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 */ 017package org.apache.commons.jexl3.internal.introspection; 018 019import java.util.List; 020import java.lang.reflect.Array; 021 022/** 023 * Specialized executor to get a property from a List or array. 024 * @since 2.0 025 */ 026public final class ListGetExecutor extends AbstractExecutor.Get { 027 /** The java.lang.reflect.Array.get method used as an active marker in ListGet. */ 028 private static final java.lang.reflect.Method ARRAY_GET = 029 initMarker(Array.class, "get", Object.class, Integer.TYPE); 030 /** The java.util.obj.get method used as an active marker in ListGet. */ 031 private static final java.lang.reflect.Method LIST_GET = 032 initMarker(List.class, "get", Integer.TYPE); 033 /** The property. */ 034 private final Integer property; 035 036 /** 037 * Attempts to discover a ListGetExecutor. 038 * 039 * @param is the introspector 040 * @param clazz the class to find the get method from 041 * @param index the index to use as an argument to the get method 042 * @return the executor if found, null otherwise 043 */ 044 public static ListGetExecutor discover(final Introspector is, final Class<?> clazz, final Integer index) { 045 if (index != null) { 046 if (clazz.isArray()) { 047 return new ListGetExecutor(clazz, ARRAY_GET, index); 048 } 049 if (List.class.isAssignableFrom(clazz)) { 050 return new ListGetExecutor(clazz, LIST_GET, index); 051 } 052 } 053 return null; 054 } 055 056 /** 057 * Creates an instance. 058 * @param clazz he class the get method applies to 059 * @param method the method held by this executor 060 * @param index the index to use as an argument to the get method 061 */ 062 private ListGetExecutor(final Class<?> clazz, final java.lang.reflect.Method method, final Integer index) { 063 super(clazz, method); 064 property = index; 065 } 066 067 @Override 068 public Object getTargetProperty() { 069 return property; 070 } 071 072 @Override 073 public Object invoke(final Object obj) { 074 if (method == ARRAY_GET) { 075 return Array.get(obj, property); 076 } 077 return ((List<?>) obj).get(property); 078 } 079 080 @Override 081 public Object tryInvoke(final Object obj, final Object identifier) { 082 final Integer index = castInteger(identifier); 083 if (obj != null && method != null 084 && objectClass.equals(obj.getClass()) 085 && index != null) { 086 if (method == ARRAY_GET) { 087 return Array.get(obj, index); 088 } 089 return ((List<?>) obj).get(index); 090 } 091 return TRY_FAILED; 092 } 093}