    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    }