com.google.common.collect.ImmutableMultimap Maven / Gradle / Ivy
/*
* Copyright (C) 2008 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 static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import java.io.Serializable;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.Nullable;
/**
* An immutable {@link Multimap}. Does not permit null keys or values.
*
* Unlike {@link Multimaps#unmodifiableMultimap(Multimap)}, which is
* a view of a separate multimap which can still change, an instance of
* {@code ImmutableMultimap} contains its own data and will never
* change. {@code ImmutableMultimap} 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.
*
*
Note: 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.
*
*
In addition to methods defined by {@link Multimap}, an {@link #inverse}
* method is also supported.
*
*
See the Guava User Guide article on
* immutable collections.
*
* @author Jared Levy
* @since 2.0 (imported from Google Collections Library)
*/
@GwtCompatible(emulated = true)
public abstract class ImmutableMultimap extends AbstractMultimap
implements Serializable {
/** Returns an empty multimap. */
public static ImmutableMultimap of() {
return ImmutableListMultimap.of();
}
/**
* Returns an immutable multimap containing a single entry.
*/
public static ImmutableMultimap of(K k1, V v1) {
return ImmutableListMultimap.of(k1, v1);
}
/**
* Returns an immutable multimap containing the given entries, in order.
*/
public static ImmutableMultimap of(K k1, V v1, K k2, V v2) {
return ImmutableListMultimap.of(k1, v1, k2, v2);
}
/**
* Returns an immutable multimap containing the given entries, in order.
*/
public static ImmutableMultimap of(
K k1, V v1, K k2, V v2, K k3, V v3) {
return ImmutableListMultimap.of(k1, v1, k2, v2, k3, v3);
}
/**
* Returns an immutable multimap containing the given entries, in order.
*/
public static ImmutableMultimap of(
K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
return ImmutableListMultimap.of(k1, v1, k2, v2, k3, v3, k4, v4);
}
/**
* Returns an immutable multimap containing the given entries, in order.
*/
public static ImmutableMultimap of(
K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
return ImmutableListMultimap.of(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5);
}
// looking for of() with > 5 entries? Use the builder instead.
/**
* Returns a new builder. The generated builder is equivalent to the builder
* created by the {@link Builder} constructor.
*/
public static Builder builder() {
return new Builder();
}
/**
* Multimap for {@link ImmutableMultimap.Builder} that maintains key and
* value orderings, allows duplicate values, and performs better than
* {@link LinkedListMultimap}.
*/
private static class BuilderMultimap extends AbstractMapBasedMultimap {
BuilderMultimap() {
super(new LinkedHashMap>());
}
@Override Collection createCollection() {
return Lists.newArrayList();
}
private static final long serialVersionUID = 0;
}
/**
* A builder for creating immutable multimap instances, especially
* {@code public static final} multimaps ("constant multimaps"). Example:
* {@code
*
* static final Multimap STRING_TO_INTEGER_MULTIMAP =
* new ImmutableMultimap.Builder()
* .put("one", 1)
* .putAll("several", 1, 2, 3)
* .putAll("many", 1, 2, 3, 4, 5)
* .build();}
*
* 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 class Builder {
Multimap builderMultimap = new BuilderMultimap();
Comparator keyComparator;
Comparator valueComparator;
/**
* Creates a new builder. The returned builder is equivalent to the builder
* generated by {@link ImmutableMultimap#builder}.
*/
public Builder() {}
/**
* Adds a key-value mapping to the built multimap.
*/
public Builder put(K key, V value) {
checkEntryNotNull(key, value);
builderMultimap.put(key, value);
return this;
}
/**
* Adds an entry to the built multimap.
*
* @since 11.0
*/
public Builder put(Entry entry) {
return put(entry.getKey(), entry.getValue());
}
/**
* Stores a collection of values with the same key in the built multimap.
*
* @throws NullPointerException if {@code key}, {@code values}, or any
* element in {@code values} is null. The builder is left in an invalid
* state.
*/
public Builder putAll(K key, Iterable values) {
if (key == null) {
throw new NullPointerException(
"null key in entry: null=" + Iterables.toString(values));
}
Collection valueList = builderMultimap.get(key);
for (V value : values) {
checkEntryNotNull(key, value);
valueList.add(value);
}
return this;
}
/**
* Stores an array of values with the same key in the built multimap.
*
* @throws NullPointerException if the key or any value is null. The builder
* is left in an invalid state.
*/
public Builder putAll(K key, V... values) {
return putAll(key, Arrays.asList(values));
}
/**
* Stores another multimap's entries in the built multimap. The generated
* multimap's key and value orderings correspond to the iteration ordering
* of the {@code multimap.asMap()} view, with new keys and values following
* any existing keys and values.
*
* @throws NullPointerException if any key or value in {@code multimap} is
* null. The builder is left in an invalid state.
*/
public Builder putAll(Multimap multimap) {
for (Entry> entry
: multimap.asMap().entrySet()) {
putAll(entry.getKey(), entry.getValue());
}
return this;
}
/**
* Specifies the ordering of the generated multimap's keys.
*
* @since 8.0
*/
public Builder orderKeysBy(Comparator keyComparator) {
this.keyComparator = checkNotNull(keyComparator);
return this;
}
/**
* Specifies the ordering of the generated multimap's values for each key.
*
* @since 8.0
*/
public Builder orderValuesBy(Comparator valueComparator) {
this.valueComparator = checkNotNull(valueComparator);
return this;
}
/**
* Returns a newly-created immutable multimap.
*/
public ImmutableMultimap build() {
if (valueComparator != null) {
for (Collection values : builderMultimap.asMap().values()) {
List list = (List ) values;
Collections.sort(list, valueComparator);
}
}
if (keyComparator != null) {
Multimap sortedCopy = new BuilderMultimap();
List>> entries = Lists.newArrayList(
builderMultimap.asMap().entrySet());
Collections.sort(
entries,
Ordering.from(keyComparator).onKeys());
for (Map.Entry> entry : entries) {
sortedCopy.putAll(entry.getKey(), entry.getValue());
}
builderMultimap = sortedCopy;
}
return copyOf(builderMultimap);
}
}
/**
* Returns an immutable 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.
*
* 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 ImmutableMultimap copyOf(
Multimap multimap) {
if (multimap instanceof ImmutableMultimap) {
@SuppressWarnings("unchecked") // safe since multimap is not writable
ImmutableMultimap kvMultimap
= (ImmutableMultimap) multimap;
if (!kvMultimap.isPartialView()) {
return kvMultimap;
}
}
return ImmutableListMultimap.copyOf(multimap);
}
final transient ImmutableMap> map;
final transient int size;
// These constants allow the deserialization code to set final fields. This
// holder class makes sure they are not initialized unless an instance is
// deserialized.
@GwtIncompatible("java serialization is not supported")
static class FieldSettersHolder {
static final Serialization.FieldSetter
MAP_FIELD_SETTER = Serialization.getFieldSetter(
ImmutableMultimap.class, "map");
static final Serialization.FieldSetter
SIZE_FIELD_SETTER = Serialization.getFieldSetter(
ImmutableMultimap.class, "size");
static final Serialization.FieldSetter
EMPTY_SET_FIELD_SETTER = Serialization.getFieldSetter(
ImmutableSetMultimap.class, "emptySet");
}
ImmutableMultimap(ImmutableMap> map,
int size) {
this.map = map;
this.size = size;
}
// mutators (not supported)
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public ImmutableCollection removeAll(Object key) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public ImmutableCollection replaceValues(K key,
Iterable values) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public void clear() {
throw new UnsupportedOperationException();
}
/**
* Returns an immutable collection of the values for the given key. If no
* mappings in the multimap have the provided key, an empty immutable
* collection is returned. The values are in the same order as the parameters
* used to build this multimap.
*/
@Override
public abstract ImmutableCollection get(K key);
/**
* Returns an immutable multimap which is the inverse of this one. For every
* key-value mapping in the original, the result will have a mapping with
* key and value reversed.
*
* @since 11.0
*/
public abstract ImmutableMultimap inverse();
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public boolean put(K key, V value) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public boolean putAll(K key, Iterable values) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public boolean putAll(Multimap multimap) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the multimap unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public boolean remove(Object key, Object value) {
throw new UnsupportedOperationException();
}
/**
* Returns {@code true} if this immutable multimap's implementation contains references to
* user-created objects that aren't accessible via this multimap's methods. This is generally
* used to determine whether {@code copyOf} implementations should make an explicit copy to avoid
* memory leaks.
*/
boolean isPartialView() {
return map.isPartialView();
}
// accessors
@Override
public boolean containsKey(@Nullable Object key) {
return map.containsKey(key);
}
@Override
public boolean containsValue(@Nullable Object value) {
return value != null && super.containsValue(value);
}
@Override
public int size() {
return size;
}
// views
/**
* Returns an immutable set of the distinct keys in this multimap. These keys
* are ordered according to when they first appeared during the construction
* of this multimap.
*/
@Override
public ImmutableSet keySet() {
return map.keySet();
}
/**
* Returns an immutable map that associates each key with its corresponding
* values in the multimap.
*/
@Override
@SuppressWarnings("unchecked") // a widening cast
public ImmutableMap> asMap() {
return (ImmutableMap) map;
}
@Override
Map> createAsMap() {
throw new AssertionError("should never be called");
}
/**
* 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.
*/
@Override
public ImmutableCollection> entries() {
return (ImmutableCollection>) super.entries();
}
@Override
ImmutableCollection> createEntries() {
return new EntryCollection(this);
}
private static class EntryCollection
extends ImmutableCollection> {
final ImmutableMultimap multimap;
EntryCollection(ImmutableMultimap multimap) {
this.multimap = multimap;
}
@Override public UnmodifiableIterator> iterator() {
return multimap.entryIterator();
}
@Override boolean isPartialView() {
return multimap.isPartialView();
}
@Override
public int size() {
return multimap.size();
}
@Override public boolean contains(Object object) {
if (object instanceof Entry) {
Entry entry = (Entry) object;
return multimap.containsEntry(entry.getKey(), entry.getValue());
}
return false;
}
private static final long serialVersionUID = 0;
}
private abstract class Itr extends UnmodifiableIterator {
final Iterator>> mapIterator = asMap().entrySet().iterator();
K key = null;
Iterator valueIterator = Iterators.emptyIterator();
abstract T output(K key, V value);
@Override
public boolean hasNext() {
return mapIterator.hasNext() || valueIterator.hasNext();
}
@Override
public T next() {
if (!valueIterator.hasNext()) {
Entry> mapEntry = mapIterator.next();
key = mapEntry.getKey();
valueIterator = mapEntry.getValue().iterator();
}
return output(key, valueIterator.next());
}
}
@Override
UnmodifiableIterator> entryIterator() {
return new Itr>() {
@Override
Entry output(K key, V value) {
return Maps.immutableEntry(key, value);
}
};
}
/**
* Returns a collection, which may contain duplicates, of all keys. The number
* of times a key appears in the returned multiset equals the number of
* mappings the key has in the multimap. Duplicate keys appear consecutively
* in the multiset's iteration order.
*/
@Override
public ImmutableMultiset keys() {
return (ImmutableMultiset) super.keys();
}
@Override
ImmutableMultiset createKeys() {
return new Keys();
}
@SuppressWarnings("serial") // Uses writeReplace, not default serialization
class Keys extends ImmutableMultiset {
@Override
public boolean contains(@Nullable Object object) {
return containsKey(object);
}
@Override
public int count(@Nullable Object element) {
Collection values = map.get(element);
return (values == null) ? 0 : values.size();
}
@Override
public Set elementSet() {
return keySet();
}
@Override
public int size() {
return ImmutableMultimap.this.size();
}
@Override
Multiset.Entry getEntry(int index) {
Map.Entry> entry = map.entrySet().asList().get(index);
return Multisets.immutableEntry(entry.getKey(), entry.getValue().size());
}
@Override
boolean isPartialView() {
return true;
}
}
/**
* Returns an immutable collection of the values in this multimap. Its
* iterator traverses the values for the first key, the values for the second
* key, and so on.
*/
@Override
public ImmutableCollection values() {
return (ImmutableCollection) super.values();
}
@Override
ImmutableCollection createValues() {
return new Values(this);
}
@Override
UnmodifiableIterator valueIterator() {
return new Itr() {
@Override
V output(K key, V value) {
return value;
}
};
}
private static final class Values extends ImmutableCollection {
private transient final ImmutableMultimap multimap;
Values(ImmutableMultimap multimap) {
this.multimap = multimap;
}
@Override
public boolean contains(@Nullable Object object) {
return multimap.containsValue(object);
}
@Override public UnmodifiableIterator iterator() {
return multimap.valueIterator();
}
@GwtIncompatible("not present in emulated superclass")
@Override
int copyIntoArray(Object[] dst, int offset) {
for (ImmutableCollection valueCollection : multimap.map.values()) {
offset = valueCollection.copyIntoArray(dst, offset);
}
return offset;
}
@Override
public int size() {
return multimap.size();
}
@Override boolean isPartialView() {
return true;
}
private static final long serialVersionUID = 0;
}
private static final long serialVersionUID = 0;
}