/*
 * @(#)$Id: GroupState.java,v 1.8 2001/06/19 22:34:45 Bear Exp $
 *
 * Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */
package com.sun.msv.reader.xmlschema;

import com.sun.msv.datatype.xsd.XSDatatype;
import com.sun.msv.grammar.Expression;
import com.sun.msv.grammar.ReferenceContainer;
import com.sun.msv.grammar.xmlschema.GroupDeclExp;
import com.sun.msv.grammar.xmlschema.XMLSchemaSchema;
import com.sun.msv.util.StartTagInfo;
import com.sun.msv.reader.State;
import org.xml.sax.Locator;

/**
 * used to parse <group> element.
 * 
 * @author <a href="mailto:kohsuke.kawaguchi@eng.sun.com">Kohsuke KAWAGUCHI</a>
 */
public class GroupState extends RedefinableDeclState {
	
	protected State createChildState( StartTagInfo tag ) {
		final XMLSchemaReader reader = (XMLSchemaReader)this.reader;
		// TODO: group reference is prohibited under group element.
		return reader.createModelGroupState(this,tag);
	}

	protected ReferenceContainer getContainer() {
		return ((XMLSchemaReader)reader).currentSchema.groupDecls;
	}
	
	protected Expression initialExpression() {
		final XMLSchemaReader reader = (XMLSchemaReader)this.reader;
		
		if( startTag.containsAttribute("ref") ) {
			// this this tag has @ref.
			Expression exp = reader.resolveQNameRef(
				startTag, "ref",
				new XMLSchemaReader.RefResolver() {
					public ReferenceContainer get( XMLSchemaSchema g ) {
						return g.groupDecls;
					}
				} );
			if( exp==null )		return Expression.epsilon;	// couldn't resolve QName.
			return exp;
		}
		
		return null;	// use null to indicate that there is no child expression.
	}

	protected Expression castExpression( Expression halfCastedExpression, Expression newChildExpression ) {
		if( halfCastedExpression!=null ) {
			reader.reportError( reader.ERR_MORE_THAN_ONE_CHILD_EXPRESSION );
			return halfCastedExpression;
		}
		
		return newChildExpression;	// the first one.
	}
	
	
	protected Expression annealExpression(Expression contentType) {
		final XMLSchemaReader reader = (XMLSchemaReader)this.reader;
		
		if( !isGlobal() )		return contentType;
		
		
		// this <group> element is global.
		// register this as a global group definition.
			
		String name = startTag.getAttribute("name");
		if( name==null ) {
			reader.reportError( reader.ERR_MISSING_ATTRIBUTE, "group", "name" );
			// recover by returning a meaningless value, thereby ignoring this declaration.
			return Expression.nullSet;
		}
		
		if( contentType==null ) {
			reader.reportError( reader.ERR_MISSING_CHILD_EXPRESSION );
			return Expression.nullSet;
		}
		
		GroupDeclExp decl;
		if( isRedefine() )
			decl = (GroupDeclExp)super.oldDecl;
		else {
			decl = reader.currentSchema.groupDecls.getOrCreate(name);
			if( decl.exp!=null )
				reader.reportError( 
					new Locator[]{this.location,reader.getDeclaredLocationOf(decl)},
					reader.ERR_DUPLICATE_GROUP_DEFINITION,
					new Object[]{name} );
		}
		reader.setDeclaredLocationOf(decl);
		decl.exp = contentType;

		return decl;
	}
}