[COLLECTIONS] Submission of DelegateMap

[Daniel Rall <dl...@finemaltcoding.com>]

This provides a convenient Map wrapper (such as for cases where
Collections.synchronizedMap() just won't do).  It was reviewed by
Leonard Richardson <le...@apache.org>.

- Dan


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package org.apache.commons.collections;

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

/** 
 * <p>delegate - a person authorized to act as representative for
 * another</p>
 *
 * <p>This <code>Map</code> wraps another <code>Map</code>
 * implementation, using the wrapped instance for its default
 * implementation.  This class is used as a framework on which to
 * build to extensions for its wrapped <code>Map</code> object which
 * would be unavailable or inconvenient via sub-classing (but usable
 * via composition).</p>
 *
 * <p>An example use case is where the wrapped <code>Map</code> needs
 * synchronization (to make it thread-safe), but the <code>Map</code>
 * returned by <code>Collections.synchronizedMap(map)</code>
 * hides part of <code>map</code>'s public interface.</p>
 *
 * @author <a href="mailto:dlr@collab.net">Daniel Rall</a>
 * @since 2.0
 */
public abstract class DelegateMap implements Map {
    
    /**
     * The <code>Map</code> used for default implementations.
     */
    protected Map map;

    /**
     * Creates a new instance acting as a representative for the
     * specified <code>Map</code>.
     *
     * @param map The <code>Map</code> to whose operations to wrap.
     */
    public DelegateMap(Map map) {
        this.map = map;
    }

    public void clear() {
        map.clear();
    }

    public boolean containsKey(Object key) {
        return map.containsKey(key);
    }

    public boolean containsValue(Object value) {
        return map.containsValue(value);
    }

    public Set entrySet() {
        return map.entrySet();
    }

    public boolean equals(Object map) {
        return map.equals(map);
    }

    public Object get(Object key) {
        return map.get(key);
    }

    public int hashCode() {
        return map.hashCode();
    }

    public boolean isEmpty() {
        return map.isEmpty();
    }

    public Set keySet() {
        return map.keySet();
    }

    public Object put(Object key, Object value) {
        return map.put(key, value);
    }

    public void putAll(Map t) {
        map.putAll(t);
    }

    public Object remove(Object key) {
        return map.remove(key);
    }

    public int size() {
        return map.size();
    }

    public Collection values() {
        return map.values();
    }
   
}

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