1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache license, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the license for the specific language governing permissions and
15 * limitations under the license.
16 */
17
18 package org.apache.commons.text.lookup;
19
20 import java.util.Objects;
21
22 import javax.script.ScriptEngine;
23 import javax.script.ScriptEngineManager;
24
25 import org.apache.commons.text.StringSubstitutor;
26
27 /**
28 * Executes the script with the given engine name.
29 * <p>
30 * Execute the script with the engine name in the format "EngineName:Script".
31 * </p>
32 * <p>
33 * For example: {@code "javascript:3 + 4"}.
34 * </p>
35 * <p>
36 * Using a {@link StringSubstitutor}:
37 * </p>
38 *
39 * <pre>
40 * StringSubstitutor.createInterpolator().replace("${script:javascript:3 + 4}"));
41 * </pre>
42 *
43 * @since 1.5
44 */
45 final class ScriptStringLookup extends AbstractStringLookup {
46
47 /**
48 * Defines the singleton for this class.
49 */
50 static final ScriptStringLookup INSTANCE = new ScriptStringLookup();
51
52 /**
53 * No need to build instances for now.
54 */
55 private ScriptStringLookup() {
56 // empty
57 }
58
59 /**
60 * Execute the script with the engine name in the format "EngineName:Script". Extra colons will be ignored.
61 * <p>
62 * For example: {@code "javascript:3 + 4"}.
63 * </p>
64 *
65 * @param key the engine:script to execute, may be null
66 * @return The value returned by the execution.
67 */
68 @Override
69 public String lookup(final String key) {
70 if (key == null) {
71 return null;
72 }
73 final String[] keys = key.split(SPLIT_STR, 2);
74 final int keyLen = keys.length;
75 if (keyLen != 2) {
76 throw IllegalArgumentExceptions.format("Bad script key format [%s]; expected format is EngineName:Script.",
77 key);
78 }
79 final String engineName = keys[0];
80 final String script = keys[1];
81 try {
82 final ScriptEngine scriptEngine = new ScriptEngineManager().getEngineByName(engineName);
83 if (scriptEngine == null) {
84 throw new IllegalArgumentException("No script engine named " + engineName);
85 }
86 return Objects.toString(scriptEngine.eval(script), null);
87 } catch (final Exception e) {
88 throw IllegalArgumentExceptions.format(e, "Error in script engine [%s] evaluating script [%s].", engineName,
89 script);
90 }
91 }
92
93 }