2 * Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.yangtools.util;
10 import static com.google.common.base.Preconditions.checkArgument;
11 import static java.util.Objects.requireNonNull;
13 import com.google.common.annotations.Beta;
14 import com.google.common.collect.ImmutableMap;
15 import com.google.common.collect.UnmodifiableIterator;
16 import java.io.IOException;
17 import java.io.ObjectInputStream;
18 import java.io.ObjectOutputStream;
19 import java.io.Serializable;
20 import java.lang.reflect.Field;
21 import java.util.AbstractMap.SimpleImmutableEntry;
22 import java.util.AbstractSet;
23 import java.util.ArrayList;
24 import java.util.Arrays;
25 import java.util.Collection;
26 import java.util.Iterator;
27 import java.util.List;
30 import org.eclipse.jdt.annotation.NonNull;
31 import org.eclipse.jdt.annotation.Nullable;
34 * Implementation of the {@link Map} interface which stores a set of immutable mappings using a key-to-offset map and
35 * a backing array. This is useful for situations where the same key set is shared across a multitude of maps, as this
36 * class uses a global cache to share the key-to-offset mapping.
39 * In case the set of keys is statically known, you can use {@link ImmutableOffsetMapTemplate} to efficiently create
40 * {@link ImmutableOffsetMap} instances.
42 * @param <K> the type of keys maintained by this map
43 * @param <V> the type of mapped values
46 public abstract class ImmutableOffsetMap<K, V> implements UnmodifiableMapPhase<K, V>, Serializable {
47 static final class Ordered<K, V> extends ImmutableOffsetMap<K, V> {
48 private static final long serialVersionUID = 1L;
50 Ordered(final ImmutableMap<K, Integer> offsets, final V[] objects) {
51 super(offsets, objects);
55 public @NonNull MutableOffsetMap<K, V> toModifiableMap() {
56 return MutableOffsetMap.orderedCopyOf(this);
60 void setFields(final List<K> keys, final V[] values) throws IOException {
61 setField(this, OFFSETS_FIELD, OffsetMapCache.orderedOffsets(keys));
62 setField(this, ARRAY_FIELD, values);
66 static final class Unordered<K, V> extends ImmutableOffsetMap<K, V> {
67 private static final long serialVersionUID = 1L;
69 Unordered(final ImmutableMap<K, Integer> offsets, final V[] objects) {
70 super(offsets, objects);
74 public @NonNull MutableOffsetMap<K, V> toModifiableMap() {
75 return MutableOffsetMap.unorderedCopyOf(this);
79 void setFields(final List<K> keys, final V[] values) throws IOException {
80 final Map<K, Integer> newOffsets = OffsetMapCache.unorderedOffsets(keys);
82 setField(this, OFFSETS_FIELD, newOffsets);
83 setField(this, ARRAY_FIELD, OffsetMapCache.adjustedArray(newOffsets, keys, values));
87 private static final long serialVersionUID = 1L;
89 private final transient @NonNull ImmutableMap<K, Integer> offsets;
90 private final transient @NonNull V[] objects;
91 private transient int hashCode;
94 * Construct a new instance backed by specified key-to-offset map and array of objects.
96 * @param offsets Key-to-offset map, may not be null
97 * @param objects Array of value object, may not be null. The array is stored as is, the caller
98 * is responsible for ensuring its contents remain unmodified.
100 ImmutableOffsetMap(final ImmutableMap<K, Integer> offsets, final V[] objects) {
101 this.offsets = requireNonNull(offsets);
102 this.objects = requireNonNull(objects);
103 checkArgument(offsets.size() == objects.length);
107 public abstract @NonNull MutableOffsetMap<K, V> toModifiableMap();
109 abstract void setFields(List<K> keys, V[] values) throws IOException;
112 * Create an {@link ImmutableOffsetMap} as a copy of an existing map. This is actually not completely true, as this
113 * method returns an {@link ImmutableMap} for empty and singleton inputs, as those are more memory-efficient. This
114 * method also recognizes {@link ImmutableOffsetMap} and {@link SharedSingletonMap} on input, and returns it back
115 * without doing anything else. It also recognizes {@link MutableOffsetMap} (as returned by
116 * {@link #toModifiableMap()}) and makes an efficient copy of its contents. All other maps are converted to an
117 * {@link ImmutableOffsetMap} with the same iteration order as input.
119 * @param map Input map, may not be null.
120 * @return An isolated, immutable copy of the input map
121 * @throws NullPointerException if {@code map} or any of its elements is null.
123 public static <K, V> @NonNull Map<K, V> orderedCopyOf(final @NonNull Map<K, V> map) {
124 final Map<K, V> common = commonCopy(map);
125 if (common != null) {
129 final int size = map.size();
131 // Efficient single-entry implementation
132 final Entry<K, V> e = map.entrySet().iterator().next();
133 return SharedSingletonMap.orderedOf(e.getKey(), e.getValue());
136 final ImmutableMap<K, Integer> offsets = OffsetMapCache.orderedOffsets(map.keySet());
137 @SuppressWarnings("unchecked")
138 final V[] array = (V[]) new Object[offsets.size()];
139 for (Entry<K, V> e : map.entrySet()) {
140 array[offsets.get(e.getKey())] = e.getValue();
143 return new Ordered<>(offsets, array);
147 * Create an {@link ImmutableOffsetMap} as a copy of an existing map. This is actually not completely true, as this
148 * method returns an {@link ImmutableMap} for empty and singleton inputs, as those are more memory-efficient. This
149 * method also recognizes {@link ImmutableOffsetMap} and {@link SharedSingletonMap} on input, and returns it back
150 * without doing anything else. It also recognizes {@link MutableOffsetMap} (as returned by
151 * {@link #toModifiableMap()}) and makes an efficient copy of its contents. All other maps are converted to an
152 * {@link ImmutableOffsetMap}. Iterator order is not guaranteed to be retained.
154 * @param map Input map, may not be null.
155 * @return An isolated, immutable copy of the input map
156 * @throws NullPointerException if {@code map} or any of its elements is null.
158 public static <K, V> @NonNull Map<K, V> unorderedCopyOf(final @NonNull Map<K, V> map) {
159 final Map<K, V> common = commonCopy(map);
160 if (common != null) {
164 if (map.size() == 1) {
165 // Efficient single-entry implementation
166 final Entry<K, V> e = map.entrySet().iterator().next();
167 return SharedSingletonMap.unorderedOf(e.getKey(), e.getValue());
170 final ImmutableMap<K, Integer> offsets = OffsetMapCache.unorderedOffsets(map.keySet());
171 @SuppressWarnings("unchecked")
172 final V[] array = (V[]) new Object[offsets.size()];
173 for (Entry<K, V> e : map.entrySet()) {
174 array[offsets.get(e.getKey())] = e.getValue();
177 return new Unordered<>(offsets, array);
180 private static <K, V> @Nullable Map<K, V> commonCopy(final @NonNull Map<K, V> map) {
181 // Prevent a copy. Note that ImmutableMap is not listed here because of its potentially larger keySet overhead.
182 if (map instanceof ImmutableOffsetMap || map instanceof SharedSingletonMap) {
186 // Familiar and efficient to copy
187 if (map instanceof MutableOffsetMap) {
188 return ((MutableOffsetMap<K, V>) map).toUnmodifiableMap();
192 // Shares a single object
193 return ImmutableMap.of();
200 public final int size() {
201 return offsets.size();
205 public final boolean isEmpty() {
206 return offsets.isEmpty();
210 public final int hashCode() {
216 for (Entry<K, Integer> e : offsets.entrySet()) {
217 result += e.getKey().hashCode() ^ objects[e.getValue()].hashCode();
225 public final boolean equals(final Object obj) {
229 if (!(obj instanceof Map)) {
233 if (obj instanceof ImmutableOffsetMap) {
234 final ImmutableOffsetMap<?, ?> om = (ImmutableOffsetMap<?, ?>) obj;
236 // If the offset match, the arrays have to match, too
237 if (offsets.equals(om.offsets)) {
238 return Arrays.deepEquals(objects, om.objects);
240 } else if (obj instanceof MutableOffsetMap) {
241 // Let MutableOffsetMap do the actual work.
242 return obj.equals(this);
245 final Map<?, ?> other = (Map<?, ?>)obj;
247 // Size and key sets have to match
248 if (size() != other.size() || !keySet().equals(other.keySet())) {
253 // Ensure all objects are present
254 for (Entry<K, Integer> e : offsets.entrySet()) {
255 if (!objects[e.getValue()].equals(other.get(e.getKey()))) {
259 } catch (ClassCastException e) {
260 // Can be thrown by other.get() indicating we have incompatible key types
268 public final boolean containsKey(final Object key) {
269 return offsets.containsKey(key);
273 public final boolean containsValue(final Object value) {
274 for (Object o : objects) {
275 if (value.equals(o)) {
283 public final V get(final Object key) {
285 return (offset = offsets.get(key)) == null ? null : objects[offset];
289 public final V remove(final Object key) {
290 throw new UnsupportedOperationException();
294 public final V put(final K key, final V value) {
295 throw new UnsupportedOperationException();
299 @SuppressWarnings("checkstyle:parameterName")
300 public final void putAll(final Map<? extends K, ? extends V> m) {
301 throw new UnsupportedOperationException();
305 public final void clear() {
306 throw new UnsupportedOperationException();
310 public final Set<K> keySet() {
311 return offsets.keySet();
315 public final @NonNull Collection<V> values() {
316 return new ConstantArrayCollection<>(objects);
320 public final @NonNull Set<Entry<K, V>> entrySet() {
321 return new EntrySet();
325 public final String toString() {
326 final StringBuilder sb = new StringBuilder("{");
327 final Iterator<K> it = offsets.keySet().iterator();
329 while (it.hasNext()) {
330 sb.append(it.next()).append('=').append(objects[offset++]);
337 return sb.append('}').toString();
340 final @NonNull ImmutableMap<K, Integer> offsets() {
344 final @NonNull V[] objects() {
348 private final class EntrySet extends AbstractSet<Entry<K, V>> {
350 public @NonNull Iterator<Entry<K, V>> iterator() {
351 final Iterator<Entry<K, Integer>> it = offsets.entrySet().iterator();
352 return new UnmodifiableIterator<Entry<K, V>>() {
354 public boolean hasNext() {
359 public Entry<K, V> next() {
360 final Entry<K, Integer> e = it.next();
361 return new SimpleImmutableEntry<>(e.getKey(), objects[e.getValue()]);
368 return offsets.size();
372 private void writeObject(final ObjectOutputStream out) throws IOException {
373 out.writeInt(offsets.size());
374 for (Entry<K, V> e : entrySet()) {
375 out.writeObject(e.getKey());
376 out.writeObject(e.getValue());
380 private static final Field OFFSETS_FIELD = fieldFor("offsets");
381 private static final Field ARRAY_FIELD = fieldFor("objects");
383 private static @NonNull Field fieldFor(final @NonNull String name) {
386 f = ImmutableOffsetMap.class.getDeclaredField(name);
387 } catch (NoSuchFieldException | SecurityException e) {
388 throw new IllegalStateException("Failed to lookup field " + name, e);
391 f.setAccessible(true);
395 private static void setField(final @NonNull ImmutableOffsetMap<?, ?> map, final @NonNull Field field,
396 final Object value) throws IOException {
398 field.set(map, value);
399 } catch (IllegalArgumentException | IllegalAccessException e) {
400 throw new IOException("Failed to set field " + field, e);
404 @SuppressWarnings("unchecked")
405 private void readObject(final @NonNull ObjectInputStream in) throws IOException, ClassNotFoundException {
406 final int s = in.readInt();
408 final List<K> keys = new ArrayList<>(s);
409 final V[] values = (V[]) new Object[s];
411 for (int i = 0; i < s; ++i) {
412 keys.add((K)in.readObject());
413 values[i] = (V)in.readObject();
416 setFields(keys, values);