/*
 * @(#)$Id: LaxDefaultNameClass.java,v 1.8 2001/10/10 23:19:12 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.grammar.xmlschema;

import com.sun.msv.grammar.NameClass;
import com.sun.msv.grammar.AnyNameClass;
import com.sun.msv.grammar.SimpleNameClass;
import com.sun.msv.grammar.NameClassVisitor;
import com.sun.msv.grammar.DifferenceNameClass;
import com.sun.msv.util.StringPair;
import java.util.Set;

/**
 * Special name class implementation used for the wild card of the "lax" mode.
 * 
 * <p>
 * In "lax" mode, we need a name class that matches all undefined names.
 * Although it is possible to use DifferenceNameClass for this purpose,
 * it is not a cost-efficient way because typically it becomes very large.
 * (If there are twenty element declarations, we'll need twenty DifferenceNameClass
 * to exclude all defined names).
 * 
 * <p>
 * This name class uses a {@link Set} to hold multiple names. If a name
 * is contained in that set, it'll be rejected. If a name is not contained,
 * it'll be accepted.
 * 
 * <p>
 * Special care is taken to make this NC as seamless as possible.
 * When the visit method is called, the equivalent name class is constructed
 * internally and the visitor will visit that name class. In this way, the visitors
 * won't notice the existance of this "special" name class.
 * 
 * @author <a href="mailto:kohsuke.kawaguchi@sun.com">Kohsuke KAWAGUCHI</a>
 */
public class LaxDefaultNameClass extends NameClass {
	
	/**
	 * @param base
	 *		this name class accepts a name if
	 *		<ol>
	 *		 <li>it's in the 'base" name class and
	 *		 <li>it's not one of those excluded names
	 */
	public LaxDefaultNameClass( NameClass _base ) {
		this.base = _base;
		names.add( new StringPair(NAMESPACE_WILDCARD,LOCALNAME_WILDCARD) );
	}
	
	private NameClass base;
	
	public Object visit( NameClassVisitor visitor ) {
		// create equivalent name class and let visitor visit it.
		if( equivalentNameClass==null ) {
			NameClass nc = base;
			StringPair[] items = (StringPair[])names.toArray(new StringPair[0]);
			for( int i=0; i<items.length; i++ ) {
				if( items[i].namespaceURI==NAMESPACE_WILDCARD
				 || items[i].localName==LOCALNAME_WILDCARD )
					continue;
				
				nc = new DifferenceNameClass(nc,
					new SimpleNameClass(items[i]));
			}
			equivalentNameClass = nc;
		}
		
		return equivalentNameClass.visit(visitor);
	}
	
	/**
	 * equivalent name class by conventional primitives.
	 * Initially null, and created on demand.
	 */
	protected NameClass equivalentNameClass;
	
	public boolean accepts( String namespaceURI, String localName ) {
		return base.accepts(namespaceURI,localName) &&
				!names.contains( new StringPair(namespaceURI,localName) );
	}
	
	/**
	 * set of {@link StringPair}s.
	 * each item represents one name.
	 * it also contains WILDCARD as entry.
	 */
	private final Set names = new java.util.HashSet();
	
	/**
	 * add a name so that this name will be rejected by the accepts method.
	 */
	public void addName( String namespaceURI, String localName ) {
		names.add( new StringPair(namespaceURI,localName) );
		names.add( new StringPair(namespaceURI,LOCALNAME_WILDCARD) );
		names.add( new StringPair(NAMESPACE_WILDCARD,localName) );
	}
}