/*
 * Copyright 1999-2002,2004,2005 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

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

import org.apache.xerces.impl.dtd.XMLContentSpec;
import org.apache.xerces.xni.QName;

/**
 * Content model leaf node.
 * 
 * @xerces.internal
 *
 * @version $Id: CMLeaf.java 327940 2005-10-24 03:22:51Z mrglavas $
 */
public class CMLeaf 
    extends CMNode {

    //
    // Data
    //

    /** This is the element that this leaf represents. */
    private QName fElement = new QName();

    /**
     * Part of the algorithm to convert a regex directly to a DFA
     * numbers each leaf sequentially. If its -1, that means its an
     * epsilon node. Zero and greater are non-epsilon positions.
     */
    private int fPosition = -1;

    //
    // Constructors
    //

    /** Constructs a content model leaf. */
    public CMLeaf(QName element, int position)  {
        super(XMLContentSpec.CONTENTSPECNODE_LEAF);

        // Store the element index and position
        fElement.setValues(element);
        fPosition = position;
    }

    /** Constructs a content model leaf. */
    public CMLeaf(QName element)  {
        super(XMLContentSpec.CONTENTSPECNODE_LEAF);

        // Store the element index and position
        fElement.setValues(element);
    }

    //
    // Package methods
    //

    final QName getElement()
    {
        return fElement;
    }

    final int getPosition()
    {
        return fPosition;
    }

    final void setPosition(int newPosition)
    {
        fPosition = newPosition;
    }

    //
    // CMNode methods
    //

    // package

    public boolean isNullable() 
    {
        // Leaf nodes are never nullable unless its an epsilon node
        return (fPosition == -1);
    }

    public String toString()
    {
        StringBuffer strRet = new StringBuffer(fElement.toString());
        strRet.append(" (");
        strRet.append(fElement.uri);
        strRet.append(',');
        strRet.append(fElement.localpart);
        strRet.append(')');
        if (fPosition >= 0) {
            strRet.append(" (Pos:")
                  .append(Integer.toString(fPosition))
                  .append(')');
        }
        return strRet.toString();
    }

    // protected

    protected void calcFirstPos(CMStateSet toSet) 
    {
        // If we are an epsilon node, then the first pos is an empty set
        if (fPosition == -1)
            toSet.zeroBits();

        // Otherwise, its just the one bit of our position
        else
            toSet.setBit(fPosition);
    }

    protected void calcLastPos(CMStateSet toSet) 
    {
        // If we are an epsilon node, then the last pos is an empty set
        if (fPosition == -1)
            toSet.zeroBits();

        // Otherwise, its just the one bit of our position
        else
            toSet.setBit(fPosition);
    }

} // class CMLeaf