content: /*
   * ElementMap.java August 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;
  
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Retention;
  
  /**
   * The <code>ElementMap</code> annotation represents a method or field
   * that is a <code>Map</code> for storing key value pairs. The map 
   * 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;map class="java.util.HashMap"&gt;
   *       &lt;entry key="one"&gt;value one&lt;/entry&gt;
   *       &lt;entry key="two"&gt;value two&lt;/entry&gt;
   *       &lt;entry key="three"&gt;value three&lt;/entry&gt;  
   *    &lt;/map&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 maps available from the Java collections framework. This 
   * annotation can support both primitive and composite values and 
   * keys enabling just about any configuration to be used.
   * <pre>
   *
   *    &lt;map class="java.util.HashMap"&gt;
   *       &lt;entry key="1"&gt;
   *          &lt;value&gt;value one&lt;/value&gt;
   *       &lt;/entry&gt;
   *       &lt;entry key="2"&gt;
   *          &lt;value&gt;value two&lt;/value&gt;
   *       &lt;/entry&gt;
   *       &lt;entry key="3"&gt;
   *          &lt;value&gt;value three&lt;/value&gt;
   *       &lt;/entry&gt; 
   *    &lt;/map&gt;
   * 
   * </pre>
   * The above XML is an example of the output for an composite value
   * object. Composite and primitive values can be used without any
   * specified attributes, in such a case names for primitives are the
   * names of the objects they represent. Also, if desired these 
   * default names can be overridden using the provided attributes
   * making the resulting XML entirely configurable.
   * 
   * @author Niall Gallagher
   */
  @Retention(RetentionPolicy.RUNTIME)
  public @interface ElementMap {
  
     /**
      * 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 the name of the entry XML element 
      * that wraps the key and value elements. If specified the entry
      * value specified will be used instead of the default name of 
      * the element. This is used to ensure the resulting XML is 
      * configurable to the requirements of the generated XML. 
      * 
      * @return this returns the entry XML element for each entry
      */
     String entry() default ""; 
  
     /**
      * This is used to provide a value XML element for each of the
      * values within the map. This essentially wraps the entity to
      * be serialized such that there is an extra XML element present.
      * This can be used to override the default names of primitive
      * values, however it can also be used to wrap composite values. 
      * 
      * @return this returns the value XML element for each value
      */
     String value() default "";
  
     /**
      * This is used to provide a key XML element for each of the
      * keys within the map. This essentially wraps the entity to
      * be serialized such that there is an extra XML element present.
      * This can be used to override the default names of primitive
      * keys, however it can also be used to wrap composite keys. 
      * 
      * @return this returns the key XML element for each key
      */
     String key() default "";
     
     /**
      * Represents the type of key the element map contains. This
      * type is used to deserialize the XML entry key from the map. 
      * 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 map. If 
      * this is not specified then the type can be determined from the
      * generic parameter of the annotated <code>Map</code> object.
      * 
      * @return the type of the entry key deserialized from the XML
      */
     Class keyType() default void.class;
     
     /**
      * Represents the type of value the element map contains. This
      * type is used to deserialize the XML entry value from the map. 
      * 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 map. If 
      * this is not specified then the type can be determined from the
      * generic parameter of the annotated <code>Map</code> object.
      * 
      * @return the type of the entry value deserialized from the XML
      */
     Class valueType() default void.class;
  
     /**
      * Represents whether the key value is to be an attribute or an
      * element. This allows the key to be embedded within the entry
      * XML element allowing for a more compact representation. Only
      * primitive key objects can be represented as an attribute. For
      * example a <code>java.util.Date</code> or a string could be
      * represented as an attribute key for the generated XML. 
      *  
      * @return true if the key is to be inlined as an attribute
      */
     boolean attribute() 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 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 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 map. 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;
  }
  