diff options
Diffstat (limited to 'subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/IMemoryView.java')
-rw-r--r-- | subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/IMemoryView.java | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/IMemoryView.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/IMemoryView.java new file mode 100644 index 00000000..add575c6 --- /dev/null +++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/IMemoryView.java | |||
@@ -0,0 +1,205 @@ | |||
1 | /******************************************************************************* | ||
2 | * Copyright (c) 2010-2018, Gabor Bergmann, IncQueryLabs Ltd. | ||
3 | * This program and the accompanying materials are made available under the | ||
4 | * terms of the Eclipse Public License v. 2.0 which is available at | ||
5 | * http://www.eclipse.org/legal/epl-v20.html. | ||
6 | * | ||
7 | * SPDX-License-Identifier: EPL-2.0 | ||
8 | *******************************************************************************/ | ||
9 | package tools.refinery.viatra.runtime.matchers.util; | ||
10 | |||
11 | import java.util.Iterator; | ||
12 | import java.util.Map; | ||
13 | import java.util.Map.Entry; | ||
14 | import java.util.Set; | ||
15 | import java.util.function.BiConsumer; | ||
16 | import java.util.stream.Stream; | ||
17 | import java.util.stream.StreamSupport; | ||
18 | |||
19 | /** | ||
20 | * A read-only view on a memory containing a positive or negative number of equal() copies for some values. | ||
21 | * During iterations, each distinct value is iterated only once. | ||
22 | * | ||
23 | * <p> See {@link IMemory}. | ||
24 | * | ||
25 | * <p> Implementors must provide semantic (not identity-based) hashCode() and equals() using the static helpers {@link #hashCode(IMemoryView)} and {@link #equals(IMemoryView, Object)} here. | ||
26 | * | ||
27 | * @author Gabor Bergmann | ||
28 | * | ||
29 | * @since 2.0 | ||
30 | */ | ||
31 | public interface IMemoryView<T> extends Iterable<T> { | ||
32 | |||
33 | /** | ||
34 | * Returns the number of occurrences of the given value. | ||
35 | * | ||
36 | * @return the number of occurrences | ||
37 | */ | ||
38 | int getCount(T value); | ||
39 | |||
40 | /** | ||
41 | * Returns the number of occurrences of the given value (which may be of any type). | ||
42 | * | ||
43 | * @return the number of occurrences | ||
44 | */ | ||
45 | int getCountUnsafe(Object value); | ||
46 | |||
47 | /** | ||
48 | * @return true if the given value is contained with a nonzero multiplicity | ||
49 | */ | ||
50 | boolean containsNonZero(T value); | ||
51 | |||
52 | /** | ||
53 | * @return true if the given value (which may be of any type) is contained with a nonzero multiplicity | ||
54 | */ | ||
55 | boolean containsNonZeroUnsafe(Object value); | ||
56 | |||
57 | /** | ||
58 | * @return the number of distinct values | ||
59 | */ | ||
60 | int size(); | ||
61 | |||
62 | /** | ||
63 | * | ||
64 | * @return iff contains at least one value with non-zero occurrences | ||
65 | */ | ||
66 | boolean isEmpty(); | ||
67 | |||
68 | /** | ||
69 | * The set of distinct values | ||
70 | */ | ||
71 | Set<T> distinctValues(); | ||
72 | |||
73 | |||
74 | /** | ||
75 | * Where supported, returns the stored element that is equal to the given value, or null if none. | ||
76 | * Useful for canonicalization in case of non-identity equals(). | ||
77 | * | ||
78 | * <p> For collections that do not support canonicalization, simply returns the argument if contained, null if none. | ||
79 | * | ||
80 | * @return a value equal to the argument if such a value is stored, or null if none | ||
81 | */ | ||
82 | default T theContainedVersionOf(T value) { | ||
83 | if (containsNonZero(value)) return value; else return null; | ||
84 | } | ||
85 | |||
86 | /** | ||
87 | * Where supported, returns the stored element that is equal to the given value (of any type), | ||
88 | * or null if none. | ||
89 | * Useful for canonicalization in case of non-identity equals(). | ||
90 | * | ||
91 | * <p> For collections that do not support canonicalization, simply returns the argument if contained, null if none. | ||
92 | * | ||
93 | * @return a value equal to the argument if such a value is stored, or null if none | ||
94 | */ | ||
95 | @SuppressWarnings("unchecked") | ||
96 | default T theContainedVersionOfUnsafe(Object value) { | ||
97 | if (containsNonZeroUnsafe(value)) return (T) value; else return null; | ||
98 | } | ||
99 | |||
100 | |||
101 | /** | ||
102 | * @return an unmodifiable view of contained values with their multiplicities | ||
103 | */ | ||
104 | default Iterable<Map.Entry<T, Integer>> entriesWithMultiplicities() { | ||
105 | return () -> { | ||
106 | Iterator<T> wrapped = distinctValues().iterator(); | ||
107 | return new Iterator<Map.Entry<T, Integer>> () { | ||
108 | @Override | ||
109 | public boolean hasNext() { | ||
110 | return wrapped.hasNext(); | ||
111 | } | ||
112 | |||
113 | @Override | ||
114 | public Map.Entry<T, Integer> next() { | ||
115 | T key = wrapped.next(); | ||
116 | int count = getCount(key); | ||
117 | return new Map.Entry<T, Integer>(){ | ||
118 | @Override | ||
119 | public T getKey() { | ||
120 | return key; | ||
121 | } | ||
122 | |||
123 | @Override | ||
124 | public Integer getValue() { | ||
125 | return count; | ||
126 | } | ||
127 | |||
128 | @Override | ||
129 | public Integer setValue(Integer value) { | ||
130 | throw new UnsupportedOperationException(); | ||
131 | } | ||
132 | |||
133 | @Override | ||
134 | public String toString() { | ||
135 | return String.format("%d of %s", count, key); | ||
136 | } | ||
137 | |||
138 | }; | ||
139 | } | ||
140 | |||
141 | }; | ||
142 | }; | ||
143 | } | ||
144 | |||
145 | /** | ||
146 | * Process contained values with their multiplicities | ||
147 | */ | ||
148 | default void forEachEntryWithMultiplicities(BiConsumer<T, Integer> entryConsumer) { | ||
149 | for (T value : distinctValues()) { | ||
150 | entryConsumer.accept(value, getCount(value)); | ||
151 | } | ||
152 | } | ||
153 | |||
154 | |||
155 | /** | ||
156 | * For compatibility with legacy code relying on element-to-integer maps. | ||
157 | * @return an unmodifiable view of contained values with their multiplicities | ||
158 | */ | ||
159 | public default Map<T, Integer> asMap() { | ||
160 | return new MemoryViewBackedMapView<>(this); | ||
161 | } | ||
162 | |||
163 | /** | ||
164 | * For compatibility with legacy code relying on element-to-integer maps. | ||
165 | * @return an unmodifiable view of contained values with their multiplicities | ||
166 | */ | ||
167 | public static <T> IMemoryView<T> fromMap(Map<T, Integer> wrapped) { | ||
168 | return new MapBackedMemoryView<>(wrapped); | ||
169 | } | ||
170 | |||
171 | /** | ||
172 | * @return a stream of values, iterable once | ||
173 | * @since 2.1 | ||
174 | */ | ||
175 | public default Stream<T> asStream() { | ||
176 | return StreamSupport.stream(spliterator(), false); | ||
177 | } | ||
178 | |||
179 | /** | ||
180 | * Provides semantic equality comparison. | ||
181 | */ | ||
182 | public static <T> boolean equals(IMemoryView<T> self, Object obj) { | ||
183 | if (obj instanceof IMemoryView<?>) { | ||
184 | IMemoryView<?> other = (IMemoryView<?>) obj; | ||
185 | if (other.size() != self.size()) return false; | ||
186 | for (Entry<?, Integer> entry : other.entriesWithMultiplicities()) { | ||
187 | if ( !entry.getValue().equals(self.getCountUnsafe(entry.getKey()))) | ||
188 | return false; | ||
189 | } | ||
190 | return true; | ||
191 | } | ||
192 | return false; | ||
193 | } | ||
194 | |||
195 | /** | ||
196 | * Provides semantic hashCode() comparison. | ||
197 | */ | ||
198 | public static <T> int hashCode(IMemoryView<T> memory) { | ||
199 | int hashCode = 0; | ||
200 | for (T value : memory.distinctValues()) { | ||
201 | hashCode += value.hashCode() ^ Integer.hashCode(memory.getCount(value)); | ||
202 | } | ||
203 | return hashCode; | ||
204 | } | ||
205 | } \ No newline at end of file | ||