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 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> 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 * @since 3.0
035 */
036public class InstantiateTransformer<T> implements Transformer<Class<? extends T>, T> {
037
038    /** Singleton instance that uses the no arg constructor */
039    @SuppressWarnings("rawtypes")
040    private static final Transformer NO_ARG_INSTANCE = new InstantiateTransformer<>();
041
042    /** The constructor parameter types */
043    private final Class<?>[] iParamTypes;
044    /** The constructor arguments */
045    private final Object[] iArgs;
046
047    /**
048     * Get a typed no-arg instance.
049     *
050     * @param <T>  the type of the objects to be created
051     * @return Transformer&lt;Class&lt;? extends T&gt;, T&gt;
052     */
053    public static <T> Transformer<Class<? extends T>, T> instantiateTransformer() {
054        return NO_ARG_INSTANCE;
055    }
056
057    /**
058     * Transformer method that performs validation.
059     *
060     * @param <T>  the type of the objects to be created
061     * @param paramTypes  the constructor parameter types
062     * @param args  the constructor arguments
063     * @return an instantiate transformer
064     * @throws IllegalArgumentException if paramTypes does not match args
065     */
066    public static <T> Transformer<Class<? extends T>, T> instantiateTransformer(final Class<?>[] paramTypes,
067                                                                                final Object[] args) {
068        if (((paramTypes == null) && (args != null))
069            || ((paramTypes != null) && (args == null))
070            || ((paramTypes != null) && (args != null) && (paramTypes.length != args.length))) {
071            throw new IllegalArgumentException("Parameter types must match the arguments");
072        }
073
074        if (paramTypes == null || paramTypes.length == 0) {
075            return new InstantiateTransformer<>();
076        }
077        return new InstantiateTransformer<>(paramTypes, args);
078    }
079
080    /**
081     * Constructor for no arg instance.
082     */
083    private InstantiateTransformer() {
084        super();
085        iParamTypes = null;
086        iArgs = null;
087    }
088
089    /**
090     * Constructor that performs no validation.
091     * Use <code>instantiateTransformer</code> 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        super();
100        iParamTypes = paramTypes != null ? paramTypes.clone() : null;
101        iArgs = args != null ? args.clone() : null;
102    }
103
104    /**
105     * Transforms the input Class object to a result by instantiation.
106     *
107     * @param input  the input object to transform
108     * @return the transformed result
109     */
110    @Override
111    public T transform(final Class<? extends T> input) {
112        try {
113            if (input == null) {
114                throw new FunctorException(
115                    "InstantiateTransformer: Input object was not an instanceof Class, it was a null object");
116            }
117            final Constructor<? extends T> con = input.getConstructor(iParamTypes);
118            return con.newInstance(iArgs);
119        } catch (final NoSuchMethodException ex) {
120            throw new FunctorException("InstantiateTransformer: The constructor must exist and be public ");
121        } catch (final InstantiationException ex) {
122            throw new FunctorException("InstantiateTransformer: InstantiationException", ex);
123        } catch (final IllegalAccessException ex) {
124            throw new FunctorException("InstantiateTransformer: Constructor must be public", ex);
125        } catch (final InvocationTargetException ex) {
126            throw new FunctorException("InstantiateTransformer: Constructor threw an exception", ex);
127        }
128    }
129
130}