1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.maven.plugins.scripting;
20
21 import javax.script.Bindings;
22 import javax.script.ScriptContext;
23 import javax.script.ScriptEngine;
24 import javax.script.ScriptEngineManager;
25 import javax.script.ScriptException;
26
27 import org.apache.maven.plugin.logging.Log;
28 import org.apache.maven.plugins.scripting.engine.ContextAwareEngine;
29
30 /**
31 * Evaluates a script in the appropriate context and return its possibly null result
32 * @author Rusi Popov
33 */
34 abstract class AbstractScriptEvaluator {
35
36 /**
37 * @param bindings not null bindings to provide to the script to execute
38 * @param log engine logger if context aware
39 * @return the possibly null result the script produced
40 * @throws UnsupportedScriptEngineException when the engine is not configured correctly
41 * @throws ScriptException if an error occurs in script.
42 */
43 protected final Object eval(Bindings bindings, Log log) throws ScriptException, UnsupportedScriptEngineException {
44 ScriptEngineManager manager = new ScriptEngineManager();
45 ScriptEngine engine = getEngine(manager);
46 if (engine instanceof ContextAwareEngine) {
47 ((ContextAwareEngine) engine).setLog(log);
48 }
49 ScriptContext context = engine.getContext();
50
51 context.setBindings(bindings, ScriptContext.GLOBAL_SCOPE);
52
53 return eval(engine, context);
54 }
55
56 /**
57 * AbstractScriptEvaluator the script
58 * @param engine not null
59 * @param context not null, initialized
60 * @return possibly null result of the script
61 * @throws ScriptException if an error occurs in script.
62 */
63 protected abstract Object eval(ScriptEngine engine, ScriptContext context) throws ScriptException;
64
65 /**
66 * @param manager not null
67 * @return non-null engine to execute the script
68 * @throws UnsupportedScriptEngineException when no engine could be identified
69 */
70 protected abstract ScriptEngine getEngine(ScriptEngineManager manager) throws UnsupportedScriptEngineException;
71 }