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 package org.apache.commons.jexl3.internal.introspection;
18
19 import java.lang.reflect.Array;
20 import java.util.List;
21
22 /**
23 * Specialized executor to get a property from a List or array.
24 *
25 * @since 2.0
26 */
27 public final class ListGetExecutor extends AbstractExecutor.Get {
28
29 /** The java.lang.reflect.Array.get method used as an active marker in ListGet. */
30 private static final java.lang.reflect.Method ARRAY_GET =
31 initMarker(Array.class, "get", Object.class, Integer.TYPE);
32
33 /** The java.util.obj.get method used as an active marker in ListGet. */
34 private static final java.lang.reflect.Method LIST_GET =
35 initMarker(List.class, "get", Integer.TYPE);
36
37 /**
38 * Attempts to discover a ListGetExecutor.
39 *
40 * @param is the introspector
41 * @param clazz the class to find the get method from
42 * @param index the index to use as an argument to the get method
43 * @return the executor if found, null otherwise
44 */
45 public static ListGetExecutor discover(final Introspector is, final Class<?> clazz, final Integer index) {
46 if (index != null) {
47 if (clazz.isArray()) {
48 return new ListGetExecutor(clazz, ARRAY_GET, index);
49 }
50 // we still need to ensure permissions grant access to get(...)
51 if (List.class.isAssignableFrom(clazz) && is.getMethod(clazz, "get", index) != null) {
52 return new ListGetExecutor(clazz, LIST_GET, index);
53 }
54 }
55 return null;
56 }
57
58 /** The property. */
59 private final Integer property;
60
61 /**
62 * Creates an instance.
63 *
64 * @param clazz he class the get method applies to
65 * @param method the method held by this executor
66 * @param index the index to use as an argument to the get method
67 */
68 private ListGetExecutor(final Class<?> clazz, final java.lang.reflect.Method method, final Integer index) {
69 super(clazz, method);
70 property = index;
71 }
72
73 @Override
74 public Object getTargetProperty() {
75 return property;
76 }
77
78 @Override
79 public Object invoke(final Object obj) {
80 if (method == ARRAY_GET) {
81 return Array.get(obj, property);
82 }
83 return ((List<?>) obj).get(property);
84 }
85
86 @Override
87 public Object tryInvoke(final Object obj, final Object identifier) {
88 final Integer index = castInteger(identifier);
89 if (obj != null && method != null
90 && objectClass.equals(obj.getClass())
91 && index != null) {
92 if (method == ARRAY_GET) {
93 return Array.get(obj, index);
94 }
95 return ((List<?>) obj).get(index);
96 }
97 return TRY_FAILED;
98 }
99 }