UnionUnmarshaller

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 * $Id$
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package org.exolab.castor.xml.schema.reader;

//-- imported classes and packages
import java.util.StringTokenizer;

import org.exolab.castor.xml.AttributeSet;
import org.exolab.castor.xml.Namespaces;
import org.exolab.castor.xml.XMLException;
import org.exolab.castor.xml.schema.Annotation;
import org.exolab.castor.xml.schema.Schema;
import org.exolab.castor.xml.schema.SchemaContext;
import org.exolab.castor.xml.schema.SchemaNames;
import org.exolab.castor.xml.schema.SimpleType;
import org.exolab.castor.xml.schema.Union;

/**
 * A class for Unmarshalling XML Schema Union types
 *
 * @author <a href="mailto:kvisco@intalio.com">Keith Visco</a>
 * @version $Revision$ $Date: 2003-03-03 00:05:44 -0700 (Mon, 03 Mar 2003) $
**/
public class UnionUnmarshaller extends ComponentReader {

      //--------------------/
     //- Member Variables -/
    //--------------------/

    /**
     * The current ComponentReader
    **/
    private ComponentReader _unmarshaller;

    /**
     * The current branch depth
    **/
    private int _depth = 0;

    /**
     * The Union we are unmarshalling
    **/
    private Union _union = null;

    /**
     * The parent Schema for the Union
    **/
    private Schema _schema = null;

    private boolean _foundAnnotation   = false;
    private boolean _foundSimpleType   = false;

      //----------------/
     //- Constructors -/
    //----------------/

    /**
     * Creates a new IdentityConstraintUnmarshaller
     *
     * @param schemaContext the {@link SchemaContext} to get some configuration settings from
     * @param atts the AttributeList
    **/
    public UnionUnmarshaller(
            final SchemaContext schemaContext,
            final Schema schema,
            final AttributeSet atts)
    throws XMLException {
        super(schemaContext);

        if (schema == null) {
            String err = "'schema' must not be null.";
            throw new IllegalStateException(err);
        }
        _schema = schema;

        _union = new Union(_schema);
        _union.setId(atts.getValue(SchemaNames.ID_ATTR));

        String memberTypes = atts.getValue(SchemaNames.MEMBER_TYPES_ATTR);
        processMemberTypes(memberTypes);

    } //-- UnionUnmarshaller

      //-----------/
     //- Methods -/
    //-----------/

    /**
     * Returns the name of the element that this ComponentReader
     * handles
     * @return the name of the element that this ComponentReader
     * handles
    **/
    public String elementName() {
        return SchemaNames.UNION;
    } //-- elementName

    /**
     * Returns the Object created by this ComponentReader
     *
     * @return the Object created by this ComponentReader
    **/
    public Object getObject() {
        return _union;
    } //-- getObject

    public void finish()
        throws XMLException
    {
        //-- do nothing
    } //-- finish

    /**
     * Signals the start of an element with the given name.
     *
     * @param name the NCName of the element. It is an error
     * if the name is a QName (ie. contains a prefix).
     * @param namespace the namespace of the element. This may be null.
     * Note: A null namespace is not the same as the default namespace unless
     * the default namespace is also null.
     * @param atts the AttributeSet containing the attributes associated
     * with the element.
     * @param nsDecls the namespace declarations being declared for this
     * element. This may be null.
    **/
    public void startElement(String name, String namespace, AttributeSet atts,
        Namespaces nsDecls)
        throws XMLException
    {
        //-- Do delagation if necessary
        if (_unmarshaller != null) {
            _unmarshaller.startElement(name, namespace, atts, nsDecls);
            ++_depth;
            return;
        }

        if (SchemaNames.ANNOTATION.equals(name)) {

            if (_foundAnnotation)
                error("Only one (1) annotation may appear as a child of '" +
                    elementName() + "'.");

            if (_foundSimpleType)
                error("An annotation may only appear as the first child of '"+
                    elementName() + "'.");

            _foundAnnotation = true;
            _unmarshaller = new AnnotationUnmarshaller(getSchemaContext(), atts);
        }
        else if (SchemaNames.SIMPLE_TYPE.equals(name)) {
            _foundSimpleType = true;
            _unmarshaller = new SimpleTypeUnmarshaller(getSchemaContext(), _schema, atts);
        }
        else illegalElement(name);

    } //-- startElement

    /**
     * Signals to end of the element with the given name.
     *
     * @param name the NCName of the element. It is an error
     * if the name is a QName (ie. contains a prefix).
     * @param namespace the namespace of the element.
    **/
    public void endElement(String name, String namespace)
        throws XMLException
    {

        //-- Do delagation if necessary
        if ((_unmarshaller != null) && (_depth > 0)) {
            _unmarshaller.endElement(name, namespace);
            --_depth;
            return;
        }

        //-- have unmarshaller perform any necessary clean up
        _unmarshaller.finish();

        if (SchemaNames.ANNOTATION.equals(name)) {
            _union.setLocalAnnotation((Annotation)_unmarshaller.getObject());
        }
        else if (SchemaNames.SIMPLE_TYPE.equals(name)) {

            SimpleType simpleType =
                (SimpleType)_unmarshaller.getObject();

            //-- make sure type is not another Union
            if (simpleType instanceof Union) {
                String err = "A 'union' may only contain SimpleTypes of "+
                    "the atomic or list variety.";
                error(err);
            }
            //-- make sure type is atomic or list
            // XXXX to be added later

            _union.addMemberType(simpleType);
        }


        _unmarshaller = null;
    } //-- endElement

    public void characters(char[] ch, int start, int length)
        throws XMLException
    {
        //-- Do delagation if necessary
        if (_unmarshaller != null) {
            _unmarshaller.characters(ch, start, length);
        }
    } //-- characters


    /**
     * Processes the given string into the referenced simpleTypes
     * for the Union being unmarshalled.
     *
     * @param memberTypes the memberTypes list.
    **/
    private void processMemberTypes(String memberTypes) {
        if ((memberTypes == null) || (memberTypes.length() == 0))
            return;

        StringTokenizer st = new StringTokenizer(memberTypes);
        while (st.hasMoreTokens()) {
            String typeName = st.nextToken();
            SimpleType simpleType = _schema.getSimpleType(typeName);
            if (simpleType != null) {
                _union.addMemberType(simpleType);
            }
            else {
                _union.addMemberType(typeName);
            }

        }
    } //-- processMemberTypes

} //-- UnionUnmarshaller