/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999-2002 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 CONSEQUENCEUENTIAL 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) 1999, International
 * Business Machines, Inc., http://www.apache.org.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.xerces.impl.xs.models;

import org.apache.xerces.impl.dtd.models.CMNode;
import org.apache.xerces.impl.dtd.models.CMStateSet;
import org.apache.xerces.impl.xs.XSModelGroupImpl;

/**
 *
 * Content model Bin-Op node.
 *
 * @author Neil Graham, IBM
 * @version $$
 */
public class XSCMBinOp extends CMNode {
    // -------------------------------------------------------------------
    //  Constructors
    // -------------------------------------------------------------------
    public XSCMBinOp(int type, CMNode leftNode, CMNode rightNode) 
    {
        super(type);

        // Insure that its one of the types we require
        if ((type() != XSModelGroupImpl.MODELGROUP_CHOICE)
        &&  (type() != XSModelGroupImpl.MODELGROUP_SEQUENCE)) {
            throw new RuntimeException("ImplementationMessages.VAL_BST");
        }

        // Store the nodes and init any data that needs it
        fLeftChild = leftNode;
        fRightChild = rightNode;
    }


    // -------------------------------------------------------------------
    //  Package, final methods
    // -------------------------------------------------------------------
    final CMNode getLeft() {
        return fLeftChild;
    }

    final CMNode getRight() {
        return fRightChild;
    }


    // -------------------------------------------------------------------
    //  Package, inherited methods
    // -------------------------------------------------------------------
    public boolean isNullable() {
        //
        //  If its an alternation, then if either child is nullable then
        //  this node is nullable. If its a concatenation, then both of
        //  them have to be nullable.
        //
        if (type() == XSModelGroupImpl.MODELGROUP_CHOICE)
            return (fLeftChild.isNullable() || fRightChild.isNullable());
        else if (type() == XSModelGroupImpl.MODELGROUP_SEQUENCE)
            return (fLeftChild.isNullable() && fRightChild.isNullable());
        else
            throw new RuntimeException("ImplementationMessages.VAL_BST");
    }


    // -------------------------------------------------------------------
    //  Protected, inherited methods
    // -------------------------------------------------------------------
    protected void calcFirstPos(CMStateSet toSet) {
        if (type() == XSModelGroupImpl.MODELGROUP_CHOICE) {
            // Its the the union of the first positions of our children.
            toSet.setTo(fLeftChild.firstPos());
            toSet.union(fRightChild.firstPos());
        }
         else if (type() == XSModelGroupImpl.MODELGROUP_SEQUENCE) {
            //
            //  If our left child is nullable, then its the union of our
            //  children's first positions. Else is our left child's first
            //  positions.
            //
            toSet.setTo(fLeftChild.firstPos());
            if (fLeftChild.isNullable())
                toSet.union(fRightChild.firstPos());
        }
         else {
            throw new RuntimeException("ImplementationMessages.VAL_BST");
        }
    }

    protected void calcLastPos(CMStateSet toSet) {
        if (type() == XSModelGroupImpl.MODELGROUP_CHOICE) {
            // Its the the union of the first positions of our children.
            toSet.setTo(fLeftChild.lastPos());
            toSet.union(fRightChild.lastPos());
        }
        else if (type() == XSModelGroupImpl.MODELGROUP_SEQUENCE) {
            //
            //  If our right child is nullable, then its the union of our
            //  children's last positions. Else is our right child's last
            //  positions.
            //
            toSet.setTo(fRightChild.lastPos());
            if (fRightChild.isNullable())
                toSet.union(fLeftChild.lastPos());
        }
        else {
            throw new RuntimeException("ImplementationMessages.VAL_BST");
        }
    }


    // -------------------------------------------------------------------
    //  Private data members
    //
    //  fLeftChild
    //  fRightChild
    //      These are the references to the two nodes that are on either
    //      side of this binary operation.
    // -------------------------------------------------------------------
    private CMNode  fLeftChild;
    private CMNode  fRightChild;
} // XSCMBinOp

