    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
    018package org.apache.commons.jexl3.internal.introspection;
    019
    020import java.util.Map;
    021
    022/**
    023 * Specialized executor to get a property from a Map.
    024 * @since 2.0
    025 */
    026public final class MapGetExecutor extends AbstractExecutor.Get {
    027    /** The java.util.map.get method used as an active marker in MapGet. */
    028    private static final java.lang.reflect.Method MAP_GET =
    029            initMarker(Map.class, "get", Object.class);
    030    /** The property. */
    031    private final Object property;
    032
    033    /**
    034     * Attempts to discover a MapGetExecutor.
    035     *
    036     * @param is the introspector
    037     * @param clazz the class to find the get method from
    038     * @param identifier the key to use as an argument to the get method
    039     * @return the executor if found, null otherwise
    040     */
    041    public static MapGetExecutor discover(final Introspector is, final Class<?> clazz, final Object identifier) {
    042        if (Map.class.isAssignableFrom(clazz)) {
    043            return new MapGetExecutor(clazz, MAP_GET, identifier);
    044        }
    045        return null;
    046    }
    047
    048    /**
    049     * Creates an instance.
    050     * @param clazz he class the get method applies to
    051     * @param method the method held by this executor
    052     * @param key the property to get
    053     */
    054    private MapGetExecutor(final Class<?> clazz, final java.lang.reflect.Method method, final Object key) {
    055        super(clazz, method);
    056        property = key;
    057    }
    058
    059    @Override
    060    public Object getTargetProperty() {
    061        return property;
    062    }
    063
    064    @Override
    065    public Object invoke(final Object obj) {
    066        @SuppressWarnings("unchecked") // ctor only allows Map instances - see discover() method
    067        final Map<Object, ?> map = (Map<Object, ?>) obj;
    068        return map.get(property);
    069    }
    070
    071    @Override
    072    public Object tryInvoke(final Object obj, final Object key) {
    073        if (obj != null
    074            && method != null
    075            && objectClass.equals(obj.getClass())
    076            && ((property == null && key == null)
    077                || (property != null && key != null && property.getClass().equals(key.getClass())))) {
    078            @SuppressWarnings("unchecked") // ctor only allows Map instances - see discover() method
    079            final Map<Object, ?> map = (Map<Object, ?>) obj;
    080            return map.get(key);
    081        }
    082        return TRY_FAILED;
    083    }
    084}