/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2001-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xerces" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 2001, International
 * Business Machines, Inc., http://www.apache.org.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package com.sun.org.apache.xerces.internal.impl.xs.models;

import com.sun.org.apache.xerces.internal.xni.QName;
import com.sun.org.apache.xerces.internal.impl.xs.SubstitutionGroupHandler;
import com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaException;

import java.util.Vector;

/**
 * XSEmptyCM is a derivative of the abstract content model base class that
 * handles a content model with no chilren (elements).
 *
 * This model validated on the way in.
 *
 * @author Elena Litani, Lisa Martin
 * @author IBM
 * @version $Id: XSEmptyCM.java,v 1.6 2003/03/11 15:48:33 sandygao Exp $
 */
public class XSEmptyCM  implements XSCMValidator {

    //
    // Constants
    //

    // start the content model: did not see any children
    private static final short STATE_START = 0;
    
    private static final Vector EMPTY = new Vector(0);

    //
    // Data
    //

    //
    // XSCMValidator methods
    //

    /**
     * This methods to be called on entering a first element whose type
     * has this content model. It will return the initial state of the content model
     *
     * @return Start state of the content model
     */
    public int[] startContentModel(){
        return (new int[] {STATE_START});
    }


    /**
     * The method corresponds to one transaction in the content model.
     *
     * @param elementName
     * @param state  Current state
     * @return element index corresponding to the element from the Schema grammar
     */
    public Object oneTransition (QName elementName, int[] currentState, SubstitutionGroupHandler subGroupHandler){

        // error state
        if (currentState[0] < 0) {
            currentState[0] = XSCMValidator.SUBSEQUENT_ERROR;
            return null;
        }

        currentState[0] = XSCMValidator.FIRST_ERROR;
        return null;
    }


    /**
     * The method indicates the end of list of children
     *
     * @param state  Current state of the content model
     * @return true if the last state was a valid final state
     */
    public boolean endContentModel (int[] currentState){
        boolean isFinal =  false;
        int state = currentState[0];

        // restore content model state:

        // error
        if (state < 0) {
            return false;
        }


        return true;
    }

    /**
     * check whether this content violates UPA constraint.
     *
     * @param errors to hold the UPA errors
     * @return true if this content model contains other or list wildcard
     */
    public boolean checkUniqueParticleAttribution(SubstitutionGroupHandler subGroupHandler) throws XMLSchemaException {
        return false;
    }

    /**
     * Check which elements are valid to appear at this point. This method also
     * works if the state is in error, in which case it returns what should
     * have been seen.
     * 
     * @param state  the current state
     * @return       a Vector whose entries are instances of
     *               either XSWildcardDecl or XSElementDecl.
     */
    public Vector whatCanGoHere(int[] state) {
        return EMPTY;
    }
    
} // class XSEmptyCM