org.xchain.impl.CommandList.java Source code

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Here is the source code for org.xchain.impl.CommandList.java

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/**
 *    Copyright 2011 meltmedia
 *
 *    Licensed 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
 *    limitations under the License.
 */
package org.xchain.impl;

import org.xchain.Command;
import org.xchain.Filter;
import org.apache.commons.jxpath.JXPathContext;
import java.util.ArrayList;
import java.util.ListIterator;

/**
 * Almost an exact port of the class org.apache.commons.chain.impl.ChainBase, except the
 * nested chains are represented with a java.util.ArrayList instead of an array.
 *
 * @author Craig R. McClanahan
 * @author Christian Trimble
 */
public class CommandList extends ArrayList<Command> implements Command {
    public boolean execute(JXPathContext context) throws Exception {
        // Verify our parameters
        if (context == null) {
            throw new IllegalArgumentException();
        }

        // Execute the commands in this list until one returns true
        // or throws an exception
        boolean saveResult = false;
        Exception saveException = null;
        ListIterator<Command> iterator = listIterator();
        while (iterator.hasNext()) {
            try {
                saveResult = iterator.next().execute(context);
                if (saveResult) {
                    break;
                }
            } catch (Exception e) {
                saveException = e;
                break;
            }
        }

        boolean handled = false;
        boolean result = false;
        while (iterator.hasPrevious()) {
            Object previous = iterator.previous();
            if (previous instanceof Filter) {
                try {
                    result = ((Filter) previous).postProcess(context, saveException);
                    if (result) {
                        handled = true;
                    }
                } catch (Exception e) {
                    // Silently ignore
                }
            }
        }

        // Return the exception or result state from the last execute()
        if ((saveException != null) && !handled) {
            throw saveException;
        } else {
            return (saveResult);
        }
    }
}