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The Commons Jexl library is an implementation of the JSTL Expression Language with extensions.
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.jexl2.internal;
import java.util.List;
import java.lang.reflect.Array;
/**
* Specialized executor to get a property from a List or array.
* @since 2.0
*/
public final class ListGetExecutor extends AbstractExecutor.Get {
/** The java.lang.reflect.Array.get method used as an active marker in ListGet. */
private static final java.lang.reflect.Method ARRAY_GET =
initMarker(Array.class, "get", Object.class, Integer.TYPE);
/** The java.util.obj.get method used as an active marker in ListGet. */
private static final java.lang.reflect.Method LIST_GET =
initMarker(List.class, "get", Integer.TYPE);
/** The property. */
private final Integer property;
/**
* Creates an instance checking for the List interface or Array capability.
* @param is the introspector
* @param clazz the class to introspect
* @param key the key to use in obj.get(key)
*/
public ListGetExecutor(Introspector is, Class clazz, Integer key) {
super(clazz, discover(clazz));
property = key;
}
/** {@inheritDoc} */
@Override
public Object getTargetProperty() {
return property;
}
/**
* Get the property from the obj or array.
* @param obj the List/array.
* @return obj.get(key)
*/
@Override
public Object execute(final Object obj) {
if (method == ARRAY_GET) {
return java.lang.reflect.Array.get(obj, property.intValue());
} else {
return ((List) obj).get(property.intValue());
}
}
/** {@inheritDoc} */
@Override
public Object tryExecute(final Object obj, Object key) {
if (obj != null && method != null
&& objectClass.equals(obj.getClass())
&& key instanceof Integer) {
if (method == ARRAY_GET) {
return java.lang.reflect.Array.get(obj, ((Integer) key).intValue());
} else {
return ((List) obj).get(((Integer) key).intValue());
}
}
return TRY_FAILED;
}
/**
* Finds the method to perform the get on a obj of array.
* @param clazz the class to introspect
* @return a marker method, obj.get or array.get
*/
static java.lang.reflect.Method discover(Class clazz) {
//return discoverList(false, clazz, property);
if (clazz.isArray()) {
return ARRAY_GET;
}
if (List.class.isAssignableFrom(clazz)) {
return LIST_GET;
}
return null;
}
}