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.jexl2.internal;
019import java.util.List;
020import java.lang.reflect.Array;
021/**
022 * Specialized executor to set a property in a List or array.
023 * @since 2.0
024 */
025public final class ListSetExecutor extends AbstractExecutor.Set {
026        /** The java.lang.reflect.Array.get method used as an active marker in ListGet. */
027    private static final java.lang.reflect.Method ARRAY_SET =
028            initMarker(Array.class, "set", Object.class, Integer.TYPE, Object.class);
029    /** The java.util.obj.set method used as an active marker in ListSet. */
030    private static final java.lang.reflect.Method LIST_SET =
031            initMarker(List.class, "set", Integer.TYPE, Object.class);
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 that might implement the map interface
039     * @param key the key to use in obj.set(key,value)
040     * @param value the value to use in obj.set(key,value)
041     */
042    public ListSetExecutor(Introspector is, Class<?> clazz, Integer key, Object value) {
043        super(clazz, discover(clazz));
044        property = key;
045    }
046
047    /** {@inheritDoc} */
048    @Override
049    public Object getTargetProperty() {
050        return property;
051    }
052    
053    /** {@inheritDoc} */
054    @Override
055    public Object execute(final Object obj, Object value) {
056        if (method == ARRAY_SET) {
057            java.lang.reflect.Array.set(obj, property.intValue(), value);
058        } else {
059            @SuppressWarnings("unchecked") // LSE should only be created for array or list types
060            final List<Object> list = (List<Object>) obj;
061            list.set(property.intValue(), value);
062        }
063        return value;
064    }
065
066    /** {@inheritDoc} */
067    @Override
068    public Object tryExecute(final Object obj, Object key, Object value) {
069        if (obj != null && method != null
070            && objectClass.equals(obj.getClass())
071            && key instanceof Integer) {
072            if (method == ARRAY_SET) {
073                Array.set(obj, ((Integer) key).intValue(), value);
074            } else {
075                @SuppressWarnings("unchecked")  // LSE should only be created for array or list types
076                final List<Object> list = (List<Object>) obj;
077                list.set(((Integer) key).intValue(), value);
078            }
079            return value;
080        }
081        return TRY_FAILED;
082    }
083
084
085    /**
086     * Finds the method to perform 'set' on a obj of array.
087     * @param clazz the class to introspect
088     * @return a marker method, obj.set or array.set
089     */
090    static java.lang.reflect.Method discover(Class<?> clazz) {
091        if (clazz.isArray()) {
092            // we could verify if the call can be performed but it does not change
093            // the fact we would fail...
094            // Class<?> formal = clazz.getComponentType();
095            // Class<?> actual = value == null? Object.class : value.getClass();
096            // if (IntrospectionUtils.isMethodInvocationConvertible(formal, actual, false)) {
097                return ARRAY_SET;
098            // }
099        }
100        if (List.class.isAssignableFrom(clazz)) {
101            return LIST_SET;
102        }
103        return null;
104    }
105}