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 com.google.common.annotations.Beta;
11 import com.google.common.base.Preconditions;
12 import com.google.common.collect.ImmutableMap;
13 import com.google.common.collect.UnmodifiableIterator;
14 import java.io.IOException;
15 import java.io.ObjectInputStream;
16 import java.io.ObjectOutputStream;
17 import java.io.Serializable;
18 import java.lang.reflect.Field;
19 import java.util.AbstractMap.SimpleImmutableEntry;
20 import java.util.AbstractSet;
21 import java.util.ArrayList;
22 import java.util.Arrays;
23 import java.util.Collection;
24 import java.util.Iterator;
25 import java.util.List;
28 import javax.annotation.Nonnull;
31 * Implementation of the {@link Map} interface which stores a set of immutable mappings using a key-to-offset map and
32 * a backing array. This is useful for situations where the same key set is shared across a multitude of maps, as this
33 * class uses a global cache to share the key-to-offset mapping.
35 * @param <K> the type of keys maintained by this map
36 * @param <V> the type of mapped values
39 public abstract class ImmutableOffsetMap<K, V> implements UnmodifiableMapPhase<K, V>, Serializable {
40 static final class Ordered<K, V> extends ImmutableOffsetMap<K, V> {
41 private static final long serialVersionUID = 1L;
43 Ordered(final Map<K, Integer> offsets, final V[] objects) {
44 super(offsets, objects);
48 public MutableOffsetMap<K, V> toModifiableMap() {
49 return MutableOffsetMap.orderedCopyOf(this);
53 void setFields(final List<K> keys, final V[] values) throws IOException {
54 setField(this, OFFSETS_FIELD, OffsetMapCache.orderedOffsets(keys));
55 setField(this, ARRAY_FIELD, values);
59 static final class Unordered<K, V> extends ImmutableOffsetMap<K, V> {
60 private static final long serialVersionUID = 1L;
62 Unordered(final Map<K, Integer> offsets, final V[] objects) {
63 super(offsets, objects);
67 public MutableOffsetMap<K, V> toModifiableMap() {
68 return MutableOffsetMap.unorderedCopyOf(this);
72 void setFields(final List<K> keys, final V[] values) throws IOException {
73 final Map<K, Integer> offsets = OffsetMapCache.unorderedOffsets(keys);
75 setField(this, OFFSETS_FIELD, offsets);
76 setField(this, ARRAY_FIELD, OffsetMapCache.adjustedArray(offsets, keys, values));
80 private static final long serialVersionUID = 1L;
82 private transient final Map<K, Integer> offsets;
83 private transient final V[] objects;
84 private transient int hashCode;
87 * Construct a new instance backed by specified key-to-offset map and array of objects.
89 * @param offsets Key-to-offset map, may not be null
90 * @param objects Array of value object, may not be null. The array is stored as is, the caller
91 * is responsible for ensuring its contents remain unmodified.
93 ImmutableOffsetMap(@Nonnull final Map<K, Integer> offsets, @Nonnull final V[] objects) {
94 this.offsets = Preconditions.checkNotNull(offsets);
95 this.objects = Preconditions.checkNotNull(objects);
96 Preconditions.checkArgument(offsets.size() == objects.length);
100 public abstract MutableOffsetMap<K, V> toModifiableMap();
102 abstract void setFields(List<K> keys, V[] values) throws IOException;
105 * Create an {@link ImmutableOffsetMap} as a copy of an existing map. This is actually not completely true,
106 * as this method returns an {@link ImmutableMap} for empty and singleton inputs, as those are more memory-efficient.
107 * This method also recognizes {@link ImmutableOffsetMap} on input, and returns it back without doing anything else.
108 * It also recognizes {@link MutableOffsetMap} (as returned by {@link #toModifiableMap()}) and makes an efficient
109 * copy of its contents. All other maps are converted to an {@link ImmutableOffsetMap} with the same iteration
112 * @param m Input map, may not be null.
113 * @return An isolated, immutable copy of the input map
115 @Nonnull public static <K, V> Map<K, V> orderedCopyOf(@Nonnull final Map<K, V> m) {
116 // Prevent a copy. Note that ImmutableMap is not listed here because of its potentially larger keySet overhead.
117 if (m instanceof ImmutableOffsetMap || m instanceof SharedSingletonMap) {
121 // Familiar and efficient to copy
122 if (m instanceof MutableOffsetMap) {
123 return ((MutableOffsetMap<K, V>) m).toUnmodifiableMap();
126 final int size = m.size();
128 // Shares a single object
129 return ImmutableMap.of();
132 // Efficient single-entry implementation
133 final Entry<K, V> e = m.entrySet().iterator().next();
134 return SharedSingletonMap.orderedOf(e.getKey(), e.getValue());
137 final Map<K, Integer> offsets = OffsetMapCache.orderedOffsets(m.keySet());
138 @SuppressWarnings("unchecked")
139 final V[] array = (V[]) new Object[offsets.size()];
140 for (Entry<K, V> e : m.entrySet()) {
141 array[offsets.get(e.getKey())] = e.getValue();
144 return new Ordered<>(offsets, array);
148 * Create an {@link ImmutableOffsetMap} as a copy of an existing map. This is actually not completely true,
149 * as this method returns an {@link ImmutableMap} for empty and singleton inputs, as those are more memory-efficient.
150 * This method also recognizes {@link ImmutableOffsetMap} on input, and returns it back without doing anything else.
151 * It also recognizes {@link MutableOffsetMap} (as returned by {@link #toModifiableMap()}) and makes an efficient
152 * copy of its contents. All other maps are converted to an {@link ImmutableOffsetMap}. Iterator order is not
153 * guaranteed to be retained.
155 * @param m Input map, may not be null.
156 * @return An isolated, immutable copy of the input map
158 @Nonnull public static <K, V> Map<K, V> unorderedCopyOf(@Nonnull final Map<K, V> m) {
159 // Prevent a copy. Note that ImmutableMap is not listed here because of its potentially larger keySet overhead.
160 if (m instanceof ImmutableOffsetMap || m instanceof SharedSingletonMap) {
164 // Familiar and efficient to copy
165 if (m instanceof MutableOffsetMap) {
166 return ((MutableOffsetMap<K, V>) m).toUnmodifiableMap();
169 final int size = m.size();
171 // Shares a single object
172 return ImmutableMap.of();
175 // Efficient single-entry implementation
176 final Entry<K, V> e = m.entrySet().iterator().next();
177 return SharedSingletonMap.unorderedOf(e.getKey(), e.getValue());
180 final Map<K, Integer> offsets = OffsetMapCache.unorderedOffsets(m.keySet());
181 @SuppressWarnings("unchecked")
182 final V[] array = (V[]) new Object[offsets.size()];
183 for (Entry<K, V> e : m.entrySet()) {
184 array[offsets.get(e.getKey())] = e.getValue();
187 return new Unordered<>(offsets, array);
191 public final int size() {
192 return offsets.size();
196 public final boolean isEmpty() {
197 return offsets.isEmpty();
201 public final int hashCode() {
207 for (Entry<K, Integer> e : offsets.entrySet()) {
208 result += e.getKey().hashCode() ^ objects[e.getValue()].hashCode();
216 public final boolean equals(final Object o) {
220 if (!(o instanceof Map)) {
224 if (o instanceof ImmutableOffsetMap) {
225 final ImmutableOffsetMap<?, ?> om = (ImmutableOffsetMap<?, ?>) o;
227 // If the offset match, the arrays have to match, too
228 if (offsets.equals(om.offsets)) {
229 return Arrays.deepEquals(objects, om.objects);
231 } else if (o instanceof MutableOffsetMap) {
232 // Let MutableOffsetMap do the actual work.
233 return o.equals(this);
236 final Map<?, ?> other = (Map<?, ?>)o;
238 // Size and key sets have to match
239 if (size() != other.size() || !keySet().equals(other.keySet())) {
244 // Ensure all objects are present
245 for (Entry<K, Integer> e : offsets.entrySet()) {
246 if (!objects[e.getValue()].equals(other.get(e.getKey()))) {
250 } catch (ClassCastException e) {
251 // Can be thrown by other.get() indicating we have incompatible key types
259 public final boolean containsKey(final Object key) {
260 return offsets.containsKey(key);
264 public final boolean containsValue(final Object value) {
265 for (Object o : objects) {
266 if (value.equals(o)) {
274 public final V get(final Object key) {
275 final Integer offset = offsets.get(key);
276 return offset == null ? null : objects[offset];
280 public final V remove(final Object key) {
281 throw new UnsupportedOperationException();
285 public final V put(final K key, final V value) {
286 throw new UnsupportedOperationException();
290 public final void putAll(final Map<? extends K, ? extends V> m) {
291 throw new UnsupportedOperationException();
295 public final void clear() {
296 throw new UnsupportedOperationException();
300 public final Set<K> keySet() {
301 return offsets.keySet();
305 public final Collection<V> values() {
306 return new ConstantArrayCollection<>(objects);
310 public final Set<Entry<K, V>> entrySet() {
311 return new EntrySet();
315 public final String toString() {
316 final StringBuilder sb = new StringBuilder("{");
317 final Iterator<K> it = offsets.keySet().iterator();
319 while (it.hasNext()) {
320 sb.append(it.next());
322 sb.append(objects[i++]);
329 return sb.append('}').toString();
332 final Map<K, Integer> offsets() {
336 final V[] objects() {
340 private final class EntrySet extends AbstractSet<Entry<K, V>> {
342 public Iterator<Entry<K, V>> iterator() {
343 final Iterator<Entry<K, Integer>> it = offsets.entrySet().iterator();
345 return new UnmodifiableIterator<Entry<K, V>>() {
347 public boolean hasNext() {
352 public Entry<K, V> next() {
353 final Entry<K, Integer> e = it.next();
354 return new SimpleImmutableEntry<>(e.getKey(), objects[e.getValue()]);
361 return offsets.size();
365 private void writeObject(final ObjectOutputStream out) throws IOException {
366 out.writeInt(offsets.size());
367 for (Entry<K, V> e : entrySet()) {
368 out.writeObject(e.getKey());
369 out.writeObject(e.getValue());
373 private static final Field OFFSETS_FIELD = fieldFor("offsets");
374 private static final Field ARRAY_FIELD = fieldFor("objects");
376 private static Field fieldFor(final String name) {
379 f = ImmutableOffsetMap.class.getDeclaredField(name);
380 } catch (NoSuchFieldException | SecurityException e) {
381 throw new IllegalStateException("Failed to lookup field " + name, e);
384 f.setAccessible(true);
388 private static void setField(final ImmutableOffsetMap<?, ?> map, final Field field, final Object value) throws IOException {
390 field.set(map, value);
391 } catch (IllegalArgumentException | IllegalAccessException e) {
392 throw new IOException("Failed to set field " + field, e);
396 @SuppressWarnings("unchecked")
397 private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
398 final int s = in.readInt();
400 final List<K> keys = new ArrayList<>(s);
401 final V[] values = (V[]) new Object[s];
403 for (int i = 0; i < s; ++i) {
404 keys.add((K)in.readObject());
405 values[i] = (V)in.readObject();
408 setFields(keys, values);