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.collections4.functors;
018
019import java.lang.reflect.Constructor;
020import java.lang.reflect.InvocationTargetException;
021
022import org.apache.commons.collections4.FunctorException;
023import org.apache.commons.collections4.Transformer;
024
025/**
026 * Transformer implementation that creates a new object instance by reflection.
027 * <p>
028 * <strong>WARNING:</strong> from v4.1 onwards this class will <strong>not</strong> be serializable anymore
029 * in order to prevent potential remote code execution exploits. Please refer to
030 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
031 * for more details.
032 * </p>
033 *
034 * @param <T> the type of the input and result to the function.
035 * @since 3.0
036 */
037public class InstantiateTransformer<T> implements Transformer<Class<? extends T>, T> {
038
039    /** Singleton instance that uses the no arg constructor */
040    @SuppressWarnings("rawtypes")
041    private static final Transformer NO_ARG_INSTANCE = new InstantiateTransformer<>();
042
043    /**
044     * Gets a typed no-arg instance.
045     *
046     * @param <T>  the type of the objects to be created
047     * @return Transformer&lt;Class&lt;? extends T&gt;, T&gt;
048     */
049    public static <T> Transformer<Class<? extends T>, T> instantiateTransformer() {
050        return NO_ARG_INSTANCE;
051    }
052    /**
053     * Transformer method that performs validation.
054     *
055     * @param <T>  the type of the objects to be created
056     * @param paramTypes  the constructor parameter types
057     * @param args  the constructor arguments
058     * @return an instantiate transformer
059     * @throws IllegalArgumentException if paramTypes does not match args
060     */
061    public static <T> Transformer<Class<? extends T>, T> instantiateTransformer(final Class<?>[] paramTypes,
062                                                                                final Object[] args) {
063        if (paramTypes == null && args != null
064            || paramTypes != null && args == null
065            || paramTypes != null && args != null && paramTypes.length != args.length) {
066            throw new IllegalArgumentException("Parameter types must match the arguments");
067        }
068
069        if (paramTypes == null || paramTypes.length == 0) {
070            return new InstantiateTransformer<>();
071        }
072        return new InstantiateTransformer<>(paramTypes, args);
073    }
074
075    /** The constructor parameter types */
076    private final Class<?>[] iParamTypes;
077
078    /** The constructor arguments */
079    private final Object[] iArgs;
080
081    /**
082     * Constructor for no arg instance.
083     */
084    private InstantiateTransformer() {
085        iParamTypes = null;
086        iArgs = null;
087    }
088
089    /**
090     * Constructor that performs no validation.
091     * Use {@code instantiateTransformer} if you want that.
092     * <p>
093     * Note: from 4.0, the input parameters will be cloned
094     *
095     * @param paramTypes  the constructor parameter types
096     * @param args  the constructor arguments
097     */
098    public InstantiateTransformer(final Class<?>[] paramTypes, final Object[] args) {
099        iParamTypes = paramTypes != null ? paramTypes.clone() : null;
100        iArgs = args != null ? args.clone() : null;
101    }
102
103    /**
104     * Transforms the input Class object to a result by instantiation.
105     *
106     * @param input  the input object to transform
107     * @return the transformed result
108     */
109    @Override
110    public T transform(final Class<? extends T> input) {
111        try {
112            if (input == null) {
113                throw new FunctorException(
114                    "InstantiateTransformer: Input object was not an instanceof Class, it was a null object");
115            }
116            final Constructor<? extends T> con = input.getConstructor(iParamTypes);
117            return con.newInstance(iArgs);
118        } catch (final NoSuchMethodException ex) {
119            throw new FunctorException("InstantiateTransformer: The constructor must exist and be public ");
120        } catch (final InstantiationException ex) {
121            throw new FunctorException("InstantiateTransformer: InstantiationException", ex);
122        } catch (final IllegalAccessException ex) {
123            throw new FunctorException("InstantiateTransformer: Constructor must be public", ex);
124        } catch (final InvocationTargetException ex) {
125            throw new FunctorException("InstantiateTransformer: Constructor threw an exception", ex);
126        }
127    }
128
129}