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.svl;
018
019import static org.apache.juneau.commons.utils.ThrowableUtils.*;
020
021import java.io.*;
022
023/**
024 * Abstract superclass of all Simple Var Language variables that resolve to simple returned string values.
025 *
026 * <p>
027 * Note the difference between this class and {@link StreamedVar} that streams values to writers.
028 * <br>Unlike the {@link StreamedVar} class, the returned value from this class can contain nested variables that will be
029 * recursively resolved by {@link VarResolver}.
030 *
031 * <p>
032 * Subclasses must implement the following method:
033 * <ul class='javatree'>
034 *    <li class='jm'>{@link #resolve(VarResolverSession, String)}
035 * </ul>
036 *
037 * <h5 class='section'>See Also:</h5><ul>
038 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/SimpleVariableLanguageBasics">Simple Variable Language Basics</a>
039 * </ul>
04009 */
041public abstract class SimpleVar extends Var {
042
043   /**
044    * Constructor.
045    *
046    * @param name The variable name (e.g. <js>"C"</js> for variables of the form <js>"$C{...}"</js>)
047    */
048   protected SimpleVar(String name) {
049      super(name, false);
050   }
051
052   @Override /* Overridden from Var */
053   public void resolveTo(VarResolverSession session, Writer w, String arg) throws Exception {
054      throw unsupportedOp("Cannot call streamTo() on SimpleVar class");
055   }
056}