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.traversers;

import org.apache.xerces.impl.xs.SchemaGrammar;
import org.apache.xerces.impl.xs.SchemaSymbols;
import org.apache.xerces.impl.xs.XSAnnotationImpl;
import org.apache.xerces.impl.xs.XSConstraints;
import org.apache.xerces.impl.xs.XSGroupDecl;
import org.apache.xerces.impl.xs.XSModelGroupImpl;
import org.apache.xerces.impl.xs.XSParticleDecl;
import org.apache.xerces.impl.xs.util.XInt;
import org.apache.xerces.impl.xs.util.XSObjectListImpl;
import org.apache.xerces.util.DOMUtil;
import org.apache.xerces.util.XMLSymbols;
import org.apache.xerces.xni.QName;
import org.apache.xerces.xs.XSObjectList;
import org.w3c.dom.Element;


The model group schema component traverser.

  Content: (annotation?, (all | choice | sequence))


Author:Rahul Srivastava, Sun Microsystems Inc., Elena Litani, IBM, Lisa Martin,  IBM
@xerces.internal
Version:$Id: XSDGroupTraverser.java 819653 2009-09-28 17:29:56Z knoaman $
/**
 * The model group schema component traverser.
 *
 * <group
 *   name = NCName>
 *   Content: (annotation?, (all | choice | sequence))
 * </group>
 *
 * @xerces.internal 
 *
 * @author Rahul Srivastava, Sun Microsystems Inc.
 * @author Elena Litani, IBM
 * @author Lisa Martin,  IBM
 * @version $Id: XSDGroupTraverser.java 819653 2009-09-28 17:29:56Z knoaman $
 */
class  XSDGroupTraverser extends XSDAbstractParticleTraverser {
    
    XSDGroupTraverser (XSDHandler handler,
            XSAttributeChecker gAttrCheck) {
        
        super(handler, gAttrCheck);
    }
    
    XSParticleDecl traverseLocal(Element elmNode,
            XSDocumentInfo schemaDoc,
            SchemaGrammar grammar) {
        
        // General Attribute Checking for elmNode declared locally
        Object[] attrValues = fAttrChecker.checkAttributes(elmNode, false,
                schemaDoc);
        QName refAttr = (QName) attrValues[XSAttributeChecker.ATTIDX_REF];
        XInt  minAttr = (XInt)  attrValues[XSAttributeChecker.ATTIDX_MINOCCURS];
        XInt  maxAttr = (XInt)  attrValues[XSAttributeChecker.ATTIDX_MAXOCCURS];
        
        XSGroupDecl group = null;
        
        // ref should be here.
        if (refAttr == null) {
            reportSchemaError("s4s-att-must-appear", new Object[]{"group (local)", "ref"}, elmNode);
        } else {
            // get global decl
            // index is a particle index.
            group = (XSGroupDecl)fSchemaHandler.getGlobalDecl(schemaDoc, XSDHandler.GROUP_TYPE, refAttr, elmNode);
        }
        
        XSAnnotationImpl annotation = null;
        // no children other than "annotation?" are allowed
        Element child = DOMUtil.getFirstChildElement(elmNode);
        if (child != null && DOMUtil.getLocalName(child).equals(SchemaSymbols.ELT_ANNOTATION)) {
            annotation = traverseAnnotationDecl(child, attrValues, false, schemaDoc);
            child = DOMUtil.getNextSiblingElement(child);
        } 
        else {
            String text = DOMUtil.getSyntheticAnnotation(elmNode);
            if (text != null) {
                annotation = traverseSyntheticAnnotation(elmNode, text, attrValues, false, schemaDoc);
            }
        }
        
        if (child != null) {
            reportSchemaError("s4s-elt-must-match.1", new Object[]{"group (local)", "(annotation?)", DOMUtil.getLocalName(elmNode)}, elmNode);
        }
        
        int minOccurs = minAttr.intValue();
        int maxOccurs = maxAttr.intValue();
        
        XSParticleDecl particle = null;
        
        // not empty group, not empty particle
        if (group != null && group.fModelGroup != null &&
                !(minOccurs == 0 && maxOccurs == 0)) {
            // create a particle to contain this model group
            if (fSchemaHandler.fDeclPool != null) {
                particle = fSchemaHandler.fDeclPool.getParticleDecl();
            } else {        
                particle = new XSParticleDecl();
            }
            particle.fType = XSParticleDecl.PARTICLE_MODELGROUP;
            particle.fValue = group.fModelGroup;
            particle.fMinOccurs = minOccurs;
            particle.fMaxOccurs = maxOccurs;
            if (group.fModelGroup.fCompositor == XSModelGroupImpl.MODELGROUP_ALL) {
                Long defaultVals = (Long)attrValues[XSAttributeChecker.ATTIDX_FROMDEFAULT];
                particle = checkOccurrences(particle, SchemaSymbols.ELT_GROUP,
                        (Element)elmNode.getParentNode(), GROUP_REF_WITH_ALL,
                        defaultVals.longValue());
            }
            if (refAttr != null) {
                XSObjectList annotations;
                if (annotation != null) {
                    annotations = new XSObjectListImpl();
                    ((XSObjectListImpl) annotations).addXSObject(annotation);
                } else {
                    annotations = XSObjectListImpl.EMPTY_LIST;
                }
                particle.fAnnotations = annotations;
            } else {
                particle.fAnnotations = group.fAnnotations;
            }
        }
        
        fAttrChecker.returnAttrArray(attrValues, schemaDoc);
        
        return particle;
        
    } // traverseLocal
    
    XSGroupDecl traverseGlobal(Element elmNode,
            XSDocumentInfo schemaDoc,
            SchemaGrammar grammar) {
        
        // General Attribute Checking for elmNode declared globally
        Object[] attrValues = fAttrChecker.checkAttributes(elmNode, true,
                schemaDoc);
        String  strNameAttr = (String)  attrValues[XSAttributeChecker.ATTIDX_NAME];
        
        // must have a name
        if (strNameAttr == null) {
            reportSchemaError("s4s-att-must-appear", new Object[]{"group (global)", "name"}, elmNode);
        }
        
        // Create the group defi up-front, so it can be passed
        // to the traversal methods
        XSGroupDecl group = new XSGroupDecl();
        XSParticleDecl particle = null;
        
        // must have at least one child
        Element l_elmChild = DOMUtil.getFirstChildElement(elmNode);
        XSAnnotationImpl annotation = null;
        if (l_elmChild == null) {
            reportSchemaError("s4s-elt-must-match.2",
                    new Object[]{"group (global)", "(annotation?, (all | choice | sequence))"},
                    elmNode);
        } else {
            String childName = l_elmChild.getLocalName();
            if (childName.equals(SchemaSymbols.ELT_ANNOTATION)) {
                annotation = traverseAnnotationDecl(l_elmChild, attrValues, true, schemaDoc);
                l_elmChild = DOMUtil.getNextSiblingElement(l_elmChild);
                if (l_elmChild != null)
                    childName = l_elmChild.getLocalName();
            }
            else {
                String text = DOMUtil.getSyntheticAnnotation(elmNode);
                if (text != null) {
                    annotation = traverseSyntheticAnnotation(elmNode, text, attrValues, false, schemaDoc);
                }
            }
            
            if (l_elmChild == null) {
                reportSchemaError("s4s-elt-must-match.2",
                        new Object[]{"group (global)", "(annotation?, (all | choice | sequence))"},
                        elmNode);
            } else if (childName.equals(SchemaSymbols.ELT_ALL)) {
                particle = traverseAll(l_elmChild, schemaDoc, grammar, CHILD_OF_GROUP, group);
            } else if (childName.equals(SchemaSymbols.ELT_CHOICE)) {
                particle = traverseChoice(l_elmChild, schemaDoc, grammar, CHILD_OF_GROUP, group);
            } else if (childName.equals(SchemaSymbols.ELT_SEQUENCE)) {
                particle = traverseSequence(l_elmChild, schemaDoc, grammar, CHILD_OF_GROUP, group);
            } else {
                reportSchemaError("s4s-elt-must-match.1",
                        new Object[]{"group (global)", "(annotation?, (all | choice | sequence))", DOMUtil.getLocalName(l_elmChild)},
                        l_elmChild);
            }
            
            if (l_elmChild != null &&
                    DOMUtil.getNextSiblingElement(l_elmChild) != null) {
                reportSchemaError("s4s-elt-must-match.1",
                        new Object[]{"group (global)", "(annotation?, (all | choice | sequence))",
                        DOMUtil.getLocalName(DOMUtil.getNextSiblingElement(l_elmChild))},
                        DOMUtil.getNextSiblingElement(l_elmChild));
            }
        }
        
        // add global group declaration to the grammar
        if (strNameAttr != null) {
            group.fName = strNameAttr;
            group.fTargetNamespace = schemaDoc.fTargetNamespace;
            if (particle == null) {
                particle = XSConstraints.getEmptySequence(); 
            }
            group.fModelGroup = (XSModelGroupImpl)particle.fValue;
            XSObjectList annotations;
            if (annotation != null) {
                annotations = new XSObjectListImpl();
                ((XSObjectListImpl) annotations).addXSObject(annotation);
            } else {
                annotations = XSObjectListImpl.EMPTY_LIST;
            }
            group.fAnnotations = annotations;
            // Add group declaration to grammar
            if (grammar.getGlobalGroupDecl(group.fName) == null) {
                grammar.addGlobalGroupDecl(group);
            }

            // also add it to extended map
            final String loc = fSchemaHandler.schemaDocument2SystemId(schemaDoc);
            final XSGroupDecl group2 = grammar.getGlobalGroupDecl(group.fName, loc);
            if (group2 == null) {
                grammar.addGlobalGroupDecl(group, loc);
            }

            // handle duplicates
            if (fSchemaHandler.fTolerateDuplicates) {
                if (group2 != null) {
                    group = group2;
                }
                fSchemaHandler.addGlobalGroupDecl(group); 
            }
        }
        else {
            // name attribute is not there, don't return this group.
            group = null;
        }

        if (group != null) { 
            // store groups redefined by restriction in the grammar so
            // that we can get at them at full-schema-checking time.
            Object redefinedGrp = fSchemaHandler.getGrpOrAttrGrpRedefinedByRestriction(XSDHandler.GROUP_TYPE,
                    new QName(XMLSymbols.EMPTY_STRING, strNameAttr, strNameAttr, schemaDoc.fTargetNamespace),
                    schemaDoc, elmNode);
            if (redefinedGrp != null) {
                // store in grammar
                grammar.addRedefinedGroupDecl(group, (XSGroupDecl)redefinedGrp,
                        fSchemaHandler.element2Locator(elmNode));
            }
        }
        
        fAttrChecker.returnAttrArray(attrValues, schemaDoc);
        
        return group;
        
    } // traverseGlobal
}