org.xchain.impl.FilterChainImpl.java Source code

Introduction

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

Source

/**
 *    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.Chain;
import org.xchain.Filter;
import org.apache.commons.jxpath.JXPathContext;
import java.util.List;
import java.util.ArrayList;
import java.util.ListIterator;
import java.util.LinkedList;

/**
 * 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 FilterChainImpl implements Filter, Chain {
    public static ThreadLocal<LinkedList<ListIterator<Command>>> iteratorStackThreadLocal = new ThreadLocal<LinkedList<ListIterator<Command>>>();

    protected List<Command> commandList = new ArrayList<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 = commandList.listIterator();
        while (iterator.hasNext()) {
            try {
                saveResult = iterator.next().execute(context);
                if (saveResult) {
                    break;
                }
            } catch (Exception e) {
                saveException = e;
                break;
            }
        }

        pushIterator(iterator);

        if (saveException != null) {
            throw saveException;
        }

        return saveResult;
    }

    public boolean postProcess(JXPathContext context, Exception exception) {
        ListIterator<Command> iterator = popIterator();

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

    public List<Command> getCommandList() {
        return commandList;
    }

    public void addCommand(Command command) {
        getCommandList().add(command);
    }

    public LinkedList<ListIterator<Command>> getIteratorStack() {
        LinkedList<ListIterator<Command>> iteratorStack = iteratorStackThreadLocal.get();

        if (iteratorStack == null) {
            iteratorStack = new LinkedList<ListIterator<Command>>();
            iteratorStackThreadLocal.set(iteratorStack);
        }

        return iteratorStack;
    }

    protected void pushIterator(ListIterator<Command> iterator) {
        getIteratorStack().addFirst(iterator);
    }

    protected ListIterator<Command> popIterator() {
        return getIteratorStack().removeFirst();
    }

}