https://xerces.apache.org/xerces2-j/: Xerces2 is the next generation of high performance, fully compliant XML parsers in the Apache Xerces family. This new version of Xerces introduces the Xerces Native Interface (XNI), a complete framework for building parser components and configurations that is extremely modular and easy to program. The Apache Xerces2 parser is the reference implementation of XNI but other parser components, configurations, and parsers can be written using the Xerces Native Interface. For complete design and implementation documents, refer to the XNI Manual. Xerces2 is a fully conforming XML Schema 1.0 processor. A partial experimental implementation of the XML Schema 1.1 Structures and Datatypes Working Drafts (December 2009) and an experimental implementation of the XML Schema Definition Language (XSD): Component Designators (SCD) Candidate Recommendation (January 2010) are provided for evaluation. For more information, refer to the XML Schema page. Xerces2 also provides a complete implementation of the Document Object Model Level 3 Core and Load/Save W3C Recommendations and provides a complete implementation of the XML Inclusions (XInclude) W3C Recommendation. It also provides support for OASIS XML Catalogs v1.1. Xerces2 is able to parse documents written according to the XML 1.1 Recommendation, except that it does not yet provide an option to enable normalization checking as described in section 2.13 of this specification. It also handles namespaces according to the XML Namespaces 1.1 Recommendation, and will correctly serialize XML 1.1 documents if the DOM level 3 load/save APIs are in use. 
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.xs.models;

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


Content model leaf node.

Author:Neil Graham, IBM
@xerces.internal
Version:$Id: XSCMLeaf.java 572112 2007-09-02 19:11:51Z mrglavas $
/**
 * Content model leaf node.
 *
 * @xerces.internal 
 *
 * @author Neil Graham, IBM
 * @version $Id: XSCMLeaf.java 572112 2007-09-02 19:11:51Z mrglavas $
 */
public class XSCMLeaf
    extends CMNode {

    //
    // Data
    //

    
This is the leaf: element decl or wildcard decl. 
/** This is the leaf: element decl or wildcard decl. */
    private final Object fLeaf;
    
    
Identify the particle: for UPA checking

/**
     * Identify the particle: for UPA checking
     */
    private int fParticleId = -1;

    
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.

/**
     * 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. 
/** Constructs a content model leaf. */
    public XSCMLeaf(int type, Object leaf, int id, int position)  {
        super(type);

        // Store the element index and position
        fLeaf = leaf;
        fParticleId = id;
        fPosition = position;
    }

    //
    // Package methods
    //

    final Object getLeaf() {
        return fLeaf;
    }
    
    final int getParticleId() {
        return fParticleId;
    }

    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(fLeaf.toString());
        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 XSCMLeaf