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 *  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
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package org.apache.commons.collections.map;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Iterator;
import java.util.Map;

import org.apache.commons.collections.Transformer;

Decorates another Map to transform objects that are added.

The Map put methods and Map.Entry setValue method are affected by this class.
Thus objects must be removed or searched for using their transformed form.
For example, if the transformation converts Strings to Integers, you must
use the Integer form to remove objects.

Note that TransformedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedMap(Map<Object,Object>). This class may throw exceptions when accessed by concurrent threads without synchronization. 

This class is Serializable from Commons Collections 3.1.
Author:
Stephen Colebourne
Since:
Commons Collections 3.0
Version:
$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $/**
 * Decorates another <code>Map</code> to transform objects that are added.
 * <p>
 * The Map put methods and Map.Entry setValue method are affected by this class.
 * Thus objects must be removed or searched for using their transformed form.
 * For example, if the transformation converts Strings to Integers, you must
 * use the Integer form to remove objects.
 * <p>
 * <strong>Note that TransformedMap is not synchronized and is not thread-safe.</strong>
 * If you wish to use this map from multiple threads concurrently, you must use
 * appropriate synchronization. The simplest approach is to wrap this map
 * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw 
 * exceptions when accessed by concurrent threads without synchronization.
 * <p>
 * This class is Serializable from Commons Collections 3.1.
 *
 * @since Commons Collections 3.0
 * @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
 * 
 * @author Stephen Colebourne
 */
public class TransformedMap
        extends AbstractInputCheckedMapDecorator
        implements Serializable {

    
Serialization version /** Serialization version */
    private static final long serialVersionUID = 7023152376788900464L;

    
The transformer to use for the key /** The transformer to use for the key */
    protected final Transformer keyTransformer;
    
The transformer to use for the value /** The transformer to use for the value */
    protected final Transformer valueTransformer;

    
Factory method to create a transforming map.
 If there are any elements already in the map being decorated, they are NOT transformed. Constrast this with decorateTransform. 
Params:
map –  the map to decorate, must not be null
keyTransformer –  the transformer to use for key conversion, null means no transformation
valueTransformer –  the transformer to use for value conversion, null means no transformation
Throws:
IllegalArgumentException – if map is null/**
     * Factory method to create a transforming map.
     * <p>
     * If there are any elements already in the map being decorated, they
     * are NOT transformed.
     * Constrast this with {@link #decorateTransform}.
     * 
     * @param map  the map to decorate, must not be null
     * @param keyTransformer  the transformer to use for key conversion, null means no transformation
     * @param valueTransformer  the transformer to use for value conversion, null means no transformation
     * @throws IllegalArgumentException if map is null
     */
    public static Map decorate(Map map, Transformer keyTransformer, Transformer valueTransformer) {
        return new TransformedMap(map, keyTransformer, valueTransformer);
    }

    
Factory method to create a transforming map that will transform
existing contents of the specified map.
 If there are any elements already in the map being decorated, they will be transformed by this method. Constrast this with decorate. 
Params:
map –  the map to decorate, must not be null
keyTransformer –  the transformer to use for key conversion, null means no transformation
valueTransformer –  the transformer to use for value conversion, null means no transformation
Throws:
IllegalArgumentException – if map is null
Since:
Commons Collections 3.2/**
     * Factory method to create a transforming map that will transform
     * existing contents of the specified map.
     * <p>
     * If there are any elements already in the map being decorated, they
     * will be transformed by this method.
     * Constrast this with {@link #decorate}.
     * 
     * @param map  the map to decorate, must not be null
     * @param keyTransformer  the transformer to use for key conversion, null means no transformation
     * @param valueTransformer  the transformer to use for value conversion, null means no transformation
     * @throws IllegalArgumentException if map is null
     * @since Commons Collections 3.2
     */
    public static Map decorateTransform(Map map, Transformer keyTransformer, Transformer valueTransformer) {
        TransformedMap decorated = new TransformedMap(map, keyTransformer, valueTransformer);
        if (map.size() > 0) {
            Map transformed = decorated.transformMap(map);
            decorated.clear();
            decorated.getMap().putAll(transformed);  // avoids double transformation
        }
        return decorated;
    }

    //-----------------------------------------------------------------------
    
Constructor that wraps (not copies).

If there are any elements already in the collection being decorated, they
are NOT transformed.
Params:
map –  the map to decorate, must not be null
keyTransformer –  the transformer to use for key conversion, null means no conversion
valueTransformer –  the transformer to use for value conversion, null means no conversion
Throws:
IllegalArgumentException – if map is null/**
     * Constructor that wraps (not copies).
     * <p>
     * If there are any elements already in the collection being decorated, they
     * are NOT transformed.
     * 
     * @param map  the map to decorate, must not be null
     * @param keyTransformer  the transformer to use for key conversion, null means no conversion
     * @param valueTransformer  the transformer to use for value conversion, null means no conversion
     * @throws IllegalArgumentException if map is null
     */
    protected TransformedMap(Map map, Transformer keyTransformer, Transformer valueTransformer) {
        super(map);
        this.keyTransformer = keyTransformer;
        this.valueTransformer = valueTransformer;
    }

    //-----------------------------------------------------------------------
    
Write the map out using a custom routine.
Params:
out –  the output stream
Throws:
IOException – 
Since:
Commons Collections 3.1/**
     * Write the map out using a custom routine.
     * 
     * @param out  the output stream
     * @throws IOException
     * @since Commons Collections 3.1
     */
    private void writeObject(ObjectOutputStream out) throws IOException {
        out.defaultWriteObject();
        out.writeObject(map);
    }

    
Read the map in using a custom routine.
Params:
in –  the input stream
Throws:
IOException – 
ClassNotFoundException – 
Since:
Commons Collections 3.1/**
     * Read the map in using a custom routine.
     * 
     * @param in  the input stream
     * @throws IOException
     * @throws ClassNotFoundException
     * @since Commons Collections 3.1
     */
    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        map = (Map) in.readObject();
    }

    //-----------------------------------------------------------------------
    
Transforms a key.

The transformer itself may throw an exception if necessary.
Params:
object –  the object to transform
Throws:
the – transformed object/**
     * Transforms a key.
     * <p>
     * The transformer itself may throw an exception if necessary.
     * 
     * @param object  the object to transform
     * @throws the transformed object
     */
    protected Object transformKey(Object object) {
        if (keyTransformer == null) {
            return object;
        }
        return keyTransformer.transform(object);
    }

    
Transforms a value.

The transformer itself may throw an exception if necessary.
Params:
object –  the object to transform
Throws:
the – transformed object/**
     * Transforms a value.
     * <p>
     * The transformer itself may throw an exception if necessary.
     * 
     * @param object  the object to transform
     * @throws the transformed object
     */
    protected Object transformValue(Object object) {
        if (valueTransformer == null) {
            return object;
        }
        return valueTransformer.transform(object);
    }

    
Transforms a map.

The transformer itself may throw an exception if necessary.
Params:
map –  the map to transform
Throws:
the – transformed object/**
     * Transforms a map.
     * <p>
     * The transformer itself may throw an exception if necessary.
     * 
     * @param map  the map to transform
     * @throws the transformed object
     */
    protected Map transformMap(Map map) {
        if (map.isEmpty()) {
            return map;
        }
        Map result = new LinkedMap(map.size());
        for (Iterator it = map.entrySet().iterator(); it.hasNext(); ) {
            Map.Entry entry = (Map.Entry) it.next();
            result.put(transformKey(entry.getKey()), transformValue(entry.getValue()));
        }
        return result;
    }

    
Override to transform the value when using setValue.
Params:
value –  the value to transform
Returns:
the transformed value
Since:
Commons Collections 3.1/**
     * Override to transform the value when using <code>setValue</code>.
     * 
     * @param value  the value to transform
     * @return the transformed value
     * @since Commons Collections 3.1
     */
    protected Object checkSetValue(Object value) {
        return valueTransformer.transform(value);
    }

    
Override to only return true when there is a value transformer.
Returns:
true if a value transformer is in use
Since:
Commons Collections 3.1/**
     * Override to only return true when there is a value transformer.
     * 
     * @return true if a value transformer is in use
     * @since Commons Collections 3.1
     */
    protected boolean isSetValueChecking() {
        return (valueTransformer != null);
    }

    //-----------------------------------------------------------------------
    public Object put(Object key, Object value) {
        key = transformKey(key);
        value = transformValue(value);
        return getMap().put(key, value);
    }

    public void putAll(Map mapToCopy) {
        mapToCopy = transformMap(mapToCopy);
        getMap().putAll(mapToCopy);
    }

}