1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
/*
* Copyright (C) 2011 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.collect;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import com.google.common.collect.Multiset.Entry;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.SortedSet;
/**
* Utilities for dealing with sorted collections of all types.
*
* @author Louis Wasserman
*/
@GwtCompatible
final class SortedIterables {
private SortedIterables() {}
/**
* Returns {@code true} if {@code elements} is a sorted collection using an ordering equivalent
* to {@code comparator}.
*/
public static boolean hasSameComparator(Comparator<?> comparator, Iterable<?> elements) {
checkNotNull(comparator);
checkNotNull(elements);
Comparator<?> comparator2;
if (elements instanceof SortedSet) {
SortedSet<?> sortedSet = (SortedSet<?>) elements;
comparator2 = sortedSet.comparator();
if (comparator2 == null) {
comparator2 = (Comparator) Ordering.natural();
}
} else if (elements instanceof SortedIterable) {
comparator2 = ((SortedIterable<?>) elements).comparator();
} else {
comparator2 = null;
}
return comparator.equals(comparator2);
}
/**
* Returns a sorted collection of the unique elements according to the specified comparator. Does
* not check for null.
*/
@SuppressWarnings("unchecked")
public static <E> Collection<E> sortedUnique(
Comparator<? super E> comparator, Iterator<E> elements) {
SortedSet<E> sortedSet = Sets.newTreeSet(comparator);
Iterators.addAll(sortedSet, elements);
return sortedSet;
}
/**
* Returns a sorted collection of the unique elements according to the specified comparator. Does
* not check for null.
*/
@SuppressWarnings("unchecked")
public static <E> Collection<E> sortedUnique(
Comparator<? super E> comparator, Iterable<E> elements) {
if (elements instanceof Multiset) {
elements = ((Multiset<E>) elements).elementSet();
}
if (elements instanceof Set) {
if (hasSameComparator(comparator, elements)) {
return (Set<E>) elements;
}
List<E> list = Lists.newArrayList(elements);
Collections.sort(list, comparator);
return list;
}
E[] array = (E[]) Iterables.toArray(elements);
if (!hasSameComparator(comparator, elements)) {
Arrays.sort(array, comparator);
}
return uniquifySortedArray(comparator, array);
}
private static <E> Collection<E> uniquifySortedArray(
Comparator<? super E> comparator, E[] array) {
if (array.length == 0) {
return Collections.emptySet();
}
int length = 1;
for (int i = 1; i < array.length; i++) {
int cmp = comparator.compare(array[i], array[length - 1]);
if (cmp != 0) {
array[length++] = array[i];
}
}
if (length < array.length) {
array = ObjectArrays.arraysCopyOf(array, length);
}
return Arrays.asList(array);
}
/**
* Returns a collection of multiset entries representing the counts of the distinct elements, in
* sorted order. Does not check for null.
*/
public static <E> Collection<Multiset.Entry<E>> sortedCounts(
Comparator<? super E> comparator, Iterator<E> elements) {
TreeMultiset<E> multiset = TreeMultiset.create(comparator);
Iterators.addAll(multiset, elements);
return multiset.entrySet();
}
/**
* Returns a collection of multiset entries representing the counts of the distinct elements, in
* sorted order. Does not check for null.
*/
public static <E> Collection<Multiset.Entry<E>> sortedCounts(
Comparator<? super E> comparator, Iterable<E> elements) {
if (elements instanceof Multiset) {
Multiset<E> multiset = (Multiset<E>) elements;
if (hasSameComparator(comparator, elements)) {
return multiset.entrySet();
}
List<Multiset.Entry<E>> entries = Lists.newArrayList(multiset.entrySet());
Collections.sort(
entries, Ordering.from(comparator).onResultOf(new Function<Multiset.Entry<E>, E>() {
@Override
public E apply(Entry<E> entry) {
return entry.getElement();
}
}));
return entries;
} else if (elements instanceof Set) { // known distinct
Collection<E> sortedElements;
if (hasSameComparator(comparator, elements)) {
sortedElements = (Collection<E>) elements;
} else {
List<E> list = Lists.newArrayList(elements);
Collections.sort(list, comparator);
sortedElements = list;
}
return singletonEntries(sortedElements);
} else if (hasSameComparator(comparator, elements)) {
E current = null;
int currentCount = 0;
List<Multiset.Entry<E>> sortedEntries = Lists.newArrayList();
for (E e : elements) {
if (currentCount > 0) {
if (comparator.compare(current, e) == 0) {
currentCount++;
} else {
sortedEntries.add(Multisets.immutableEntry(current, currentCount));
current = e;
currentCount = 1;
}
} else {
current = e;
currentCount = 1;
}
}
if (currentCount > 0) {
sortedEntries.add(Multisets.immutableEntry(current, currentCount));
}
return sortedEntries;
}
TreeMultiset<E> multiset = TreeMultiset.create(comparator);
Iterables.addAll(multiset, elements);
return multiset.entrySet();
}
static <E> Collection<Multiset.Entry<E>> singletonEntries(Collection<E> set) {
return Collections2.transform(set, new Function<E, Multiset.Entry<E>>() {
@Override
public Entry<E> apply(E elem) {
return Multisets.immutableEntry(elem, 1);
}
});
}
}
|
