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.jexl3.internal.introspection;
19
20 import java.util.Map;
21
22 /**
23 * Specialized executor to get a property from a Map.
24 * @since 2.0
25 */
26 public final class MapGetExecutor extends AbstractExecutor.Get {
27 /** The java.util.map.get method used as an active marker in MapGet. */
28 private static final java.lang.reflect.Method MAP_GET =
29 initMarker(Map.class, "get", Object.class);
30 /** The property. */
31 private final Object property;
32
33 /**
34 * Attempts to discover a MapGetExecutor.
35 *
36 * @param is the introspector
37 * @param clazz the class to find the get method from
38 * @param identifier the key to use as an argument to the get method
39 * @return the executor if found, null otherwise
40 */
41 public static MapGetExecutor discover(final Introspector is, final Class<?> clazz, final Object identifier) {
42 // we still need to ensure permissions grant access to get(...)
43 if (Map.class.isAssignableFrom(clazz) && is.getMethod(clazz, "get", identifier) != null) {
44 return new MapGetExecutor(clazz, MAP_GET, identifier);
45 }
46 return null;
47 }
48
49 /**
50 * Creates an instance.
51 * @param clazz he class the get method applies to
52 * @param method the method held by this executor
53 * @param key the property to get
54 */
55 private MapGetExecutor(final Class<?> clazz, final java.lang.reflect.Method method, final Object key) {
56 super(clazz, method);
57 property = key;
58 }
59
60 @Override
61 public Object getTargetProperty() {
62 return property;
63 }
64
65 @Override
66 public Object invoke(final Object obj) {
67 @SuppressWarnings("unchecked") // ctor only allows Map instances - see discover() method
68 final Map<Object, ?> map = (Map<Object, ?>) obj;
69 return map.get(property);
70 }
71
72 @Override
73 public Object tryInvoke(final Object obj, final Object key) {
74 if (obj != null
75 && method != null
76 && objectClass.equals(obj.getClass())
77 && ((property == null && key == null)
78 || (property != null && key != null && property.getClass().equals(key.getClass())))) {
79 @SuppressWarnings("unchecked") // ctor only allows Map instances - see discover() method
80 final Map<Object, ?> map = (Map<Object, ?>) obj;
81 return map.get(key);
82 }
83 return TRY_FAILED;
84 }
85 }