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 * https://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 * <p>
43 * Public access is through {@link StringLookupFactory}.
44 * </p>
45 *
46 * @see StringLookupFactory
47 * @since 1.5
48 */
49 final class ScriptStringLookup extends AbstractStringLookup {
50
51 /**
52 * Defines the singleton for this class.
53 */
54 static final ScriptStringLookup INSTANCE = new ScriptStringLookup();
55
56 /**
57 * No need to build instances for now.
58 */
59 private ScriptStringLookup() {
60 // empty
61 }
62
63 /**
64 * Execute the script with the engine name in the format "EngineName:Script". Extra colons will be ignored.
65 * <p>
66 * For example: {@code "javascript:3 + 4"}.
67 * </p>
68 *
69 * @param key the engine:script to execute, may be null.
70 * @return The value returned by the execution.
71 */
72 @Override
73 public String lookup(final String key) {
74 if (key == null) {
75 return null;
76 }
77 final String[] keys = key.split(SPLIT_STR, 2);
78 final int keyLen = keys.length;
79 if (keyLen != 2) {
80 throw IllegalArgumentExceptions.format("Bad script key format [%s]; expected format is EngineName:Script.",
81 key);
82 }
83 final String engineName = keys[0];
84 final String script = keys[1];
85 try {
86 final ScriptEngine scriptEngine = new ScriptEngineManager().getEngineByName(engineName);
87 if (scriptEngine == null) {
88 throw new IllegalArgumentException("No script engine named " + engineName);
89 }
90 return Objects.toString(scriptEngine.eval(script), null);
91 } catch (final Exception e) {
92 throw IllegalArgumentExceptions.format(e, "Error in script engine [%s] evaluating script [%s].", engineName,
93 script);
94 }
95 }
96
97 }