org.apache.commons.collections4.bidimap.DualTreeBidiMap Maven / Gradle / Ivy
Show all versions of commons-collections4 Show documentation
/*
* 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.commons.collections4.bidimap;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import org.apache.commons.collections4.BidiMap;
import org.apache.commons.collections4.OrderedBidiMap;
import org.apache.commons.collections4.OrderedMap;
import org.apache.commons.collections4.OrderedMapIterator;
import org.apache.commons.collections4.ResettableIterator;
import org.apache.commons.collections4.SortedBidiMap;
import org.apache.commons.collections4.map.AbstractSortedMapDecorator;
/**
* Implementation of {@link BidiMap} that uses two {@link TreeMap} instances.
*
* The setValue() method on iterators will succeed only if the new value being set is
* not already in the bidimap.
*
* When considering whether to use this class, the {@link TreeBidiMap} class should
* also be considered. It implements the interface using a dedicated design, and does
* not store each object twice, which can save on memory use.
*
* NOTE: From Commons Collections 3.1, all subclasses will use {@link TreeMap}
* and the flawed createMap method is ignored.
*
* @param the type of the keys in this map
* @param the type of the values in this map
* @since 3.0
*/
public class DualTreeBidiMap extends AbstractDualBidiMap
implements SortedBidiMap, Serializable {
/** Ensure serialization compatibility */
private static final long serialVersionUID = 721969328361809L;
/** The key comparator to use */
private final Comparator comparator;
/** The value comparator to use */
private final Comparator valueComparator;
/**
* Creates an empty DualTreeBidiMap
*/
public DualTreeBidiMap() {
super(new TreeMap(), new TreeMap());
this.comparator = null;
this.valueComparator = null;
}
/**
* Constructs a DualTreeBidiMap and copies the mappings from
* specified Map.
*
* @param map the map whose mappings are to be placed in this map
*/
public DualTreeBidiMap(final Map map) {
super(new TreeMap(), new TreeMap());
putAll(map);
this.comparator = null;
this.valueComparator = null;
}
/**
* Constructs a {@link DualTreeBidiMap} using the specified {@link Comparator}.
*
* @param keyComparator the comparator
* @param valueComparator the values comparator to use
*/
public DualTreeBidiMap(final Comparator keyComparator, final Comparator valueComparator) {
super(new TreeMap(keyComparator), new TreeMap(valueComparator));
this.comparator = keyComparator;
this.valueComparator = valueComparator;
}
/**
* Constructs a {@link DualTreeBidiMap} that decorates the specified maps.
*
* @param normalMap the normal direction map
* @param reverseMap the reverse direction map
* @param inverseBidiMap the inverse BidiMap
*/
protected DualTreeBidiMap(final Map normalMap, final Map reverseMap,
final BidiMap inverseBidiMap) {
super(normalMap, reverseMap, inverseBidiMap);
this.comparator = ((SortedMap) normalMap).comparator();
this.valueComparator = ((SortedMap) reverseMap).comparator();
}
/**
* Creates a new instance of this object.
*
* @param normalMap the normal direction map
* @param reverseMap the reverse direction map
* @param inverseMap the inverse BidiMap
* @return new bidi map
*/
@Override
protected DualTreeBidiMap createBidiMap(final Map normalMap, final Map reverseMap,
final BidiMap inverseMap) {
return new DualTreeBidiMap<>(normalMap, reverseMap, inverseMap);
}
//-----------------------------------------------------------------------
@Override
public Comparator comparator() {
return ((SortedMap) normalMap).comparator();
}
@Override
public Comparator valueComparator() {
return ((SortedMap) reverseMap).comparator();
}
@Override
public K firstKey() {
return ((SortedMap) normalMap).firstKey();
}
@Override
public K lastKey() {
return ((SortedMap) normalMap).lastKey();
}
@Override
public K nextKey(final K key) {
if (isEmpty()) {
return null;
}
if (normalMap instanceof OrderedMap) {
return ((OrderedMap) normalMap).nextKey(key);
}
final SortedMap sm = (SortedMap) normalMap;
final Iterator it = sm.tailMap(key).keySet().iterator();
it.next();
if (it.hasNext()) {
return it.next();
}
return null;
}
@Override
public K previousKey(final K key) {
if (isEmpty()) {
return null;
}
if (normalMap instanceof OrderedMap) {
return ((OrderedMap) normalMap).previousKey(key);
}
final SortedMap sm = (SortedMap) normalMap;
final SortedMap hm = sm.headMap(key);
if (hm.isEmpty()) {
return null;
}
return hm.lastKey();
}
//-----------------------------------------------------------------------
/**
* Obtains an ordered map iterator.
*
* This implementation copies the elements to an ArrayList in order to
* provide the forward/backward behaviour.
*
* @return a new ordered map iterator
*/
@Override
public OrderedMapIterator mapIterator() {
return new BidiOrderedMapIterator<>(this);
}
public SortedBidiMap inverseSortedBidiMap() {
return inverseBidiMap();
}
public OrderedBidiMap inverseOrderedBidiMap() {
return inverseBidiMap();
}
//-----------------------------------------------------------------------
@Override
public SortedMap headMap(final K toKey) {
final SortedMap sub = ((SortedMap) normalMap).headMap(toKey);
return new ViewMap<>(this, sub);
}
@Override
public SortedMap tailMap(final K fromKey) {
final SortedMap sub = ((SortedMap) normalMap).tailMap(fromKey);
return new ViewMap<>(this, sub);
}
@Override
public SortedMap subMap(final K fromKey, final K toKey) {
final SortedMap sub = ((SortedMap) normalMap).subMap(fromKey, toKey);
return new ViewMap<>(this, sub);
}
@Override
public SortedBidiMap inverseBidiMap() {
return (SortedBidiMap) super.inverseBidiMap();
}
//-----------------------------------------------------------------------
/**
* Internal sorted map view.
*/
protected static class ViewMap extends AbstractSortedMapDecorator {
/**
* Constructor.
* @param bidi the parent bidi map
* @param sm the subMap sorted map
*/
protected ViewMap(final DualTreeBidiMap bidi, final SortedMap sm) {
// the implementation is not great here...
// use the normalMap as the filtered map, but reverseMap as the full map
// this forces containsValue and clear to be overridden
super(new DualTreeBidiMap<>(sm, bidi.reverseMap, bidi.inverseBidiMap));
}
@Override
public boolean containsValue(final Object value) {
// override as default implementation uses reverseMap
return decorated().normalMap.containsValue(value);
}
@Override
public void clear() {
// override as default implementation uses reverseMap
for (final Iterator it = keySet().iterator(); it.hasNext();) {
it.next();
it.remove();
}
}
@Override
public SortedMap headMap(final K toKey) {
return new ViewMap<>(decorated(), super.headMap(toKey));
}
@Override
public SortedMap tailMap(final K fromKey) {
return new ViewMap<>(decorated(), super.tailMap(fromKey));
}
@Override
public SortedMap subMap(final K fromKey, final K toKey) {
return new ViewMap<>(decorated(), super.subMap(fromKey, toKey));
}
@Override
protected DualTreeBidiMap decorated() {
return (DualTreeBidiMap) super.decorated();
}
@Override
public K previousKey(final K key) {
return decorated().previousKey(key);
}
@Override
public K nextKey(final K key) {
return decorated().nextKey(key);
}
}
//-----------------------------------------------------------------------
/**
* Inner class MapIterator.
*/
protected static class BidiOrderedMapIterator implements OrderedMapIterator, ResettableIterator {
/** The parent map */
private final AbstractDualBidiMap parent;
/** The iterator being decorated */
private ListIterator> iterator;
/** The last returned entry */
private Map.Entry last = null;
/**
* Constructor.
* @param parent the parent map
*/
protected BidiOrderedMapIterator(final AbstractDualBidiMap parent) {
super();
this.parent = parent;
iterator = new ArrayList<>(parent.entrySet()).listIterator();
}
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public K next() {
last = iterator.next();
return last.getKey();
}
@Override
public boolean hasPrevious() {
return iterator.hasPrevious();
}
@Override
public K previous() {
last = iterator.previous();
return last.getKey();
}
@Override
public void remove() {
iterator.remove();
parent.remove(last.getKey());
last = null;
}
@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");
}
final V oldValue = parent.put(last.getKey(), value);
// Map.Entry specifies that the behavior is undefined when the backing map
// has been modified (as we did with the put), so we also set the value
last.setValue(value);
return oldValue;
}
@Override
public void reset() {
iterator = new ArrayList<>(parent.entrySet()).listIterator();
last = null;
}
@Override
public String toString() {
if (last != null) {
return "MapIterator[" + getKey() + "=" + getValue() + "]";
}
return "MapIterator[]";
}
}
// Serialization
//-----------------------------------------------------------------------
private void writeObject(final ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(normalMap);
}
private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
normalMap = new TreeMap<>(comparator);
reverseMap = new TreeMap<>(valueComparator);
@SuppressWarnings("unchecked") // will fail at runtime if the stream is incorrect
final Map map = (Map) in.readObject();
putAll(map);
}
}