element.java

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/* kXML
 *
 * The contents of this file are subject to the Enhydra Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License
 * on the Enhydra web site ( http://www.enhydra.org/ ).
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific terms governing rights and limitations
 * under the License.
 *
 * The Initial Developer of kXML is Stefan Haustein. Copyright (C)
 * 2000, 2001 Stefan Haustein, D-46045 Oberhausen (Rhld.),
 * Germany. All Rights Reserved.
 *
 * Contributor(s): Paul Palaszewski, Wilhelm Fitzpatrick, 
 *                 Eric Foster-Johnson
 *
 * */

package org.kxml.kdom;

import java.io.*;
import java.util.*;

import org.kxml.*;
import org.kxml.io.*;
import org.kxml.parser.*;


/** In order to create an element, please use the createElement method
    instead of invoking the constructor directly. The right place to
    add user defined initialization code is the init method. */

public class Element extends Node {

    protected String namespace;
    protected String name;
    protected Vector attributes;
    protected Node parent;
    protected PrefixMap prefixMap;

    
    public Element () {
    }


   /** @deprecated
       The init method is invoked by createElement setParent . */
    
    public Element init (Node parent, String namespace, 
			 String name, Vector attributes) {
	this.parent = parent;
	return this;
    }
    
 
    /** removes all children and attributes */

    public void clear () {
	setAttributes (new Vector ());

	for (int i = getChildCount ()-1; i >= 0; i--) 
	    removeChild (i);
    }


    /** Forwards creation request to parent if any, otherwise
	calls super.createElement. Please note: For no
        namespace, please use Xml.NO_NAMESPACE, null is not a legal
        value. Currently, null is converted to Xml.NO_NAMESPACE, but
        future versions may throw an exception. */


    public Element createElement (String namespace, String name) {

	return (this.parent == null) 
	    ? super.createElement (namespace, name)
	    : this.parent.createElement (namespace, name);
    }


   
    /** Returns the attribute at the given index. */

    public Attribute getAttribute (int index) {
	return (Attribute) attributes.elementAt (index);
    }


    /** convenience method for getAttribute (Xml.NO_NAMESPACE, name) */

    public Attribute getAttribute (String name) {
	return getAttribute (Xml.NO_NAMESPACE, name);
    }


    /** returns the attribute with the given namespace and name.
	Please use null as placeholder for any namespace or
        Xml.NO_NAMESPACE for no namespace.
       */

    public Attribute getAttribute (String namespace, String name) {

	int len = getAttributeCount ();

	for (int i = 0; i < len; i++) {
	    Attribute attr = getAttribute (i);    
	    if (name.equals (attr.getName ()) 
		&& (namespace == null || namespace.equals (attr.getNamespace ())))
		
		return attr;  
	}
	return null;
    }


    /** Returns the number of attributes of this element. */
   
    public int getAttributeCount () {
	return attributes == null ? 0 : attributes.size ();
    }


    /** Returns a Vector containing all Attributes. The Vector is not
	copied. Modification is not allowed. */

    public Vector getAttributes () {
	return attributes;
    }


    /** Returns the document this element is a member of. The document
	is determined by ascending to the parent of the root element.
	If the element is not contained in a document, null is
	returned. */

    public Document getDocument () {

	if (parent instanceof Document) 
	    return (Document) parent;

	if (parent instanceof Element) 
	    return ((Element) parent).getDocument ();

	return null;
    }


    /** returns the (local) name of the element */


    public String getName () {
	return name;
    }


    /** returns the namespace of the element */

    public String getNamespace () {
	return namespace;
    }
    

    /** Returns the parent node of this element */

    public Node getParent () {
	return parent;
    }


    /** Returns the parent element if available, null otherwise */

    public Element getParentElement () {
	return (parent instanceof Element) ? ((Element) parent) : null;
    }



    /** Returns the namespace prefix map of this Element. */

    public PrefixMap getPrefixMap () {
	return prefixMap;
    }



    /** Returns the value of the given attribute.  If the attribute
	does not exist, an exception is thrown. If a null value shall
	be returned for not existing attributes, please use
	getValueDefault (name, null) instead. */
    
    public String getValue (String name) {
	Attribute attr = getAttribute (Xml.NO_NAMESPACE, name);
	return attr == null ? null : attr.getValue ();
    }
    
    
    /** Returns the value of the given attribute, or the given default
        value if the desired attribute does not exist. */
    
    public String getValueDefault (String name, String dflt) {
	Attribute attr = getAttribute (Xml.NO_NAMESPACE, name);
	return attr == null ? dflt : attr.getValue ();
    }
    

    /** Builds the child elements from the given Parser. By overwriting parse, 
	an element can take complete control over parsing its subtree. */

    public void parse (AbstractXmlParser parser) throws IOException {

	StartTag startTag = (StartTag) parser.read ();

	name = startTag.getName ();
	namespace = startTag.getNamespace ();
	attributes = startTag.getAttributes ();
	setPrefixMap (startTag.getPrefixMap ());

	super.parse (parser);

	if (startTag != null 
	    && !startTag.getDegenerated () 
	    && getChildCount () == 0) 

	    addChild (Xml.WHITESPACE, "");

	parser.read (Xml.END_TAG, startTag.getNamespace (), startTag.getName ());
    }

    
  /** Removes the attribute at the given index */

    public void removeAttribute (int index) {
	attributes.removeElementAt (index);
    }

   


    /** Replaces all attributes by the given Vector. Caution: The
	Vector is not copied. */

    public void setAttributes (Vector attributes) {
	this.attributes = attributes;
    }


    /** sets the given attribute */

    public void setAttribute (Attribute attribute) {
	if (attributes == null) 
	    attributes = new Vector ();
	else
	    for (int i = attributes.size () -1; i >= 0; i--) {
		Attribute attr = (Attribute) attributes.elementAt (i);
		if (attr.getName ().equals (attribute.getName ()) 
		    && attr.getNamespace ().equals (attribute.getNamespace ())) { 
		    attributes.setElementAt (attribute, i);
		    return;
		}
	    }

	attributes.addElement (attribute);
    }

    /** sets the value of the given attribute to the given string. 
        Convenience method for setAttribute (new Attribute (name, value));
    */

    public void setValue (String name, String value) {
	setAttribute (new Attribute (name, value));
    }


    /** sets the name of the element */

    public void setName (String name) {
	this.name = name;
    }


    /** sets the namespace of the element. Please note: For no
        namespace, please use Xml.NO_NAMESPACE, null is not a legal
        value. Currently, null is converted to Xml.NO_NAMESPACE, but
        future versions may throw an exception. */

    public void setNamespace (String namespace) {
	this.namespace = namespace == null ? Xml.NO_NAMESPACE : namespace;
    }


    /** Sets the Parent of this element. Automatically called from the
	add method.  The right place for replacements of the
	deprectated init method. Please use with care, you can simply
	create inconsitencies in the document tree structure using
	this method!  */

    protected void setParent (Node parent){
	this.parent = parent;
	if (init (parent, namespace, name, attributes) != this) 
	    throw new RuntimeException ("init must return this");
    }



    /** Sets the namespace prefix map of this Node. */

    public void setPrefixMap (PrefixMap prefixMap) {
	this.prefixMap = prefixMap;
    }    


    
    /** Writes this element and all children to the given XmlWriter. */


    public void write (AbstractXmlWriter writer) throws IOException {

	writer.startTag (getPrefixMap (), getNamespace (), getName ());

	int len = getAttributeCount ();
	
	for (int i = 0; i < len; i++) {
	    Attribute attr = getAttribute (i);
	    writer.attribute (attr.getNamespace (), 
				   attr.getName (), attr.getValue ());
	}
	
	writeChildren (writer);

	writer.endTag ();
    }
}