/*
* Copyright (c) 2001 World Wide Web Consortium,
* (Massachusetts Institute of Technology, Institut National de
* Recherche en Informatique et en Automatique, Keio University). All
* Rights Reserved. This program is distributed under the W3C's Software
* Intellectual Property License. This program is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY; without even
* the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE.
* See W3C License http://www.w3.org/Consortium/Legal/ for more details.
*/
//package org.w3c.dom;
package org.apache.xerces.dom3;
import org.w3c.dom.DOMImplementation;
import org.apache.xerces.dom3.DOMImplementationSource;
import java.util.StringTokenizer;
import java.util.Vector;
/**
* This class holds the list of registered DOMImplementations. It is first
* initialized based on the content of the space separated list of classnames
* contained in the System Property "org.w3c.dom.DOMImplementationSourceList".
*
* <p>Subsequently, additional sources can be registered and implementations
* can be queried based on a list of requested features.
*
* <p>This provides an application with an implementation independent starting
* point.
*
* @see DOMImplementation
* @see DOMImplementationSource
*/
public class DOMImplementationRegistry
{
// The system property to specify the DOMImplementationSource class names.
public static String PROPERTY = "org.w3c.dom.DOMImplementationSourceList";
private static Vector sources = new Vector();
private static boolean initialized = false;
private static void initialize() throws ClassNotFoundException,
InstantiationException, IllegalAccessException
{
initialized = true;
String p = System.getProperty(PROPERTY);
if (p == null) {
return;
}
StringTokenizer st = new StringTokenizer(p);
while (st.hasMoreTokens()) {
Object source = Class.forName(st.nextToken()).newInstance();
sources.addElement(source);
}
}
/**
* Return the first registered implementation that has the desired features,
* or null if none is found.
*
* @param features A string that specifies which features are required.
* This is a space separated list in which each feature is
* specified by its name optionally followed by a space
* and a version number.
* This is something like: "XML 1.0 Traversal Events 2.0"
* @return An implementation that has the desired features, or
* <code>null</code> if this source has none.
*/
public static DOMImplementation getDOMImplementation(String features)
throws ClassNotFoundException,
InstantiationException, IllegalAccessException
{
if (!initialized) {
initialize();
}
int len = sources.size();
for (int i = 0; i < len; i++) {
DOMImplementationSource source =
(DOMImplementationSource) sources.elementAt(i);
DOMImplementation impl = source.getDOMImplementation(features);
if (impl != null) {
return impl;
}
}
return null;
}
/**
* Register an implementation.
*/
public static void addSource(DOMImplementationSource s)
throws ClassNotFoundException,
InstantiationException, IllegalAccessException
{
if (!initialized) {
initialize();
}
sources.addElement(s);
// update system property accordingly
StringBuffer b = new StringBuffer(System.getProperty(PROPERTY));
b.append(" " + s.getClass().getName());
System.setProperty(PROPERTY, b.toString());
}
}