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/* gnu.java.beans.decoder.VoidHandler

   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;

public class VoidHandler extends AbstractElementHandler

{

    /**

     * @param PersistenceParser

     */

    VoidHandler(ElementHandler parent)

    {

        super(parent, true);

    }

    protected Context startElement(

        Attributes attributes,

        ExceptionListener exceptionListener)

        throws AssemblyException

    {

        Context ctx = startElementImpl(attributes);

        ctx.setStatement(true);

        return ctx;

    }

    private Context startElementImpl(Attributes attributes)

        throws AssemblyException

    {

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

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

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

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

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

        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 ...

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

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

                    // if the id is null the result cannot be by the decoder accessed but the

                    // constructor may have side effects (e.g. registering itself in a global registry)

                    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);

            }

            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 an element by index

            if (index != null)

            {

                // note: whether this resolves into get(i) or set(i, o) depends on the

                // number of arguments and is decided by the ObjectAssembler

                try

                {

                    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 invocation where the propertyName is

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

                // to upper case and prepend 'set'

                // Note: This will be a setter-method because the <void> tag implies that no return

                // value is expected (but a side effect)

                return new PropertyContext(id, propertyName);

        }

        // if code reaches this point the tag has wrong attributes. The following test

        // does not make it better but can provide are more specific error message for

        // a common mistake: <void> tags are not allowed to have an idref attribute

        throw new AssemblyException(

            new IllegalArgumentException(

                (attributes.getValue("idref") == null)

                    ? "Missing attributes for <void> tag"

                    : "<void> does not support 'idref' attribute."));

    }

}