/*
 * 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.html.dom;

import java.io.StringWriter;
import java.lang.reflect.Constructor;
import java.util.Hashtable;
import java.util.Locale;

import org.apache.xerces.dom.DocumentImpl;
import org.apache.xerces.dom.ElementImpl;
import org.w3c.dom.Attr;
import org.w3c.dom.DOMException;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.UserDataHandler;
import org.w3c.dom.html.HTMLBodyElement;
import org.w3c.dom.html.HTMLCollection;
import org.w3c.dom.html.HTMLDocument;
import org.w3c.dom.html.HTMLElement;
import org.w3c.dom.html.HTMLFrameSetElement;
import org.w3c.dom.html.HTMLHeadElement;
import org.w3c.dom.html.HTMLHtmlElement;
import org.w3c.dom.html.HTMLTitleElement;

Implements an HTML document. Provides access to the top level element in the
document, its body and title.
 Several methods create new nodes of all basic types (comment, text, element, etc.). These methods create new nodes but do not place them in the document tree. The nodes may be placed in the document tree using Node.appendChild or Node.insertBefore, or they may be placed in some other document tree. 
 Note: <FRAMESET> documents are not supported at the moment, neither are direct document writing (open, write) and HTTP attribute methods (getURL, getCookie). 
Author:
Assaf Arkin
See Also:
HTMLDocument
@xerces.internal
Version:
$Revision: 1029415 $ $Date: 2010-10-31 22:32:22 +0530 (Sun, 31 Oct 2010) $/**
 * Implements an HTML document. Provides access to the top level element in the
 * document, its body and title.
 * <P>
 * Several methods create new nodes of all basic types (comment, text, element,
 * etc.). These methods create new nodes but do not place them in the document
 * tree. The nodes may be placed in the document tree using {@link
 * org.w3c.dom.Node#appendChild} or {@link org.w3c.dom.Node#insertBefore}, or
 * they may be placed in some other document tree.
 * <P>
 * Note: &lt;FRAMESET&gt; documents are not supported at the moment, neither
 * are direct document writing ({@link #open}, {@link #write}) and HTTP attribute
 * methods ({@link #getURL}, {@link #getCookie}).
 *
 * @xerces.internal

 *
 * @version $Revision: 1029415 $ $Date: 2010-10-31 22:32:22 +0530 (Sun, 31 Oct 2010) $
 * @author <a href="mailto:arkin@exoffice.com">Assaf Arkin</a>
 * @see org.w3c.dom.html.HTMLDocument
 */
public class HTMLDocumentImpl
    extends DocumentImpl
    implements HTMLDocument
{

    private static final long serialVersionUID = 4285791750126227180L;

    
Holds HTMLCollectionImpl object with live collection of all
anchors in document. This reference is on demand only once.
/**
     * Holds <code>HTMLCollectionImpl</code> object with live collection of all
     * anchors in document. This reference is on demand only once.
     */
    private HTMLCollectionImpl    _anchors;


    
Holds HTMLCollectionImpl object with live collection of all
forms in document. This reference is on demand only once.
/**
     * Holds <code>HTMLCollectionImpl</code> object with live collection of all
     * forms in document. This reference is on demand only once.
     */
    private HTMLCollectionImpl    _forms;


    
Holds HTMLCollectionImpl object with live collection of all
images in document. This reference is on demand only once.
/**
     * Holds <code>HTMLCollectionImpl</code> object with live collection of all
     * images in document. This reference is on demand only once.
     */
    private HTMLCollectionImpl    _images;


    
Holds HTMLCollectionImpl object with live collection of all
links in document. This reference is on demand only once.
/**
     * Holds <code>HTMLCollectionImpl</code> object with live collection of all
     * links in document. This reference is on demand only once.
     */
    private HTMLCollectionImpl    _links;


    
Holds HTMLCollectionImpl object with live collection of all
applets in document. This reference is on demand only once.
/**
     * Holds <code>HTMLCollectionImpl</code> object with live collection of all
     * applets in document. This reference is on demand only once.
     */
    private HTMLCollectionImpl    _applets;


    
Holds string writer used by direct manipulation operation (open. write, etc) to write new contents into the document and parse that text into a document tree. /**
     * Holds string writer used by direct manipulation operation ({@link #open}.
     * {@link #write}, etc) to write new contents into the document and parse
     * that text into a document tree.
     */
    private StringWriter        _writer;


    
Holds names and classes of HTML element types. When an element with a particular tag name is created, the matching Class is used to create the element object. For example, <A> matches HTMLAnchorElementImpl. This static table is shared across all HTML documents. 
See Also:
createElement/**
     * Holds names and classes of HTML element types. When an element with a
     * particular tag name is created, the matching {@link java.lang.Class}
     * is used to create the element object. For example, &lt;A&gt; matches
     * {@link HTMLAnchorElementImpl}. This static table is shared across all
     * HTML documents.
     *
     * @see #createElement
     */
    private static Hashtable        _elementTypesHTML;


    
Signature used to locate constructor of HTML element classes. This
static array is shared across all HTML documents.
See Also:
createElement/**
     * Signature used to locate constructor of HTML element classes. This
     * static array is shared across all HTML documents.
     *
     * @see #createElement
     */
    private static final Class[]    _elemClassSigHTML =
                new Class[] { HTMLDocumentImpl.class, String.class };


    /**
     */
    public HTMLDocumentImpl()
    {
        super();
        populateElementTypes();
    }


    public synchronized Element getDocumentElement()
    {
        Node    html;
        Node    child;
        Node    next;

        // The document element is the top-level HTML element of the HTML
        // document. Only this element should exist at the top level.
        // If the HTML element is found, all other elements that might
        // precede it are placed inside the HTML element.
        html = getFirstChild();
        while ( html != null )
        {
            if ( html instanceof HTMLHtmlElement )
            {
                // REVISIT: [Q] Why is this code even here? In fact, the
                //          original code is in error because it will
                //          try to move ALL nodes to be children of the
                //          HTML tag. This is not the intended behavior
                //          for comments and processing instructions
                //          outside the root element; it will throw a
                //          hierarchy request error exception for doctype
                //          nodes; *and* this code shouldn't even be
                //          needed because the parser should never build
                //          a document that contains more than a single
                //          root element, anyway! -Ac
                /***
                synchronized ( html )
                {
                    child = getFirstChild();
                    while ( child != null && child != html )
                    {
                        next = child.getNextSibling();
                        html.appendChild( child );
                        child = next;
                    }
                }
                /***/
                return (HTMLElement) html;
            }
            html = html.getNextSibling();
        }

        // HTML element must exist. Create a new element and dump the
        // entire contents of the document into it in the same order as
        // they appear now.
        html = new HTMLHtmlElementImpl( this, "HTML" );
        child = getFirstChild();
        while ( child != null )
        {
            next = child.getNextSibling();
            html.appendChild( child );
            child = next;
        }
        appendChild( html );
        return (HTMLElement) html;
    }


    
Obtains the <HEAD> element in the document, creating one if does not exist before. The <HEAD> element is the first element in the <HTML> in the document. The <HTML> element is obtained by calling getDocumentElement. If the element does not exist, one is created. 
 Called by getTitle, setTitle, getBody and setBody to assure the document has the <HEAD> element correctly placed. 
Returns:
The <HEAD> element/**
     * Obtains the &lt;HEAD&gt; element in the document, creating one if does
     * not exist before. The &lt;HEAD&gt; element is the first element in the
     * &lt;HTML&gt; in the document. The &lt;HTML&gt; element is obtained by
     * calling {@link #getDocumentElement}. If the element does not exist, one
     * is created.
     * <P>
     * Called by {@link #getTitle}, {@link #setTitle}, {@link #getBody} and
     * {@link #setBody} to assure the document has the &lt;HEAD&gt; element
     * correctly placed.
     *
     * @return The &lt;HEAD&gt; element
     */
    public synchronized HTMLElement getHead()
    {
        Node    head;
        Node    html;
        Node    child;
        Node    next;

        // Call getDocumentElement() to get the HTML element that is also the
        // top-level element in the document. Get the first element in the
        // document that is called HEAD. Work with that.
        html = getDocumentElement();
        synchronized ( html )
        {
            head = html.getFirstChild();
            while ( head != null && ! ( head instanceof HTMLHeadElement ) )
                head = head.getNextSibling();
            // HEAD exists but might not be first element in HTML: make sure
            // it is and return it.
            if ( head != null )
            {
                synchronized ( head )
                {
                    child = html.getFirstChild();
                    while ( child != null && child != head )
                    {
                        next = child.getNextSibling();
                        head.insertBefore( child, head.getFirstChild() );
                        child = next;
                    }
                }
                return (HTMLElement) head;
            }

            // Head does not exist, create a new one, place it at the top of the
            // HTML element and return it.
            head = new HTMLHeadElementImpl( this, "HEAD" );
            html.insertBefore( head, html.getFirstChild() );
        }
        return (HTMLElement) head;
    }


    public synchronized String getTitle()
    {
        HTMLElement head;
        NodeList    list;
        Node        title;

        // Get the HEAD element and look for the TITLE element within.
        // When found, make sure the TITLE is a direct child of HEAD,
        // and return the title's text (the Text node contained within).
        head = getHead();
        list = head.getElementsByTagName( "TITLE" );
        if ( list.getLength() > 0 ) {
            title = list.item( 0 );
            return ( (HTMLTitleElement) title ).getText();
        }
        // No TITLE found, return an empty string.
        return "";
    }


    public synchronized void setTitle( String newTitle )
    {
        HTMLElement head;
        NodeList    list;
        Node        title;

        // Get the HEAD element and look for the TITLE element within.
        // When found, make sure the TITLE is a direct child of HEAD,
        // and set the title's text (the Text node contained within).
        head = getHead();
        list = head.getElementsByTagName( "TITLE" );
        if ( list.getLength() > 0 ) {
            title = list.item( 0 );
            if ( title.getParentNode() != head )
                head.appendChild( title );
            ( (HTMLTitleElement) title ).setText( newTitle );
        }
        else
        {
            // No TITLE found, create a new element and place it at the end
            // of the HEAD element.
            title = new HTMLTitleElementImpl( this, "TITLE" );
            ( (HTMLTitleElement) title ).setText( newTitle );
            head.appendChild( title );
        }
    }


    public synchronized HTMLElement getBody()
    {
        Node    html;
        Node    head;
        Node    body;
        Node    child;
        Node    next;

        // Call getDocumentElement() to get the HTML element that is also the
        // top-level element in the document. Get the first element in the
        // document that is called BODY. Work with that.
        html = getDocumentElement();
        head = getHead();
        synchronized ( html )
        {
            body = head.getNextSibling();
            while ( body != null && ! ( body instanceof HTMLBodyElement )
                    && ! ( body instanceof HTMLFrameSetElement ) )
                body = body.getNextSibling();

            // BODY/FRAMESET exists but might not be second element in HTML
            // (after HEAD): make sure it is and return it.
            if ( body != null )
            {
                synchronized ( body )
                {
                    child = head.getNextSibling();
                    while ( child != null && child != body )
                    {
                        next = child.getNextSibling();
                        body.insertBefore( child, body.getFirstChild() );
                        child = next;
                    }
                }
                return (HTMLElement) body;
            }

            // BODY does not exist, create a new one, place it in the HTML element
            // right after the HEAD and return it.
            body = new HTMLBodyElementImpl( this, "BODY" );
            html.appendChild( body );
        }
        return (HTMLElement) body;
    }


    public synchronized void setBody( HTMLElement newBody )
    {
        Node    html;
        Node    body;
        Node    head;
        Node    child;
        NodeList list;

        synchronized ( newBody )
        {
            // Call getDocumentElement() to get the HTML element that is also the
            // top-level element in the document. Get the first element in the
            // document that is called BODY. Work with that.
            html = getDocumentElement();
            head = getHead();
            synchronized ( html )
            {
                list = this.getElementsByTagName( "BODY" );
                if ( list.getLength() > 0 ) {
                    // BODY exists but might not follow HEAD in HTML. If not,
                    // make it so and replce it. Start with the HEAD and make
                    // sure the BODY is the first element after the HEAD.
                    body = list.item( 0 );
                    synchronized ( body )
                    {
                        child = head;
                        while ( child != null )
                        {
                            if ( child instanceof Element )
                            {
                                if ( child != body )
                                    html.insertBefore( newBody, child );
                                else
                                    html.replaceChild( newBody, body );
                                return;
                            }
                            child = child.getNextSibling();
                        }
                        html.appendChild( newBody );
                    }
                    return;
                }
                // BODY does not exist, place it in the HTML element
                // right after the HEAD.
                html.appendChild( newBody );
            }
        }
    }


    public synchronized Element getElementById( String elementId )
    {
        Element idElement = super.getElementById(elementId);
        if (idElement != null) {
            return idElement;
        }
        return getElementById( elementId, this );
    }


    public NodeList getElementsByName( String elementName )
    {
        return new NameNodeListImpl( this, elementName );
    }


    public final NodeList getElementsByTagName( String tagName )
    {
        return super.getElementsByTagName( tagName.toUpperCase(Locale.ENGLISH) );
    }


    public final NodeList getElementsByTagNameNS( String namespaceURI,
                                                  String localName )
    {
        if ( namespaceURI != null && namespaceURI.length() > 0 ) {
            return super.getElementsByTagNameNS( namespaceURI, localName.toUpperCase(Locale.ENGLISH) );
        }
        return super.getElementsByTagName( localName.toUpperCase(Locale.ENGLISH) );
    }


    
Xerces-specific constructor. "localName" is passed in, so we don't need
to create a new String for it.
Params:
namespaceURI – The namespace URI of the element to
                    create.
qualifiedName – The qualified name of the element type to
                     instantiate.
localpart –     The local name of the element to instantiate.
Throws:
DOMException – INVALID_CHARACTER_ERR: Raised if the specified
                     name contains an invalid character.
Returns:
Element A new Element object with the following attributes:/**
     * Xerces-specific constructor. "localName" is passed in, so we don't need
     * to create a new String for it.
     *
     * @param namespaceURI The namespace URI of the element to
     *                     create.
     * @param qualifiedName The qualified name of the element type to
     *                      instantiate.
     * @param localpart     The local name of the element to instantiate.
     * @return Element A new Element object with the following attributes:
     * @throws DOMException INVALID_CHARACTER_ERR: Raised if the specified
     *                      name contains an invalid character.
     */
    public Element createElementNS(String namespaceURI, String qualifiedName,
                                   String localpart)
        throws DOMException
    {
        return createElementNS(namespaceURI, qualifiedName);
    }

    public Element createElementNS( String namespaceURI, String qualifiedName )
    {
        if ( namespaceURI == null || namespaceURI.length() == 0 ) {
            return createElement( qualifiedName );
        }
        return super.createElementNS( namespaceURI, qualifiedName );
    }


    public Element createElement( String tagName )
        throws DOMException
    {
        Class        elemClass;
        Constructor    cnst;

        // First, make sure tag name is all upper case, next get the associated
        // element class. If no class is found, generate a generic HTML element.
        // Do so also if an unexpected exception occurs.
        tagName = tagName.toUpperCase(Locale.ENGLISH);
        elemClass = (Class) _elementTypesHTML.get( tagName );
        if ( elemClass != null )
        {
            // Get the constructor for the element. The signature specifies an
            // owner document and a tag name. Use the constructor to instantiate
            // a new object and return it.
            try
            {
                cnst = elemClass.getConstructor( _elemClassSigHTML );
                return (Element) cnst.newInstance( new Object[] { this, tagName } );
            }
            catch ( Exception except )
            {
                /*
                Throwable thrw;

                if ( except instanceof java.lang.reflect.InvocationTargetException )
                    thrw = ( (java.lang.reflect.InvocationTargetException) except ).getTargetException();
                else
                    thrw = except;
                System.out.println( "Exception " + thrw.getClass().getName() );
                System.out.println( thrw.getMessage() );
                */
                throw new IllegalStateException( "HTM15 Tag '" + tagName + "' associated with an Element class that failed to construct.\n" + tagName);
            }
        }
        return new HTMLElementImpl( this, tagName );
    }


    
Creates an Attribute having this Document as its OwnerDoc. Overrides CoreDocumentImpl.createAttribute and returns and attribute whose name is lower case. 
Params:
name – The name of the attribute
Throws:
DOMException – (INVALID_NAME_ERR) if the attribute name
  is not acceptable
Returns:
An attribute whose name is all lower case/**
     * Creates an Attribute having this Document as its OwnerDoc.
     * Overrides {@link DocumentImpl#createAttribute} and returns
     * and attribute whose name is lower case.
     *
     * @param name The name of the attribute
     * @return An attribute whose name is all lower case
     * @throws DOMException(INVALID_NAME_ERR) if the attribute name
     *   is not acceptable
     */
    public Attr createAttribute( String name )
        throws DOMException
    {
        return super.createAttribute( name.toLowerCase(Locale.ENGLISH) );
    }

    
    public String getReferrer()
    {
        // Information not available on server side.
        return null;
    }


    public String getDomain()
    {
        // Information not available on server side.
        return null;
    }


    public String getURL()
    {
        // Information not available on server side.
        return null;
    }


    public String getCookie()
    {
        // Information not available on server side.
        return null;
    }


    public void setCookie( String cookie )
    {
        // Information not available on server side.
    }


    public HTMLCollection getImages()
    {
        // For more information see HTMLCollection#collectionMatch
        if ( _images == null )
            _images = new HTMLCollectionImpl( getBody(), HTMLCollectionImpl.IMAGE );
        return _images;
    }


    public HTMLCollection getApplets()
    {
        // For more information see HTMLCollection#collectionMatch
        if ( _applets == null )
            _applets = new HTMLCollectionImpl( getBody(), HTMLCollectionImpl.APPLET );
        return _applets;
    }


    public HTMLCollection getLinks()
    {
        // For more information see HTMLCollection#collectionMatch
        if ( _links == null )
            _links = new HTMLCollectionImpl( getBody(), HTMLCollectionImpl.LINK );
        return _links;
    }


    public HTMLCollection getForms()
    {
        // For more information see HTMLCollection#collectionMatch
        if ( _forms == null )
            _forms = new HTMLCollectionImpl( getBody(), HTMLCollectionImpl.FORM );
        return _forms;
    }


    public HTMLCollection getAnchors()
    {
        // For more information see HTMLCollection#collectionMatch
        if ( _anchors == null )
            _anchors = new HTMLCollectionImpl( getBody(), HTMLCollectionImpl.ANCHOR );
        return _anchors;
    }


    public void open()
    {
        // When called an in-memory is prepared. The document tree is still
        // accessible the old way, until this writer is closed.
        if ( _writer == null )
            _writer = new StringWriter();
    }


    public void close()
    {
        // ! NOT IMPLEMENTED, REQUIRES PARSER !
        if ( _writer != null )
        {
            _writer = null;
        }
    }


    public void write( String text )
    {
        // Write a string into the in-memory writer.
        if ( _writer != null )
            _writer.write( text );
    }


    public void writeln( String text )
    {
        // Write a line into the in-memory writer.
        if ( _writer != null )
            _writer.write( text + "\n" );
    }


    public Node cloneNode( boolean deep )
    {
        HTMLDocumentImpl newdoc = new HTMLDocumentImpl();
        callUserDataHandlers(this, newdoc, UserDataHandler.NODE_CLONED);
        cloneNode(newdoc, deep);
        return newdoc;
    }
    
    
    /* (non-Javadoc)
     * @see CoreDocumentImpl#canRenameElements()
     */
    protected boolean canRenameElements(String newNamespaceURI, String newNodeName, ElementImpl el) {
        if (el.getNamespaceURI() != null) {
            // element is not HTML:
            // can be renamed if not changed to HTML
            return newNamespaceURI != null;
        }
        
        // check whether a class change is required
        Class newClass = (Class) _elementTypesHTML.get(newNodeName.toUpperCase(Locale.ENGLISH));
        Class oldClass = (Class) _elementTypesHTML.get(el.getTagName());
        return newClass == oldClass;
    }

    
    
Recursive method retreives an element by its id attribute. Called by getElementById(String). 
Params:
elementId – The id value to look for
Returns:
The node in which to look for/**
     * Recursive method retreives an element by its <code>id</code> attribute.
     * Called by {@link #getElementById(String)}.
     *
     * @param elementId The <code>id</code> value to look for
     * @return The node in which to look for
     */
    private Element getElementById( String elementId, Node node )
    {
        Node    child;
        Element    result;

        child = node.getFirstChild();
        while ( child != null )
        {
            if ( child instanceof Element )
            {
                if ( elementId.equals( ( (Element) child ).getAttribute( "id" ) ) )
                    return (Element) child;
                result = getElementById( elementId, child );
                if ( result != null )
                    return result;
            }
            child = child.getNextSibling();
        }
        return null;
    }


    
Called by the constructor to populate the element types list (see _elementTypesHTML). Will be called multiple times but populate the list only the first time. Replacement for static constructor. /**
     * Called by the constructor to populate the element types list (see {@link
     * #_elementTypesHTML}). Will be called multiple times but populate the list
     * only the first time. Replacement for static constructor.
     */
    private synchronized static void populateElementTypes()
    {
        // This class looks like it is due to some strange
        // (read: inconsistent) JVM bugs.
        // Initially all this code was placed in the static constructor,
        // but that caused some early JVMs (1.1) to go mad, and if a
        // class could not be found (as happened during development),
        // the JVM would die.
        // Bertrand Delacretaz <bdelacretaz@worldcom.ch> pointed out
        // several configurations where HTMLAnchorElementImpl.class
        // failed, forcing me to revert back to Class.forName().

        if ( _elementTypesHTML != null )
            return;
        _elementTypesHTML = new Hashtable( 63 );
        populateElementType( "A", "HTMLAnchorElementImpl" );
        populateElementType( "APPLET", "HTMLAppletElementImpl" );
        populateElementType( "AREA", "HTMLAreaElementImpl" );
        populateElementType( "BASE",  "HTMLBaseElementImpl" );
        populateElementType( "BASEFONT", "HTMLBaseFontElementImpl" );
        populateElementType( "BLOCKQUOTE", "HTMLQuoteElementImpl" );
        populateElementType( "BODY", "HTMLBodyElementImpl" );
        populateElementType( "BR", "HTMLBRElementImpl" );
        populateElementType( "BUTTON", "HTMLButtonElementImpl" );
        populateElementType( "DEL", "HTMLModElementImpl" );
        populateElementType( "DIR", "HTMLDirectoryElementImpl" );
        populateElementType( "DIV",  "HTMLDivElementImpl" );
        populateElementType( "DL", "HTMLDListElementImpl" );
        populateElementType( "FIELDSET", "HTMLFieldSetElementImpl" );
        populateElementType( "FONT", "HTMLFontElementImpl" );
        populateElementType( "FORM", "HTMLFormElementImpl" );
        populateElementType( "FRAME","HTMLFrameElementImpl" );
        populateElementType( "FRAMESET", "HTMLFrameSetElementImpl" );
        populateElementType( "HEAD", "HTMLHeadElementImpl" );
        populateElementType( "H1", "HTMLHeadingElementImpl" );
        populateElementType( "H2", "HTMLHeadingElementImpl" );
        populateElementType( "H3", "HTMLHeadingElementImpl" );
        populateElementType( "H4", "HTMLHeadingElementImpl" );
        populateElementType( "H5", "HTMLHeadingElementImpl" );
        populateElementType( "H6", "HTMLHeadingElementImpl" );
        populateElementType( "HR", "HTMLHRElementImpl" );
        populateElementType( "HTML", "HTMLHtmlElementImpl" );
        populateElementType( "IFRAME", "HTMLIFrameElementImpl" );
        populateElementType( "IMG", "HTMLImageElementImpl" );
        populateElementType( "INPUT", "HTMLInputElementImpl" );
        populateElementType( "INS", "HTMLModElementImpl" );
        populateElementType( "ISINDEX", "HTMLIsIndexElementImpl" );
        populateElementType( "LABEL", "HTMLLabelElementImpl" );
        populateElementType( "LEGEND", "HTMLLegendElementImpl" );
        populateElementType( "LI", "HTMLLIElementImpl" );
        populateElementType( "LINK", "HTMLLinkElementImpl" );
        populateElementType( "MAP", "HTMLMapElementImpl" );
        populateElementType( "MENU", "HTMLMenuElementImpl" );
        populateElementType( "META", "HTMLMetaElementImpl" );
        populateElementType( "OBJECT", "HTMLObjectElementImpl" );
        populateElementType( "OL", "HTMLOListElementImpl" );
        populateElementType( "OPTGROUP", "HTMLOptGroupElementImpl" );
        populateElementType( "OPTION", "HTMLOptionElementImpl" );
        populateElementType( "P", "HTMLParagraphElementImpl" );
        populateElementType( "PARAM", "HTMLParamElementImpl" );
        populateElementType( "PRE", "HTMLPreElementImpl" );
        populateElementType( "Q", "HTMLQuoteElementImpl" );
        populateElementType( "SCRIPT", "HTMLScriptElementImpl" );
        populateElementType( "SELECT", "HTMLSelectElementImpl" );
        populateElementType( "STYLE", "HTMLStyleElementImpl" );
        populateElementType( "TABLE", "HTMLTableElementImpl" );
        populateElementType( "CAPTION", "HTMLTableCaptionElementImpl" );
        populateElementType( "TD", "HTMLTableCellElementImpl" );
        populateElementType( "TH", "HTMLTableCellElementImpl" );
        populateElementType( "COL", "HTMLTableColElementImpl" );
        populateElementType( "COLGROUP", "HTMLTableColElementImpl" );
        populateElementType( "TR", "HTMLTableRowElementImpl" );
        populateElementType( "TBODY", "HTMLTableSectionElementImpl" );
        populateElementType( "THEAD", "HTMLTableSectionElementImpl" );
        populateElementType( "TFOOT", "HTMLTableSectionElementImpl" );
        populateElementType( "TEXTAREA", "HTMLTextAreaElementImpl" );
        populateElementType( "TITLE", "HTMLTitleElementImpl" );
        populateElementType( "UL", "HTMLUListElementImpl" );
    }


    private static void populateElementType( String tagName, String className )
    {
        try {
            _elementTypesHTML.put( tagName,
                ObjectFactory.findProviderClass("org.apache.html.dom." + className,
                    HTMLDocumentImpl.class.getClassLoader(), true) );
        } catch ( Exception except ) {
            throw new RuntimeException( "HTM019 OpenXML Error: Could not find or execute class " + className + " implementing HTML element " + tagName
                                  + "\n" + className + "\t" + tagName);
        }
    }


}