/*
    * 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 javax.faces.webapp;
  
  import javax.faces.component.UIComponent;
  import javax.faces.component.ValueHolder;
  import javax.faces.convert.Converter;
  import javax.servlet.jsp.JspException;
  import javax.servlet.jsp.tagext.Tag;
  import javax.servlet.jsp.tagext.TagSupport;
  
  /**
   * @since 1.2
   */
  public abstract class ConverterELTag extends TagSupport
  {
      private static final long serialVersionUID = -616834506829108081L;
  
      @Override
      public int doStartTag() throws JspException
      {
          UIComponentClassicTagBase componentTag = UIComponentELTag.getParentUIComponentClassicTagBase(pageContext);
          if (componentTag == null)
          {
              throw new JspException("no parent UIComponentTag found");
          }
          if (!componentTag.getCreated())
          {
              return Tag.SKIP_BODY;
          }
  
          UIComponent component = componentTag.getComponentInstance();
          if (component == null)
          {
              throw new JspException("parent UIComponentTag has no UIComponent");
          }
          if (!(component instanceof ValueHolder))
          {
              throw new JspException("UIComponent is no ValueHolder");
          }
  
          Converter converter = createConverter();
  
          ((ValueHolder)component).setConverter(converter);
  
          return Tag.SKIP_BODY;
      }
  
      protected abstract Converter createConverter() throws JspException;
  }