content: /*
   * Instance.java January 2007
   *
   * Copyright (C) 2007, 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.Value;
  
  /**
   * The <code>Instance</code> object creates a type that is represented 
   * by an XML element. Typically the <code>getInstance</code> method 
   * acts as a proxy to the classes new instance method, which takes no 
   * arguments. Simply delegating to <code>Class.newInstance</code> will 
   * sometimes not be sufficient, is such cases reflectively acquiring 
   * the classes constructor may be required in order to pass arguments.
   * 
   * @author Niall Gallagher
   * 
   * @see Value
   */
  interface Instance {
     
     /**
      * This method is used to acquire an instance of the type that
      * is defined by this object. If for some reason the type can
      * not be instantiated an exception is thrown from this.
      * 
      * @return an instance of the type this object represents
      */
     Object getInstance() throws Exception;
     
     /**
      * This method is used acquire the value from the type and if
      * possible replace the value for the type. If the value can
      * not be replaced then an exception should be thrown. This 
      * is used to allow primitives to be inserted into a graph.
      * 
      * @param value this is the value to insert as the type
      * 
      * @return an instance of the type this object represents
      */
     Object setInstance(Object value) throws Exception;
     
     /**
      * This is used to determine if the type is a reference type.
      * A reference type is a type that does not require any XML
      * deserialization based on its annotations. Values that are
      * references could be substitutes objects or existing ones. 
      * 
      * @return this returns true if the object is a reference
      */
     boolean isReference();
     
     /**
      * This is the type of the object instance that will be created
      * by the <code>getInstance</code> method. This allows the 
      * deserialization process to perform checks against the field.
      * 
      * @return the type of the object that will be instantiated
      */
     Class getType();
  }