JSONChildParser.java

/*******************************************************************************
 * Copyright (c) 2009, 2012 SpringSource, a divison of VMware, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     SpringSource, a division of VMware, Inc. - initial API and implementation
 *******************************************************************************/

package org.eclipse.virgo.ide.internal.utils.json;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

/**
 * Provides a simple parser that visits children objects safely, whether they exist as single JSON objects, JSON arrays,
 * or not at all.
 *
 * Usage: Simply give the parser the parent object and child key, and implement {@link #parse(JSONObject)} with the
 * processing you need.
 *
 * (The existing JSON files often store single value entities as objects not as a JSON Array of size 1.)
 *
 * @author Miles Parker
 *
 */
public abstract class JSONChildParser implements SimpleJSONParser {

    String key;

    JSONObject parent;

    /**
     * Constructs and executes the parser.
     *
     * @param parent Any parent JSON object.
     * @param key A key within the parent that identifies an object, an array, or nothing at all.
     */
    public JSONChildParser(JSONObject parent, String key) throws JSONException {
        super();
        this.key = key;
        this.parent = parent;
        apply();
    }

    private void apply() throws JSONException {
        if (this.parent.has(this.key)) {
            Object packageNode = this.parent.get(this.key);
            if (packageNode instanceof JSONObject) {
                JSONObject packageObject = (JSONObject) packageNode;
                parse(packageObject);
            } else {
                JSONArray packageArray = (JSONArray) packageNode;
                for (int i = 0; i < packageArray.length(); i++) {
                    JSONObject packageObject = (JSONObject) packageArray.get(i);
                    parse(packageObject);
                }
            }
        }
    }
}