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