content: /*
   * PrimitiveValue.java July 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.Type;
  import com.aliyun.odps.simpleframework.xml.stream.InputNode;
  import com.aliyun.odps.simpleframework.xml.stream.OutputNode;
  import com.aliyun.odps.simpleframework.xml.stream.Style;
  
  /**
   * The <code>PrimitiveValue</code> is used to serialize a primitive 
   * value to and from a node. If a value name is provided in the 
   * annotation then this will serialize and deserialize that value 
   * with the given name, if the value is primitive and no name is
   * specified then the value is written inline, that is without any
   * enclosing XML element.
   * <pre>
   * 
   *    &lt;entry key="one"&gt;example one&lt;/entry&gt;
   *    &lt;entry key="two"&gt;example two&lt;/entry&gt;
   *    &lt;entry key="three"&gt;example three&lt;/entry&gt;    
   * 
   * </pre>
   * Allowing the value to be written as either an XML element or an
   * inline text value enables a more flexible means for representing 
   * the value. The only condition for having an inline value is that
   * the key is specified as an attribute in the annotation.
   * 
   * @author Niall Gallagher
   * 
   * @see CompositeMap
   */
  class PrimitiveValue implements Converter {
     
     /**
      * The primitive factory used to resolve the primitive to a string.
      */
     private final PrimitiveFactory factory;
     
     /**
      * This is the context used to support the serialization process.
      */
     private final Context context;
     
     /**
      * The primitive converter used to read the value from the node.
      */
     private final Primitive root;
     
     /**
      * This is the style used to style the XML names for the value.
      */
     private final Style style;
     
     /**
      * The entry object contains the details on how to write the value.
      */
     private final Entry entry; 
     
     /**
      * Represents the primitive type the value is serialized to and from.
      */
     private final Type type;
     
     /**
      * Constructor for the <code>PrimitiveValue</code> object. This is 
      * used to create the value object which converts the map value to 
      * an instance of the value type. This can also resolve references. 
      * 
      * @param context this is the context object used for serialization
      * @param entry this is the entry object that describes entries
      * @param type this is the type that this converter deals with
      */   
     public PrimitiveValue(Context context, Entry entry, Type type) {
        this.factory = new PrimitiveFactory(context, type);
        this.root = new Primitive(context, type);
        this.style = context.getStyle();
        this.context = context;
        this.entry = entry;
        this.type = type;
     }
     
     /**
      * This method is used to read the value value from the node. The 
      * value read from the node is resolved using the template filter.
      * If the value value can not be found according to the annotation
      * attributes then an exception is thrown.
      * 
      * @param node this is the node to read the value object from
      * 
      * @return this returns the value deserialized from the node
      */ 
     public Object read(InputNode node) throws Exception {
        Class expect = type.getType();
        String name = entry.getValue();
        
        if(!entry.isInline()) {
           if(name == null) {
              name = context.getName(expect);
           }
           return readElement(node, name);
        }
        return readAttribute(node, name);
     }
     
     /**
      * This method is used to read the value value from the node. The 
      * value read from the node is resolved using the template filter.
      * If the value value can not be found according to the annotation
      * attributes then an exception is thrown.
      * 
      * @param node this is the node to read the value object from
      * @param value this is the value to deserialize in to
      * 
      * @return this returns the value deserialized from the node
      * 
      * @throws Exception if value is not null an exception is thrown
      */ 
     public Object read(InputNode node, Object value) throws Exception {
        Class expect = type.getType();
        
        if(value != null) {
           throw new PersistenceException("Can not read value of %s for %s", expect, entry);
        }
        return read(node);
     }
     
     /**
      * This method is used to read the element value from the node. The 
      * value read from the node is resolved using the template filter.
      * If the value value can not be found according to the annotation
      * attributes then null is assumed and returned.
      * 
      * @param node this is the node to read the value object from
      * @param key this is the name of the value XML element
      * 
      * @return this returns the value deserialized from the node
      */ 
     private Object readElement(InputNode node, String key) throws Exception {
        String name = style.getAttribute(key);
        InputNode child = node.getNext(name);
        
        if(child == null) {
           return null;        
        }
        return root.read(child);      
     }
     
     /**
      * This method is used to read the text value from the node. The 
      * value read from the node is resolved using the template filter.
      * If the value value can not be found according to the annotation
      * attributes then null is assumed and returned.
      * 
      * @param node this is the node to read the value object from
      * @param name this is the name of the value XML attribute, if any
      * 
      * @return this returns the value deserialized from the node
      */ 
     private Object readAttribute(InputNode node, String name) throws Exception {
        if(name != null) {
           name = style.getAttribute(name);
           node = node.getAttribute(name);
        }       
        if(node == null) {
           return null;        
        }
        return root.read(node);      
     }
     
     /**
      * This method is used to validate the value from the node. The 
      * value read from the node is resolved using the template filter.
      * If the value value can not be found according to the annotation
      * attributes then null is assumed and the node is valid.
      * 
      * @param node this is the node to read the value object from
      * 
      * @return this returns true if the primitive key is valid
      */ 
     public boolean validate(InputNode node) throws Exception {
        Class expect = type.getType();
        String name = entry.getValue();
        
        if(!entry.isInline()) {
           if(name == null) {
              name = context.getName(expect);
           }
           return validateElement(node, name);
        }
        return validateAttribute(node, name);
     }
     
     /**
      * This method is used to validate the value from the node. The 
      * value read from the node is resolved using the template filter.
      * If the value value can not be found according to the annotation
      * attributes then null is assumed and the node is valid.
      *  
      * @param node this is the node to read the value object from
      * @param key this is the name of the node to be validated
      * 
      * @return this returns true if the primitive key is valid
      */    
     private boolean validateElement(InputNode node, String key) throws Exception {
        String name = style.getAttribute(key);
        InputNode child = node.getNext(name);
        
        if(child == null) {
           return true;        
        }
        return root.validate(node);
     }
     
     /**
      * This method is used to validate the value from the node. The 
      * value read from the node is resolved using the template filter.
      * If the value value can not be found according to the annotation
      * attributes then null is assumed and the node is valid.
      *  
      * @param node this is the node to read the value object from
      * @param key this is the name of the node to be validated
      * 
      * @return this returns true if the primitive key is valid
      */    
     private boolean validateAttribute(InputNode node, String key) throws Exception {
        if(key != null) {
           key = style.getAttribute(key);
           node = node.getNext(key);
        }
        if(node == null) {
           return true;        
        }
        return root.validate(node);
     }
  
     /**
      * This method is used to write the value to the specified node.
      * The value written to the node can be an attribute or an element
      * depending on the annotation attribute values. This method will
      * maintain references for serialized elements.
      * 
      * @param node this is the node that the value is written to
      * @param item this is the item that is to be written
      */
     public void write(OutputNode node, Object item) throws Exception {
        Class expect = type.getType();
        String name = entry.getValue();
        
        if(!entry.isInline()) {
           if(name == null) {
              name = context.getName(expect);
           } 
           writeElement(node, item, name);
        } else {
           writeAttribute(node, item, name);
        }
     }
     
     /**
      * This method is used to write the value to the specified node.
      * The value written to the node can be an attribute or an element
      * depending on the annotation attribute values. This method will
      * maintain references for serialized elements.
      * 
      * @param node this is the node that the value is written to
      * @param item this is the item that is to be written
      * @param key this is the name of the element to be created
      */   
     private void writeElement(OutputNode node, Object item, String key) throws Exception {
        String name = style.getAttribute(key);
        OutputNode child = node.getChild(name);
  
        if(item != null) {        
           if(!isOverridden(child, item)) {
              root.write(child, item);
           }
        }
     }
     
     /**
      * This method is used to write the value to the specified node.
      * The value written to the node can be an attribute or an element
      * depending on the annotation attribute values. This method will
      * maintain references for serialized elements.
      * 
      * @param node this is the node that the value is written to
      * @param item this is the item that is to be written
      * @param key this is the name of the attribute to be created
      */   
     private void writeAttribute(OutputNode node, Object item, String key) throws Exception {
        if(item != null) {
           if(key != null) {
              key = style.getAttribute(key);
              node = node.setAttribute(key, null);
           }     
           root.write(node, item);
        }
     }
     
     /**
      * This is used to determine whether the specified value has been
      * overridden by the strategy. If the item has been overridden
      * then no more serialization is require for that value, this is
      * effectively telling the serialization process to stop writing.
      * 
      * @param node the node that a potential override is written to
      * @param value this is the object instance to be serialized
      * 
      * @return returns true if the strategy overrides the object
      */
     private boolean isOverridden(OutputNode node, Object value) throws Exception{
        return factory.setOverride(type, value, node);
     }
  
  }
  