/*
 * 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.dom;

import java.util.ArrayList;

import org.apache.xerces.impl.xs.XSImplementationImpl;
import org.w3c.dom.DOMImplementation;
import org.w3c.dom.DOMImplementationList;

/**
 * Allows to retrieve <code>XSImplementation</code>, DOM Level 3 Core and LS implementations
 * and PSVI implementation.
 * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/core.html#DOMImplementationSource'>Document Object Model (DOM) Level 3 Core Specification</a>.
 * 
 * @xerces.internal
 * 
 * @author Elena Litani, IBM
 * @version $Id: DOMXSImplementationSourceImpl.java 603686 2007-12-12 17:51:23Z mrglavas $
 */
public class DOMXSImplementationSourceImpl
    extends DOMImplementationSourceImpl {
    
    /**
     * A method to request a DOM implementation.
     * @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 DOMImplementation getDOMImplementation(String features) {
        DOMImplementation impl = super.getDOMImplementation(features);
        if (impl != null){
            return impl;
        }
        // if not try the PSVIDOMImplementation
        impl = PSVIDOMImplementationImpl.getDOMImplementation();
        if (testImpl(impl, features)) {
            return impl;
        }
        // if not try the XSImplementation
        impl = XSImplementationImpl.getDOMImplementation();
        if (testImpl(impl, features)) {
            return impl;
        }
        
        return null;
    }
    
    /**
     * A method to request a list of DOM implementations that support the 
     * specified features and versions, as specified in .
     * @param features A string that specifies which features and versions 
     *   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 3.0 Traversal +Events 
     *   2.0"
     * @return A list of DOM implementations that support the desired 
     *   features.
     */
    public DOMImplementationList getDOMImplementationList(String features) {
        final ArrayList implementations = new ArrayList();

        // first check whether the CoreDOMImplementation would do
        DOMImplementationList list = super.getDOMImplementationList(features);
        // Add core DOMImplementations
        for (int i = 0; i < list.getLength(); ++i) {
            implementations.add(list.item(i));
        }

        DOMImplementation impl = PSVIDOMImplementationImpl.getDOMImplementation();
        if (testImpl(impl, features)) {
            implementations.add(impl);
        }

        impl = XSImplementationImpl.getDOMImplementation();
        if (testImpl(impl, features)) {
            implementations.add(impl);
        }
        return new DOMImplementationListImpl(implementations); 
    }
}
