CollectionSelectorProvider.java

/*
 *  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.isis.viewer.wicket.ui.components.collection.selector;

import org.apache.wicket.Component;

public interface CollectionSelectorProvider {
    CollectionSelectorPanel getSelectorDropdownPanel();

    public static class Util {

        /**
         * Searches up the component hierarchy looking for a parent that implements
         * {@link org.apache.isis.viewer.wicket.ui.components.collection.selector.CollectionSelectorProvider}.
         *
         * @return the panel, or null (if there are no alternative views)
         */
        public static CollectionSelectorPanel getCollectionSelectorProvider(Component component) {
            while(component != null) {
                if(component instanceof CollectionSelectorProvider) {
                    final CollectionSelectorPanel selectorDropdownPanelIfAny = ((CollectionSelectorProvider) component).getSelectorDropdownPanel();
                    return selectorDropdownPanelIfAny;
                }
                component = component.getParent();
            }
            throw new IllegalStateException("Could not locate parent that implements CollectionSelectorProvider");
        }
    }

}