001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.html;
014
015import java.util.*;
016
017import org.apache.juneau.html.annotation.*;
018import org.apache.juneau.svl.*;
019
020/**
021 * HTML widget variable resolver.
022 *
023 * <p>
024 * The format for this var is <js>"$W{widgetName}"</js>.
025 *
026 * <p>
027 * Widgets are simple class that produce some sort of string based on a passed-in HTTP request.
028 *
029 * <p>
030 * They're registered via the following mechanisms:
031 * <ul>
032 *    <li>{@link HtmlDocConfig#widgets() @HtmlDocConfig(widgets)}
033 * </ul>
034 *
035 * <ul class='seealso'>
036 *    <li class='link'>{@doc RestSvlVariables}
037 * </ul>
038 */
039public class HtmlWidgetVar extends SimpleVar {
040
041   /**
042    * The name of the session or context object that identifies the object containing the widgets to resolve.
043    */
044   public static final String SESSION_htmlWidgets = "htmlWidgets";
045
046   /**
047    * The name of this variable.
048    */
049   public static final String NAME = "W";
050
051   /**
052    * Constructor.
053    */
054   public HtmlWidgetVar() {
055      super(NAME);
056   }
057
058   @SuppressWarnings("unchecked")
059   @Override /* Parameter */
060   public String resolve(VarResolverSession session, String key) throws Exception {
061      Map<String,HtmlWidget> widgets = (Map<String,HtmlWidget>)session.getSessionObject(Object.class, SESSION_htmlWidgets, false);
062
063      HtmlWidget w = widgets.get(key);
064      if (w == null)
065         return "unknown-widget-"+key;
066
067      return w.getHtml(session);
068   }
069
070   @Override
071   public boolean canResolve(VarResolverSession session) {
072      return session.hasSessionObject(SESSION_htmlWidgets);
073   }
074}