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package com.sun.tools.internal.xjc.reader.xmlschema.parser;

import java.util.HashSet;
import java.util.Set;
import java.util.Stack;

import javax.xml.namespace.QName;

import com.sun.tools.internal.xjc.reader.Const;
import com.sun.xml.internal.bind.v2.WellKnownNamespace;

import org.xml.sax.Attributes;
import org.xml.sax.ErrorHandler;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.XMLFilterImpl;

Checks if binding declarations are placed where they are allowed.
 For example, if a <jaxb:property> customization is given under the <xs:simpleContent> element, this class raises an error. 

our main checkpoint of misplaced customizations are in BGMBuilder.
There, we mark a customization whenever we use it. At the end of the
day, we look for unmarked customizations and raise errors for them.

Between this approach and the JAXB spec 1.0 is a problem that
the spec allows/prohibits customizations at schema element level,
while BGMBuilder and XSOM works on schema component levels.
 For example, a property customization is allowed on a complex type schema component, but it's only allowed on the <complexType> element. The spec team informed us that they would consider resolving this discrepancy in favor of RI, but meanwhile we need to detect errors correctly. 

This filter is implemented for this purpose.
Customization and allowed locations
- globalBinding/schemaBinding
    schema
- class
    complexType(*), modelGroupDecl, modelGroup, element
- property
    attribute, element, any, modelGroup, modelGroupRef, complexType(*)
- javaType
    simpleType(*)
- typesafeEnumClass
    simpleType(*)
- typesafeEnumMember
    simpleType(*), enumeration
Components marked with '*' needs a check by this component
since more than one schema element corresponds to one schema component
of that type.
 For simple types, customizations are allowed only under the <xs:simpleType> element, and for complex types they are allowed only under the <xs:cimplexType> element. 

So the bottom line is that it would be suffice if we just make sure
that no customization will be attached under other elements of
simple types and complex types. Those are:
- simpleType/restriction
- list
- union
- complexType/(simple or complex)Content
- complexType/(simple or complex)Content/(restriction of extension)
Author:

    Kohsuke Kawaguchi (kohsuke.kawaguchi@sun.com)/**
 * Checks if binding declarations are placed where they are allowed.
 *
 * <p>
 * For example, if a {@code <jaxb:property>} customization is given under
 * the {@code <xs:simpleContent>} element, this class raises an error.
 *
 * <p>
 * our main checkpoint of misplaced customizations are in BGMBuilder.
 * There, we mark a customization whenever we use it. At the end of the
 * day, we look for unmarked customizations and raise errors for them.
 *
 * <p>
 * Between this approach and the JAXB spec 1.0 is a problem that
 * the spec allows/prohibits customizations at schema element level,
 * while BGMBuilder and XSOM works on schema component levels.
 *
 * <p>
 * For example, a property customization is allowed on a complex type
 * schema component, but it's only allowed on the {@code <complexType>}
 * element. The spec team informed us that they would consider resolving
 * this discrepancy in favor of RI, but meanwhile we need to detect
 * errors correctly.
 *
 * <p>
 * This filter is implemented for this purpose.
 *
 *
 * <h2>Customization and allowed locations</h2>
 *
 * - globalBinding/schemaBinding
 *     schema
 *
 * - class
 *     complexType(*), modelGroupDecl, modelGroup, element
 *
 * - property
 *     attribute, element, any, modelGroup, modelGroupRef, complexType(*)
 *
 * - javaType
 *     simpleType(*)
 *
 * - typesafeEnumClass
 *     simpleType(*)
 *
 * - typesafeEnumMember
 *     simpleType(*), enumeration
 *
 * Components marked with '*' needs a check by this component
 * since more than one schema element corresponds to one schema component
 * of that type.
 *
 * <p>
 * For simple types, customizations are allowed only under the {@code <xs:simpleType>}
 * element, and for complex types they are allowed only under the
 * {@code <xs:cimplexType>} element.
 *
 * <p>
 * So the bottom line is that it would be suffice if we just make sure
 * that no customization will be attached under other elements of
 * simple types and complex types. Those are:
 *
 * - simpleType/restriction
 * - list
 * - union
 * - complexType/(simple or complex)Content
 * - complexType/(simple or complex)Content/(restriction of extension)
 *
 * @author
 *     Kohsuke Kawaguchi (kohsuke.kawaguchi@sun.com)
 */
public class CustomizationContextChecker extends XMLFilterImpl {

    
Keep names of all the ancestor elements. /** Keep names of all the ancestor elements. */
    private final Stack<QName> elementNames = new Stack<QName>();

    private final ErrorHandler errorHandler;

    private Locator locator;

    
Set of element names that cannot have JAXB customizations. /** Set of element names that cannot have JAXB customizations. */
    private static final Set<String> prohibitedSchemaElementNames = new HashSet<String>();

    
Params:
_errorHandler – 
     Detected errors will be sent to this object./**
     * @param _errorHandler
     *      Detected errors will be sent to this object.
     */
    public CustomizationContextChecker( ErrorHandler _errorHandler ) {
        this.errorHandler = _errorHandler;
    }

    static {
        prohibitedSchemaElementNames.add("restriction");
        prohibitedSchemaElementNames.add("extension");
        prohibitedSchemaElementNames.add("simpleContent");
        prohibitedSchemaElementNames.add("complexContent");
        prohibitedSchemaElementNames.add("list");
        prohibitedSchemaElementNames.add("union");
    }




    
Gets the stack top. /** Gets the stack top. */
    private QName top() {
        return elementNames.peek();
    }

    public void startElement(String namespaceURI, String localName, String qName, Attributes atts) throws SAXException {
        QName newElement = new QName(namespaceURI,localName);

        if( newElement.getNamespaceURI().equals(Const.JAXB_NSURI)
         && top().getNamespaceURI().equals(WellKnownNamespace.XML_SCHEMA) ) {
            // we hit a JAXB customization. the stack top should be
            // <xs:appinfo>
            if( elementNames.size()>=3 ) {
                // the above statement checks if the following statement doesn't
                // cause an exception.
                QName schemaElement = elementNames.get( elementNames.size()-3 );
                if( prohibitedSchemaElementNames.contains(schemaElement.getLocalPart()) ) {
                    // the owner schema element is in the wanted list.
                    errorHandler.error( new SAXParseException(
                        Messages.format(
                            Messages.ERR_UNACKNOWLEDGED_CUSTOMIZATION,
                            localName ),
                        locator ) );
                }
            }


        }

        elementNames.push(newElement);

        super.startElement(namespaceURI, localName, qName, atts );
    }

    public void endElement(String namespaceURI, String localName, String qName)
        throws SAXException {

        super.endElement(namespaceURI, localName, qName);

        elementNames.pop();
    }

    public void setDocumentLocator(Locator locator) {
        super.setDocumentLocator(locator);
        this.locator = locator;
    }

}