/*

  * 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.myfaces.taglib.core;

 import javax.servlet.jsp.tagext.TagSupport;

 import javax.servlet.jsp.JspException;

 import javax.faces.webapp.UIComponentClassicTagBase;

 import javax.faces.webapp.UIComponentELTag;

 import javax.faces.component.UIComponent;

 import javax.faces.context.FacesContext;

 import javax.el.ValueExpression;

 import javax.el.ELContext;

 import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFJspAttribute;

 import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFJspTag;

 /**

  * This tag associates an attribute with the nearest parent UIComponent.

  * <p>

  * When the value is not an EL expression, this tag has the same effect as calling component.getAttributes.put(name,

  * value). When the attribute name specified matches a standard property of the component, that property is set. However

  * it is also valid to assign attributes to components using any arbitrary name; the component itself won't make any use

  * of these but other objects such as custom renderers, validators or action listeners can later retrieve the attribute

  * from the component by name.

  * </p>

  * <p>

  * When the value is an EL expression, this tag has the same effect as calling component.setValueBinding. A call to

  * method component.getAttributes().get(name) will then cause that expression to be evaluated and the result of the

  * expression is returned, not the original EL expression string.

  * </p>

  * <p>

  * See the javadoc for UIComponent.getAttributes for more details.

  * </p>

  * <p>

  * Unless otherwise specified, all attributes accept static values or EL expressions.

  * </p>

  * 

  * @author Manfred Geiler (latest modification by $Author$)

  * @author Bruno Aranda (JSR-252)

  * @version $Revision$ $Date$

  */

 @JSFJspTag(name = "f:attribute", bodyContent = "empty")

 public class AttributeTag extends TagSupport

 {

     private static final long serialVersionUID = 31476300171678632L;

     private ValueExpression _nameExpression;

     private ValueExpression _valueExpression;

     /**

      * The name of the attribute.

      * 

      * @param nameExpression

      */

     @JSFJspAttribute(className="javax.el.ValueExpression",

             deferredValueType="java.lang.String")

     public void setName(ValueExpression nameExpression)

     {

         _nameExpression = nameExpression;

     }

     /**

      * The attribute's value.

      * 

      * @param valueExpression

      */

     @JSFJspAttribute(className="javax.el.ValueExpression",

             deferredValueType="java.lang.Object")

     public void setValue(ValueExpression valueExpression)

     {

         _valueExpression = valueExpression;

     }

     @Override

     public int doStartTag() throws JspException

     {

         UIComponentClassicTagBase componentTag = UIComponentELTag.getParentUIComponentClassicTagBase(pageContext);

         if (componentTag == null)

         {

             throw new JspException("no parent UIComponentTag found");

         }

         UIComponent component = componentTag.getComponentInstance();

         if (component == null)

         {

             throw new JspException("parent UIComponentTag has no UIComponent");

         }

         FacesContext facesContext = FacesContext.getCurrentInstance();

         ELContext elContext = facesContext.getELContext();

         String name = null;

         Object value = null;

         boolean isLiteral = false;

         if (_nameExpression != null)

         {

             name = (String)_nameExpression.getValue(elContext);

         }

         if (_valueExpression != null)

         {

             isLiteral = _valueExpression.isLiteralText();

             value = _valueExpression.getValue(elContext);

         }

         if (name != null)

         {

             if (component.getAttributes().get(name) == null)

             {

                 if (isLiteral)

                 {

                     component.getAttributes().put(name, value);

                 }

                 else

                 {

                     component.setValueExpression(name, _valueExpression);

                 }

             }

         }

         return SKIP_BODY;

     }

     @Override

     public void release()

     {

         super.release();

         _nameExpression = null;

         _valueExpression = null;

     }

 }