org.apache.commons.collections.bidimap.DualTreeBidiMap 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.commons.collections.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.collections.BidiMap;
import org.apache.commons.collections.OrderedBidiMap;
import org.apache.commons.collections.OrderedMap;
import org.apache.commons.collections.OrderedMapIterator;
import org.apache.commons.collections.ResettableIterator;
import org.apache.commons.collections.SortedBidiMap;
import org.apache.commons.collections.map.AbstractSortedMapDecorator;
/**
* Implementation of BidiMap that uses two 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 TreeMap
* and the flawed createMap method is ignored.
*
* @since Commons Collections 3.0
* @version $Id: DualTreeBidiMap.java 646777 2008-04-10 12:33:15Z niallp $
*
* @author Matthew Hawthorne
* @author Stephen Colebourne
*/
public class DualTreeBidiMap
extends AbstractDualBidiMap implements SortedBidiMap, Serializable {
/** Ensure serialization compatibility */
private static final long serialVersionUID = 721969328361809L;
/** The comparator to use */
protected final Comparator comparator;
/**
* Creates an empty DualTreeBidiMap
*/
public DualTreeBidiMap() {
super(new TreeMap(), new TreeMap());
this.comparator = 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(Map map) {
super(new TreeMap(), new TreeMap());
putAll(map);
this.comparator = null;
}
/**
* Constructs a DualTreeBidiMap using the specified Comparator.
*
* @param comparator the Comparator
*/
public DualTreeBidiMap(Comparator comparator) {
super(new TreeMap(comparator), new TreeMap(comparator));
this.comparator = comparator;
}
/**
* Constructs a 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(Map normalMap, Map reverseMap, BidiMap inverseBidiMap) {
super(normalMap, reverseMap, inverseBidiMap);
this.comparator = ((SortedMap) normalMap).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
*/
protected BidiMap createBidiMap(Map normalMap, Map reverseMap, BidiMap inverseMap) {
return new DualTreeBidiMap(normalMap, reverseMap, inverseMap);
}
//-----------------------------------------------------------------------
public Comparator comparator() {
return ((SortedMap) maps[0]).comparator();
}
public Object firstKey() {
return ((SortedMap) maps[0]).firstKey();
}
public Object lastKey() {
return ((SortedMap) maps[0]).lastKey();
}
public Object nextKey(Object key) {
if (isEmpty()) {
return null;
}
if (maps[0] instanceof OrderedMap) {
return ((OrderedMap) maps[0]).nextKey(key);
}
SortedMap sm = (SortedMap) maps[0];
Iterator it = sm.tailMap(key).keySet().iterator();
it.next();
if (it.hasNext()) {
return it.next();
}
return null;
}
public Object previousKey(Object key) {
if (isEmpty()) {
return null;
}
if (maps[0] instanceof OrderedMap) {
return ((OrderedMap) maps[0]).previousKey(key);
}
SortedMap sm = (SortedMap) maps[0];
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
*/
public OrderedMapIterator orderedMapIterator() {
return new BidiOrderedMapIterator(this);
}
public SortedBidiMap inverseSortedBidiMap() {
return (SortedBidiMap) inverseBidiMap();
}
public OrderedBidiMap inverseOrderedBidiMap() {
return (OrderedBidiMap) inverseBidiMap();
}
//-----------------------------------------------------------------------
public SortedMap headMap(Object toKey) {
SortedMap sub = ((SortedMap) maps[0]).headMap(toKey);
return new ViewMap(this, sub);
}
public SortedMap tailMap(Object fromKey) {
SortedMap sub = ((SortedMap) maps[0]).tailMap(fromKey);
return new ViewMap(this, sub);
}
public SortedMap subMap(Object fromKey, Object toKey) {
SortedMap sub = ((SortedMap) maps[0]).subMap(fromKey, toKey);
return new ViewMap(this, sub);
}
//-----------------------------------------------------------------------
/**
* Internal sorted map view.
*/
protected static class ViewMap extends AbstractSortedMapDecorator {
/** The parent bidi map. */
final DualTreeBidiMap bidi;
/**
* Constructor.
* @param bidi the parent bidi map
* @param sm the subMap sorted map
*/
protected ViewMap(DualTreeBidiMap bidi, SortedMap sm) {
// the implementation is not great here...
// use the maps[0] as the filtered map, but maps[1] as the full map
// this forces containsValue and clear to be overridden
super((SortedMap) bidi.createBidiMap(sm, bidi.maps[1], bidi.inverseBidiMap));
this.bidi = (DualTreeBidiMap) map;
}
public boolean containsValue(Object value) {
// override as default implementation jumps to [1]
return bidi.maps[0].containsValue(value);
}
public void clear() {
// override as default implementation jumps to [1]
for (Iterator it = keySet().iterator(); it.hasNext();) {
it.next();
it.remove();
}
}
public SortedMap headMap(Object toKey) {
return new ViewMap(bidi, super.headMap(toKey));
}
public SortedMap tailMap(Object fromKey) {
return new ViewMap(bidi, super.tailMap(fromKey));
}
public SortedMap subMap(Object fromKey, Object toKey) {
return new ViewMap(bidi, super.subMap(fromKey, toKey));
}
}
//-----------------------------------------------------------------------
/**
* Inner class MapIterator.
*/
protected static class BidiOrderedMapIterator implements OrderedMapIterator, ResettableIterator {
/** The parent map */
protected final AbstractDualBidiMap parent;
/** The iterator being decorated */
protected ListIterator iterator;
/** The last returned entry */
private Map.Entry last = null;
/**
* Constructor.
* @param parent the parent map
*/
protected BidiOrderedMapIterator(AbstractDualBidiMap parent) {
super();
this.parent = parent;
iterator = new ArrayList(parent.entrySet()).listIterator();
}
public boolean hasNext() {
return iterator.hasNext();
}
public Object next() {
last = (Map.Entry) iterator.next();
return last.getKey();
}
public boolean hasPrevious() {
return iterator.hasPrevious();
}
public Object previous() {
last = (Map.Entry) iterator.previous();
return last.getKey();
}
public void remove() {
iterator.remove();
parent.remove(last.getKey());
last = null;
}
public Object getKey() {
if (last == null) {
throw new IllegalStateException("Iterator getKey() can only be called after next() and before remove()");
}
return last.getKey();
}
public Object getValue() {
if (last == null) {
throw new IllegalStateException("Iterator getValue() can only be called after next() and before remove()");
}
return last.getValue();
}
public Object setValue(Object value) {
if (last == null) {
throw new IllegalStateException("Iterator setValue() can only be called after next() and before remove()");
}
if (parent.maps[1].containsKey(value) &&
parent.maps[1].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);
}
public void reset() {
iterator = new ArrayList(parent.entrySet()).listIterator();
last = null;
}
public String toString() {
if (last != null) {
return "MapIterator[" + getKey() + "=" + getValue() + "]";
} else {
return "MapIterator[]";
}
}
}
// Serialization
//-----------------------------------------------------------------------
private void writeObject(ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(maps[0]);
}
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
maps[0] = new TreeMap(comparator);
maps[1] = new TreeMap(comparator);
Map map = (Map) in.readObject();
putAll(map);
}
}