/*
* Copyright (C) 2009 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.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.TreeMap;
import javax.annotation.Nullable;
/**
* An immutable {@link SetMultimap} with reliable user-specified key and value
* iteration order. Does not permit null keys or values.
*
* <p>Unlike {@link Multimaps#unmodifiableSetMultimap(SetMultimap)}, which is
* a <i>view</i> of a separate multimap which can still change, an instance of
* {@code ImmutableSetMultimap} contains its own data and will <i>never</i>
* change. {@code ImmutableSetMultimap} is convenient for
* {@code public static final} multimaps ("constant multimaps") and also lets
* you easily make a "defensive copy" of a multimap provided to your class by
* a caller.
*
* <p><b>Note:</b> Although this class is not final, it cannot be subclassed as
* it has no public or protected constructors. Thus, instances of this class
* are guaranteed to be immutable.
*
* @author Mike Ward
* @since 2.0 (imported from Google Collections Library)
*/
@GwtCompatible(serializable = true, emulated = true)
public class ImmutableSetMultimap<K, V>
extends ImmutableMultimap<K, V>
implements SetMultimap<K, V> {
/** Returns the empty multimap. */
// Casting is safe because the multimap will never hold any elements.
@SuppressWarnings("unchecked")
public static <K, V> ImmutableSetMultimap<K, V> of() {
return (ImmutableSetMultimap<K, V>) EmptyImmutableSetMultimap.INSTANCE;
}
/**
* Returns an immutable multimap containing a single entry.
*/
public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1) {
ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
builder.put(k1, v1);
return builder.build();
}
/**
* Returns an immutable multimap containing the given entries, in order.
* Repeated occurrences of an entry (according to {@link Object#equals}) after
* the first are ignored.
*/
public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2) {
ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
builder.put(k1, v1);
builder.put(k2, v2);
return builder.build();
}
/**
* Returns an immutable multimap containing the given entries, in order.
* Repeated occurrences of an entry (according to {@link Object#equals}) after
* the first are ignored.
*/
public static <K, V> ImmutableSetMultimap<K, V> of(
K k1, V v1, K k2, V v2, K k3, V v3) {
ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
builder.put(k1, v1);
builder.put(k2, v2);
builder.put(k3, v3);
return builder.build();
}
/**
* Returns an immutable multimap containing the given entries, in order.
* Repeated occurrences of an entry (according to {@link Object#equals}) after
* the first are ignored.
*/
public static <K, V> ImmutableSetMultimap<K, V> of(
K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
builder.put(k1, v1);
builder.put(k2, v2);
builder.put(k3, v3);
builder.put(k4, v4);
return builder.build();
}
/**
* Returns an immutable multimap containing the given entries, in order.
* Repeated occurrences of an entry (according to {@link Object#equals}) after
* the first are ignored.
*/
public static <K, V> ImmutableSetMultimap<K, V> of(
K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
builder.put(k1, v1);
builder.put(k2, v2);
builder.put(k3, v3);
builder.put(k4, v4);
builder.put(k5, v5);
return builder.build();
}
// looking for of() with > 5 entries? Use the builder instead.
/**
* Returns a new {@link Builder}.
*/
public static <K, V> Builder<K, V> builder() {
return new Builder<K, V>();
}
/**
* Multimap for {@link ImmutableSetMultimap.Builder} that maintains key
* and value orderings and performs better than {@link LinkedHashMultimap}.
*/
private static class BuilderMultimap<K, V> extends AbstractMultimap<K, V> {
BuilderMultimap() {
super(new LinkedHashMap<K, Collection<V>>());
}
@Override Collection<V> createCollection() {
return Sets.newLinkedHashSet();
}
private static final long serialVersionUID = 0;
}
/**
* Multimap for {@link ImmutableSetMultimap.Builder} that sorts keys and
* maintains value orderings.
*/
private static class SortedKeyBuilderMultimap<K, V>
extends AbstractMultimap<K, V> {
SortedKeyBuilderMultimap(
Comparator<? super K> keyComparator, Multimap<K, V> multimap) {
super(new TreeMap<K, Collection<V>>(keyComparator));
putAll(multimap);
}
@Override Collection<V> createCollection() {
return Sets.newLinkedHashSet();
}
private static final long serialVersionUID = 0;
}
/**
* A builder for creating immutable {@code SetMultimap} instances, especially
* {@code public static final} multimaps ("constant multimaps"). Example:
* <pre> {@code
*
* static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
* new ImmutableSetMultimap.Builder<String, Integer>()
* .put("one", 1)
* .putAll("several", 1, 2, 3)
* .putAll("many", 1, 2, 3, 4, 5)
* .build();}</pre>
*
* Builder instances can be reused; it is safe to call {@link #build} multiple
* times to build multiple multimaps in series. Each multimap contains the
* key-value mappings in the previously created multimaps.
*
* @since 2.0 (imported from Google Collections Library)
*/
public static final class Builder<K, V>
extends ImmutableMultimap.Builder<K, V> {
/**
* Creates a new builder. The returned builder is equivalent to the builder
* generated by {@link ImmutableSetMultimap#builder}.
*/
public Builder() {
builderMultimap = new BuilderMultimap<K, V>();
}
/**
* Adds a key-value mapping to the built multimap if it is not already
* present.
*/
@Override public Builder<K, V> put(K key, V value) {
builderMultimap.put(checkNotNull(key), checkNotNull(value));
return this;
}
@Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
Collection<V> collection = builderMultimap.get(checkNotNull(key));
for (V value : values) {
collection.add(checkNotNull(value));
}
return this;
}
@Override public Builder<K, V> putAll(K key, V... values) {
return putAll(key, Arrays.asList(values));
}
@Override public Builder<K, V> putAll(
Multimap<? extends K, ? extends V> multimap) {
for (Map.Entry<? extends K, ? extends Collection<? extends V>> entry
: multimap.asMap().entrySet()) {
putAll(entry.getKey(), entry.getValue());
}
return this;
}
/**
* {@inheritDoc}
*
* @since 8.0
*/
@Beta @Override
public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
builderMultimap = new SortedKeyBuilderMultimap<K, V>(
checkNotNull(keyComparator), builderMultimap);
return this;
}
/**
* Specifies the ordering of the generated multimap's values for each key.
*
* <p>If this method is called, the sets returned by the {@code get()}
* method of the generated multimap and its {@link Multimap#asMap()} view
* are {@link ImmutableSortedSet} instances. However, serialization does not
* preserve that property, though it does maintain the key and value
* ordering.
*
* @since 8.0
*/
// TODO: Make serialization behavior consistent.
@Beta @Override
public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
super.orderValuesBy(valueComparator);
return this;
}
/**
* Returns a newly-created immutable set multimap.
*/
@Override public ImmutableSetMultimap<K, V> build() {
return copyOf(builderMultimap, valueComparator);
}
}
/**
* Returns an immutable set multimap containing the same mappings as
* {@code multimap}. The generated multimap's key and value orderings
* correspond to the iteration ordering of the {@code multimap.asMap()} view.
* Repeated occurrences of an entry in the multimap after the first are
* ignored.
*
* <p>Despite the method name, this method attempts to avoid actually copying
* the data when it is safe to do so. The exact circumstances under which a
* copy will or will not be performed are undocumented and subject to change.
*
* @throws NullPointerException if any key or value in {@code multimap} is
* null
*/
public static <K, V> ImmutableSetMultimap<K, V> copyOf(
Multimap<? extends K, ? extends V> multimap) {
return copyOf(multimap, null);
}
private static <K, V> ImmutableSetMultimap<K, V> copyOf(
Multimap<? extends K, ? extends V> multimap,
Comparator<? super V> valueComparator) {
checkNotNull(multimap); // eager for GWT
if (multimap.isEmpty() && valueComparator == null) {
return of();
}
if (multimap instanceof ImmutableSetMultimap) {
@SuppressWarnings("unchecked") // safe since multimap is not writable
ImmutableSetMultimap<K, V> kvMultimap
= (ImmutableSetMultimap<K, V>) multimap;
if (!kvMultimap.isPartialView()) {
return kvMultimap;
}
}
ImmutableMap.Builder<K, ImmutableSet<V>> builder = ImmutableMap.builder();
int size = 0;
for (Map.Entry<? extends K, ? extends Collection<? extends V>> entry
: multimap.asMap().entrySet()) {
K key = entry.getKey();
Collection<? extends V> values = entry.getValue();
ImmutableSet<V> set = (valueComparator == null)
? ImmutableSet.copyOf(values)
: ImmutableSortedSet.copyOf(valueComparator, values);
if (!set.isEmpty()) {
builder.put(key, set);
size += set.size();
}
}
return new ImmutableSetMultimap<K, V>(
builder.build(), size, valueComparator);
}
// Returned by get() when values are sorted and a missing key is provided.
private final transient ImmutableSortedSet<V> emptySet;
ImmutableSetMultimap(ImmutableMap<K, ImmutableSet<V>> map, int size,
@Nullable Comparator<? super V> valueComparator) {
super(map, size);
this.emptySet = (valueComparator == null)
? null : ImmutableSortedSet.<V>emptySet(valueComparator);
}
// views
/**
* Returns an immutable set of the values for the given key. If no mappings
* in the multimap have the provided key, an empty immutable set is returned.
* The values are in the same order as the parameters used to build this
* multimap.
*/
@Override public ImmutableSet<V> get(@Nullable K key) {
// This cast is safe as its type is known in constructor.
ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
if (set != null) {
return set;
} else if (emptySet != null) {
return emptySet;
} else {
return ImmutableSet.<V>of();
}
}
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
*/
@Override public ImmutableSet<V> removeAll(Object key) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
*/
@Override public ImmutableSet<V> replaceValues(
K key, Iterable<? extends V> values) {
throw new UnsupportedOperationException();
}
private transient ImmutableSet<Map.Entry<K, V>> entries;
/**
* Returns an immutable collection of all key-value pairs in the multimap.
* Its iterator traverses the values for the first key, the values for the
* second key, and so on.
*/
// TODO(kevinb): Fix this so that two copies of the entries are not created.
@Override public ImmutableSet<Map.Entry<K, V>> entries() {
ImmutableSet<Map.Entry<K, V>> result = entries;
return (result == null)
? (entries = ImmutableSet.copyOf(super.entries()))
: result;
}
/**
* @serialData number of distinct keys, and then for each distinct key: the
* key, the number of values for that key, and the key's values
*/
@GwtIncompatible("java.io.ObjectOutputStream")
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
Serialization.writeMultimap(this, stream);
}
@GwtIncompatible("java.io.ObjectInputStream")
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
int keyCount = stream.readInt();
if (keyCount < 0) {
throw new InvalidObjectException("Invalid key count " + keyCount);
}
ImmutableMap.Builder<Object, ImmutableSet<Object>> builder
= ImmutableMap.builder();
int tmpSize = 0;
for (int i = 0; i < keyCount; i++) {
Object key = stream.readObject();
int valueCount = stream.readInt();
if (valueCount <= 0) {
throw new InvalidObjectException("Invalid value count " + valueCount);
}
Object[] array = new Object[valueCount];
for (int j = 0; j < valueCount; j++) {
array[j] = stream.readObject();
}
ImmutableSet<Object> valueSet = ImmutableSet.copyOf(array);
if (valueSet.size() != array.length) {
throw new InvalidObjectException(
"Duplicate key-value pairs exist for key " + key);
}
builder.put(key, valueSet);
tmpSize += valueCount;
}
ImmutableMap<Object, ImmutableSet<Object>> tmpMap;
try {
tmpMap = builder.build();
} catch (IllegalArgumentException e) {
throw (InvalidObjectException)
new InvalidObjectException(e.getMessage()).initCause(e);
}
FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
}
@GwtIncompatible("not needed in emulated source.")
private static final long serialVersionUID = 0;
}
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