HashtableStoreSupport.java

/*******************************************************************************
 * Copyright (c) 2012-present Jakub Kováč, Jozef Brandýs, Katarína Kotrlová,
 * Pavol Lukča, Ladislav Pápay, Viktor Tomkovič, Tatiana Tóthová
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/

package algvis.core.history;

import java.util.Hashtable;

public class HashtableStoreSupport {
    private static final Object nullObject = new Object();

    /**
     * Stores the (key, value) pair in the state. Value may be null and it is
     * stored only if state contains the key.
     * 
     * @param state
     * @param key
     * @param value
     */
    public static void store(Hashtable<Object, Object> state, Object key,
        Object value) {
        if (!state.containsKey(key)) {
            if (value == null) {
                state.put(key, nullObject);
            } else {
                state.put(key, value);
            }
        }
    }

    // TODO store collection support
    // public static void storeCollection(Hashtable<Object, Object> state,
    // String key, AbstractSet abstractSet) {
    // storeCollection(state, key, (Collection) abstractSet);
    // }
    //
    // public static void storeCollection(Hashtable<Object, Object> state,
    // String key, AbstractList abstractList) {
    // storeCollection(state, key, (Collection) abstractList);
    // }
    //
    // private static void storeCollection(Hashtable<Object, Object> state,
    // String key, Collection collection) {
    // if (collection == null) {
    // state.put(key, nullObject);
    // } else {
    // state.put(key, collection);
    // int hash = collection.hashCode();
    // collectionSizes.put(hash, collection.size());
    // int i = 0;
    // for (Object o : collection) {
    // String oKey = key + Integer.toString(i++);
    // String oKey = Integer.toString(o.hashCode());
    // store(state, oKey, o);
    // // TODO if o instanceof Collection
    // if (o instanceof StateEditable) {
    // ((StateEditable) o).storeState(state);
    // }
    // }
    // }
    // }

    /**
     * Converts the nullObject into null.
     * 
     * @param obj
     * @return obj or null
     */
    public static Object restore(Object obj) {
        return nullObject.equals(obj) ? null : obj;
    }

    // public static void reStoreCollection(AbstractSet abstractSet) {
    // reStoreCollection((Collection) abstractSet);
    // }
    //
    // public static void reStoreCollection(Hashtable<Object, Object> state,
    // Object key, AbstractList abstractList) {
    // reStoreCollection((Collection) abstractList);
    // }
    //
    // private static Object reStoreCollection(Hashtable<Object, Object> state,
    // Object key, Collection collection) {
    // int i;
    // for (Object o : collection) {
    // Object oE = state.get(key);
    // }
    //
    // if (collection == null) {
    // state.put(key, nullObject);
    // } else {
    // state.put(key, collection);
    // for (Object o : collection) {
    // String oKey = key + Integer.toString(o.hashCode());
    // store(state, oKey, o);
    // if (o instanceof StateEditable) {
    // ((StateEditable) o).storeState(state);
    // }
    // }
    // }
    // return null;
    // }
}