abstractdualbidimap.java

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/*
 *  Copyright 2003-2004 The Apache Software Foundation
 *
 *  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 org.apache.commons.collections.bidimap;

import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.collections.BidiMap;
import org.apache.commons.collections.MapIterator;
import org.apache.commons.collections.ResettableIterator;
import org.apache.commons.collections.collection.AbstractCollectionDecorator;
import org.apache.commons.collections.iterators.AbstractIteratorDecorator;
import org.apache.commons.collections.keyvalue.AbstractMapEntryDecorator;

/**
 * Abstract <code>BidiMap</code> implemented using two maps.
 * <p>
 * An implementation can be written simply by implementing the
 * <code>createMap</code> method.
 * 
 * @see DualHashBidiMap
 * @see DualTreeBidiMap
 * @since Commons Collections 3.0
 * @version $Id: AbstractDualBidiMap.java,v 1.14 2004/06/22 21:54:35 scolebourne Exp $
 * 
 * @author Matthew Hawthorne
 * @author Stephen Colebourne
 */
public abstract class AbstractDualBidiMap implements BidiMap {

    /**
     * Delegate map array.  The first map contains standard entries, and the 
     * second contains inverses.
     */
    protected transient final Map[] maps = new Map[2];
    /**
     * Inverse view of this map.
     */
    protected transient BidiMap inverseBidiMap = null;
    /**
     * View of the keys.
     */
    protected transient Set keySet = null;
    /**
     * View of the values.
     */
    protected transient Collection values = null;
    /**
     * View of the entries.
     */
    protected transient Set entrySet = null;

    /**
     * Creates an empty map, initialised by <code>createMap</code>.
     * <p>
     * This constructor remains in place for deserialization.
     * All other usage is deprecated in favour of
     * {@link #AbstractDualBidiMap(Map, Map)}.
     */
    protected AbstractDualBidiMap() {
        super();
        maps[0] = createMap();
        maps[1] = createMap();
    }

    /**
     * Creates an empty map using the two maps specified as storage.
     * <p>
     * The two maps must be a matching pair, normal and reverse.
     * They will typically both be empty.
     * <p>
     * Neither map is validated, so nulls may be passed in.
     * If you choose to do this then the subclass constructor must populate
     * the <code>maps[]</code> instance variable itself.
     * 
     * @param normalMap  the normal direction map
     * @param reverseMap  the reverse direction map
     * @since Commons Collections 3.1
     */
    protected AbstractDualBidiMap(Map normalMap, Map reverseMap) {
        super();
        maps[0] = normalMap;
        maps[1] = reverseMap;
    }

    /** 
     * Constructs a map that decorates the specified maps,
     * used by the subclass <code>createBidiMap</code> implementation.
     *
     * @param normalMap  the normal direction map
     * @param reverseMap  the reverse direction map
     * @param inverseBidiMap  the inverse BidiMap
     */
    protected AbstractDualBidiMap(Map normalMap, Map reverseMap, BidiMap inverseBidiMap) {
        super();
        maps[0] = normalMap;
        maps[1] = reverseMap;
        this.inverseBidiMap = inverseBidiMap;
    }

    /**
     * Creates a new instance of the map used by the subclass to store data.
     * <p>
     * This design is deeply flawed and has been deprecated.
     * It relied on subclass data being used during a superclass constructor.
     * 
     * @return the map to be used for internal storage
     * @deprecated For constructors, use the new two map constructor.
     * For deserialization, populate the maps array directly in readObject.
     */
    protected Map createMap() {
        return null;
    }

    /**
     * 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
    //-----------------------------------------------------------------------
    public Object get(Object key) {
        return maps[0].get(key);
    }

    public int size() {
        return maps[0].size();
    }

    public boolean isEmpty() {
        return maps[0].isEmpty();
    }

    public boolean containsKey(Object key) {
        return maps[0].containsKey(key);
    }

    public boolean equals(Object obj) {
        return maps[0].equals(obj);
    }

    public int hashCode() {
        return maps[0].hashCode();
    }

    public String toString() {
        return maps[0].toString();
    }

    // BidiMap changes
    //-----------------------------------------------------------------------
    public Object put(Object key, Object value) {
        if (maps[0].containsKey(key)) {
            maps[1].remove(maps[0].get(key));
        }
        if (maps[1].containsKey(value)) {
            maps[0].remove(maps[1].get(value));
        }
        final Object obj = maps[0].put(key, value);
        maps[1].put(value, key);
        return obj;
    }
    
    public void putAll(Map map) {
        for (Iterator it = map.entrySet().iterator(); it.hasNext();) {
            Map.Entry entry = (Map.Entry) it.next();
            put(entry.getKey(), entry.getValue());
        }
    }

    public Object remove(Object key) {
        Object value = null;
        if (maps[0].containsKey(key)) {
            value = maps[0].remove(key);
            maps[1].remove(value);
        }
        return value;
    }

    public void clear() {
        maps[0].clear();
        maps[1].clear();
    }

    public boolean containsValue(Object value) {
        return maps[1].containsKey(value);
    }

    // BidiMap
    //-----------------------------------------------------------------------
    /**
     * Obtains a <code>MapIterator</code> over the map.
     * The iterator implements <code>ResetableMapIterator</code>.
     * This implementation relies on the entrySet iterator.
     * <p>
     * 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
     */
    public MapIterator mapIterator() {
        return new BidiMapIterator(this);
    }
    
    public Object getKey(Object value) {
        return maps[1].get(value);
    }

    public Object removeValue(Object value) {
        Object key = null;
        if (maps[1].containsKey(value)) {
            key = maps[1].remove(value);
            maps[0].remove(key);
        }
        return key;
    }

    public BidiMap inverseBidiMap() {
        if (inverseBidiMap == null) {
            inverseBidiMap = createBidiMap(maps[1], maps[0], 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
     */
    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(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
     */
    public Collection 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(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.
     * <p>
     * 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
     */
    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(Iterator iterator) {
        return new EntrySetIterator(iterator, this);
    }

    //-----------------------------------------------------------------------
    /**
     * Inner class View.
     */
    protected static abstract class View extends AbstractCollectionDecorator {
        
        /** 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(Collection coll, AbstractDualBidiMap parent) {
            super(coll);
            this.parent = parent;
        }

        public boolean removeAll(Collection coll) {
            if (parent.isEmpty() || coll.isEmpty()) {
                return false;
            }
            boolean modified = false;
            Iterator it = iterator();
            while (it.hasNext()) {
                if (coll.contains(it.next())) {
                    it.remove();
                    modified = true;
                }
            }
            return modified;
        }

        public boolean retainAll(Collection coll) {
            if (parent.isEmpty()) {