/**
* GUI Commands
* Copyright 2005 Andrew Pietsch
*
* 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.
*
* $Id: AbstractBuilder.java,v 1.7 2006/02/26 00:59:04 pietschy Exp $
*/
package org.pietschy.command;
import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import java.util.ResourceBundle;
/**
* Provides common methods required by all builders.
*
* @author andrewp
* @version $Revision: 1.7 $
*/
public class
AbstractBuilder
{
private static final String _ID_ = "$Id: AbstractBuilder.java,v 1.7 2006/02/26 00:59:04 pietschy Exp $";
private CommandManager commandManager;
/**
* Gets the associated {@link CommandManager} for the builder to use as required. This will be
* configured when the builder is installed. The {@link CommandManager}
* is typically used to gain access the the class loader and resource bundle.
*
* @return the associated {@link CommandManager}.
* @see CommandManager#getClassLoader
*/
public CommandManager
getCommandManager()
{
return commandManager;
}
/**
* Sets the associated {@link CommandManager} for the builder to use as required. This will be
* configured when the builder is installed. The {@link CommandManager}
* is typically used to gain access the the class loader and resource bundle.
*
* @param commandManager the associated {@link CommandManager}.
* @see CommandManager#getClassLoader
*/
public void
setCommandManager(CommandManager commandManager)
{
this.commandManager = commandManager;
}
/**
* Gets the textural value of an element. If the element has {@link Names#I18N_ATTRIBUTE} then
* this method will attempt to load the value from the resource bundle.
*
* @param element the element whose text value is to be extracted.
* @return the text value of the element
*/
protected String
getElementText(Element element)
{
Attr i18nAttribute = element.getAttributeNode(Names.I18N_ATTRIBUTE);
if (i18nAttribute != null)
{
String key = i18nAttribute.getValue();
ResourceBundle bundle = getCommandManager().getResourceBundle();
if (bundle == null)
throw new IllegalStateException("resource bundle is null, unable to resolve resource '" + key + "' on " + getElementPath(element));
return bundle.getString(key);
}
return Util.getElementText(element);
}
/**
* Gets an attribute from an element. If the attribute is prefixed with {@link Names#I18N_ATTRIBUTE_PREFIX} then
* this method will attempt to load the attribute from the resource bundle. This method returns null if
* the the requested attribute isn't present.
*
* @param element the element constaining the attribute
* @param attributeName the attribute name
* @return the attribute value, or null if the attribute doesn't exist.
*/
protected String
getAttribute(Element element, String attributeName)
{
Attr attribute = element.getAttributeNode(attributeName);
if (attribute == null)
return null;
String value = attribute.getValue();
if (value.startsWith(Names.I18N_ATTRIBUTE_PREFIX))
{
String key = value.substring(Names.I18N_ATTRIBUTE_PREFIX.length());
ResourceBundle bundle = getCommandManager().getResourceBundle();
if (bundle == null)
throw new IllegalStateException("resource bundle is null, unable to resolve attribute '" + attributeName + "' on " + getElementPath(element));
value = bundle.getString(key);
}
return value;
}
/**
* Checks if the specified element is empty. Emply elements are those that have no children (not
* even an empty text node). A empty node is specified in the form <text/>. Empty
* nodes are used to signify that a particular face element is null and that it shouldn't inherit
* from its parent.
*
* @param element the element to check.
* @return true if the element has no children and no attributes, false otherwise.
*/
protected boolean
isEmptyElement(Element element)
{
return (!element.hasChildNodes() && !element.hasAttributes());
}
/**
* Returns a string representing the elements position in the command heirarchy. This method is only intended
* to produce debug information.
*
* @param element the element to examine.
* @return a string representing the elements posistion in the configuration heirarchy.
*/
public String
getElementPath(Element element)
{
// todo (ap): update this to display command ids
// element.
return element.getTagName() + " at unknown location";//element.getUniquePath();
}
/**
* Tests if the specified element has been conditionally included.
*
* This method will always return true
* if there is no include-if element. If present, this method will evaulate the exprerssion using
* {@link ConditionEvaluator#evaluate(String)} returning the result.
*
* @param e the element that may or may not have a include-if attriubte.
* @return false if and only if there is an include-if attribute and the
* expression evaluates to false.
*/
protected boolean
isIncluded(Element e)
{
String expression = getAttribute(e, Names.INCLUDE_IF_ATTRIBUTE);
if (expression == null)
return true;
try
{
// if the condition is false, we skip the element
return getCommandManager().getConditionEvaluator().evaluate(expression);
}
catch (EvaluationException ee)
{
throw new RuntimeException("Couldn't parse conditon", ee);
}
}
protected void
populateProperties(Command command, Element commandRoot)
{
NodeList elements = commandRoot.getElementsByTagName(Names.PROPERTY_ELEMENT);
for (int i = 0; i < elements.getLength(); i++)
{
Element e = (Element) elements.item(i);
command.putProperty(getAttribute(e, Names.NAME_ATTRIBUTE), getElementText(e).trim());
}
}
}