contains(Comparable) contained} within the range.
127   *
128   * <p>Note that this method will return ranges with unbounded endpoints if {@link BoundType#OPEN}
129   * is requested for a domain minimum or maximum.  For example, if {@code set} was created from the
130   * range {@code [1..Integer.MAX_VALUE]} then {@code set.range(CLOSED, OPEN)} must return
131   * {@code [1..∞)}.
132   *
133   * @throws NoSuchElementException if this set is empty
134   */
135  public abstract Range<C> range(BoundType lowerBoundType, BoundType upperBoundType);
136
137  /** Returns a short-hand representation of the contents such as {@code "[1..100]"}. */
138  @Override public String toString() {
139    return range().toString();
140  }
141
142  /**
143   * Not supported. {@code ContiguousSet} instances are constructed with {@link #create}. This
144   * method exists only to hide {@link ImmutableSet#builder} from consumers of {@code
145   * ContiguousSet}.
146   *
147   * @throws UnsupportedOperationException always
148   * @deprecated Use {@link #create}.
149   */
150  @Deprecated public static <E> ImmutableSortedSet.Builder<E> builder() {
151    throw new UnsupportedOperationException();
152  }
153}
154
155