Subversion Repositories openrisc

/* gnu.java.beans.decoder.ObjectHandler

   Copyright (C) 2004 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package gnu.java.beans.decoder;

import java.beans.ExceptionListener;

import org.xml.sax.Attributes;

/** An ObjectHandler parses the <object> tag and thereby creates various

 * Context implementations.

 *

 * @author Robert Schuster

 *

 */

public class ObjectHandler extends AbstractElementHandler

{

  /**

   * XXX: Can all results be stored with an object id?

   *

   *

   * @param PersistenceParser

   */

  ObjectHandler(ElementHandler parent)

  {

    super(parent, true);

  }

  protected Context startElement(Attributes attributes, ExceptionListener exceptionListener)

    throws AssemblyException

  {

    String className = attributes.getValue("class");

    String methodName = attributes.getValue("method");

    String fieldName = attributes.getValue("field");

    String index = attributes.getValue("index");

    String propertyName = attributes.getValue("property");

    String id = attributes.getValue("id");

    String idRef = attributes.getValue("idref");

    /* first check if we just want to access an existing object (idref present)

     *

     * note: <object idref="foo" method="bar"/> is not valid to call method "bar"

     * on the object with id "foo". Instead this should return the object "foo"

     * itself. The right way to this is:

     * <object idref="foo">

     *         <object method="bar"/>

     * </object>

     *

     * This means that if idref is present class, method, field, index and

     * property are obsolete.

     */

    if (idRef != null)

      // reactivates an existing object and giving it another name if id exists

      return new ObjectContext(id, getObject(idRef));

    // decides whether we are in a static (className present) or dynamic context

    if (className != null)

      {

        try

          {

            Class klass = instantiateClass(className);

            // class name exists which means that we are in a static context.

            // so we may want to ...

            // access a static field if the fieldName exists

            if (fieldName != null)

              {

                try

                  {

                    return new ObjectContext(id,

                                             klass.getField(fieldName).get(null));

                  }

                catch (NoSuchFieldException nsfe)

                  {

                    throw new AssemblyException(nsfe);

                  }

                catch (IllegalAccessException iae)

                  {

                    throw new AssemblyException(iae);

                  }

              }

            // (falling through is important!)

            // run a constructor if methodName is "new" or null

            if (methodName == null || methodName.equals("new"))

              return new ConstructorContext(id, klass);

            // (falling through is important!)

            // run a static method on the given class (if methodName exists, which is implied already)

            return new StaticMethodContext(id, klass, methodName);

            // XXX: should fail if unexpected attributes are present?

          }

        catch (ClassNotFoundException cnfe)

          {

            throw new AssemblyException(cnfe);

          }

      }

    else

      {

        // className does not exist which means we are in the context of

        // some object and want to ...

        // access the get(int index) method if index != null

        if (index != null)

          {

            try

              {

                // Note: http://java.sun.com/products/jfc/tsc/articles/persistence3/ says

                // that <void index="4"/> will make up a get()-call. But this is wrong because

                // <void/> tags never return values (to the surrounding context)

                return new IndexContext(id, Integer.parseInt(index));

              }

            catch (NumberFormatException nfe)

              {

                throw new AssemblyException(nfe);

              }

          }

        // access a method if methodName exists

        if (methodName != null)

          return new MethodContext(id, methodName);

        // (falling through is important!)

        // access a property if a propertyName exists

        if (propertyName != null && propertyName.length() > 0)

          // this is reported as an ordinary method access where the propertyName is

          // converted into a 'getter'-method name: convert first character of property name

          // to upper case and prepend 'get'

          // Note: This will be a getter-method because the <object> tag implies that a return

          // value is expected.

          return new PropertyContext(id, propertyName);

      }

    throw new AssemblyException(new IllegalArgumentException("Wrong or missing attributes for <object> tag."));

  }

}