LanguageType.java

/*
 * @(#)$Id: LanguageType.java,v 1.15 2002/11/07 16:49:29 kk122374 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.datatype.xsd;

import java.util.Hashtable;
import org.relaxng.datatype.ValidationContext;


/**
 * "language" type.
 * 
 * type of the value object is <code>java.lang.String</code>.
 * See http://www.w3.org/TR/xmlschema-2/#language for the spec
 * 
 * @author <a href="mailto:kohsuke.kawaguchi@eng.sun.com">Kohsuke KAWAGUCHI</a>
 */
public class LanguageType extends TokenType {
	
	public static final LanguageType theInstance = new LanguageType();
	private LanguageType() { super("language",false); }
	
	final public XSDatatype getBaseType() {
		return TokenType.theInstance;
	}
	
	public Object _createValue( String content, ValidationContext context ) {
		/*	RFC1766 defines the following BNF
		
			 Language-Tag = Primary-tag *( "-" Subtag )
			 Primary-tag = 1*8ALPHA
			 Subtag = 1*8ALPHA

			Whitespace is not allowed within the tag.
			All tags are to be treated as case insensitive.
		*/
		
		final int len = content.length();
		int i=0; int tokenSize=0;
		
		while( i<len ) {
			final char ch = content.charAt(i++);
			if( ('a'<=ch && ch<='z') || ('A'<=ch && ch<='Z') ) {
				tokenSize++;
				if( tokenSize==9 )
					return null;	// maximum 8 characters are allowed.
			} else
			if( ch=='-' ) {
				if( tokenSize==0 )	return null;	// at least one alphabet preceeds '-'
				tokenSize=0;
			} else
				return null;	// invalid characters
		}
		
		if( tokenSize==0 )	return null;	// this means either string is empty or ends with '-'
		
		return content.toLowerCase();
	}
}