content: /*
   * ElementList.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>ElementList</code> annotation represents a method or
   * field that is a <code>Collection</code> for storing entries. The
   * collection object deserialized is typically of the same type as
   * the field. However, a <code>class</code> attribute can be used to
   * override the field type, however the type must be assignable.
   * <pre>
   * 
   *    &lt;list class="java.util.ArrayList"&gt;
   *       &lt;entry name="one"/&gt;
   *       &lt;entry name="two"/&gt;
   *       &lt;entry name="three"/&gt;  
   *    &lt;/list&gt;
   * 
   * </pre>
   * If a <code>class</code> attribute is not provided and the type or
   * the field or method is abstract, a suitable match is searched for 
   * from the collections available from the Java collections framework.
   * This annotation can also compose an inline list of XML elements. 
   * An inline list contains no parent or containing element.
   * <pre>
   *
   *    &lt;entry name="one"/&gt;
   *    &lt;entry name="two"/&gt;
   *    &lt;entry name="three"/&gt;  
   * 
   * </pre>
   * The above XML is an example of the output for an inline list of
   * XML elements. In such a list the annotated field or method must
   * not be given a name. Instead the name is acquired from the name of
   * the entry type. For example if the <code>type</code> attribute of
   * this was set to an object <code>example.Entry</code> then the name 
   * of the entry list would be taken as the root name of the object
   * as taken from the <code>Root</code> annotation for that object.
   * 
   * @author Niall Gallagher
   */
  @Retention(RetentionPolicy.RUNTIME)
  public @interface ElementList {
     
     /**
      * This represents the name of the XML element. Annotated fields
      * 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. Also, if
      * the list is inline then this must not be specified.
      * 
      * @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 list. 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 "";
     
     /**
      * Represents the type of object the element list contains. This
      * type is used to deserialize the XML elements from the list. 
      * The object typically represents the deserialized type, but can
      * represent a subclass of the type deserialized as determined
      * by the <code>class</code> attribute value for the list. If 
      * this is not specified then the type can be determined from the
      * generic parameter of the annotated <code>Collection</code>.
      * 
      * @return the type of the element deserialized from the XML
      */
     Class type() default void.class;
     
     /**
      * 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;
     
     /**
      * Determines whether the element list is inlined with respect
      * to the parent XML element. An inlined element list does not
      * contain an enclosing element. It is simple a sequence of 
      * elements that appear one after another within an element.
      * As such an inline element list must not have a name. 
      *
      * @return this returns true if the element list is inline
      */
     boolean inline() default false;
     
     /**
      * 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 list. 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;
  }