org.apache.openjpa.lib.util.collections.AbstractDualBidiMap Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.openjpa.lib.util.collections;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.function.Predicate;
/**
* Abstract {@link BidiMap} implemented using two maps.
*
* An implementation can be written simply by implementing the
* {@link #createBidiMap(Map, Map, BidiMap)} method.
*
*
* @param the type of the keys in the map
* @param the type of the values in the map
*
* @see DualHashBidiMap
* @see DualTreeBidiMap
* @since 3.0
*/
public abstract class AbstractDualBidiMap implements BidiMap {
/**
* Normal delegate map.
*/
transient Map normalMap;
/**
* Reverse delegate map.
*/
transient Map reverseMap;
/**
* Inverse view of this map.
*/
transient BidiMap inverseBidiMap = null;
/**
* View of the keys.
*/
transient Set keySet = null;
/**
* View of the values.
*/
transient Set values = null;
/**
* View of the entries.
*/
transient Set> entrySet = null;
/**
* Creates an empty map, initialised by createMap.
*
* This constructor remains in place for deserialization.
* All other usage is deprecated in favour of
* {@link #AbstractDualBidiMap(Map, Map)}.
*/
protected AbstractDualBidiMap() {
super();
}
/**
* Creates an empty map using the two maps specified as storage.
*
* The two maps must be a matching pair, normal and reverse.
* They will typically both be empty.
*
* Neither map is validated, so nulls may be passed in.
* If you choose to do this then the subclass constructor must populate
* the maps[] instance variable itself.
*
* @param normalMap the normal direction map
* @param reverseMap the reverse direction map
* @since 3.1
*/
protected AbstractDualBidiMap(final Map normalMap, final Map reverseMap) {
super();
this.normalMap = normalMap;
this.reverseMap = reverseMap;
}
/**
* Constructs a map that decorates the specified maps,
* used by the subclass createBidiMap implementation.
*
* @param normalMap the normal direction map
* @param reverseMap the reverse direction map
* @param inverseBidiMap the inverse BidiMap
*/
protected AbstractDualBidiMap(final Map normalMap, final Map reverseMap,
final BidiMap inverseBidiMap) {
super();
this.normalMap = normalMap;
this.reverseMap = reverseMap;
this.inverseBidiMap = inverseBidiMap;
}
/**
* Creates a new instance of the subclass.
*
* @param normalMap the normal direction map
* @param reverseMap the reverse direction map
* @param inverseMap this map, which is the inverse in the new map
* @return the inverse map
*/
protected abstract BidiMap createBidiMap(Map normalMap, Map reverseMap, BidiMap inverseMap);
// Map delegation
//-----------------------------------------------------------------------
@Override
public V get(final Object key) {
return normalMap.get(key);
}
@Override
public int size() {
return normalMap.size();
}
@Override
public boolean isEmpty() {
return normalMap.isEmpty();
}
@Override
public boolean containsKey(final Object key) {
return normalMap.containsKey(key);
}
@Override
public boolean equals(final Object obj) {
return normalMap.equals(obj);
}
@Override
public int hashCode() {
return normalMap.hashCode();
}
@Override
public String toString() {
return normalMap.toString();
}
// BidiMap changes
//-----------------------------------------------------------------------
@Override
public V put(final K key, final V value) {
if (normalMap.containsKey(key)) {
reverseMap.remove(normalMap.get(key));
}
if (reverseMap.containsKey(value)) {
normalMap.remove(reverseMap.get(value));
}
final V obj = normalMap.put(key, value);
reverseMap.put(value, key);
return obj;
}
@Override
public void putAll(final Map map) {
for (final Entry entry : map.entrySet()) {
put(entry.getKey(), entry.getValue());
}
}
@Override
public V remove(final Object key) {
V value = null;
if (normalMap.containsKey(key)) {
value = normalMap.remove(key);
reverseMap.remove(value);
}
return value;
}
@Override
public void clear() {
normalMap.clear();
reverseMap.clear();
}
@Override
public boolean containsValue(final Object value) {
return reverseMap.containsKey(value);
}
// BidiMap
//-----------------------------------------------------------------------
/**
* Obtains a MapIterator over the map.
* The iterator implements ResetableMapIterator.
* This implementation relies on the entrySet iterator.
*
* The setValue() methods only allow a new value to be set.
* If the value being set is already in the map, an IllegalArgumentException
* is thrown (as setValue cannot change the size of the map).
*
* @return a map iterator
*/
@Override
public MapIterator mapIterator() {
return new BidiMapIterator<>(this);
}
@Override
public K getKey(final Object value) {
return reverseMap.get(value);
}
@Override
public K removeValue(final Object value) {
K key = null;
if (reverseMap.containsKey(value)) {
key = reverseMap.remove(value);
normalMap.remove(key);
}
return key;
}
@Override
public BidiMap inverseBidiMap() {
if (inverseBidiMap == null) {
inverseBidiMap = createBidiMap(reverseMap, normalMap, this);
}
return inverseBidiMap;
}
// Map views
//-----------------------------------------------------------------------
/**
* Gets a keySet view of the map.
* Changes made on the view are reflected in the map.
* The set supports remove and clear but not add.
*
* @return the keySet view
*/
@Override
public Set keySet() {
if (keySet == null) {
keySet = new KeySet<>(this);
}
return keySet;
}
/**
* Creates a key set iterator.
* Subclasses can override this to return iterators with different properties.
*
* @param iterator the iterator to decorate
* @return the keySet iterator
*/
protected Iterator createKeySetIterator(final Iterator iterator) {
return new KeySetIterator<>(iterator, this);
}
/**
* Gets a values view of the map.
* Changes made on the view are reflected in the map.
* The set supports remove and clear but not add.
*
* @return the values view
*/
@Override
public Set values() {
if (values == null) {
values = new Values<>(this);
}
return values;
}
/**
* Creates a values iterator.
* Subclasses can override this to return iterators with different properties.
*
* @param iterator the iterator to decorate
* @return the values iterator
*/
protected Iterator createValuesIterator(final Iterator iterator) {
return new ValuesIterator<>(iterator, this);
}
/**
* Gets an entrySet view of the map.
* Changes made on the set are reflected in the map.
* The set supports remove and clear but not add.
*
* The Map Entry setValue() method only allow a new value to be set.
* If the value being set is already in the map, an IllegalArgumentException
* is thrown (as setValue cannot change the size of the map).
*
* @return the entrySet view
*/
@Override
public Set> entrySet() {
if (entrySet == null) {
entrySet = new EntrySet<>(this);
}
return entrySet;
}
/**
* Creates an entry set iterator.
* Subclasses can override this to return iterators with different properties.
*
* @param iterator the iterator to decorate
* @return the entrySet iterator
*/
protected Iterator> createEntrySetIterator(final Iterator> iterator) {
return new EntrySetIterator<>(iterator, this);
}
//-----------------------------------------------------------------------
/**
* Inner class View.
*/
protected static abstract class View extends AbstractCollectionDecorator {
/** Generated serial version ID. */
private static final long serialVersionUID = 4621510560119690639L;
/** The parent map */
protected final AbstractDualBidiMap parent;
/**
* Constructs a new view of the BidiMap.
*
* @param coll the collection view being decorated
* @param parent the parent BidiMap
*/
protected View(final Collection coll, final AbstractDualBidiMap parent) {
super(coll);
this.parent = parent;
}
@Override
public boolean equals(final Object object) {
return object == this || decorated().equals(object);
}
@Override
public int hashCode() {
return decorated().hashCode();
}
/**
* @since 4.4
*/
@Override
public boolean removeIf(Predicate filter) {
if (parent.isEmpty() || Objects.isNull(filter)) {
return false;
}
boolean modified = false;
final Iterator it = iterator();
while (it.hasNext()) {
@SuppressWarnings("unchecked")
final E e = (E) it.next();
if (filter.test(e)) {
it.remove();
modified = true;
}
}
return modified;
}
@Override
public boolean removeAll(final Collection coll) {
if (parent.isEmpty() || coll.isEmpty()) {
return false;
}
boolean modified = false;
final Iterator it = coll.iterator();
while (it.hasNext()) {
modified |= remove(it.next());
}
return modified;
}
/**
* {@inheritDoc}
*
* This implementation iterates over the elements of this bidi map, checking each element in
* turn to see if it's contained in coll. If it's not contained, it's removed
* from this bidi map. As a consequence, it is advised to use a collection type for
* coll that provides a fast (e.g. O(1)) implementation of
* {@link Collection#contains(Object)}.
*/
@Override
public boolean retainAll(final Collection coll) {
if (parent.isEmpty()) {
return false;
}
if (coll.isEmpty()) {
parent.clear();
return true;
}
boolean modified = false;
final Iterator it = iterator();
while (it.hasNext()) {
if (!coll.contains(it.next())) {
it.remove();
modified = true;
}
}
return modified;
}
@Override
public void clear() {
parent.clear();
}
}
//-----------------------------------------------------------------------
/**
* Inner class KeySet.
*/
protected static class KeySet extends View implements Set {
/** Serialization version */
private static final long serialVersionUID = -7107935777385040694L;
/**
* Constructs a new view of the BidiMap.
*
* @param parent the parent BidiMap
*/
@SuppressWarnings("unchecked")
protected KeySet(final AbstractDualBidiMap parent) {
super(parent.normalMap.keySet(), (AbstractDualBidiMap) parent);
}
@Override
public Iterator iterator() {
return parent.createKeySetIterator(super.iterator());
}
@Override
public boolean contains(final Object key) {
return parent.normalMap.containsKey(key);
}
@Override
public boolean remove(final Object key) {
if (parent.normalMap.containsKey(key)) {
final Object value = parent.normalMap.remove(key);
parent.reverseMap.remove(value);
return true;
}
return false;
}
}
/**
* Inner class KeySetIterator.
*/
protected static class KeySetIterator extends AbstractIteratorDecorator {
/** The parent map */
protected final AbstractDualBidiMap parent;
/** The last returned key */
protected K lastKey = null;
/** Whether remove is allowed at present */
protected boolean canRemove = false;
/**
* Constructor.
* @param iterator the iterator to decorate
* @param parent the parent map
*/
protected KeySetIterator(final Iterator iterator, final AbstractDualBidiMap parent) {
super(iterator);
this.parent = parent;
}
@Override
public K next() {
lastKey = super.next();
canRemove = true;
return lastKey;
}
@Override
public void remove() {
if (!canRemove) {
throw new IllegalStateException("Iterator remove() can only be called once after next()");
}
final Object value = parent.normalMap.get(lastKey);
super.remove();
parent.reverseMap.remove(value);
lastKey = null;
canRemove = false;
}
}
//-----------------------------------------------------------------------
/**
* Inner class Values.
*/
protected static class Values extends View implements Set {
/** Serialization version */
private static final long serialVersionUID = 4023777119829639864L;
/**
* Constructs a new view of the BidiMap.
*
* @param parent the parent BidiMap
*/
@SuppressWarnings("unchecked")
protected Values(final AbstractDualBidiMap parent) {
super(parent.normalMap.values(), (AbstractDualBidiMap) parent);
}
@Override
public Iterator iterator() {
return parent.createValuesIterator(super.iterator());
}
@Override
public boolean contains(final Object value) {
return parent.reverseMap.containsKey(value);
}
@Override
public boolean remove(final Object value) {
if (parent.reverseMap.containsKey(value)) {
final Object key = parent.reverseMap.remove(value);
parent.normalMap.remove(key);
return true;
}
return false;
}
}
/**
* Inner class ValuesIterator.
*/
protected static class ValuesIterator extends AbstractIteratorDecorator {
/** The parent map */
protected final AbstractDualBidiMap parent;
/** The last returned value */
protected V lastValue = null;
/** Whether remove is allowed at present */
protected boolean canRemove = false;
/**
* Constructor.
* @param iterator the iterator to decorate
* @param parent the parent map
*/
@SuppressWarnings("unchecked")
protected ValuesIterator(final Iterator iterator, final AbstractDualBidiMap parent) {
super(iterator);
this.parent = (AbstractDualBidiMap) parent;
}
@Override
public V next() {
lastValue = super.next();
canRemove = true;
return lastValue;
}
@Override
public void remove() {
if (!canRemove) {
throw new IllegalStateException("Iterator remove() can only be called once after next()");
}
super.remove(); // removes from maps[0]
parent.reverseMap.remove(lastValue);
lastValue = null;
canRemove = false;
}
}
//-----------------------------------------------------------------------
/**
* Inner class EntrySet.
*/
protected static class EntrySet extends View> implements Set> {
/** Serialization version */
private static final long serialVersionUID = 4040410962603292348L;
/**
* Constructs a new view of the BidiMap.
*
* @param parent the parent BidiMap
*/
protected EntrySet(final AbstractDualBidiMap parent) {
super(parent.normalMap.entrySet(), parent);
}
@Override
public Iterator> iterator() {
return parent.createEntrySetIterator(super.iterator());
}
@Override
public boolean remove(final Object obj) {
if (!(obj instanceof Map.Entry)) {
return false;
}
final Entry entry = (Entry) obj;
final Object key = entry.getKey();
if (parent.containsKey(key)) {
final V value = parent.normalMap.get(key);
if (value == null ? entry.getValue() == null : value.equals(entry.getValue())) {
parent.normalMap.remove(key);
parent.reverseMap.remove(value);
return true;
}
}
return false;
}
}
/**
* Inner class EntrySetIterator.
*/
protected static class EntrySetIterator extends AbstractIteratorDecorator> {
/** The parent map */
protected final AbstractDualBidiMap parent;
/** The last returned entry */
protected Entry last = null;
/** Whether remove is allowed at present */
protected boolean canRemove = false;
/**
* Constructor.
* @param iterator the iterator to decorate
* @param parent the parent map
*/
protected EntrySetIterator(final Iterator> iterator, final AbstractDualBidiMap parent) {
super(iterator);
this.parent = parent;
}
@Override
public Entry next() {
last = new MapEntry<>(super.next(), parent);
canRemove = true;
return last;
}
@Override
public void remove() {
if (!canRemove) {
throw new IllegalStateException("Iterator remove() can only be called once after next()");
}
// store value as remove may change the entry in the decorator (eg.TreeMap)
final Object value = last.getValue();
super.remove();
parent.reverseMap.remove(value);
last = null;
canRemove = false;
}
}
/**
* Inner class MapEntry.
*/
protected static class MapEntry extends AbstractMapEntryDecorator {
/** The parent map */
protected final AbstractDualBidiMap parent;
/**
* Constructor.
* @param entry the entry to decorate
* @param parent the parent map
*/
protected MapEntry(final Entry entry, final AbstractDualBidiMap parent) {
super(entry);
this.parent = parent;
}
@Override
public V setValue(final V value) {
final K key = MapEntry.this.getKey();
if (parent.reverseMap.containsKey(value) &&
parent.reverseMap.get(value) != key) {
throw new IllegalArgumentException(
"Cannot use setValue() when the object being set is already in the map");
}
parent.put(key, value);
return super.setValue(value);
}
}
/**
* Inner class MapIterator.
*/
protected static class BidiMapIterator implements MapIterator, ResettableIterator {
/** The parent map */
protected final AbstractDualBidiMap parent;
/** The iterator being wrapped */
protected Iterator> iterator;
/** The last returned entry */
protected Entry last = null;
/** Whether remove is allowed at present */
protected boolean canRemove = false;
/**
* Constructor.
* @param parent the parent map
*/
protected BidiMapIterator(final AbstractDualBidiMap parent) {
super();
this.parent = parent;
this.iterator = parent.normalMap.entrySet().iterator();
}
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public K next() {
last = iterator.next();
canRemove = true;
return last.getKey();
}
@Override
public void remove() {
if (!canRemove) {
throw new IllegalStateException("Iterator remove() can only be called once after next()");
}
// store value as remove may change the entry in the decorator (eg.TreeMap)
final V value = last.getValue();
iterator.remove();
parent.reverseMap.remove(value);
last = null;
canRemove = false;
}
@Override
public K getKey() {
if (last == null) {
throw new IllegalStateException(
"Iterator getKey() can only be called after next() and before remove()");
}
return last.getKey();
}
@Override
public V getValue() {
if (last == null) {
throw new IllegalStateException(
"Iterator getValue() can only be called after next() and before remove()");
}
return last.getValue();
}
@Override
public V setValue(final V value) {
if (last == null) {
throw new IllegalStateException(
"Iterator setValue() can only be called after next() and before remove()");
}
if (parent.reverseMap.containsKey(value) &&
parent.reverseMap.get(value) != last.getKey()) {
throw new IllegalArgumentException(
"Cannot use setValue() when the object being set is already in the map");
}
return parent.put(last.getKey(), value);
}
@Override
public void reset() {
iterator = parent.normalMap.entrySet().iterator();
last = null;
canRemove = false;
}
@Override
public String toString() {
if (last != null) {
return "MapIterator[" + getKey() + "=" + getValue() + "]";
}
return "MapIterator[]";
}
}
}