/*
 * 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;

import java.io.IOException;

import org.apache.xerces.impl.dtd.XMLDTDValidatorFilter;
import org.apache.xerces.impl.msg.XMLMessageFormatter;
import org.apache.xerces.util.XMLAttributesImpl;
import org.apache.xerces.util.XMLSymbols;
import org.apache.xerces.xni.NamespaceContext;
import org.apache.xerces.xni.QName;
import org.apache.xerces.xni.XMLDocumentHandler;
import org.apache.xerces.xni.XNIException;
import org.apache.xerces.xni.parser.XMLComponentManager;
import org.apache.xerces.xni.parser.XMLConfigurationException;
import org.apache.xerces.xni.parser.XMLDocumentSource;

The scanner acts as the source for the document
information which is communicated to the document handler.
This class scans an XML document, checks if document has a DTD, and if
DTD is not found the scanner will remove the DTD Validator from the pipeline and perform
namespace binding.
Note: This scanner should only be used when the namespace processing is on!

This component requires the following features and properties from the
component manager that uses it:

 
http://xml.org/sax/features/namespaces {true} -- if the value of this
     feature is set to false this scanner must not be used.
 
http://xml.org/sax/features/validation
 
http://apache.org/xml/features/nonvalidating/load-external-dtd
 
http://apache.org/xml/features/scanner/notify-char-refs
 
http://apache.org/xml/features/scanner/notify-builtin-refs
 
http://apache.org/xml/properties/internal/symbol-table
 
http://apache.org/xml/properties/internal/error-reporter
 
http://apache.org/xml/properties/internal/entity-manager
 
http://apache.org/xml/properties/internal/dtd-scanner

Author:
Elena Litani, IBM
@xerces.internal
Version:
$Id: XMLNSDocumentScannerImpl.java 495747 2007-01-12 21:48:00Z mrglavas $/**
 * The scanner acts as the source for the document
 * information which is communicated to the document handler.
 *
 * This class scans an XML document, checks if document has a DTD, and if
 * DTD is not found the scanner will remove the DTD Validator from the pipeline and perform
 * namespace binding.
 *
 * Note: This scanner should only be used when the namespace processing is on!
 *
 * <p>
 * This component requires the following features and properties from the
 * component manager that uses it:
 * <ul>
 *  <li>http://xml.org/sax/features/namespaces {true} -- if the value of this
 *      feature is set to false this scanner must not be used.</li>
 *  <li>http://xml.org/sax/features/validation</li>
 *  <li>http://apache.org/xml/features/nonvalidating/load-external-dtd</li>
 *  <li>http://apache.org/xml/features/scanner/notify-char-refs</li>
 *  <li>http://apache.org/xml/features/scanner/notify-builtin-refs</li>
 *  <li>http://apache.org/xml/properties/internal/symbol-table</li>
 *  <li>http://apache.org/xml/properties/internal/error-reporter</li>
 *  <li>http://apache.org/xml/properties/internal/entity-manager</li>
 *  <li>http://apache.org/xml/properties/internal/dtd-scanner</li>
 * </ul>
 * 
 * @xerces.internal

 *
 * @author Elena Litani, IBM
 *
 * @version $Id: XMLNSDocumentScannerImpl.java 495747 2007-01-12 21:48:00Z mrglavas $
 */
public class XMLNSDocumentScannerImpl
extends XMLDocumentScannerImpl {

    
If is true, the dtd validator is no longer in the pipeline
and the scanner should bind namespaces /** If is true, the dtd validator is no longer in the pipeline
      * and the scanner should bind namespaces */
    protected boolean fBindNamespaces;

    
If validating parser, make sure we report an error in the
  scanner if DTD grammar is missing./** If validating parser, make sure we report an error in the
      *   scanner if DTD grammar is missing.*/
    protected boolean fPerformValidation;

    // private data
    //

    
DTD validator /** DTD validator */
    private XMLDTDValidatorFilter fDTDValidator;
    
    
Saw spaces after element name or between attributes.
This is reserved for the case where scanning of a start element spans
several methods, as is the case when scanning the start of a root element 
where a DTD external subset may be read after scanning the element name.
/** 
     * Saw spaces after element name or between attributes.
     * 
     * This is reserved for the case where scanning of a start element spans
     * several methods, as is the case when scanning the start of a root element 
     * where a DTD external subset may be read after scanning the element name.
     */
    private boolean fSawSpace;


    
The scanner is responsible for removing DTD validator
from the pipeline if it is not needed.
Params:
dtdValidator – The DTDValidator/**
     * The scanner is responsible for removing DTD validator
     * from the pipeline if it is not needed.
     *
     * @param dtdValidator The DTDValidator
     */
    public void setDTDValidator(XMLDTDValidatorFilter dtdValidator) {
        fDTDValidator = dtdValidator;
    }

    
Scans a start element. This method will handle the binding of
namespace information and notifying the handler of the start
of the element.

[44] EmptyElemTag ::= '<' Name (S Attribute)* S? '/>'
[40] STag ::= '<' Name (S Attribute)* S? '>'


Note: This method assumes that the leading
'<' character has been consumed.

Note: This method uses the fElementQName and
fAttributes variables. The contents of these variables will be
destroyed. The caller should copy important information out of
these variables before calling this method.
Returns:
True if element is empty. (i.e. It matches
         production [44]./**
     * Scans a start element. This method will handle the binding of
     * namespace information and notifying the handler of the start
     * of the element.
     * <p>
     * <pre>
     * [44] EmptyElemTag ::= '&lt;' Name (S Attribute)* S? '/>'
     * [40] STag ::= '&lt;' Name (S Attribute)* S? '>'
     * </pre>
     * <p>
     * <strong>Note:</strong> This method assumes that the leading
     * '&lt;' character has been consumed.
     * <p>
     * <strong>Note:</strong> This method uses the fElementQName and
     * fAttributes variables. The contents of these variables will be
     * destroyed. The caller should copy important information out of
     * these variables before calling this method.
     *
     * @return True if element is empty. (i.e. It matches
     *          production [44].
     */
    protected boolean scanStartElement()
    throws IOException, XNIException {
        if (DEBUG_CONTENT_SCANNING) System.out.println(">>> scanStartElementNS()");

        // Note: namespace processing is on by default
        fEntityScanner.scanQName(fElementQName);
        // REVISIT - [Q] Why do we need this temp variable? -- mrglavas
        String rawname = fElementQName.rawname;
        if (fBindNamespaces) {
            fNamespaceContext.pushContext();
            if (fScannerState == SCANNER_STATE_ROOT_ELEMENT) {
                if (fPerformValidation) {
                    fErrorReporter.reportError(XMLMessageFormatter.XML_DOMAIN,
                                               "MSG_GRAMMAR_NOT_FOUND",
                                               new Object[]{ rawname},
                                               XMLErrorReporter.SEVERITY_ERROR);

                    if (fDoctypeName == null || !fDoctypeName.equals(rawname)) {
                        fErrorReporter.reportError( XMLMessageFormatter.XML_DOMAIN,
                                                    "RootElementTypeMustMatchDoctypedecl",
                                                    new Object[]{fDoctypeName, rawname},
                                                    XMLErrorReporter.SEVERITY_ERROR);
                    }
                }
            }
        }

        // push element stack
        fCurrentElement = fElementStack.pushElement(fElementQName);

        // attributes
        boolean empty = false;
        fAttributes.removeAllAttributes();
        do {
            // spaces
            boolean sawSpace = fEntityScanner.skipSpaces();

            // end tag?
            int c = fEntityScanner.peekChar();
            if (c == '>') {
                fEntityScanner.scanChar();
                break;
            }
            else if (c == '/') {
                fEntityScanner.scanChar();
                if (!fEntityScanner.skipChar('>')) {
                    reportFatalError("ElementUnterminated",
                                     new Object[]{rawname});
                }
                empty = true;
                break;
            }
            else if (!isValidNameStartChar(c) || !sawSpace) {
                reportFatalError("ElementUnterminated", new Object[]{rawname});
            }

            // attributes
            scanAttribute(fAttributes);

        } while (true);

        if (fBindNamespaces) {
            // REVISIT: is it required? forbit xmlns prefix for element
            if (fElementQName.prefix == XMLSymbols.PREFIX_XMLNS) {
                fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                           "ElementXMLNSPrefix",
                                           new Object[]{fElementQName.rawname},
                                           XMLErrorReporter.SEVERITY_FATAL_ERROR);
            }

            // bind the element
            String prefix = fElementQName.prefix != null
                            ? fElementQName.prefix : XMLSymbols.EMPTY_STRING;
            // assign uri to the element
            fElementQName.uri = fNamespaceContext.getURI(prefix);
            // make sure that object in the element stack is updated as well
            fCurrentElement.uri = fElementQName.uri;

            if (fElementQName.prefix == null && fElementQName.uri != null) {
                fElementQName.prefix = XMLSymbols.EMPTY_STRING;
                // making sure that the object in the element stack is updated too.
                fCurrentElement.prefix = XMLSymbols.EMPTY_STRING;
            }
            if (fElementQName.prefix != null && fElementQName.uri == null) {
                fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                           "ElementPrefixUnbound",
                                           new Object[]{fElementQName.prefix, fElementQName.rawname},
                                           XMLErrorReporter.SEVERITY_FATAL_ERROR);
            }

            // bind attributes (xmlns are already bound bellow)
            int length = fAttributes.getLength();
            // fLength = 0; //initialize structure
            for (int i = 0; i < length; i++) {
                fAttributes.getName(i, fAttributeQName);

                String aprefix = fAttributeQName.prefix != null
                                 ? fAttributeQName.prefix : XMLSymbols.EMPTY_STRING;
                String uri = fNamespaceContext.getURI(aprefix);
                // REVISIT: try removing the first "if" and see if it is faster.
                //
                if (fAttributeQName.uri != null && fAttributeQName.uri == uri) {
                    // checkDuplicates(fAttributeQName, fAttributes);
                    continue;
                }
                if (aprefix != XMLSymbols.EMPTY_STRING) {
                    fAttributeQName.uri = uri;
                    if (uri == null) {
                        fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                                   "AttributePrefixUnbound",
                                                   new Object[]{fElementQName.rawname,fAttributeQName.rawname,aprefix},
                                                   XMLErrorReporter.SEVERITY_FATAL_ERROR);
                    }
                    fAttributes.setURI(i, uri);
                    // checkDuplicates(fAttributeQName, fAttributes);
                }
            }
            
            if (length > 1) {
                QName name = fAttributes.checkDuplicatesNS();
                if (name != null) {
                    if (name.uri != null) {
                        fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                                   "AttributeNSNotUnique",
                                                   new Object[]{fElementQName.rawname, name.localpart, name.uri},
                                                   XMLErrorReporter.SEVERITY_FATAL_ERROR);
                    }
                    else {
                        fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                                   "AttributeNotUnique",
                                                   new Object[]{fElementQName.rawname, name.rawname}, 
                                                   XMLErrorReporter.SEVERITY_FATAL_ERROR);
                    }
                }
            }
        }


        // call handler
        if (fDocumentHandler != null) {
            if (empty) {

                //decrease the markup depth..
                fMarkupDepth--;

                // check that this element was opened in the same entity
                if (fMarkupDepth < fEntityStack[fEntityDepth - 1]) {
                    reportFatalError("ElementEntityMismatch",
                                     new Object[]{fCurrentElement.rawname});
                }

                fDocumentHandler.emptyElement(fElementQName, fAttributes, null);

                if (fBindNamespaces) {
                    fNamespaceContext.popContext();
                }
                //pop the element off the stack..
                fElementStack.popElement(fElementQName);
            } else {
                fDocumentHandler.startElement(fElementQName, fAttributes, null);
            }
        }

        if (DEBUG_CONTENT_SCANNING) System.out.println("<<< scanStartElement(): "+empty);
        return empty;

    } // scanStartElement():boolean

    
Scans the name of an element in a start or empty tag. 
See Also:
scanStartElement()/**
     * Scans the name of an element in a start or empty tag. 
     * 
     * @see #scanStartElement()
     */
    protected void scanStartElementName ()
        throws IOException, XNIException {
        // Note: namespace processing is on by default
        fEntityScanner.scanQName(fElementQName);
        // Must skip spaces here because the DTD scanner
        // would consume them at the end of the external subset.
        fSawSpace = fEntityScanner.skipSpaces();
    } // scanStartElementName()

    
Scans the remainder of a start or empty tag after the element name.
See Also:
scanStartElement
Returns:
True if element is empty./**
     * Scans the remainder of a start or empty tag after the element name.
     * 
     * @see #scanStartElement
     * @return True if element is empty.
     */
    protected boolean scanStartElementAfterName()
        throws IOException, XNIException {
    	
        // REVISIT - [Q] Why do we need this temp variable? -- mrglavas
        String rawname = fElementQName.rawname;
        if (fBindNamespaces) {
            fNamespaceContext.pushContext();
            if (fScannerState == SCANNER_STATE_ROOT_ELEMENT) {
                if (fPerformValidation) {
                    fErrorReporter.reportError(XMLMessageFormatter.XML_DOMAIN,
                                               "MSG_GRAMMAR_NOT_FOUND",
                                               new Object[]{ rawname},
                                               XMLErrorReporter.SEVERITY_ERROR);

                    if (fDoctypeName == null || !fDoctypeName.equals(rawname)) {
                        fErrorReporter.reportError( XMLMessageFormatter.XML_DOMAIN,
                                                    "RootElementTypeMustMatchDoctypedecl",
                                                    new Object[]{fDoctypeName, rawname},
                                                    XMLErrorReporter.SEVERITY_ERROR);
                    }
                }
            }
        }

        // push element stack
        fCurrentElement = fElementStack.pushElement(fElementQName);

        // attributes
        boolean empty = false;
        fAttributes.removeAllAttributes();
        do {
        	
            // end tag?
            int c = fEntityScanner.peekChar();
            if (c == '>') {
                fEntityScanner.scanChar();
                break;
            }
            else if (c == '/') {
                fEntityScanner.scanChar();
                if (!fEntityScanner.skipChar('>')) {
                    reportFatalError("ElementUnterminated",
                                     new Object[]{rawname});
                }
                empty = true;
                break;
            }
            else if (!isValidNameStartChar(c) || !fSawSpace) {
                reportFatalError("ElementUnterminated", new Object[]{rawname});
            }

            // attributes
            scanAttribute(fAttributes);
            
            // spaces
            fSawSpace = fEntityScanner.skipSpaces();

        } while (true);

        if (fBindNamespaces) {
            // REVISIT: is it required? forbit xmlns prefix for element
            if (fElementQName.prefix == XMLSymbols.PREFIX_XMLNS) {
                fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                           "ElementXMLNSPrefix",
                                           new Object[]{fElementQName.rawname},
                                           XMLErrorReporter.SEVERITY_FATAL_ERROR);
            }

            // bind the element
            String prefix = fElementQName.prefix != null
                            ? fElementQName.prefix : XMLSymbols.EMPTY_STRING;
            // assign uri to the element
            fElementQName.uri = fNamespaceContext.getURI(prefix);
            // make sure that object in the element stack is updated as well
            fCurrentElement.uri = fElementQName.uri;

            if (fElementQName.prefix == null && fElementQName.uri != null) {
                fElementQName.prefix = XMLSymbols.EMPTY_STRING;
                // making sure that the object in the element stack is updated too.
                fCurrentElement.prefix = XMLSymbols.EMPTY_STRING;
            }
            if (fElementQName.prefix != null && fElementQName.uri == null) {
                fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                           "ElementPrefixUnbound",
                                           new Object[]{fElementQName.prefix, fElementQName.rawname},
                                           XMLErrorReporter.SEVERITY_FATAL_ERROR);
            }

            // bind attributes (xmlns are already bound bellow)
            int length = fAttributes.getLength();
            // fLength = 0; //initialize structure
            for (int i = 0; i < length; i++) {
                fAttributes.getName(i, fAttributeQName);

                String aprefix = fAttributeQName.prefix != null
                                 ? fAttributeQName.prefix : XMLSymbols.EMPTY_STRING;
                String uri = fNamespaceContext.getURI(aprefix);
                // REVISIT: try removing the first "if" and see if it is faster.
                //
                if (fAttributeQName.uri != null && fAttributeQName.uri == uri) {
                    // checkDuplicates(fAttributeQName, fAttributes);
                    continue;
                }
                if (aprefix != XMLSymbols.EMPTY_STRING) {
                    fAttributeQName.uri = uri;
                    if (uri == null) {
                        fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                                   "AttributePrefixUnbound",
                                                   new Object[]{fElementQName.rawname,fAttributeQName.rawname,aprefix},
                                                   XMLErrorReporter.SEVERITY_FATAL_ERROR);
                    }
                    fAttributes.setURI(i, uri);
                    // checkDuplicates(fAttributeQName, fAttributes);
                }
            }
            
            if (length > 1) {
                QName name = fAttributes.checkDuplicatesNS();
                if (name != null) {
                    if (name.uri != null) {
                        fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                                   "AttributeNSNotUnique",
                                                   new Object[]{fElementQName.rawname, name.localpart, name.uri},
                                                   XMLErrorReporter.SEVERITY_FATAL_ERROR);
                    }
                    else {
                        fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                                   "AttributeNotUnique",
                                                   new Object[]{fElementQName.rawname, name.rawname}, 
                                                   XMLErrorReporter.SEVERITY_FATAL_ERROR);
                    }
                }
            }
        }


        // call handler
        if (fDocumentHandler != null) {
            if (empty) {

                //decrease the markup depth..
                fMarkupDepth--;

                // check that this element was opened in the same entity
                if (fMarkupDepth < fEntityStack[fEntityDepth - 1]) {
                    reportFatalError("ElementEntityMismatch",
                                     new Object[]{fCurrentElement.rawname});
                }

                fDocumentHandler.emptyElement(fElementQName, fAttributes, null);

                if (fBindNamespaces) {
                    fNamespaceContext.popContext();
                }
                //pop the element off the stack..
                fElementStack.popElement(fElementQName);
            } else {
                fDocumentHandler.startElement(fElementQName, fAttributes, null);
            }
        }

        if (DEBUG_CONTENT_SCANNING) System.out.println("<<< scanStartElementAfterName(): "+empty);
        return empty;
    } // scanStartElementAfterName()

    
Scans an attribute.

[41] Attribute ::= Name Eq AttValue


Note: This method assumes that the next
character on the stream is the first character of the attribute
name.

Note: This method uses the fAttributeQName and
fQName variables. The contents of these variables will be
destroyed.
Params:
attributes – The attributes list for the scanned attribute./**
     * Scans an attribute.
     * <p>
     * <pre>
     * [41] Attribute ::= Name Eq AttValue
     * </pre>
     * <p>
     * <strong>Note:</strong> This method assumes that the next
     * character on the stream is the first character of the attribute
     * name.
     * <p>
     * <strong>Note:</strong> This method uses the fAttributeQName and
     * fQName variables. The contents of these variables will be
     * destroyed.
     *
     * @param attributes The attributes list for the scanned attribute.
     */
    protected void scanAttribute(XMLAttributesImpl attributes)
    throws IOException, XNIException {
        if (DEBUG_CONTENT_SCANNING) System.out.println(">>> scanAttribute()");

        // name
        fEntityScanner.scanQName(fAttributeQName);

        // equals
        fEntityScanner.skipSpaces();
        if (!fEntityScanner.skipChar('=')) {
            reportFatalError("EqRequiredInAttribute",
                             new Object[]{fCurrentElement.rawname,fAttributeQName.rawname});
        }
        fEntityScanner.skipSpaces();

        // content
        int attrIndex;
       
        if (fBindNamespaces) {
            attrIndex = attributes.getLength();
            attributes.addAttributeNS(fAttributeQName, XMLSymbols.fCDATASymbol, null);
        }
        else {
            int oldLen = attributes.getLength();
            attrIndex = attributes.addAttribute(fAttributeQName, XMLSymbols.fCDATASymbol, null);
        	
            // WFC: Unique Att Spec
            if (oldLen == attributes.getLength()) {
                reportFatalError("AttributeNotUnique",
                                 new Object[]{fCurrentElement.rawname,
                                 fAttributeQName.rawname});
            }
        }

        // Scan attribute value and return true if the non-normalized and normalized value are the same
        boolean isSameNormalizedAttr = scanAttributeValue(this.fTempString, fTempString2,
                fAttributeQName.rawname, fIsEntityDeclaredVC, fCurrentElement.rawname);
        
        String value = fTempString.toString();
        attributes.setValue(attrIndex, value);
        // If the non-normalized and normalized value are the same, avoid creating a new string.
        if (!isSameNormalizedAttr) {
            attributes.setNonNormalizedValue(attrIndex, fTempString2.toString());
        }
        attributes.setSpecified(attrIndex, true);

        // record namespace declarations if any.
        if (fBindNamespaces) {
            
            String localpart = fAttributeQName.localpart;
            String prefix = fAttributeQName.prefix != null
                            ? fAttributeQName.prefix : XMLSymbols.EMPTY_STRING;
            // when it's of form xmlns="..." or xmlns:prefix="...",
            // it's a namespace declaration. but prefix:xmlns="..." isn't.
            if (prefix == XMLSymbols.PREFIX_XMLNS ||
                prefix == XMLSymbols.EMPTY_STRING && localpart == XMLSymbols.PREFIX_XMLNS) {

                // get the internalized value of this attribute
                String uri = fSymbolTable.addSymbol(value);

                // 1. "xmlns" can't be bound to any namespace
                if (prefix == XMLSymbols.PREFIX_XMLNS && localpart == XMLSymbols.PREFIX_XMLNS) {
                    fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                               "CantBindXMLNS",
                                               new Object[]{fAttributeQName},
                                               XMLErrorReporter.SEVERITY_FATAL_ERROR);
                }

                // 2. the namespace for "xmlns" can't be bound to any prefix
                if (uri == NamespaceContext.XMLNS_URI) {
                    fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                               "CantBindXMLNS",
                                               new Object[]{fAttributeQName},
                                               XMLErrorReporter.SEVERITY_FATAL_ERROR);
                }

                // 3. "xml" can't be bound to any other namespace than it's own
                if (localpart == XMLSymbols.PREFIX_XML) {
                    if (uri != NamespaceContext.XML_URI) {
                        fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                                   "CantBindXML",
                                                   new Object[]{fAttributeQName},
                                                   XMLErrorReporter.SEVERITY_FATAL_ERROR);
                    }
                }
                // 4. the namespace for "xml" can't be bound to any other prefix
                else {
                    if (uri ==NamespaceContext.XML_URI) {
                        fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                                   "CantBindXML",
                                                   new Object[]{fAttributeQName},
                                                   XMLErrorReporter.SEVERITY_FATAL_ERROR);
                    }
                }

                prefix = localpart != XMLSymbols.PREFIX_XMLNS ? localpart : XMLSymbols.EMPTY_STRING;

                // http://www.w3.org/TR/1999/REC-xml-names-19990114/#dt-prefix
                // We should only report an error if there is a prefix,
                // that is, the local part is not "xmlns". -SG
                if (uri == XMLSymbols.EMPTY_STRING && localpart != XMLSymbols.PREFIX_XMLNS) {
                    fErrorReporter.reportError(XMLMessageFormatter.XMLNS_DOMAIN,
                                               "EmptyPrefixedAttName",
                                               new Object[]{fAttributeQName},
                                               XMLErrorReporter.SEVERITY_FATAL_ERROR);
                }

                // declare prefix in context
                fNamespaceContext.declarePrefix(prefix, uri.length() != 0 ? uri : null);
                // bind namespace attribute to a namespace
                attributes.setURI(attrIndex, fNamespaceContext.getURI(XMLSymbols.PREFIX_XMLNS));

            }
            else {
                // attempt to bind attribute
                if (fAttributeQName.prefix != null) {
                    attributes.setURI(attrIndex, fNamespaceContext.getURI(fAttributeQName.prefix));
                }
            }
        }

        if (DEBUG_CONTENT_SCANNING) System.out.println("<<< scanAttribute()");
    } // scanAttribute(XMLAttributes)



    
Scans an end element.

[42] ETag ::= '</' Name S? '>'


Note: This method uses the fElementQName variable.
The contents of this variable will be destroyed. The caller should
copy the needed information out of this variable before calling
this method.
Returns:
The element depth./**
     * Scans an end element.
     * <p>
     * <pre>
     * [42] ETag ::= '&lt;/' Name S? '>'
     * </pre>
     * <p>
     * <strong>Note:</strong> This method uses the fElementQName variable.
     * The contents of this variable will be destroyed. The caller should
     * copy the needed information out of this variable before calling
     * this method.
     *
     * @return The element depth.
     */
    protected int scanEndElement() throws IOException, XNIException {
        if (DEBUG_CONTENT_SCANNING) System.out.println(">>> scanEndElement()");

        // pop context
        fElementStack.popElement(fElementQName) ;

        // Take advantage of the fact that next string _should_ be "fElementQName.rawName",
        //In scanners most of the time is consumed on checks done for XML characters, we can
        // optimize on it and avoid the checks done for endElement,
        //we will also avoid symbol table lookup - neeraj.bajaj@sun.com

        // this should work both for namespace processing true or false...

        //REVISIT: if the string is not the same as expected.. we need to do better error handling..
        //We can skip this for now... In any case if the string doesn't match -- document is not well formed.
        if (!fEntityScanner.skipString(fElementQName.rawname)) {
            reportFatalError("ETagRequired", new Object[]{fElementQName.rawname});
        }

        // end
        fEntityScanner.skipSpaces();
        if (!fEntityScanner.skipChar('>')) {
            reportFatalError("ETagUnterminated",
                             new Object[]{fElementQName.rawname});
        }
        fMarkupDepth--;

        //we have increased the depth for two markup "<" characters
        fMarkupDepth--;

        // check that this element was opened in the same entity
        if (fMarkupDepth < fEntityStack[fEntityDepth - 1]) {
            reportFatalError("ElementEntityMismatch",
                             new Object[]{fCurrentElement.rawname});
        }

        // call handler
        if (fDocumentHandler != null ) {

            fDocumentHandler.endElement(fElementQName, null);
            if (fBindNamespaces) {
                fNamespaceContext.popContext();
            }

        }

        return fMarkupDepth;

    } // scanEndElement():int


    public void reset(XMLComponentManager componentManager)
    throws XMLConfigurationException {

        super.reset(componentManager);
        fPerformValidation = false;
        fBindNamespaces = false;
    }

    
Creates a content dispatcher. /** Creates a content dispatcher. */
    protected Dispatcher createContentDispatcher() {
        return new NSContentDispatcher();
    } // createContentDispatcher():Dispatcher

    
Dispatcher to handle content scanning.
/**
     * Dispatcher to handle content scanning.
     */
    protected final class NSContentDispatcher
        extends ContentDispatcher {
        
        
Scan for root element hook. This method is a hook for
subclasses to add code that handles scanning for the root
element. This method will also attempt to remove DTD validator
from the pipeline, if there is no DTD grammar. If DTD validator
is no longer in the pipeline bind namespaces in the scanner.
Returns:
True if the caller should stop and return true which
         allows the scanner to switch to a new scanning
         dispatcher. A return value of false indicates that
         the content dispatcher should continue as normal./**
         * Scan for root element hook. This method is a hook for
         * subclasses to add code that handles scanning for the root
         * element. This method will also attempt to remove DTD validator
         * from the pipeline, if there is no DTD grammar. If DTD validator
         * is no longer in the pipeline bind namespaces in the scanner.
         *
         *
         * @return True if the caller should stop and return true which
         *          allows the scanner to switch to a new scanning
         *          dispatcher. A return value of false indicates that
         *          the content dispatcher should continue as normal.
         */
        protected boolean scanRootElementHook()
            throws IOException, XNIException {
       
            if (fExternalSubsetResolver != null && !fSeenDoctypeDecl
                && !fDisallowDoctype && (fValidation || fLoadExternalDTD)) {
                scanStartElementName();
                resolveExternalSubsetAndRead();
                reconfigurePipeline();
                if (scanStartElementAfterName()) {
                    setScannerState(SCANNER_STATE_TRAILING_MISC);
                    setDispatcher(fTrailingMiscDispatcher);
                    return true;
                }
            }
            else {
                reconfigurePipeline();
                if (scanStartElement()) {
                    setScannerState(SCANNER_STATE_TRAILING_MISC);
                    setDispatcher(fTrailingMiscDispatcher);
                    return true;
                }
            }
            return false;

        } // scanRootElementHook():boolean
        
        
Re-configures pipeline by removing the DTD validator 
if no DTD grammar exists. If no validator exists in the
pipeline or there is no DTD grammar, namespace binding
is performed by the scanner in the enclosing class.
/**
         * Re-configures pipeline by removing the DTD validator 
         * if no DTD grammar exists. If no validator exists in the
         * pipeline or there is no DTD grammar, namespace binding
         * is performed by the scanner in the enclosing class.
         */
        private void reconfigurePipeline() {
            if (fDTDValidator == null) {
                fBindNamespaces = true;
            }
            else if (!fDTDValidator.hasGrammar()) {
                fBindNamespaces = true;
                fPerformValidation = fDTDValidator.validate();
                // re-configure pipeline
                XMLDocumentSource source = fDTDValidator.getDocumentSource();
                XMLDocumentHandler handler = fDTDValidator.getDocumentHandler();
                source.setDocumentHandler(handler);
                if (handler != null)
                    handler.setDocumentSource(source);
                fDTDValidator.setDocumentSource(null);
                fDTDValidator.setDocumentHandler(null);
            }
        } // reconfigurePipeline()
    }

} // class XMLNSDocumentScannerImpl