iterator.java

一个工作流设计及定义的系统,可以直接与数据库结合进行系统工作流程的定义及应用.

/*
 * Copyright (c) 2005, John Mettraux, OpenWFE.org
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 * . Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.  
 * 
 * . Redistributions in binary form must reproduce the above copyright notice, 
 *   this list of conditions and the following disclaimer in the documentation 
 *   and/or other materials provided with the distribution.
 * 
 * . Neither the name of the "OpenWFE" nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without
 *   specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * $Id: Iterator.java,v 1.18 2005/07/26 20:54:47 jmettraux Exp $
 */

//
// Iterator.java
//
// [e-mail]
//
// generated with 
// jtmpl 1.1.00 16.08.2003 John Mettraux ([e-mail])
//

package openwfe.org.engine.expressions;

import openwfe.org.OpenWfeException;
import openwfe.org.engine.Definitions;
import openwfe.org.engine.launch.Launcher;
import openwfe.org.engine.workitem.InFlowWorkItem;
import openwfe.org.engine.workitem.StringAttribute;
import openwfe.org.engine.expressions.raw.RawExpression;
import openwfe.org.engine.expressions.sync.SynchableExpression;


/**
 * An iterator will iterate for IteratorExpression and 
 * ConcurrentIteratorExpression, it does the job of keeping track
 * of the loops for them.
 *
 * <p><font size=2>CVS Info :
 * <br>$Author: jmettraux $
 * <br>$Id: Iterator.java,v 1.18 2005/07/26 20:54:47 jmettraux Exp $ </font>
 *
 * @author [e-mail]
 */
public class Iterator

    implements java.io.Serializable

{
    static final long serialVersionUID = -2532616767097005828L;

    private final static org.apache.log4j.Logger log = org.apache.log4j.Logger
        .getLogger(Iterator.class.getName());

    //
    // CONSTANTS & co

    /**
     * You may determine on what to iterate with<br>
     * <ul>
     *   <li>on-value</li>
     *   <li>on-field-value</li>
     *   <li>on-variable-value</li>
     * </ul>
     * <br>
     * That's why we have this prefix.
     */
    public final static String VALUE_PREFIX
        = "on-";

    /**
     * if no TO_FIELD and no TO_VARIABLE is provided, the current iteration
     * value will be stored in the variable named here.
     */
    public final static String DEFAULT_TO_VARIABLE
        = "__iteration_value__";

    /**
     * Use this parameter to set the regex used to split the value string into 
     * the different values.
     * By default it is set to ", *"
     */
    public final static String VALUE_SEPARATOR
        = "value-separator";

    /**
     * As already stated, this default separator is ", *"
     */
    public final static String DEFAULT_VALUE_SEPARATOR
        = ", *";

    //
    // FIELDS

    private int iterationPosition = -1;
    private java.util.List iterationList = null;

    private FlowExpressionId templateId = null;

    //
    // CONSTRUCTORS

    /**
     * This constructor is necessary in order to xml-deserialize
     * the Iterator out of the pool (it is embedded in an IteratorExpression
     * though)
     */
    public Iterator ()
    {
        super();
    }

    public Iterator 
        (final FlowExpression iteratingExpression, 
         final InFlowWorkItem wi)
    throws 
        ApplyException
    {
        super();

        prepareIterationList(iteratingExpression, wi);
    }

    //
    // BEAN METHODS

    public int getIterationPosition () { return this.iterationPosition; }
    public java.util.List getIterationList () { return this.iterationList; }
    public FlowExpressionId getTemplateId () { return this.templateId; }

    public void setIterationPosition (int i) { this.iterationPosition = i; }
    public void setIterationList (java.util.List l) { this.iterationList = l; }
    public void setTemplateId (FlowExpressionId fei) { this.templateId = fei; }

    //
    // METHODS

    /**
     * Returns the current value for the iteration.
     */
    public Object currentIterationValue ()
    {
        try
        {
            return this.iterationList.get(this.iterationPosition);
        }
        catch (ArrayIndexOutOfBoundsException e)
        {
        }
        return null;
    }

    /**
     * Will return true if a next iteration step is possible.
     */
    public boolean hasNext ()
    {
        if (this.iterationList == null || this.iterationList.size() < 1)
            return false;

        boolean result =
            (this.iterationPosition < this.iterationList.size()-1);

        log.debug("hasNext() ? "+result);

        return result;
    }

    /**
     * For the given iteratingExpression and workitem, will step to
     * the next iteration.
     */
    public void next 
        (final OneChildExpression iteratingExpression, 
         final InFlowWorkItem wi)
    throws 
        OpenWfeException
    {
        if (this.templateId == null)
            this.templateId = iteratingExpression.getChildExpressionId();

        iteratingExpression.tag(wi);
        log.debug("next() tagged workitem");

        //final String sIteration = ""+this.iterationPosition+".";
        this.iterationPosition++;

        log.debug("next() iterationPosition : "+this.iterationPosition);

        log.debug("next() currentIterationValue >"+currentIterationValue()+"<");

        //
        // launch scope

        try
        {
            //
            // prepare workitem (set field if needed)
            //
            ValueUtils.determineAndSetTarget
                ("to-", // 'to-field' or 'to-variable'
                 iteratingExpression,
                 wi,
                 currentIterationValue());

            final Launcher launcher = Definitions
                .getLauncher(iteratingExpression.context());

            final FlowExpressionId subRootExpressionId = launcher.launchSub
                (wi, 
                 iteratingExpression.getId(), 
                 iteratingExpression.getChildExpressionId());

            //
            // prepare child expression (set variable if needed)
            //
            ValueUtils.determineAndSetTarget
                ("to-", // 'to-field' or 'to-variable'
                 iteratingExpression,
                 subRootExpressionId,
                 wi,
                 currentIterationValue());

            /*
            if (iteratingExpression instanceof SynchableExpression)
                //
                // in the case of a synchable expression, this iterator
                // takes care of registering the scope root expression
                // as a (awaited) child
            {
                ((SynchableExpression)iteratingExpression)
                    .getSyncExpression().addChild(subRootExpressionId);

                log.debug
                    ("next() added child to sync expression : "+
                     subRootExpressionId);
            }
            */
        }
        catch (OpenWfeException owe)
        {
            throw new ApplyException
                ("Failed to apply next scope", owe);
        }

        //
        // if last iteration, remove template
        
        if ( ! this.hasNext())
        {
            iteratingExpression.getExpressionPool()
                .removeExpression(this.templateId);

            log.debug("next() removed template "+this.templateId);
        }
    }

    //
    // other METHODS

    protected void prepareIterationList 
        (final FlowExpression iteratingExpression, 
         final InFlowWorkItem wi)
    throws 
        ApplyException
    {
        //
        // determine on what we will iterate
        
        Object val = null;
        try
        {
            val = ValueUtils
                .determineValue(VALUE_PREFIX, iteratingExpression, wi);
        }
        catch (ValueException ve)
        {
            throw new ApplyException
                ("Failed to determine value to iterate on", ve);
        }

        //
        // determine value separator regex
        
        String separatorRegex = (String)iteratingExpression.getAttributes()
            .get(VALUE_SEPARATOR);
        if (separatorRegex == null)
            separatorRegex = DEFAULT_VALUE_SEPARATOR;
        
        //
        // turn the value into a list
        
        if (val == null)
        {
            this.iterationList = null;
        }
        else if (val instanceof java.util.List)
        {
            this.iterationList = (java.util.List)val;
        }
        else if (val instanceof String ||
                 val instanceof StringAttribute)
        {
            String[] ss = val.toString().split(separatorRegex);

            this.iterationList = new java.util.ArrayList(ss.length);

            for (int i=0; i<ss.length; i++)
                this.iterationList.add(ss[i].trim());
        }
        else
        {
            throw new ApplyException
                ("value of class '"+val.getClass().getName()+
                 "' is not suitable for iteration");
        }
    }

}