001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.jexl2.internal;
019 import java.util.List;
020 import java.lang.reflect.Array;
021 /**
022 * Specialized executor to get a property from a List or array.
023 * @since 2.0
024 */
025 public final class ListGetExecutor extends AbstractExecutor.Get {
026 /** The java.lang.reflect.Array.get method used as an active marker in ListGet. */
027 private static final java.lang.reflect.Method ARRAY_GET =
028 initMarker(Array.class, "get", Object.class, Integer.TYPE);
029 /** The java.util.obj.get method used as an active marker in ListGet. */
030 private static final java.lang.reflect.Method LIST_GET =
031 initMarker(List.class, "get", Integer.TYPE);
032 /** The property. */
033 private final Integer property;
034
035 /**
036 * Creates an instance checking for the List interface or Array capability.
037 * @param is the introspector
038 * @param clazz the class to introspect
039 * @param key the key to use in obj.get(key)
040 */
041 public ListGetExecutor(Introspector is, Class<?> clazz, Integer key) {
042 super(clazz, discover(clazz));
043 property = key;
044 }
045
046 /** {@inheritDoc} */
047 @Override
048 public Object getTargetProperty() {
049 return property;
050 }
051
052 /**
053 * Get the property from the obj or array.
054 * @param obj the List/array.
055 * @return obj.get(key)
056 */
057 @Override
058 public Object execute(final Object obj) {
059 if (method == ARRAY_GET) {
060 return java.lang.reflect.Array.get(obj, property.intValue());
061 } else {
062 return ((List<?>) obj).get(property.intValue());
063 }
064 }
065
066 /** {@inheritDoc} */
067 @Override
068 public Object tryExecute(final Object obj, Object key) {
069 if (obj != null && method != null
070 && objectClass.equals(obj.getClass())
071 && key instanceof Integer) {
072 if (method == ARRAY_GET) {
073 return java.lang.reflect.Array.get(obj, ((Integer) key).intValue());
074 } else {
075 return ((List<?>) obj).get(((Integer) key).intValue());
076 }
077 }
078 return TRY_FAILED;
079 }
080
081
082 /**
083 * Finds the method to perform the get on a obj of array.
084 * @param clazz the class to introspect
085 * @return a marker method, obj.get or array.get
086 */
087 static java.lang.reflect.Method discover(Class<?> clazz) {
088 //return discoverList(false, clazz, property);
089 if (clazz.isArray()) {
090 return ARRAY_GET;
091 }
092 if (List.class.isAssignableFrom(clazz)) {
093 return LIST_GET;
094 }
095 return null;
096 }
097 }