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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.vertexium.security;

import java.lang.reflect.Constructor;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * General reflection utils
 */
class ReflectionUtils {

    private static final Class[] EMPTY_ARRAY = new Class[]{};

    /**
     * Cache of constructors for each class. Pins the classes so they
     * can't be garbage collected until ReflectionUtils can be collected.
     */
    private static final Map, Constructor> CONSTRUCTOR_CACHE =
            new ConcurrentHashMap, Constructor>();

    /**
     * Create an object for the given class and initialize it from conf
     *
     * @param theClass class of which an object is created
     * @return a new object
     */
    @SuppressWarnings("unchecked")
    public static  T newInstance(Class theClass) {
        T result;
        try {
            Constructor meth = (Constructor) CONSTRUCTOR_CACHE.get(theClass);
            if (meth == null) {
                meth = theClass.getDeclaredConstructor(EMPTY_ARRAY);
                meth.setAccessible(true);
                CONSTRUCTOR_CACHE.put(theClass, meth);
            }
            result = meth.newInstance();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return result;
    }
}