001/*
002 * Copyright (C) 2009 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 static com.google.common.base.Preconditions.checkNotNull;
020
021import com.google.common.annotations.Beta;
022import com.google.common.annotations.GwtCompatible;
023
024import java.util.Iterator;
025import java.util.NoSuchElementException;
026
027/**
028 * Static methods pertaining to {@link Range} instances.  Each of the
029 * {@link Range nine types of ranges} can be constructed with a corresponding
030 * factory method:
031 *
032 * <dl>
033 * <dt>{@code (a..b)}
034 * <dd>{@link #open}
035 * <dt>{@code [a..b]}
036 * <dd>{@link #closed}
037 * <dt>{@code [a..b)}
038 * <dd>{@link #closedOpen}
039 * <dt>{@code (a..b]}
040 * <dd>{@link #openClosed}
041 * <dt>{@code (a..+∞)}
042 * <dd>{@link #greaterThan}
043 * <dt>{@code [a..+∞)}
044 * <dd>{@link #atLeast}
045 * <dt>{@code (-∞..b)}
046 * <dd>{@link #lessThan}
047 * <dt>{@code (-∞..b]}
048 * <dd>{@link #atMost}
049 * <dt>{@code (-∞..+∞)}
050 * <dd>{@link #all}
051 * </dl>
052 *
053 * <p>Additionally, {@link Range} instances can be constructed by passing the
054 * {@link BoundType bound types} explicitly.
055 *
056 * <dl>
057 * <dt>Bounded on both ends
058 * <dd>{@link #range}
059 * <dt>Unbounded on top ({@code (a..+∞)} or {@code (a..+∞)})
060 * <dd>{@link #downTo}
061 * <dt>Unbounded on bottom ({@code (-∞..b)} or {@code (-∞..b]})
062 * <dd>{@link #upTo}
063 * </dl>
064 * 
065 * <p>See the Guava User Guide article on <a href=
066 * "http://code.google.com/p/guava-libraries/wiki/RangesExplained">
067 * {@code Range}</a>.
068 *
069 * @author Kevin Bourrillion
070 * @author Gregory Kick
071 * @since 10.0
072 */
073@GwtCompatible
074@Beta
075public final class Ranges {
076  private Ranges() {}
077
078  static <C extends Comparable<?>> Range<C> create(
079      Cut<C> lowerBound, Cut<C> upperBound) {
080    return new Range<C>(lowerBound, upperBound);
081  }
082
083  /**
084   * Returns a range that contains all values strictly greater than {@code
085   * lower} and strictly less than {@code upper}.
086   *
087   * @throws IllegalArgumentException if {@code lower} is greater than <i>or
088   *     equal to</i> {@code upper}
089   */
090  public static <C extends Comparable<?>> Range<C> open(C lower, C upper) {
091    return create(Cut.aboveValue(lower), Cut.belowValue(upper));
092  }
093
094  /**
095   * Returns a range that contains all values greater than or equal to
096   * {@code lower} and less than or equal to {@code upper}.
097   *
098   * @throws IllegalArgumentException if {@code lower} is greater than {@code
099   *     upper}
100   */
101  public static <C extends Comparable<?>> Range<C> closed(C lower, C upper) {
102    return create(Cut.belowValue(lower), Cut.aboveValue(upper));
103  }
104
105  /**
106   * Returns a range that contains all values greater than or equal to
107   * {@code lower} and strictly less than {@code upper}.
108   *
109   * @throws IllegalArgumentException if {@code lower} is greater than {@code
110   *     upper}
111   */
112  public static <C extends Comparable<?>> Range<C> closedOpen(
113      C lower, C upper) {
114    return create(Cut.belowValue(lower), Cut.belowValue(upper));
115  }
116
117  /**
118   * Returns a range that contains all values strictly greater than {@code
119   * lower} and less than or equal to {@code upper}.
120   *
121   * @throws IllegalArgumentException if {@code lower} is greater than {@code
122   *     upper}
123   */
124  public static <C extends Comparable<?>> Range<C> openClosed(
125      C lower, C upper) {
126    return create(Cut.aboveValue(lower), Cut.aboveValue(upper));
127  }
128
129  /**
130   * Returns a range that contains any value from {@code lower} to {@code
131   * upper}, where each endpoint may be either inclusive (closed) or exclusive
132   * (open).
133   *
134   * @throws IllegalArgumentException if {@code lower} is greater than {@code
135   *     upper}
136   */
137  public static <C extends Comparable<?>> Range<C> range(
138      C lower, BoundType lowerType, C upper, BoundType upperType) {
139    checkNotNull(lowerType);
140    checkNotNull(upperType);
141
142    Cut<C> lowerBound = (lowerType == BoundType.OPEN)
143        ? Cut.aboveValue(lower)
144        : Cut.belowValue(lower);
145    Cut<C> upperBound = (upperType == BoundType.OPEN)
146        ? Cut.belowValue(upper)
147        : Cut.aboveValue(upper);
148    return create(lowerBound, upperBound);
149  }
150
151  /**
152   * Returns a range that contains all values strictly less than {@code
153   * endpoint}.
154   */
155  public static <C extends Comparable<?>> Range<C> lessThan(C endpoint) {
156    return create(Cut.<C>belowAll(), Cut.belowValue(endpoint));
157  }
158
159  /**
160   * Returns a range that contains all values less than or equal to
161   * {@code endpoint}.
162   */
163  public static <C extends Comparable<?>> Range<C> atMost(C endpoint) {
164    return create(Cut.<C>belowAll(), Cut.aboveValue(endpoint));
165  }
166
167  /**
168   * Returns a range with no lower bound up to the given endpoint, which may be
169   * either inclusive (closed) or exclusive (open).
170   */
171  public static <C extends Comparable<?>> Range<C> upTo(
172      C endpoint, BoundType boundType) {
173    switch (boundType) {
174      case OPEN:
175        return lessThan(endpoint);
176      case CLOSED:
177        return atMost(endpoint);
178      default:
179        throw new AssertionError();
180    }
181  }
182
183  /**
184   * Returns a range that contains all values strictly greater than {@code
185   * endpoint}.
186   */
187  public static <C extends Comparable<?>> Range<C> greaterThan(C endpoint) {
188    return create(Cut.aboveValue(endpoint), Cut.<C>aboveAll());
189  }
190
191  /**
192   * Returns a range that contains all values greater than or equal to
193   * {@code endpoint}.
194   */
195  public static <C extends Comparable<?>> Range<C> atLeast(C endpoint) {
196    return create(Cut.belowValue(endpoint), Cut.<C>aboveAll());
197  }
198
199  /**
200   * Returns a range from the given endpoint, which may be either inclusive
201   * (closed) or exclusive (open), with no upper bound.
202   */
203  public static <C extends Comparable<?>> Range<C> downTo(
204      C endpoint, BoundType boundType) {
205    switch (boundType) {
206      case OPEN:
207        return greaterThan(endpoint);
208      case CLOSED:
209        return atLeast(endpoint);
210      default:
211        throw new AssertionError();
212    }
213  }
214
215  /** Returns a range that contains every value of type {@code C}. */
216  public static <C extends Comparable<?>> Range<C> all() {
217    return create(Cut.<C>belowAll(), Cut.<C>aboveAll());
218  }
219
220  /**
221   * Returns a range that {@linkplain Range#contains(Comparable) contains} only
222   * the given value. The returned range is {@linkplain BoundType#CLOSED closed}
223   * on both ends.
224   */
225  public static <C extends Comparable<?>> Range<C> singleton(C value) {
226    return closed(value, value);
227  }
228
229  /**
230   * Returns the minimal range that
231   * {@linkplain Range#contains(Comparable) contains} all of the given values.
232   * The returned range is {@linkplain BoundType#CLOSED closed} on both ends.
233   *
234   * @throws ClassCastException if the parameters are not <i>mutually
235   *     comparable</i>
236   * @throws NoSuchElementException if {@code values} is empty
237   * @throws NullPointerException if any of {@code values} is null
238   */
239  public static <C extends Comparable<?>> Range<C> encloseAll(
240      Iterable<C> values) {
241    checkNotNull(values);
242    if (values instanceof ContiguousSet) {
243      return ((ContiguousSet<C>) values).range();
244    }
245    Iterator<C> valueIterator = values.iterator();
246    C min = checkNotNull(valueIterator.next());
247    C max = min;
248    while (valueIterator.hasNext()) {
249      C value = checkNotNull(valueIterator.next());
250      min = Ordering.natural().min(min, value);
251      max = Ordering.natural().max(max, value);
252    }
253    return closed(min, max);
254  }
255}