content: /*
   * ObjectFactory.java July 2006
   *
   * Copyright (C) 2006, Niall Gallagher <niallg@users.sf.net>
   *
   * 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.
   */
  
  package com.aliyun.odps.simpleframework.xml.core;
  
  import com.aliyun.odps.simpleframework.xml.strategy.Type;
  import com.aliyun.odps.simpleframework.xml.strategy.Value;
  import com.aliyun.odps.simpleframework.xml.stream.InputNode;
  
  /**
   * The <code>ObjectFactory</code> is the most basic factory. This will
   * basically check to see if there is an override type within the XML
   * node provided, if there is then that is instantiated, otherwise the
   * field type is instantiated. Any type created must have a default
   * no argument constructor. If the override type is an abstract class
   * or an interface then this factory throws an exception.
   *  
   * @author Niall Gallagher
   */ 
  class ObjectFactory extends PrimitiveFactory {
     
     /**
      * Constructor for the <code>ObjectFactory</code> class. This is
      * given the field class that this should create object instances
      * of. If the field type is abstract then the XML node must have
      * sufficient information for the <code>Strategy</code> object to
      * resolve the implementation class to be instantiated.
      *
      * @param context the contextual object used by the persister 
      * @param type this is the object type to use for this factory 
      */
     public ObjectFactory(Context context, Type type, Class override) {
        super(context, type, override);
     }        
  
     /**
      * This method will instantiate an object of the field type, or if
      * the <code>Strategy</code> object can resolve a class from the
      * XML element then this is used instead. If the resulting type is
      * abstract or an interface then this method throws an exception.
      * 
      * @param node this is the node to check for the override
      * 
      * @return this returns an instance of the resulting type
      */       
     @Override
     public Instance getInstance(InputNode node) throws Exception {
        Value value = getOverride(node);
        Class expect = getType();
      
        if(value == null) { 
           if(!isInstantiable(expect)) {
              throw new InstantiationException("Cannot instantiate %s for %s", expect, type);              
           }
           return context.getInstance(expect);         
        }
        return new ObjectInstance(context, value);      
     }     
  }
  