/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2001-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Axis" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */


package org.jboss.axis.encoding;

import org.jboss.axis.message.SOAPHandler;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;

import javax.xml.namespace.QName;
import java.util.Vector;

/**
 * This interface describes the AXIS Deserializer.
 * A compliant implementiation must extend either
 * the AXIS SoapHandler (org.jboss.axis.message.SOAPHandler)
 * or the AXIS DeserializerImpl (org.jboss.axis.encoding.DeserializerImpl)
 * <p/>
 * The DeserializerImpl provides a lot of the default behavior including the
 * support for id/href.  So you may want to try extending it as opposed to
 * extending SoapHandler.
 * <p/>
 * An Axis compliant Deserializer must provide one or more
 * of the following methods:
 * <p/>
 * public &lt;constructor&gt;(Class javaType, QName xmlType)
 * public &lt;constructo&gt;()
 * <p/>
 * This will allow for construction of generic factories that introspect the class
 * to determine how to construct a deserializer.
 * The xmlType, javaType arguments are filled in with the values known by the factory.
 */
public interface Deserializer extends javax.xml.rpc.encoding.Deserializer, Callback
{

   /**
    * Get the deserialized value.
    *
    * @return Object representing deserialized value or null
    */
   public Object getValue();

   /**
    * Set the deserialized value.
    *
    * @param value Object representing deserialized value
    */
   public void setValue(Object value);

   /**
    * If the deserializer has component values (like ArrayDeserializer)
    * this method gets the specific component via the hint.
    * The default implementation returns null.
    *
    * @return Object representing deserialized value or null
    */
   public Object getValue(Object hint);

   /**
    * If the deserializer has component values (like ArrayDeserializer)
    * this method sets the specific component via the hint.
    * The default implementation does nothing.
    *
    * @param value Object representing deserialized value or null
    */
   public void setChildValue(Object value, Object hint) throws SAXException;

   /**
    * In some circumstances an element may not have
    * a type attribute, but a default type qname is known from
    * information in the container.  For example,
    * an element of an array may not have a type= attribute,
    * so the default qname is the component type of the array.
    * This method is used to communicate the default type information
    * to the deserializer.
    */
   public void setDefaultType(QName qName);

   public QName getDefaultType();

   /**
    * For deserializers of non-primitives, the value may not be
    * known until later (due to multi-referencing).  In such
    * cases the deserializer registers Target object(s).  When
    * the value is known, the set(value) will be invoked for
    * each Target registered with the Deserializer.  The Target
    * object abstracts the function of setting a target with a
    * value.  See the Target interface for more info.
    *
    * @param target Target
    */
   public void registerValueTarget(Target target);

   /**
    * Get the Value Targets of the Deserializer.
    *
    * @return Vector of Target objects or null
    */
   public Vector getValueTargets();

   /**
    * Remove the Value Targets of the Deserializer.
    */
   public void removeValueTargets();

   /**
    * Move someone else's targets to our own (see DeserializationContext)
    * <p/>
    * The DeserializationContext only allows one Deserializer to
    * wait for a unknown multi-ref'ed value.  So to ensure
    * that all of the targets are updated, this method is invoked
    * to copy the Target objects to the waiting Deserializer.
    *
    * @param other is the Deserializer to copy targets from.
    */
   public void moveValueTargets(Deserializer other);

   /**
    * Some deserializers (ArrayDeserializer) require
    * all of the component values to be known before the
    * value is complete.
    * (For the ArrayDeserializer this is important because
    * the elements are stored in an ArrayList, and all values
    * must be known before the ArrayList is converted into the
    * expected array.
    * <p/>
    * This routine is used to indicate when the components are ready.
    * The default (true) is useful for most Deserializers.
    */
   public boolean componentsReady();

   /**
    * The valueComplete() method is invoked when the
    * end tag of the element is read.  This results
    * in the setting of all registered Targets (see
    * registerValueTarget).
    * Note that the valueComplete() only processes
    * the Targets if componentReady() returns true.
    * So if you override componentReady(), then your
    * specific Deserializer will need to call valueComplete()
    * when your components are ready (See ArrayDeserializer)
    */
   public void valueComplete() throws SAXException;


   /**
    * The following are the SAX specific methods.
    * DeserializationImpl provides default behaviour, which
    * in most cases is appropriate.
    */

   /**
    * This method is invoked when an element start tag is encountered.
    * DeserializerImpl provides default behavior, which involves the following:
    * - directly handling the deserialization of a nill value
    * - handling the registration of the id value.
    * - handling the registration of a fixup if this element is an href.
    * - calling onStartElement to do the actual deserialization if not nill or href cases.
    *
    * @param namespace  is the namespace of the element
    * @param localName  is the name of the element
    * @param qName      is the prefixed qName of the element
    * @param attributes are the attributes on the element...used to get the type
    * @param context    is the DeserializationContext
    *                   <p/>
    *                   Normally a specific Deserializer (FooDeserializer) should extend DeserializerImpl.
    *                   Here is the flow that will occur in such cases:
    *                   1) DeserializerImpl.startElement(...) will be called and do the id/href/nill stuff.
    *                   2) If real deserialization needs to take place DeserializerImpl.onStartElement will be
    *                   invoked, which will attempt to install the specific Deserializer (FooDeserializer)
    *                   3) The FooDeserializer.startElement(...) will be called to do the Foo specific stuff.
    *                   This results in a call to FooDeserializer.onStartElement(...) if startElement was
    *                   not overridden.
    *                   4) The onChildElement(...) method is called for each child element.  Nothing occurs
    *                   if not overridden.  The FooDeserializer.onStartChild(...) method should return
    *                   the deserializer for the child element.
    *                   5) When the end tag is reached, the endElement(..) method is invoked.  The default
    *                   behavior is to handle hrefs/ids, call onEndElement and then call the Deserializer
    *                   valueComplete method.
    *                   <p/>
    *                   So the methods that you potentially want to override are:
    *                   onStartElement, onStartChild, componentsReady, set(object, hint)
    *                   <p/>
    *                   You probably should not override startElement or endElement.
    *                   If you need specific behaviour at the end of the element consider overriding
    *                   onEndElement.
    *                   <p/>
    *                   See the pre-existing Deserializers for more information.
    */
   public void startElement(String namespace, String localName,
                            String qName, Attributes attributes,
                            DeserializationContext context)
           throws SAXException;

   /**
    * This method is invoked after startElement when the element requires
    * deserialization (i.e. the element is not an href and the value is not nil.)
    * DeserializerImpl provides default behavior, which simply
    * involves obtaining a correct Deserializer and plugging its handler.
    *
    * @param namespace  is the namespace of the element
    * @param localName  is the name of the element
    * @param prefix     is the prefix of the element
    * @param attributes are the attributes on the element...used to get the type
    * @param context    is the DeserializationContext
    */
   public void onStartElement(String namespace, String localName,
                              String prefix, Attributes attributes,
                              DeserializationContext context)
           throws SAXException;

   /**
    * onStartChild is called on each child element.
    * The default behavior supplied by DeserializationImpl is to do nothing.
    * A specific deserializer may perform other tasks.  For example a
    * BeanDeserializer will construct a deserializer for the indicated
    * property and return it.
    *
    * @param namespace  is the namespace of the child element
    * @param localName  is the local name of the child element
    * @param prefix     is the prefix used on the name of the child element
    * @param attributes are the attributes of the child element
    * @param context    is the deserialization context.
    * @return is a Deserializer to use to deserialize a child (must be
    *         a derived class of SOAPHandler) or null if no deserialization should
    *         be performed.
    */
   public SOAPHandler onStartChild(String namespace, String localName,
                                   String prefix, Attributes attributes,
                                   DeserializationContext context)
           throws SAXException;

   /**
    * endElement is called when the end element tag is reached.
    * It handles href/id information for multi-ref processing
    * and invokes the valueComplete() method of the deserializer
    * which sets the targets with the deserialized value.
    *
    * @param namespace is the namespace of the child element
    * @param localName is the local name of the child element
    * @param context   is the deserialization context
    */
   public void endElement(String namespace, String localName,
                          DeserializationContext context)
           throws SAXException;

   /**
    * onEndElement is called by endElement.  It is not called
    * if the element has an href.
    *
    * @param namespace is the namespace of the child element
    * @param localName is the local name of the child element
    * @param context   is the deserialization context
    */
   public void onEndElement(String namespace, String localName,
                            DeserializationContext context)
           throws SAXException;

}


