com.google.common.collect.MapConstraints Maven / Gradle / Ivy
Show all versions of google-collections Show documentation
/*
* Copyright (C) 2007 Google Inc.
*
* 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 com.google.common.annotations.GwtCompatible;
import static com.google.common.base.Preconditions.checkNotNull;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.Nullable;
/**
* Factory and utilities pertaining to the {@code MapConstraint} interface.
*
* @author Mike Bostock
*/
@GwtCompatible
final class MapConstraints {
private MapConstraints() {}
/**
* Returns a constrained view of the specified entry, using the specified
* constraint. The {@link Entry#setValue} operation will be verified with the
* constraint.
*
* @param entry the entry to constrain
* @param constraint the constraint for the entry
* @return a constrained view of the specified entry
*/
private static Entry constrainedEntry(
final Entry entry,
final MapConstraint constraint) {
checkNotNull(entry);
checkNotNull(constraint);
return new ForwardingMapEntry() {
@Override protected Entry delegate() {
return entry;
}
@Override public V setValue(V value) {
constraint.checkKeyValue(getKey(), value);
return entry.setValue(value);
}
};
}
/**
* Returns a constrained view of the specified collection (or set) of entries,
* using the specified constraint. The {@link Entry#setValue} operation will
* be verified with the constraint, along with add operations on the returned
* collection. The {@code add} and {@code addAll} operations simply forward to
* the underlying collection, which throws an {@link
* UnsupportedOperationException} per the map and multimap specification.
*
* @param entries the entries to constrain
* @param constraint the constraint for the entries
* @return a constrained view of the specified entries
*/
private static Collection> constrainedEntries(
Collection> entries,
MapConstraint constraint) {
if (entries instanceof Set) {
return constrainedEntrySet((Set>) entries, constraint);
}
return new ConstrainedEntries(entries, constraint);
}
/**
* Returns a constrained view of the specified set of entries, using the
* specified constraint. The {@link Entry#setValue} operation will be verified
* with the constraint, along with add operations on the returned set. The
* {@code add} and {@code addAll} operations simply forward to the underlying
* set, which throws an {@link UnsupportedOperationException} per the map and
* multimap specification.
*
* The returned multimap is not serializable.
*
* @param entries the entries to constrain
* @param constraint the constraint for the entries
* @return a constrained view of the specified entries
*/
private static Set> constrainedEntrySet(
Set> entries,
MapConstraint constraint) {
return new ConstrainedEntrySet(entries, constraint);
}
static class ConstrainedMap extends ForwardingMap {
final Map delegate;
final MapConstraint constraint;
private transient volatile Set> entrySet;
ConstrainedMap(
Map delegate, MapConstraint constraint) {
this.delegate = checkNotNull(delegate);
this.constraint = checkNotNull(constraint);
}
@Override protected Map delegate() {
return delegate;
}
@Override public Set> entrySet() {
if (entrySet == null) {
entrySet = constrainedEntrySet(delegate.entrySet(), constraint);
}
return entrySet;
}
@Override public V put(K key, V value) {
constraint.checkKeyValue(key, value);
return delegate.put(key, value);
}
@Override public void putAll(Map map) {
delegate.putAll(checkMap(map, constraint));
}
}
/** @see MapConstraints#constrainedEntries */
private static class ConstrainedEntries
extends ForwardingCollection> {
final MapConstraint constraint;
final Collection> entries;
ConstrainedEntries(Collection> entries,
MapConstraint constraint) {
this.entries = entries;
this.constraint = constraint;
}
@Override protected Collection> delegate() {
return entries;
}
@Override public Iterator> iterator() {
final Iterator> iterator = entries.iterator();
return new ForwardingIterator>() {
@Override public Entry next() {
return constrainedEntry(iterator.next(), constraint);
}
@Override protected Iterator> delegate() {
return iterator;
}
};
}
// See Collections.CheckedMap.CheckedEntrySet for details on attacks.
@Override public Object[] toArray() {
return ObjectArrays.toArrayImpl(this);
}
@Override public T[] toArray(T[] array) {
return ObjectArrays.toArrayImpl(this, array);
}
@Override public boolean contains(Object o) {
return Maps.containsEntryImpl(delegate(), o);
}
@Override public boolean containsAll(Collection c) {
return Collections2.containsAll(this, c);
}
@Override public boolean remove(Object o) {
return Maps.removeEntryImpl(delegate(), o);
}
@Override public boolean removeAll(Collection c) {
return Iterators.removeAll(iterator(), c);
}
@Override public boolean retainAll(Collection c) {
return Iterators.retainAll(iterator(), c);
}
}
static class ConstrainedEntrySet
extends ConstrainedEntries implements Set> {
ConstrainedEntrySet(Set> entries,
MapConstraint constraint) {
super(entries, constraint);
}
// See Collections.CheckedMap.CheckedEntrySet for details on attacks.
@Override public boolean equals(@Nullable Object object) {
return Collections2.setEquals(this, object);
}
@Override public int hashCode() {
return Sets.hashCodeImpl(this);
}
}
private static Map checkMap(Map map,
MapConstraint constraint) {
Map copy = new LinkedHashMap(map);
for (Entry entry : copy.entrySet()) {
constraint.checkKeyValue(entry.getKey(), entry.getValue());
}
return copy;
}
}