src/com/sun/org/apache/xerces/internal/impl/dtd/models/CMBinOp.java

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 * The Apache Software License, Version 1.1
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 * reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 * 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
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package com.sun.org.apache.xerces.internal.impl.dtd.models;

import com.sun.org.apache.xerces.internal.impl.dtd.XMLContentSpec;

/**
 * Content model Bin-Op node.
 *
 * @xerces.internal
 *
 */
public class CMBinOp extends CMNode
{
    // -------------------------------------------------------------------
    //  Constructors
    // -------------------------------------------------------------------
    public CMBinOp(int type, CMNode leftNode, CMNode rightNode)
    {
        super(type);

        // Insure that its one of the types we require
        if ((type() != XMLContentSpec.CONTENTSPECNODE_CHOICE)
        &&  (type() != XMLContentSpec.CONTENTSPECNODE_SEQ))
        {
            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() == XMLContentSpec.CONTENTSPECNODE_CHOICE)
            return (fLeftChild.isNullable() || fRightChild.isNullable());
        else if (type() == XMLContentSpec.CONTENTSPECNODE_SEQ)
            return (fLeftChild.isNullable() && fRightChild.isNullable());
        else
            throw new RuntimeException("ImplementationMessages.VAL_BST");
    }


    // -------------------------------------------------------------------
    //  Protected, inherited methods
    // -------------------------------------------------------------------
    protected void calcFirstPos(CMStateSet toSet)
    {
        if (type() == XMLContentSpec.CONTENTSPECNODE_CHOICE)
        {
            // Its the the union of the first positions of our children.
            toSet.setTo(fLeftChild.firstPos());
            toSet.union(fRightChild.firstPos());
        }
         else if (type() == XMLContentSpec.CONTENTSPECNODE_SEQ)
        {
            //
            //  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() == XMLContentSpec.CONTENTSPECNODE_CHOICE)
        {
            // Its the the union of the first positions of our children.
            toSet.setTo(fLeftChild.lastPos());
            toSet.union(fRightChild.lastPos());
        }
         else if (type() == XMLContentSpec.CONTENTSPECNODE_SEQ)
        {
            //
            //  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;
};