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WebWork is a Java web-application development framework. It is built specifically with developer productivity and code simplicity in mind, providing robust support for building reusable UI templates, such as form controls, UI themes, internationalization, dynamic form parameter mapping to JavaBeans, robust client and server side validation, and much more.

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/*
 * Copyright (c) 2002-2003 by OpenSymphony
 * All rights reserved.
 */
package com.opensymphony.webwork.config;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;


/**
 * A Configuration implementation which stores an internal list of configuration objects. Each time
 * a config method is called (get, set, list, etc..) this class will go through the list of configurations
 * and call the method until successful.
 *
 * @author Rickard ?berg
 * @author Jason Carreira
 * @author Bill Lynch (docs)
 */
public class DelegatingConfiguration extends Configuration {

    Configuration[] configList;


    /**
     * Creates a new DelegatingConfiguration object given a list of {@link Configuration} implementations.
     *
     * @param aConfigList a list of Configuration implementations.
     */
    public DelegatingConfiguration(Configuration[] aConfigList) {
        configList = aConfigList;
    }


    /**
     * Sets the given property - calls setImpl(String, Object) method on config objects in the config
     * list until successful.
     *
     * @see #set(String, Object)
     */
    public void setImpl(String name, Object value) throws IllegalArgumentException, UnsupportedOperationException {
        // Determine which config to use by using get
        // Delegate to the other configurations
        IllegalArgumentException e = null;

        for (int i = 0; i < configList.length; i++) {
            try {
                configList[i].getImpl(name);

                // Found it, now try setting
                configList[i].setImpl(name, value);

                // Worked, now return
                return;
            } catch (IllegalArgumentException ex) {
                e = ex;

                // Try next config
            }
        }

        throw e;
    }

    /**
     * Gets the specified property - calls getImpl(String) method on config objects in config list
     * until successful.
     *
     * @see #get(String)
     */
    public Object getImpl(String name) throws IllegalArgumentException {
        // Delegate to the other configurations
        IllegalArgumentException e = null;

        for (int i = 0; i < configList.length; i++) {
            try {
                return configList[i].getImpl(name);
            } catch (IllegalArgumentException ex) {
                e = ex;

                // Try next config
            }
        }

        throw e;
    }

    /**
     * Determines if a paramter has been set - calls the isSetImpl(String) method on each config object
     * in config list. Returns true when one of the config implementations returns true. Returns
     * false otherwise.
     *
     * @see #isSet(String)
     */
    public boolean isSetImpl(String aName) {
        for (int i = 0; i < configList.length; i++) {
            if (configList[i].isSetImpl(aName)) {
                return true;
            }
        }

        return false;
    }

    /**
     * Returns a list of all property names - returns a list of all property names in all config
     * objects in config list.
     *
     * @see #list()
     */
    public Iterator listImpl() {
        boolean workedAtAll = false;

        Set settingList = new HashSet();
        UnsupportedOperationException e = null;

        for (int i = 0; i < configList.length; i++) {
            try {
                Iterator list = configList[i].listImpl();

                while (list.hasNext()) {
                    settingList.add(list.next());
                }

                workedAtAll = true;
            } catch (UnsupportedOperationException ex) {
                e = ex;

                // Try next config
            }
        }

        if (!workedAtAll) {
            throw (e == null) ? new UnsupportedOperationException() : e;
        } else {
            return settingList.iterator();
        }
    }
}