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/*
 * Copyright 2006-2018 the original author or authors.
 *
 * Licensed 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.objenesis.strategy;

import org.objenesis.instantiator.ObjectInstantiator;
import org.objenesis.instantiator.basic.AccessibleInstantiator;
import org.objenesis.instantiator.basic.ObjectInputStreamInstantiator;
import org.objenesis.instantiator.gcj.GCJInstantiator;
import org.objenesis.instantiator.perc.PercInstantiator;
import org.objenesis.instantiator.sun.SunReflectionFactoryInstantiator;

import java.io.Serializable;

import static org.objenesis.strategy.PlatformDescription.GNU;
import static org.objenesis.strategy.PlatformDescription.HOTSPOT;
import static org.objenesis.strategy.PlatformDescription.OPENJDK;
import static org.objenesis.strategy.PlatformDescription.PERC;

/**
 * Guess the best instantiator for a given class. The instantiator will instantiate the class
 * without calling any constructor. Currently, the selection doesn't depend on the class. It relies
 * on the
 * 
 * JVM version
 * JVM vendor
 * JVM vendor version
 * 
 * However, instantiators are stateful and so dedicated to their class.
 *
 * @author Henri Tremblay
 * @see ObjectInstantiator
 */
public class StdInstantiatorStrategy extends BaseInstantiatorStrategy {

    /**
     * Return an {@link ObjectInstantiator} allowing to create instance without any constructor being
     * called.
     *
     * @param type Class to instantiate
     * @return The ObjectInstantiator for the class
     */
    public  ObjectInstantiator newInstantiatorOf(Class type) {

        if(PlatformDescription.isThisJVM(HOTSPOT) || PlatformDescription.isThisJVM(OPENJDK)) {
            // Java 7 GAE was under a security manager so we use a degraded system
            if(PlatformDescription.isGoogleAppEngine() && PlatformDescription.SPECIFICATION_VERSION.equals("1.7")) {
                if(Serializable.class.isAssignableFrom(type)) {
                    return new ObjectInputStreamInstantiator<>(type);
                }
                return new AccessibleInstantiator<>(type);
            }
            // The UnsafeFactoryInstantiator would also work. But according to benchmarks, it is 2.5
            // times slower. So I prefer to use this one
            return new SunReflectionFactoryInstantiator<>(type);
        }
        else if(PlatformDescription.isThisJVM(GNU)) {
            return new GCJInstantiator<>(type);
        }
        else if(PlatformDescription.isThisJVM(PERC)) {
            return new PercInstantiator<>(type);
        }

        return new SunReflectionFactoryInstantiator<>(type);

        // Fallback instantiator, should work with most modern JVM
        //return new UnsafeFactoryInstantiator<>(type);

    }
}