content: /*
   * ElementArray.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;
  
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Retention;
  
  /**
   * The <code>ElementArray</code> annotation represents a method or 
   * field that is an array of elements. The array deserialized is the
   * same type as the field or method, all entries within the array 
   * must be a compatible type. However, a <code>class</code> attribute 
   * can be used to override an entry, this must be an assignable type.
   * <pre>
   *
   *    &lt;array length="3"&gt;
   *       &lt;entry&gt;
   *          &lt;value&gt;example text value&lt;/value&gt;
   *       &lt;/entry&gt;
   *       &lt;entry&gt;
   *          &lt;value&gt;some other value&lt;/value&gt;
   *       &lt;/entry&gt;
   *       &lt;entry/&gt;
   *    &lt;/array&gt;
   * 
   * </pre>
   * All null objects within the array are represented as an empty XML
   * element so that they can be deserialized accurately. This ensures
   * that the length attribute of the array is respected, as well as 
   * the index position of all serialized entries. The length of the 
   * array must be specified for deserialization to instantiate the 
   * array before the array values are instantiated. This is required 
   * to account for cyclical references in the object graph.
   * 
   * @author Niall Gallagher
   */
  @Retention(RetentionPolicy.RUNTIME)
  public @interface ElementArray {
     
     /**
      * This represents the name of the XML element. Annotated fields
      * or methods can optionally provide the name of the element. If 
      * no name is provided then the name of the annotated field or 
      * method will be used in its place. The name is provided if the 
      * field or method name is not suitable as an XML element name.
      * 
      * @return the name of the XML element this represents
      */
     String name() default "";
     
     /**
      * This is used to provide a name of the XML element representing
      * the entry within the array. An entry name is optional and is
      * used when the name needs to be overridden. This also ensures
      * that entry, regardless of type has the same root name.   
      * 
      * @return this returns the entry XML element for each value
      */
     String entry() default "";
     
     /**
      * This is used to determine whether the element data is written
      * in a CDATA block or not. If this is set to true then the text
      * is written within a CDATA block, by default the text is output
      * as escaped XML. Typically this is useful when this annotation
      * is applied to an array of primitives, such as strings.
      * 
      * @return true if entries are to be wrapped in a CDATA block
      */
     boolean data() default false;
     
     /**
      * Determines whether the element is required within the XML
      * document. Any field marked as not required will not have its
      * value set when the object is deserialized. If an object is to
      * be serialized only a null attribute will not appear as XML.
      * 
      * @return true if the element is required, false otherwise
      */        
     boolean required() default true;
     
     /**
      * This is used to determine if an optional field or method can
      * remain null if it does not exist. If this is false then the
      * optional element is given an empty array. This is a convenience
      * attribute which avoids having to check if the element is null
      * before providing it with a suitable default instance.
      * 
      * @return false if an optional element is always instantiated
      */
     boolean empty() default true;
  }
  