/*
* 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.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.ImmutableMapEntry.TerminalEntry;
import java.io.Serializable;
import java.util.Collections;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import javax.annotation.Nullable;
/**
* An immutable, hash-based {@link Map} with reliable user-specified iteration
* order. Does not permit null keys or values.
*
* <p>Unlike {@link Collections#unmodifiableMap}, which is a <i>view</i> of a
* separate map which can still change, an instance of {@code ImmutableMap}
* contains its own data and will <i>never</i> change. {@code ImmutableMap} is
* convenient for {@code public static final} maps ("constant maps") and also
* lets you easily make a "defensive copy" of a map provided to your class by a
* caller.
*
* <p><i>Performance notes:</i> unlike {@link HashMap}, {@code ImmutableMap} is
* not optimized for element types that have slow {@link Object#equals} or
* {@link Object#hashCode} implementations. You can get better performance by
* having your element type cache its own hash codes, and by making use of the
* cached values to short-circuit a slow {@code equals} algorithm.
*
* <p>See the Guava User Guide article on <a href=
* "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained">
* immutable collections</a>.
*
* @author Jesse Wilson
* @author Kevin Bourrillion
* @since 2.0 (imported from Google Collections Library)
*/
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // we're overriding default serialization
public abstract class ImmutableMap<K, V> implements Map<K, V>, Serializable {
/**
* Returns the empty map. This map behaves and performs comparably to
* {@link Collections#emptyMap}, and is preferable mainly for consistency
* and maintainability of your code.
*/
public static <K, V> ImmutableMap<K, V> of() {
return ImmutableBiMap.of();
}
/**
* Returns an immutable map containing a single entry. This map behaves and
* performs comparably to {@link Collections#singletonMap} but will not accept
* a null key or value. It is preferable mainly for consistency and
* maintainability of your code.
*/
public static <K, V> ImmutableMap<K, V> of(K k1, V v1) {
return ImmutableBiMap.of(k1, v1);
}
/**
* Returns an immutable map containing the given entries, in order.
*
* @throws IllegalArgumentException if duplicate keys are provided
*/
public static <K, V> ImmutableMap<K, V> of(K k1, V v1, K k2, V v2) {
return new RegularImmutableMap<K, V>(entryOf(k1, v1), entryOf(k2, v2));
}
/**
* Returns an immutable map containing the given entries, in order.
*
* @throws IllegalArgumentException if duplicate keys are provided
*/
public static <K, V> ImmutableMap<K, V> of(
K k1, V v1, K k2, V v2, K k3, V v3) {
return new RegularImmutableMap<K, V>(
entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3));
}
/**
* Returns an immutable map containing the given entries, in order.
*
* @throws IllegalArgumentException if duplicate keys are provided
*/
public static <K, V> ImmutableMap<K, V> of(
K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
return new RegularImmutableMap<K, V>(
entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4));
}
/**
* Returns an immutable map containing the given entries, in order.
*
* @throws IllegalArgumentException if duplicate keys are provided
*/
public static <K, V> ImmutableMap<K, V> of(
K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
return new RegularImmutableMap<K, V>(entryOf(k1, v1),
entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4), entryOf(k5, v5));
}
// looking for of() with > 5 entries? Use the builder instead.
/**
* Verifies that {@code key} and {@code value} are non-null, and returns a new
* immutable entry with those values.
*
* <p>A call to {@link Map.Entry#setValue} on the returned entry will always
* throw {@link UnsupportedOperationException}.
*/
static <K, V> TerminalEntry<K, V> entryOf(K key, V value) {
checkEntryNotNull(key, value);
return new TerminalEntry<K, V>(key, value);
}
/**
* Returns a new builder. The generated builder is equivalent to the builder
* created by the {@link Builder} constructor.
*/
public static <K, V> Builder<K, V> builder() {
return new Builder<K, V>();
}
static void checkNoConflict(boolean safe, String conflictDescription,
Entry<?, ?> entry1, Entry<?, ?> entry2) {
if (!safe) {
throw new IllegalArgumentException(
"Multiple entries with same " + conflictDescription + ": " + entry1 + " and " + entry2);
}
}
/**
* A builder for creating immutable map instances, especially {@code public
* static final} maps ("constant maps"). Example: <pre> {@code
*
* static final ImmutableMap<String, Integer> WORD_TO_INT =
* new ImmutableMap.Builder<String, Integer>()
* .put("one", 1)
* .put("two", 2)
* .put("three", 3)
* .build();}</pre>
*
* <p>For <i>small</i> immutable maps, the {@code ImmutableMap.of()} methods are
* even more convenient.
*
* <p>Builder instances can be reused - it is safe to call {@link #build}
* multiple times to build multiple maps in series. Each map is a superset of
* the maps created before it.
*
* @since 2.0 (imported from Google Collections Library)
*/
public static class Builder<K, V> {
TerminalEntry<K, V>[] entries;
int size;
/**
* Creates a new builder. The returned builder is equivalent to the builder
* generated by {@link ImmutableMap#builder}.
*/
public Builder() {
this(ImmutableCollection.Builder.DEFAULT_INITIAL_CAPACITY);
}
@SuppressWarnings("unchecked")
Builder(int initialCapacity) {
this.entries = new TerminalEntry[initialCapacity];
this.size = 0;
}
private void ensureCapacity(int minCapacity) {
if (minCapacity > entries.length) {
entries = ObjectArrays.arraysCopyOf(
entries, ImmutableCollection.Builder.expandedCapacity(entries.length, minCapacity));
}
}
/**
* Associates {@code key} with {@code value} in the built map. Duplicate
* keys are not allowed, and will cause {@link #build} to fail.
*/
public Builder<K, V> put(K key, V value) {
ensureCapacity(size + 1);
TerminalEntry<K, V> entry = entryOf(key, value);
// don't inline this: we want to fail atomically if key or value is null
entries[size++] = entry;
return this;
}
/**
* Adds the given {@code entry} to the map, making it immutable if
* necessary. Duplicate keys are not allowed, and will cause {@link #build}
* to fail.
*
* @since 11.0
*/
public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
return put(entry.getKey(), entry.getValue());
}
/**
* Associates all of the given map's keys and values in the built map.
* Duplicate keys are not allowed, and will cause {@link #build} to fail.
*
* @throws NullPointerException if any key or value in {@code map} is null
*/
public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
ensureCapacity(size + map.size());
for (Entry<? extends K, ? extends V> entry : map.entrySet()) {
put(entry);
}
return this;
}
/*
* TODO(kevinb): Should build() and the ImmutableBiMap & ImmutableSortedMap
* versions throw an IllegalStateException instead?
*/
/**
* Returns a newly-created immutable map.
*
* @throws IllegalArgumentException if duplicate keys were added
*/
public ImmutableMap<K, V> build() {
switch (size) {
case 0:
return of();
case 1:
return of(entries[0].getKey(), entries[0].getValue());
default:
return new RegularImmutableMap<K, V>(size, entries);
}
}
}
/**
* Returns an immutable map containing the same entries as {@code map}. If
* {@code map} somehow contains entries with duplicate keys (for example, if
* it is a {@code SortedMap} whose comparator is not <i>consistent with
* equals</i>), the results of this method are undefined.
*
* <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 map} is null
*/
public static <K, V> ImmutableMap<K, V> copyOf(
Map<? extends K, ? extends V> map) {
if ((map instanceof ImmutableMap) && !(map instanceof ImmutableSortedMap)) {
// TODO(user): Make ImmutableMap.copyOf(immutableBiMap) call copyOf()
// on the ImmutableMap delegate(), rather than the bimap itself
@SuppressWarnings("unchecked") // safe since map is not writable
ImmutableMap<K, V> kvMap = (ImmutableMap<K, V>) map;
if (!kvMap.isPartialView()) {
return kvMap;
}
} else if (map instanceof EnumMap) {
return copyOfEnumMapUnsafe(map);
}
Entry<?, ?>[] entries = map.entrySet().toArray(EMPTY_ENTRY_ARRAY);
switch (entries.length) {
case 0:
return of();
case 1:
@SuppressWarnings("unchecked") // all entries will be Entry<K, V>'s
Entry<K, V> onlyEntry = (Entry<K, V>) entries[0];
return of(onlyEntry.getKey(), onlyEntry.getValue());
default:
return new RegularImmutableMap<K, V>(entries);
}
}
// If the map is an EnumMap, it must have key type K for some <K extends Enum<K>>.
@SuppressWarnings({"unchecked", "rawtypes"})
private static <K, V> ImmutableMap<K, V> copyOfEnumMapUnsafe(Map<? extends K, ? extends V> map) {
return copyOfEnumMap((EnumMap) map);
}
private static <K extends Enum<K>, V> ImmutableMap<K, V> copyOfEnumMap(
Map<K, ? extends V> original) {
EnumMap<K, V> copy = new EnumMap<K, V>(original);
for (Map.Entry<?, ?> entry : copy.entrySet()) {
checkEntryNotNull(entry.getKey(), entry.getValue());
}
return ImmutableEnumMap.asImmutable(copy);
}
private static final Entry<?, ?>[] EMPTY_ENTRY_ARRAY = new Entry<?, ?>[0];
ImmutableMap() {}
/**
* Guaranteed to throw an exception and leave the map unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public final V put(K k, V v) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the map unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public final V remove(Object o) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the map unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public final void putAll(Map<? extends K, ? extends V> map) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the map unmodified.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@Deprecated
@Override
public final void clear() {
throw new UnsupportedOperationException();
}
@Override
public boolean isEmpty() {
return size() == 0;
}
@Override
public boolean containsKey(@Nullable Object key) {
return get(key) != null;
}
@Override
public boolean containsValue(@Nullable Object value) {
return values().contains(value);
}
// Overriding to mark it Nullable
@Override
public abstract V get(@Nullable Object key);
private transient ImmutableSet<Entry<K, V>> entrySet;
/**
* Returns an immutable set of the mappings in this map. The entries are in
* the same order as the parameters used to build this map.
*/
@Override
public ImmutableSet<Entry<K, V>> entrySet() {
ImmutableSet<Entry<K, V>> result = entrySet;
return (result == null) ? entrySet = createEntrySet() : result;
}
abstract ImmutableSet<Entry<K, V>> createEntrySet();
private transient ImmutableSet<K> keySet;
/**
* Returns an immutable set of the keys in this map. These keys are in
* the same order as the parameters used to build this map.
*/
@Override
public ImmutableSet<K> keySet() {
ImmutableSet<K> result = keySet;
return (result == null) ? keySet = createKeySet() : result;
}
ImmutableSet<K> createKeySet() {
return new ImmutableMapKeySet<K, V>(this);
}
private transient ImmutableCollection<V> values;
/**
* Returns an immutable collection of the values in this map. The values are
* in the same order as the parameters used to build this map.
*/
@Override
public ImmutableCollection<V> values() {
ImmutableCollection<V> result = values;
return (result == null) ? values = new ImmutableMapValues<K, V>(this) : result;
}
// cached so that this.multimapView().inverse() only computes inverse once
private transient ImmutableSetMultimap<K, V> multimapView;
/**
* Returns a multimap view of the map.
*
* @since 14.0
*/
@Beta
public ImmutableSetMultimap<K, V> asMultimap() {
ImmutableSetMultimap<K, V> result = multimapView;
return (result == null) ? (multimapView = createMultimapView()) : result;
}
private ImmutableSetMultimap<K, V> createMultimapView() {
ImmutableMap<K, ImmutableSet<V>> map = viewMapValuesAsSingletonSets();
return new ImmutableSetMultimap<K, V>(map, map.size(), null);
}
private ImmutableMap<K, ImmutableSet<V>> viewMapValuesAsSingletonSets() {
return new MapViewOfValuesAsSingletonSets<K, V>(this);
}
private static final class MapViewOfValuesAsSingletonSets<K, V>
extends ImmutableMap<K, ImmutableSet<V>> {
private final ImmutableMap<K, V> delegate;
MapViewOfValuesAsSingletonSets(ImmutableMap<K, V> delegate) {
this.delegate = checkNotNull(delegate);
}
@Override public int size() {
return delegate.size();
}
@Override public boolean containsKey(@Nullable Object key) {
return delegate.containsKey(key);
}
@Override public ImmutableSet<V> get(@Nullable Object key) {
V outerValue = delegate.get(key);
return (outerValue == null) ? null : ImmutableSet.of(outerValue);
}
@Override boolean isPartialView() {
return false;
}
@Override ImmutableSet<Entry<K, ImmutableSet<V>>> createEntrySet() {
return new ImmutableMapEntrySet<K, ImmutableSet<V>>() {
@Override ImmutableMap<K, ImmutableSet<V>> map() {
return MapViewOfValuesAsSingletonSets.this;
}
@Override
public UnmodifiableIterator<Entry<K, ImmutableSet<V>>> iterator() {
final Iterator<Entry<K, V>> backingIterator = delegate.entrySet().iterator();
return new UnmodifiableIterator<Entry<K, ImmutableSet<V>>>() {
@Override public boolean hasNext() {
return backingIterator.hasNext();
}
@Override public Entry<K, ImmutableSet<V>> next() {
final Entry<K, V> backingEntry = backingIterator.next();
return new AbstractMapEntry<K, ImmutableSet<V>>() {
@Override public K getKey() {
return backingEntry.getKey();
}
@Override public ImmutableSet<V> getValue() {
return ImmutableSet.of(backingEntry.getValue());
}
};
}
};
}
};
}
}
@Override public boolean equals(@Nullable Object object) {
return Maps.equalsImpl(this, object);
}
abstract boolean isPartialView();
@Override public int hashCode() {
// not caching hash code since it could change if map values are mutable
// in a way that modifies their hash codes
return entrySet().hashCode();
}
@Override public String toString() {
return Maps.toStringImpl(this);
}
/**
* Serialized type for all ImmutableMap instances. It captures the logical
* contents and they are reconstructed using public factory methods. This
* ensures that the implementation types remain as implementation details.
*/
static class SerializedForm implements Serializable {
private final Object[] keys;
private final Object[] values;
SerializedForm(ImmutableMap<?, ?> map) {
keys = new Object[map.size()];
values = new Object[map.size()];
int i = 0;
for (Entry<?, ?> entry : map.entrySet()) {
keys[i] = entry.getKey();
values[i] = entry.getValue();
i++;
}
}
Object readResolve() {
Builder<Object, Object> builder = new Builder<Object, Object>();
return createMap(builder);
}
Object createMap(Builder<Object, Object> builder) {
for (int i = 0; i < keys.length; i++) {
builder.put(keys[i], values[i]);
}
return builder.build();
}
private static final long serialVersionUID = 0;
}
Object writeReplace() {
return new SerializedForm(this);
}
}