zkoss/zk

/* StringKeysMap.java

    Purpose:
        
    Description:
        
    History:
        Tue Dec  6 22:35:32     2005, Created by tomyeh

Copyright (C) 2005 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
    This program is distributed under LGPL Version 2.1 in the hope that
    it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.web.servlet.xel;

import java.util.AbstractMap;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;

/**
 * A skeletal implementation for Map to wrap something with enumeration of
 * keys, which must be String.
 *
 * @author tomyeh
 * @since 3.0.0
 */
public abstract class StringKeysMap<V> extends AbstractMap<String, V> {
    //-- Map --//
    public boolean containsKey(Object key) {
        return (key instanceof String) && getValue((String) key) != null;
    }

    public V get(Object key) {
        return key instanceof String ? getValue((String) key) : null;
    }

    /** Returns the value associated with the specified key. */
    protected abstract V getValue(String key);

    /** Returns an enumeration of keys. */
    protected abstract Enumeration<String> getKeys();

    /** Sets the value associated with the specified key. */
    protected abstract void setValue(String key, V value);

    /** Removes the specified key. */
    protected abstract void removeValue(String key);

    private static class Key {
        protected final String _key;

        private Key(String key) {
            _key = key;
        }

        public boolean equals(Object o) {
            if (this == o)
                return true;
            return o instanceof Key && _key.equals(((Key) o)._key);
        }

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

    private class Entry extends Key implements Map.Entry<String, V> {
        private Entry(String key) {
            super(key);
        }

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

        public boolean equals(Object o) {
            if (this == o)
                return true;
            return o instanceof StringKeysMap.Entry && _key.equals(((StringKeysMap.Entry) o)._key);
        }

        public String getKey() {
            return _key;
        }

        public V getValue() {
            return StringKeysMap.this.getValue(_key);
        }

        public V setValue(V value) {
            final V old = getValue();
            StringKeysMap.this.setValue(_key, value);
            return old;
        }
    }

    /** The iterator class used to iterator the entries in this map.
     */
    public class EntryIter implements Iterator<Entry> {
        private final Enumeration<String> _keys = getKeys();
        private String _key;

        public boolean hasNext() {
            return _keys.hasMoreElements();
        }

        public Entry next() {
            if (!hasNext()) {
                throw new java.util.NoSuchElementException();
            }
            _key = _keys.nextElement();
            return new Entry(_key);
        }

        public void remove() {
            StringKeysMap.this.removeValue(_key);
        }
    }
}