elementnode2.java

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/*
 * $Id: ElementNode2.java,v 1.11 2001/04/11 02:52:37 edwingo Exp $
 *
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Crimson" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Sun Microsystems, Inc., 
 * http://www.sun.com.  For more information on the Apache Software 
 * Foundation, please see <http://www.apache.org/>.
 */

package org.apache.crimson.tree;

import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.Writer;

import java.util.Enumeration;

import org.apache.crimson.util.XmlNames;

import org.w3c.dom.*;


/**
 * Modified version of ElementNode to support DOM Level 2 methods.  This
 * class is named ElementNode2 for backward compatibility since old DOM
 * Level 1 apps may have subclassed ElementNode.
 * 
 * This class represents XML elements in a parse tree, and is often
 * subclassed to add custom behaviors.  When an XML Document object
 * is built using an <em>XmlDocumentBuilder</em> instance, simple
 * declarative configuration information may be used to control whether
 * this class, or some specialized subclass (e.g. supporting HTML DOM
 * methods) is used for elements in the resulting tree.
 *
 * <P> As well as defining new methods to provide behaviors which are
 * specific to application frameworks, such as Servlets or Swing, such
 * subclasses may also override methods such as <em>doneParse</em>
 * and <em>appendChild</em> to perform some kinds of processing during
 * tree construction.  Such processing can include transforming tree
 * structure to better suit the needs of a given application.  When
 * such transformation is done, the <em>XmlWritable</em> methods
 * may need to be overridden to make elements transform themselves back
 * to XML without losing information.  (One common transformation is
 * eliminating redundant representations of data; attributes of an XML
 * element may correspond to defaultable object properties, and so on.)
 *
 * <P> Element nodes also support a single <em>userObject</em> property,
 * which may be used to bind objects to elements where subclassing is
 * either not possible or is inappropriate.  For example, user interface
 * objects often derive from <code>java.awt.Component</code>, so that
 * they can't extend a different class (<em>ElementNode</em>).
 *
 * @see XmlDocumentBuilder
 *
 * @author David Brownell
 * @author Edwin Goei
 */
public class ElementNode2 extends NamespacedNode implements ElementEx
{
    protected AttributeSet	attributes;
    private String		idAttributeName;
    private Object		userObject;

    private static final char	tagStart [] = { '<', '/' };
    private static final char	tagEnd [] = { ' ', '/', '>' };
    
    public ElementNode2(String namespaceURI, String qName)
        throws DomEx
    {
        super(namespaceURI, qName);
    }

    /**
     * Make a clone of this node and return it.  Used for cloneNode().
     */
    ElementNode2 makeClone() {
        ElementNode2 retval = new ElementNode2(namespaceURI, qName);
        if (attributes != null) {
            retval.attributes = new AttributeSet(attributes, true);
            retval.attributes.setOwnerElement(retval);
        }
        retval.idAttributeName = idAttributeName;
        retval.userObject = userObject;
        retval.ownerDocument = ownerDocument;
        return retval;
    }

    /**
     * @return New ElementNode2 which is a copy of "this" but without
     * attributes that are defaulted in the original document.
     *
     * Used to implement Document.importNode().
     */
    ElementNode2 createCopyForImportNode(boolean deep) {
        ElementNode2 retval = new ElementNode2(namespaceURI, qName);
        if (attributes != null) {
            // Copy only "specified" Attr-s
            retval.attributes = new AttributeSet(attributes);
            retval.attributes.setOwnerElement(retval);
        }
        retval.userObject = userObject;

        if (deep) {
            // Copy ownerDocument to prevent appendChild() from throwing
            // WRONG_DOCUMENT_ERR for deep copies.  This gets changed to
            // the correct ownerDocument later in Document.importNode().
            retval.ownerDocument = ownerDocument;

            for (int i = 0; true; i++) {
                Node node = item(i);
                if (node == null) {
                    break;
                }
                if (node instanceof ElementNode2) {
                    retval.appendChild(
                        ((ElementNode2) node).createCopyForImportNode(true));
                } else {
                    retval.appendChild(node.cloneNode(true));
                }
            }
        }
        return retval;
    }

    static void checkArguments(String namespaceURI, String qualifiedName)
        throws DomEx
    {
        // [6] QName ::= (Prefix ':')? LocalPart
        // [7] Prefix ::= NCName
        // [8] LocalPart ::= NCName

	if (qualifiedName == null) {
            throw new DomEx(DomEx.NAMESPACE_ERR);
        }

	int first = qualifiedName.indexOf(':');

        if (first <= 0) {
            // no Prefix, only check LocalPart
            if (!XmlNames.isUnqualifiedName(qualifiedName)) {
                throw new DomEx(DomEx.INVALID_CHARACTER_ERR);
            }
            return;
        }

        // Prefix exists, check everything

	int last = qualifiedName.lastIndexOf(':');
	if (last != first) {
            throw new DomEx(DomEx.NAMESPACE_ERR);
        }
	
        String prefix = qualifiedName.substring(0, first);
        String localName = qualifiedName.substring(first + 1);
	if (!XmlNames.isUnqualifiedName(prefix)
                || !XmlNames.isUnqualifiedName(localName)) {
            throw new DomEx(DomEx.INVALID_CHARACTER_ERR);
        }

        // If we get here then we must have a valid prefix
        if (namespaceURI == null
            || (prefix.equals("xml") &&
                !XmlNames.SPEC_XML_URI.equals(namespaceURI))) {
            throw new DomEx(DomEx.NAMESPACE_ERR);
        }
    }

    public void trimToSize ()
    {
	super.trimToSize ();
	if (attributes != null)
	    attributes.trimToSize ();
    }

    // Assigns the element's attributes.
    void setAttributes (AttributeSet a)
    {
	AttributeSet oldAtts = attributes;

	// Check if the current AttributeSet or any attribute is readonly
	// isReadonly checks if any of the attributes in the AttributeSet
	// is readonly..
	if (oldAtts != null && oldAtts.isReadonly()) {
	    throw new DomEx(DomEx.NO_MODIFICATION_ALLOWED_ERR);
        }

	if (a != null) {
	    a.setOwnerElement(this);
        }
	attributes = a;
	if (oldAtts != null) {
	    oldAtts.setOwnerElement(null);
        }
    }

    // package private -- overrides base class method
    void checkChildType (int type)
    throws DOMException
    {
	switch (type) {
	  case ELEMENT_NODE:
	  case TEXT_NODE:
	  case COMMENT_NODE:
	  case PROCESSING_INSTRUCTION_NODE:
	  case CDATA_SECTION_NODE:
	  case ENTITY_REFERENCE_NODE:
	    return;
	  default:
	    throw new DomEx (DomEx.HIERARCHY_REQUEST_ERR);
	}
    }

    // package private -- overrides base class method
    public void setReadonly (boolean deep)
    {
	if (attributes != null)
	    attributes.setReadonly ();
	super.setReadonly (deep);
    }

    /** <b>DOM:</b> Returns the attributes of this element. */
    public NamedNodeMap getAttributes ()
    {
	if (attributes == null)
	    attributes = new AttributeSet (this);
        return attributes;
    }
        
    /**
     * Returns whether this node (if it is an element) has any attributes.
     * @since DOM Level 2
     */
    public boolean hasAttributes() {
        return attributes != null;
    }

    /**
     * Returns the element and its content as a string, which includes
     * all the markup embedded in this element.  If the element is not
     * fully constructed, the content will not be an XML tag.
     */
    public String toString ()
    {
	try {
	    CharArrayWriter	out = new CharArrayWriter ();
	    XmlWriteContext	x = new XmlWriteContext (out);
	    writeXml (x);
	    return out.toString ();
	} catch (Exception e) {
	    return super.toString ();
	}
    }
    
    
    /**
     * Writes this element and all of its children out, as well
     * formed XML.
     */
    public void writeXml (XmlWriteContext context) throws IOException
    {
	Writer	out = context.getWriter ();

	if (qName == null)