com.google.common.collect.MapConstraints Maven / Gradle / Ivy
/*
* Copyright (C) 2007 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 java.util.Collection;
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 java.util.SortedSet;
import javax.annotation.Nullable;
/**
* Factory and utilities pertaining to the {@code MapConstraint} interface.
*
* @see Constraints
* @author Mike Bostock
* @since 3.0
*/
@Beta
@GwtCompatible
public final class MapConstraints {
private MapConstraints() {}
/**
* Returns a constraint that verifies that neither the key nor the value is
* null. If either is null, a {@link NullPointerException} is thrown.
*/
public static MapConstraint notNull() {
return NotNullMapConstraint.INSTANCE;
}
// enum singleton pattern
private enum NotNullMapConstraint implements MapConstraint {
INSTANCE;
@Override
public void checkKeyValue(Object key, Object value) {
checkNotNull(key);
checkNotNull(value);
}
@Override public String toString() {
return "Not null";
}
}
/**
* Returns a constrained view of the specified map, using the specified
* constraint. Any operations that add new mappings will call the provided
* constraint. However, this method does not verify that existing mappings
* satisfy the constraint.
*
* The returned map is not serializable.
*
* @param map the map to constrain
* @param constraint the constraint that validates added entries
* @return a constrained view of the specified map
*/
public static Map constrainedMap(
Map map, MapConstraint constraint) {
return new ConstrainedMap(map, constraint);
}
/**
* Returns a constrained view of the specified multimap, using the specified
* constraint. Any operations that add new mappings will call the provided
* constraint. However, this method does not verify that existing mappings
* satisfy the constraint.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that are not
* constrained.
*
*
The returned multimap is not serializable.
*
* @param multimap the multimap to constrain
* @param constraint the constraint that validates added entries
* @return a constrained view of the multimap
*/
public static Multimap constrainedMultimap(
Multimap multimap, MapConstraint constraint) {
return new ConstrainedMultimap(multimap, constraint);
}
/**
* Returns a constrained view of the specified list multimap, using the
* specified constraint. Any operations that add new mappings will call the
* provided constraint. However, this method does not verify that existing
* mappings satisfy the constraint.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that are not
* constrained.
*
*
The returned multimap is not serializable.
*
* @param multimap the multimap to constrain
* @param constraint the constraint that validates added entries
* @return a constrained view of the specified multimap
*/
public static ListMultimap constrainedListMultimap(
ListMultimap multimap,
MapConstraint constraint) {
return new ConstrainedListMultimap(multimap, constraint);
}
/**
* Returns a constrained view of the specified set multimap, using the
* specified constraint. Any operations that add new mappings will call the
* provided constraint. However, this method does not verify that existing
* mappings satisfy the constraint.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that are not
* constrained.
*
The returned multimap is not serializable.
*
* @param multimap the multimap to constrain
* @param constraint the constraint that validates added entries
* @return a constrained view of the specified multimap
*/
public static SetMultimap constrainedSetMultimap(
SetMultimap multimap,
MapConstraint constraint) {
return new ConstrainedSetMultimap(multimap, constraint);
}
/**
* Returns a constrained view of the specified sorted-set multimap, using the
* specified constraint. Any operations that add new mappings will call the
* provided constraint. However, this method does not verify that existing
* mappings satisfy the constraint.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that are not
* constrained.
*
The returned multimap is not serializable.
*
* @param multimap the multimap to constrain
* @param constraint the constraint that validates added entries
* @return a constrained view of the specified multimap
*/
public static SortedSetMultimap constrainedSortedSetMultimap(
SortedSetMultimap multimap,
MapConstraint constraint) {
return new ConstrainedSortedSetMultimap(multimap, constraint);
}
/**
* 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 {@code asMap} entry, using the
* specified constraint. The {@link Entry#setValue} operation will be verified
* with the constraint, and the collection returned by {@link Entry#getValue}
* will be similarly constrained.
*
* @param entry the {@code asMap} entry to constrain
* @param constraint the constraint for the entry
* @return a constrained view of the specified entry
*/
private static Entry> constrainedAsMapEntry(
final Entry> entry,
final MapConstraint constraint) {
checkNotNull(entry);
checkNotNull(constraint);
return new ForwardingMapEntry>() {
@Override protected Entry> delegate() {
return entry;
}
@Override public Collection getValue() {
return Constraints.constrainedTypePreservingCollection(
entry.getValue(), new Constraint() {
@Override
public V checkElement(V value) {
constraint.checkKeyValue(getKey(), value);
return value;
}
});
}
};
}
/**
* Returns a constrained view of the specified set of {@code asMap} entries,
* using the specified constraint. The {@link Entry#setValue} operation will
* be verified with the constraint, and the collection returned by {@link
* Entry#getValue} will be similarly constrained. The {@code add} and {@code
* addAll} operations simply forward to the underlying set, which throws an
* {@link UnsupportedOperationException} per the multimap specification.
*
* @param entries the entries to constrain
* @param constraint the constraint for the entries
* @return a constrained view of the entries
*/
private static Set>> constrainedAsMapEntries(
Set>> entries,
MapConstraint constraint) {
return new ConstrainedAsMapEntries(entries, constraint);
}
/**
* 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);
}
/** @see MapConstraints#constrainedMap */
static class ConstrainedMap extends ForwardingMap {
private final Map delegate;
final MapConstraint constraint;
private transient 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() {
Set> result = entrySet;
if (result == null) {
entrySet = result =
constrainedEntrySet(delegate.entrySet(), constraint);
}
return result;
}
@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));
}
}
/**
* Returns a constrained view of the specified bimap, using the specified
* constraint. Any operations that modify the bimap will have the associated
* keys and values verified with the constraint.
*
* The returned bimap is not serializable.
*
* @param map the bimap to constrain
* @param constraint the constraint that validates added entries
* @return a constrained view of the specified bimap
*/
public static BiMap constrainedBiMap(
BiMap map, MapConstraint constraint) {
return new ConstrainedBiMap(map, null, constraint);
}
/** @see MapConstraints#constrainedBiMap */
private static class ConstrainedBiMap extends ConstrainedMap
implements BiMap {
/*
* We could switch to racy single-check lazy init and remove volatile, but
* there's a downside. That's because this field is also written in the
* constructor. Without volatile, the constructor's write of the existing
* inverse BiMap could occur after inverse()'s read of the field's initial
* null value, leading inverse() to overwrite the existing inverse with a
* doubly indirect version. This wouldn't be catastrophic, but it's
* something to keep in mind if we make the change.
*
* Note that UnmodifiableBiMap *does* use racy single-check lazy init.
* TODO(cpovirk): pick one and standardize
*/
volatile BiMap inverse;
ConstrainedBiMap(BiMap delegate, @Nullable BiMap inverse,
MapConstraint constraint) {
super(delegate, constraint);
this.inverse = inverse;
}
@Override protected BiMap delegate() {
return (BiMap) super.delegate();
}
@Override
public V forcePut(K key, V value) {
constraint.checkKeyValue(key, value);
return delegate().forcePut(key, value);
}
@Override
public BiMap inverse() {
if (inverse == null) {
inverse = new ConstrainedBiMap(delegate().inverse(), this,
new InverseConstraint(constraint));
}
return inverse;
}
@Override public Set values() {
return delegate().values();
}
}
/** @see MapConstraints#constrainedBiMap */
private static class InverseConstraint implements MapConstraint {
final MapConstraint constraint;
public InverseConstraint(MapConstraint constraint) {
this.constraint = checkNotNull(constraint);
}
@Override
public void checkKeyValue(K key, V value) {
constraint.checkKeyValue(value, key);
}
}
/** @see MapConstraints#constrainedMultimap */
private static class ConstrainedMultimap
extends ForwardingMultimap {
final MapConstraint constraint;
final Multimap delegate;
transient Collection> entries;
transient Map> asMap;
public ConstrainedMultimap(Multimap delegate,
MapConstraint constraint) {
this.delegate = checkNotNull(delegate);
this.constraint = checkNotNull(constraint);
}
@Override protected Multimap delegate() {
return delegate;
}
@Override public Map> asMap() {
Map> result = asMap;
if (result == null) {
final Map> asMapDelegate = delegate.asMap();
asMap = result = new ForwardingMap>() {
Set>> entrySet;
Collection> values;
@Override protected Map> delegate() {
return asMapDelegate;
}
@Override public Set>> entrySet() {
Set>> result = entrySet;
if (result == null) {
entrySet = result = constrainedAsMapEntries(
asMapDelegate.entrySet(), constraint);
}
return result;
}
@SuppressWarnings("unchecked")
@Override public Collection get(Object key) {
try {
Collection collection = ConstrainedMultimap.this.get((K) key);
return collection.isEmpty() ? null : collection;
} catch (ClassCastException e) {
return null; // key wasn't a K
}
}
@Override public Collection> values() {
Collection> result = values;
if (result == null) {
values = result = new ConstrainedAsMapValues(
delegate().values(), entrySet());
}
return result;
}
@Override public boolean containsValue(Object o) {
return values().contains(o);
}
};
}
return result;
}
@Override public Collection> entries() {
Collection> result = entries;
if (result == null) {
entries = result = constrainedEntries(delegate.entries(), constraint);
}
return result;
}
@Override public Collection get(final K key) {
return Constraints.constrainedTypePreservingCollection(
delegate.get(key), new Constraint() {
@Override
public V checkElement(V value) {
constraint.checkKeyValue(key, value);
return value;
}
});
}
@Override public boolean put(K key, V value) {
constraint.checkKeyValue(key, value);
return delegate.put(key, value);
}
@Override public boolean putAll(K key, Iterable values) {
return delegate.putAll(key, checkValues(key, values, constraint));
}
@Override public boolean putAll(
Multimap multimap) {
boolean changed = false;
for (Entry entry : multimap.entries()) {
changed |= put(entry.getKey(), entry.getValue());
}
return changed;
}
@Override public Collection replaceValues(
K key, Iterable values) {
return delegate.replaceValues(key, checkValues(key, values, constraint));
}
}
/** @see ConstrainedMultimap#asMap */
private static class ConstrainedAsMapValues
extends ForwardingCollection> {
final Collection> delegate;
final Set>> entrySet;
/**
* @param entrySet map entries, linking each key with its corresponding
* values, that already enforce the constraint
*/
ConstrainedAsMapValues(Collection> delegate,
Set>> entrySet) {
this.delegate = delegate;
this.entrySet = entrySet;
}
@Override protected Collection> delegate() {
return delegate;
}
@Override public Iterator> iterator() {
final Iterator>> iterator = entrySet.iterator();
return new Iterator>() {
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public Collection next() {
return iterator.next().getValue();
}
@Override
public void remove() {
iterator.remove();
}
};
}
@Override public Object[] toArray() {
return standardToArray();
}
@Override public T[] toArray(T[] array) {
return standardToArray(array);
}
@Override public boolean contains(Object o) {
return standardContains(o);
}
@Override public boolean containsAll(Collection c) {
return standardContainsAll(c);
}
@Override public boolean remove(Object o) {
return standardRemove(o);
}
@Override public boolean removeAll(Collection c) {
return standardRemoveAll(c);
}
@Override public boolean retainAll(Collection c) {
return standardRetainAll(c);
}
}
/** @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 standardToArray();
}
@Override public T[] toArray(T[] array) {
return standardToArray(array);
}
@Override public boolean contains(Object o) {
return Maps.containsEntryImpl(delegate(), o);
}
@Override public boolean containsAll(Collection c) {
return standardContainsAll(c);
}
@Override public boolean remove(Object o) {
return Maps.removeEntryImpl(delegate(), o);
}
@Override public boolean removeAll(Collection c) {
return standardRemoveAll(c);
}
@Override public boolean retainAll(Collection c) {
return standardRetainAll(c);
}
}
/** @see MapConstraints#constrainedEntrySet */
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 Sets.equalsImpl(this, object);
}
@Override public int hashCode() {
return Sets.hashCodeImpl(this);
}
}
/** @see MapConstraints#constrainedAsMapEntries */
static class ConstrainedAsMapEntries
extends ForwardingSet>> {
private final MapConstraint constraint;
private final Set>> entries;
ConstrainedAsMapEntries(Set>> entries,
MapConstraint constraint) {
this.entries = entries;
this.constraint = constraint;
}
@Override protected Set>> delegate() {
return entries;
}
@Override public Iterator>> iterator() {
final Iterator>> iterator = entries.iterator();
return new ForwardingIterator>>() {
@Override public Entry> next() {
return constrainedAsMapEntry(iterator.next(), constraint);
}
@Override protected Iterator>> delegate() {
return iterator;
}
};
}
// See Collections.CheckedMap.CheckedEntrySet for details on attacks.
@Override public Object[] toArray() {
return standardToArray();
}
@Override public T[] toArray(T[] array) {
return standardToArray(array);
}
@Override public boolean contains(Object o) {
return Maps.containsEntryImpl(delegate(), o);
}
@Override public boolean containsAll(Collection c) {
return standardContainsAll(c);
}
@Override public boolean equals(@Nullable Object object) {
return standardEquals(object);
}
@Override public int hashCode() {
return standardHashCode();
}
@Override public boolean remove(Object o) {
return Maps.removeEntryImpl(delegate(), o);
}
@Override public boolean removeAll(Collection c) {
return standardRemoveAll(c);
}
@Override public boolean retainAll(Collection c) {
return standardRetainAll(c);
}
}
private static class ConstrainedListMultimap
extends ConstrainedMultimap implements ListMultimap {
ConstrainedListMultimap(ListMultimap delegate,
MapConstraint constraint) {
super(delegate, constraint);
}
@Override public List get(K key) {
return (List) super.get(key);
}
@Override public List removeAll(Object key) {
return (List) super.removeAll(key);
}
@Override public List replaceValues(
K key, Iterable values) {
return (List) super.replaceValues(key, values);
}
}
private static class ConstrainedSetMultimap
extends ConstrainedMultimap implements SetMultimap {
ConstrainedSetMultimap(SetMultimap delegate,
MapConstraint constraint) {
super(delegate, constraint);
}
@Override public Set get(K key) {
return (Set) super.get(key);
}
@Override public Set> entries() {
return (Set>) super.entries();
}
@Override public Set removeAll(Object key) {
return (Set) super.removeAll(key);
}
@Override public Set replaceValues(
K key, Iterable values) {
return (Set) super.replaceValues(key, values);
}
}
private static class ConstrainedSortedSetMultimap
extends ConstrainedSetMultimap implements SortedSetMultimap {
ConstrainedSortedSetMultimap(SortedSetMultimap delegate,
MapConstraint constraint) {
super(delegate, constraint);
}
@Override public SortedSet get(K key) {
return (SortedSet) super.get(key);
}
@Override public SortedSet removeAll(Object key) {
return (SortedSet) super.removeAll(key);
}
@Override public SortedSet replaceValues(
K key, Iterable values) {
return (SortedSet) super.replaceValues(key, values);
}
@Override
public Comparator valueComparator() {
return ((SortedSetMultimap) delegate()).valueComparator();
}
}
private static Collection checkValues(K key,
Iterable values,
MapConstraint constraint) {
Collection copy = Lists.newArrayList(values);
for (V value : copy) {
constraint.checkKeyValue(key, value);
}
return copy;
}
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;
}
}