001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.rest.server.view.freemarker;
018
019import org.apache.juneau.rest.server.*;
020
021/**
022 * Request-scoped handle so FreeMarker {@code TemplateDirectiveModel}s can resolve per-request
023 * asset URLs during {@code template.process}.
024 *
025 * <p>
026 * {@link FreemarkerViewRenderer} opens the scope around its {@code template.process(...)} call and
027 * always closes it in a {@code finally}, so directives such as {@code <@page toolkit=...>} can reach
028 * the in-flight {@link RestRequest} (e.g. to call {@code ViewsMixin.viewAssetUrl}) without threading
029 * it through every template model.
030 *
031 * @since 10.0.0
032 */
033public final class FreemarkerRenderScope {
034
035   private static final ThreadLocal<RestRequest> REQ = new ThreadLocal<>();
036
037   private FreemarkerRenderScope() {}
038
039   static void open(RestRequest req) {
040      REQ.set(req);
041   }
042
043   static void close() {
044      REQ.remove();
045   }
046
047   /**
048    * Returns the request for the in-flight FreeMarker render.
049    *
050    * @return The {@link RestRequest} for the in-flight FreeMarker render, or {@code null} if none.
051    */
052   public static RestRequest request() {
053      return REQ.get();
054   }
055}