RELEASE_2_1_13/src/blocks/forms/java/org/apache/cocoon/forms/formmodel/AbstractWidget.java - cocoon - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You 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.apache.cocoon.forms.formmodel;

 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;

 import org.apache.cocoon.forms.FormsConstants;
 import org.apache.cocoon.forms.event.CreateEvent;
 import org.apache.cocoon.forms.event.ValueChangedListenerEnabled;
 import org.apache.cocoon.forms.event.WidgetEvent;
 import org.apache.cocoon.forms.validation.ValidationErrorAware;
 import org.apache.cocoon.forms.validation.WidgetValidator;
 import org.apache.cocoon.util.location.Location;
 import org.apache.cocoon.xml.AttributesImpl;

 import org.xml.sax.ContentHandler;
 import org.xml.sax.SAXException;

 /**
  * Abstract base class for Widget implementations. Provides functionality
  * common to many widgets.
  *
  * @version $Id$
  */
 public abstract class AbstractWidget implements Widget {

     /**
      * Containing parent-widget to this widget.
      * NOTE: avoid directly accessing this member since subclasses can mask this
      * property through own implemented getParent()
      */
     private Widget parent;

     /**
      * The widget's own state
      */
     private WidgetState state = WidgetState.ACTIVE;

     /**
      * Lazy loaded reference to the top-level form.
      */
     private Form form;

     /**
      * Validation-rules local to the widget instance
      */
     private List validators;

     /**
      * Storage for the widget allocated attributes
      */
     private Map attributes;

     /**
      * The result of the last call to {@link #validate()}.
      */
     protected boolean wasValid = true;


     protected AbstractWidget(AbstractWidgetDefinition definition) {
         this.state = definition.getState();
     }

     /**
      * Called after widget's environment has been setup,
      * to allow for any contextual initalization, such as
      * looking up case widgets for union widgets.
      */
     public void initialize() {
         ((AbstractWidgetDefinition)getDefinition()).widgetCreated(this);
     }

     /**
      * Gets the id of this widget.
      */
     public String getId() {
         return getDefinition().getId();
     }

     public String getName() {
         return getId();
     }

     /**
      * Concrete subclasses should allow access to their underlaying Definition
      * through this method.
      *
      * If subclasses decide to return <code>null</code> they should also organize
      * own implementations of {@link #getId()}, {@link #getLocation()},
      * {@link #validate()}, {@link #generateLabel(ContentHandler)} and
      * {@link #generateDisplayData(ContentHandler)} to avoid NPE's.
      *
      * @return the widgetDefinition from which this widget was instantiated.
      *        (See {@link org.apache.cocoon.forms.formmodel.WidgetDefinition#createInstance()})
      */
     public abstract WidgetDefinition getDefinition();

     /**
      * @return the location-information (file, line and column) where this widget was
      * configured.
      */
     public Location getLocation() {
         return getDefinition().getLocation();
     }

     /**
      * @return The parent-widget of this widget.
      */
     // This method is final in order for other methods in this class to use this.parent
     public final Widget getParent() {
         return this.parent;
     }

     /**
      * Sets the parent-widget of this widget.
      * This is a write-once property.
      *
      * @param widget the parent-widget of this one.
      * @throws IllegalStateException when the parent had already been set.
      */
     public void setParent(Widget widget) {
         if (this.parent != null) {
             throw new IllegalStateException("The parent of widget " + getRequestParameterName() + " should only be set once.");
         }
         this.parent = widget;
     }

     /**
      * @return the form where this widget belongs to.
      */
     public Form getForm() {
         if (this.form == null) {
             Widget myParent = getParent();
             if (myParent == null) {
                 this.form = (Form)this;
             } else {
                 this.form = myParent.getForm();
             }
         }
         return this.form;
     }

     public WidgetState getState() {
         return this.state;
     }

     public void setState(WidgetState state) {
         if (state == null) {
             throw new IllegalArgumentException("A widget state cannot be set to null");
         }
         this.state = state;

         // Update the browser
         getForm().addWidgetUpdate(this);
     }

     public WidgetState getCombinedState() {
         if (this.parent == null) {
             return this.state;
         }
         return WidgetState.strictest(this.state, this.parent.getCombinedState());
     }

     // Cached param names, used to speed up execution of the method below while
     // still allowing ids to change (e.g. repeater rows when they are reordered).
     private String cachedParentParamName;
     private String cachedParamName;

     /**
      * Should be called when a widget's own name has changed, in order to clear
      * internal caches used to compute request parameters.
      */
     protected void widgetNameChanged() {
         this.cachedParentParamName = null;
         this.cachedParamName = null;
     }

     public String getFullName() {
         return getRequestParameterName();
     }

     public String getRequestParameterName() {

         if (this.parent == null) {
             return getId();
         }

         String parentParamName = parent.getRequestParameterName();
         if (parentParamName.equals(this.cachedParentParamName)) {
             // Parent name hasn't changed, so ours hasn't changed too
             return this.cachedParamName;
         }

         // Compute our name and cache it
         this.cachedParentParamName = parentParamName;
         if (this.cachedParentParamName.length() == 0) {
             // the top level form returns an id == ""
             this.cachedParamName = getId();
         } else {
             this.cachedParamName = this.cachedParentParamName + "." + getId();
         }

         return this.cachedParamName;
     }

     public Widget lookupWidget(String path) {

         if (path == null || path.length() == 0) {
             return this;
         }

         Widget relativeWidget;
         String relativePath;
         int sepPosition = path.indexOf("" + Widget.PATH_SEPARATOR);

         if (sepPosition < 0) {
             //last step
             if (path.startsWith("..")) return getParent();
             return getChild(path);
         } else if (sepPosition == 0) {
             //absolute path
             relativeWidget = getForm();
             relativePath = path.substring(1);
         } else {
             if (path.startsWith(".." + Widget.PATH_SEPARATOR))  {
                 relativeWidget = getParent();
                 relativePath = path.substring(3);
             } else {
                 String childId = path.substring(0, sepPosition );
                 relativeWidget = getChild(childId);
                 relativePath = path.substring(sepPosition+1);
             }
         }

         if (relativeWidget == null) {
             return null;
         }

         return relativeWidget.lookupWidget(relativePath);
     }

     /**
      * Concrete widgets that contain actual child widgets should override to
      * return the actual child-widget.
      *
      * @param id of the child-widget
      * @return <code>null</code> if not overriden.
      */
     protected Widget getChild(String id) {
         return null;
     }

     public Widget getWidget(String id) {
         throw new UnsupportedOperationException("getWidget(id) got deprecated from the API. \n" +
                                                 "Consider using getChild(id) or even lookupWidget(path) instead.");
     }

     public Object getValue() {
         throw new UnsupportedOperationException("Widget " + this + " has no value, at " + getLocation());
     }

     public void setValue(Object object) {
         throw new UnsupportedOperationException("Widget " + this + " has no value, at " + getLocation());
     }

     public boolean isRequired() {
         return false;
     }

     /**
      * {@inheritDoc}
      *
      * Abstract implementation throws a {@link UnsupportedOperationException}.
      * Concrete subclass widgets need to override when supporting event broadcasting.
      */
     public void broadcastEvent(WidgetEvent event) {
         if (event instanceof CreateEvent) {
             ((AbstractWidgetDefinition) getDefinition()).fireCreateEvent((CreateEvent) event);
         } else {
             throw new UnsupportedOperationException("Widget " + getRequestParameterName() + " doesn't handle events.");
         }
     }

     /**
      * Add a validator to this widget instance.
      *
      * @param validator
      */
     public void addValidator(WidgetValidator validator) {
         if (this.validators == null) {
             this.validators = new ArrayList();
         }
         this.validators.add(validator);
     }

     /**
      * Remove a validator from this widget instance
      *
      * @param validator
      * @return <code>true</code> if the validator was found.
      */
     public boolean removeValidator(WidgetValidator validator) {
         if (this.validators != null) {
             return this.validators.remove(validator);
         }
         return false;
     }

     /**
      * @see org.apache.cocoon.forms.formmodel.Widget#validate()
      */
     public boolean validate() {
         // Consider widget valid if it is not validating values.
         if (!getCombinedState().isValidatingValues()) {
             this.wasValid = true;
             return true;
         }

         // Test validators from the widget definition
         if (!getDefinition().validate(this)) {
             // Failed
             this.wasValid = false;
             return false;
         }
         // Definition successful, test local validators
         if (this.validators != null) {
             Iterator iter = this.validators.iterator();
             while(iter.hasNext()) {
                 WidgetValidator validator = (WidgetValidator)iter.next();
                 if (!validator.validate(this)) {
                     this.wasValid = false;
                     return false;
                 }
             }
         }

         // Successful validation

         if (this instanceof ValidationErrorAware) {
             // Clear validation error if any
             ((ValidationErrorAware)this).setValidationError(null);
         }

         this.wasValid = true;
         return true;
     }

     /**
      * @see org.apache.cocoon.forms.formmodel.Widget#isValid()
      */
     public boolean isValid() {
         return this.wasValid;
     }

     /**
      * {@inheritDoc}
      *
      * Delegates to the {@link #getDefinition()} to generate the 'label' part of
      * the display-data of this widget.
      *
      * Subclasses should override if the getDefinition can return <code>null</code>
      * to avoid NPE's
      *
      * @param contentHandler
      * @throws SAXException
      */
     public void generateLabel(ContentHandler contentHandler) throws SAXException {
         if (getCombinedState().isDisplayingValues()) {
             getDefinition().generateDisplayData("label", contentHandler);
         }
     }

     /**
      * Generates nested additional content nested inside the main element for this
      * widget which is generated by {@link #generateSaxFragment(ContentHandler, Locale)}
      *
      * The implementation on the AbstractWidget level inserts no additional XML.
      * Subclasses need to override to insert widget specific content.
      *
      * @param contentHandler to send the SAX events to
      * @param locale in which context potential content needs to be put.
      * @throws SAXException
      */
     protected void generateItemSaxFragment(ContentHandler contentHandler, Locale locale) throws SAXException {
         // Do nothing
     }

     /**
      * The XML element name used in {@link #generateSaxFragment(ContentHandler, Locale)}
      * to produce the wrapping element for all the XML-instance-content of this Widget.
      *
      * @return the main elementname for this widget's sax-fragment.
      */
     protected abstract String getXMLElementName();

     /**
      * The XML attributes used in {@link #generateSaxFragment(ContentHandler, Locale)}
      * to be placed on the wrapping element for all the XML-instance-content of this Widget.
      *
      * This automatically adds @id={@link #getRequestParameterName()} to that element.
      * Concrete subclasses should call super.getXMLElementAttributes and possibly
      * add additional attributes.
      *
      * Note: the @id is not added for those widgets who's getId() returns <code>null</code>
      * (e.g. top-level container widgets like 'form').  The contract of returning a non-null
      * {@link AttributesImpl} is however maintained.
      *
      * @return the attributes for the main element for this widget's sax-fragment.
      */
     protected AttributesImpl getXMLElementAttributes() {
         AttributesImpl attrs = new AttributesImpl();
         // top-level widget-containers like forms might have their id set to ""
         // for those the @id should not be included.
         if (getId().length() != 0) {
             attrs.addCDATAAttribute("id", getRequestParameterName());
         }

         // Add the "state" attribute
         attrs.addCDATAAttribute("state", getCombinedState().getName());

         // Add the "listening" attribute is the value has change listeners
         if (this instanceof ValueChangedListenerEnabled &&
             ((ValueChangedListenerEnabled)this).hasValueChangedListeners()) {
             attrs.addCDATAAttribute("listening", "true");
         }
         return attrs;
     }

     /**
      * Delegates to the {@link #getDefinition()} of this widget to generate a common
      * set of 'display' data. (i.e. help, label, hint,...)
      *
      * Subclasses should override if the getDefinition can return <code>null</code>
      * to avoid NPE's.
      *
      * @param contentHandler where to send the SAX events to.
      * @throws SAXException
      *
      * @see WidgetDefinition#generateDisplayData(ContentHandler)
      */
     protected void generateDisplayData(ContentHandler contentHandler) throws SAXException {
         getDefinition().generateDisplayData(contentHandler);
     }

     /**
      * {@inheritDoc}
      *
      * This will generate some standard XML consisting of a simple wrapper
      * element (name provided by {@link #getXMLElementName()}) with attributes
      * (provided by {@link #getXMLElementAttributes()} around anything injected
      * in by both {@link #generateDisplayData(ContentHandler)} and
      * {@link #generateItemSaxFragment(ContentHandler, Locale)}.
      *
      * <pre>
      * &lt;fi:{@link #getXMLElementName()} {@link #getXMLElementAttributes()} &gt;
      *   {@link #generateDisplayData(ContentHandler)} (i.e. help, label, ...)
      *
      *   {@link #generateItemSaxFragment(ContentHandler, Locale)}
      * &lt;/fi:{@link #getXMLElementName()} &gt;
      * </pre>
      *
      * @param contentHandler to send the SAX events to
      * @param locale in which context potential content needs to be put.
      * @throws SAXException
      */
     public void generateSaxFragment(ContentHandler contentHandler, Locale locale)
     throws SAXException {

         if (getCombinedState().isDisplayingValues()) {
             // FIXME: we may want to strip out completely widgets that aren't updated when in AJAX mode
             String element = this.getXMLElementName();
             AttributesImpl attrs = getXMLElementAttributes();
             contentHandler.startElement(FormsConstants.INSTANCE_NS, element, FormsConstants.INSTANCE_PREFIX_COLON + element, attrs);

             generateDisplayData(contentHandler);

             if (locale == null) {
                 locale = getForm().getLocale();
             }

             generateItemSaxFragment(contentHandler, locale);

             contentHandler.endElement(FormsConstants.INSTANCE_NS, element, FormsConstants.INSTANCE_PREFIX_COLON + element);

         } else {
             // Generate a placeholder that can be used later by AJAX updates
             AttributesImpl attrs = new AttributesImpl();
             attrs.addCDATAAttribute("id", getRequestParameterName());
             contentHandler.startElement(FormsConstants.INSTANCE_NS, "placeholder", FormsConstants.INSTANCE_PREFIX_COLON + "placeholder", attrs);
             contentHandler.endElement(FormsConstants.INSTANCE_NS, "placeholder", FormsConstants.INSTANCE_PREFIX_COLON + "placeholder");
         }
     }

     public Object getAttribute(String name) {
         Object result = null;

         // First check locally
         if (this.attributes != null) {
             result = this.attributes.get(name);
         }

         // Fall back to the definition's attributes
         if (result == null) {
             result = getDefinition().getAttribute(name);
         }

         return result;
     }

     public void setAttribute(String name, Object value) {
         if (this.attributes == null) {
             this.attributes = new HashMap();
         }
         this.attributes.put(name, value);
     }

     public void removeAttribute(String name) {
         if (this.attributes != null) {
             this.attributes.remove(name);
         }
     }

     public String toString() {
         String className = this.getClass().getName();
         int last = className.lastIndexOf('.');
         if (last != -1) {
             className = className.substring(last+1);
         }

         String name = getRequestParameterName();
         return name.length() == 0 ? className : className + " '" + getRequestParameterName() + "'";
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You 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.apache.cocoon.forms.formmodel;

	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Locale;
	import java.util.Map;

	import org.apache.cocoon.forms.FormsConstants;
	import org.apache.cocoon.forms.event.CreateEvent;
	import org.apache.cocoon.forms.event.ValueChangedListenerEnabled;
	import org.apache.cocoon.forms.event.WidgetEvent;
	import org.apache.cocoon.forms.validation.ValidationErrorAware;
	import org.apache.cocoon.forms.validation.WidgetValidator;
	import org.apache.cocoon.util.location.Location;
	import org.apache.cocoon.xml.AttributesImpl;

	import org.xml.sax.ContentHandler;
	import org.xml.sax.SAXException;

	/**
	* Abstract base class for Widget implementations. Provides functionality
	* common to many widgets.
	*
	* @version $Id$
	*/
	public abstract class AbstractWidget implements Widget {

	/**
	* Containing parent-widget to this widget.
	* NOTE: avoid directly accessing this member since subclasses can mask this
	* property through own implemented getParent()
	*/
	private Widget parent;

	/**
	* The widget's own state
	*/
	private WidgetState state = WidgetState.ACTIVE;

	/**
	* Lazy loaded reference to the top-level form.
	*/
	private Form form;

	/**
	* Validation-rules local to the widget instance
	*/
	private List validators;

	/**
	* Storage for the widget allocated attributes
	*/
	private Map attributes;

	/**
	* The result of the last call to {@link #validate()}.
	*/
	protected boolean wasValid = true;


	protected AbstractWidget(AbstractWidgetDefinition definition) {
	this.state = definition.getState();
	}

	/**
	* Called after widget's environment has been setup,
	* to allow for any contextual initalization, such as
	* looking up case widgets for union widgets.
	*/
	public void initialize() {
	((AbstractWidgetDefinition)getDefinition()).widgetCreated(this);
	}

	/**
	* Gets the id of this widget.
	*/
	public String getId() {
	return getDefinition().getId();
	}

	public String getName() {
	return getId();
	}

	/**
	* Concrete subclasses should allow access to their underlaying Definition
	* through this method.
	*
	* If subclasses decide to return <code>null</code> they should also organize
	* own implementations of {@link #getId()}, {@link #getLocation()},
	* {@link #validate()}, {@link #generateLabel(ContentHandler)} and
	* {@link #generateDisplayData(ContentHandler)} to avoid NPE's.
	*
	* @return the widgetDefinition from which this widget was instantiated.
	* (See {@link org.apache.cocoon.forms.formmodel.WidgetDefinition#createInstance()})
	*/
	public abstract WidgetDefinition getDefinition();

	/**
	* @return the location-information (file, line and column) where this widget was
	* configured.
	*/
	public Location getLocation() {
	return getDefinition().getLocation();
	}

	/**
	* @return The parent-widget of this widget.
	*/
	// This method is final in order for other methods in this class to use this.parent
	public final Widget getParent() {
	return this.parent;
	}

	/**
	* Sets the parent-widget of this widget.
	* This is a write-once property.
	*
	* @param widget the parent-widget of this one.
	* @throws IllegalStateException when the parent had already been set.
	*/
	public void setParent(Widget widget) {
	if (this.parent != null) {
	throw new IllegalStateException("The parent of widget " + getRequestParameterName() + " should only be set once.");
	}
	this.parent = widget;
	}

	/**
	* @return the form where this widget belongs to.
	*/
	public Form getForm() {
	if (this.form == null) {
	Widget myParent = getParent();
	if (myParent == null) {
	this.form = (Form)this;
	} else {
	this.form = myParent.getForm();
	}
	}
	return this.form;
	}

	public WidgetState getState() {
	return this.state;
	}

	public void setState(WidgetState state) {
	if (state == null) {
	throw new IllegalArgumentException("A widget state cannot be set to null");
	}
	this.state = state;

	// Update the browser
	getForm().addWidgetUpdate(this);
	}

	public WidgetState getCombinedState() {
	if (this.parent == null) {
	return this.state;
	}
	return WidgetState.strictest(this.state, this.parent.getCombinedState());
	}

	// Cached param names, used to speed up execution of the method below while
	// still allowing ids to change (e.g. repeater rows when they are reordered).
	private String cachedParentParamName;
	private String cachedParamName;

	/**
	* Should be called when a widget's own name has changed, in order to clear
	* internal caches used to compute request parameters.
	*/
	protected void widgetNameChanged() {
	this.cachedParentParamName = null;
	this.cachedParamName = null;
	}

	public String getFullName() {
	return getRequestParameterName();
	}

	public String getRequestParameterName() {

	if (this.parent == null) {
	return getId();
	}

	String parentParamName = parent.getRequestParameterName();
	if (parentParamName.equals(this.cachedParentParamName)) {
	// Parent name hasn't changed, so ours hasn't changed too
	return this.cachedParamName;
	}

	// Compute our name and cache it
	this.cachedParentParamName = parentParamName;
	if (this.cachedParentParamName.length() == 0) {
	// the top level form returns an id == ""
	this.cachedParamName = getId();
	} else {
	this.cachedParamName = this.cachedParentParamName + "." + getId();
	}

	return this.cachedParamName;
	}

	public Widget lookupWidget(String path) {

	if (path == null \|\| path.length() == 0) {
	return this;
	}

	Widget relativeWidget;
	String relativePath;
	int sepPosition = path.indexOf("" + Widget.PATH_SEPARATOR);

	if (sepPosition < 0) {
	//last step
	if (path.startsWith("..")) return getParent();
	return getChild(path);
	} else if (sepPosition == 0) {
	//absolute path
	relativeWidget = getForm();
	relativePath = path.substring(1);
	} else {
	if (path.startsWith(".." + Widget.PATH_SEPARATOR)) {
	relativeWidget = getParent();
	relativePath = path.substring(3);
	} else {
	String childId = path.substring(0, sepPosition );
	relativeWidget = getChild(childId);
	relativePath = path.substring(sepPosition+1);
	}
	}

	if (relativeWidget == null) {
	return null;
	}

	return relativeWidget.lookupWidget(relativePath);
	}

	/**
	* Concrete widgets that contain actual child widgets should override to
	* return the actual child-widget.
	*
	* @param id of the child-widget
	* @return <code>null</code> if not overriden.
	*/
	protected Widget getChild(String id) {
	return null;
	}

	public Widget getWidget(String id) {
	throw new UnsupportedOperationException("getWidget(id) got deprecated from the API. \n" +
	"Consider using getChild(id) or even lookupWidget(path) instead.");
	}

	public Object getValue() {
	throw new UnsupportedOperationException("Widget " + this + " has no value, at " + getLocation());
	}

	public void setValue(Object object) {
	throw new UnsupportedOperationException("Widget " + this + " has no value, at " + getLocation());
	}

	public boolean isRequired() {
	return false;
	}

	/**
	* {@inheritDoc}
	*
	* Abstract implementation throws a {@link UnsupportedOperationException}.
	* Concrete subclass widgets need to override when supporting event broadcasting.
	*/
	public void broadcastEvent(WidgetEvent event) {
	if (event instanceof CreateEvent) {
	((AbstractWidgetDefinition) getDefinition()).fireCreateEvent((CreateEvent) event);
	} else {
	throw new UnsupportedOperationException("Widget " + getRequestParameterName() + " doesn't handle events.");
	}
	}

	/**
	* Add a validator to this widget instance.
	*
	* @param validator
	*/
	public void addValidator(WidgetValidator validator) {
	if (this.validators == null) {
	this.validators = new ArrayList();
	}
	this.validators.add(validator);
	}

	/**
	* Remove a validator from this widget instance
	*
	* @param validator
	* @return <code>true</code> if the validator was found.
	*/
	public boolean removeValidator(WidgetValidator validator) {
	if (this.validators != null) {
	return this.validators.remove(validator);
	}
	return false;
	}

	/**
	* @see org.apache.cocoon.forms.formmodel.Widget#validate()
	*/
	public boolean validate() {
	// Consider widget valid if it is not validating values.
	if (!getCombinedState().isValidatingValues()) {
	this.wasValid = true;
	return true;
	}

	// Test validators from the widget definition
	if (!getDefinition().validate(this)) {
	// Failed
	this.wasValid = false;
	return false;
	}
	// Definition successful, test local validators
	if (this.validators != null) {
	Iterator iter = this.validators.iterator();
	while(iter.hasNext()) {
	WidgetValidator validator = (WidgetValidator)iter.next();
	if (!validator.validate(this)) {
	this.wasValid = false;
	return false;
	}
	}
	}

	// Successful validation

	if (this instanceof ValidationErrorAware) {
	// Clear validation error if any
	((ValidationErrorAware)this).setValidationError(null);
	}

	this.wasValid = true;
	return true;
	}

	/**
	* @see org.apache.cocoon.forms.formmodel.Widget#isValid()
	*/
	public boolean isValid() {
	return this.wasValid;
	}

	/**
	* {@inheritDoc}
	*
	* Delegates to the {@link #getDefinition()} to generate the 'label' part of
	* the display-data of this widget.
	*
	* Subclasses should override if the getDefinition can return <code>null</code>
	* to avoid NPE's
	*
	* @param contentHandler
	* @throws SAXException
	*/
	public void generateLabel(ContentHandler contentHandler) throws SAXException {
	if (getCombinedState().isDisplayingValues()) {
	getDefinition().generateDisplayData("label", contentHandler);
	}
	}

	/**
	* Generates nested additional content nested inside the main element for this
	* widget which is generated by {@link #generateSaxFragment(ContentHandler, Locale)}
	*
	* The implementation on the AbstractWidget level inserts no additional XML.
	* Subclasses need to override to insert widget specific content.
	*
	* @param contentHandler to send the SAX events to
	* @param locale in which context potential content needs to be put.
	* @throws SAXException
	*/
	protected void generateItemSaxFragment(ContentHandler contentHandler, Locale locale) throws SAXException {
	// Do nothing
	}

	/**
	* The XML element name used in {@link #generateSaxFragment(ContentHandler, Locale)}
	* to produce the wrapping element for all the XML-instance-content of this Widget.
	*
	* @return the main elementname for this widget's sax-fragment.
	*/
	protected abstract String getXMLElementName();

	/**
	* The XML attributes used in {@link #generateSaxFragment(ContentHandler, Locale)}
	* to be placed on the wrapping element for all the XML-instance-content of this Widget.
	*
	* This automatically adds @id={@link #getRequestParameterName()} to that element.
	* Concrete subclasses should call super.getXMLElementAttributes and possibly
	* add additional attributes.
	*
	* Note: the @id is not added for those widgets who's getId() returns <code>null</code>
	* (e.g. top-level container widgets like 'form'). The contract of returning a non-null
	* {@link AttributesImpl} is however maintained.
	*
	* @return the attributes for the main element for this widget's sax-fragment.
	*/
	protected AttributesImpl getXMLElementAttributes() {
	AttributesImpl attrs = new AttributesImpl();
	// top-level widget-containers like forms might have their id set to ""
	// for those the @id should not be included.
	if (getId().length() != 0) {
	attrs.addCDATAAttribute("id", getRequestParameterName());
	}

	// Add the "state" attribute
	attrs.addCDATAAttribute("state", getCombinedState().getName());

	// Add the "listening" attribute is the value has change listeners
	if (this instanceof ValueChangedListenerEnabled &&
	((ValueChangedListenerEnabled)this).hasValueChangedListeners()) {
	attrs.addCDATAAttribute("listening", "true");
	}
	return attrs;
	}

	/**
	* Delegates to the {@link #getDefinition()} of this widget to generate a common
	* set of 'display' data. (i.e. help, label, hint,...)
	*
	* Subclasses should override if the getDefinition can return <code>null</code>
	* to avoid NPE's.
	*
	* @param contentHandler where to send the SAX events to.
	* @throws SAXException
	*
	* @see WidgetDefinition#generateDisplayData(ContentHandler)
	*/
	protected void generateDisplayData(ContentHandler contentHandler) throws SAXException {
	getDefinition().generateDisplayData(contentHandler);
	}

	/**
	* {@inheritDoc}
	*
	* This will generate some standard XML consisting of a simple wrapper
	* element (name provided by {@link #getXMLElementName()}) with attributes
	* (provided by {@link #getXMLElementAttributes()} around anything injected
	* in by both {@link #generateDisplayData(ContentHandler)} and
	* {@link #generateItemSaxFragment(ContentHandler, Locale)}.
	*
	* <pre>
	* <fi:{@link #getXMLElementName()} {@link #getXMLElementAttributes()} >
	* {@link #generateDisplayData(ContentHandler)} (i.e. help, label, ...)
	*
	* {@link #generateItemSaxFragment(ContentHandler, Locale)}
	* </fi:{@link #getXMLElementName()} >
	* </pre>
	*
	* @param contentHandler to send the SAX events to
	* @param locale in which context potential content needs to be put.
	* @throws SAXException
	*/
	public void generateSaxFragment(ContentHandler contentHandler, Locale locale)
	throws SAXException {

	if (getCombinedState().isDisplayingValues()) {
	// FIXME: we may want to strip out completely widgets that aren't updated when in AJAX mode
	String element = this.getXMLElementName();
	AttributesImpl attrs = getXMLElementAttributes();
	contentHandler.startElement(FormsConstants.INSTANCE_NS, element, FormsConstants.INSTANCE_PREFIX_COLON + element, attrs);

	generateDisplayData(contentHandler);

	if (locale == null) {
	locale = getForm().getLocale();
	}

	generateItemSaxFragment(contentHandler, locale);

	contentHandler.endElement(FormsConstants.INSTANCE_NS, element, FormsConstants.INSTANCE_PREFIX_COLON + element);

	} else {
	// Generate a placeholder that can be used later by AJAX updates
	AttributesImpl attrs = new AttributesImpl();
	attrs.addCDATAAttribute("id", getRequestParameterName());
	contentHandler.startElement(FormsConstants.INSTANCE_NS, "placeholder", FormsConstants.INSTANCE_PREFIX_COLON + "placeholder", attrs);
	contentHandler.endElement(FormsConstants.INSTANCE_NS, "placeholder", FormsConstants.INSTANCE_PREFIX_COLON + "placeholder");
	}
	}

	public Object getAttribute(String name) {
	Object result = null;

	// First check locally
	if (this.attributes != null) {
	result = this.attributes.get(name);
	}

	// Fall back to the definition's attributes
	if (result == null) {
	result = getDefinition().getAttribute(name);
	}

	return result;
	}

	public void setAttribute(String name, Object value) {
	if (this.attributes == null) {
	this.attributes = new HashMap();
	}
	this.attributes.put(name, value);
	}

	public void removeAttribute(String name) {
	if (this.attributes != null) {
	this.attributes.remove(name);
	}
	}

	public String toString() {
	String className = this.getClass().getName();
	int last = className.lastIndexOf('.');
	if (last != -1) {
	className = className.substring(last+1);
	}

	String name = getRequestParameterName();
	return name.length() == 0 ? className : className + " '" + getRequestParameterName() + "'";
	}
	}