com.hazelcast.org.apache.calcite.util.Compatible Maven / Gradle / Ivy
/*
* 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 com.hazelcast.org.apache.calcite.util;
import java.lang.invoke.MethodHandles;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
/** Compatibility layer.
*
* Allows to use advanced functionality if the latest JDK or Guava version
* is present.
*/
public interface Compatible {
Compatible INSTANCE = new Factory().create();
/** Same as {@code MethodHandles#privateLookupIn()}.
* (On JDK 8, only {@link MethodHandles#lookup()} is available. */
MethodHandles.Lookup lookupPrivate(Class clazz);
/** Creates the implementation of Compatible suitable for the
* current environment. */
class Factory {
Compatible create() {
return (Compatible) Proxy.newProxyInstance(
Compatible.class.getClassLoader(),
new Class[] {Compatible.class}, (proxy, method, args) -> {
if (method.getName().equals("lookupPrivate")) {
// Use MethodHandles.privateLookupIn if it is available (JDK 9
// and above)
@SuppressWarnings("rawtypes")
final Class clazz = (Class) args[0];
try {
final Method privateLookupMethod =
MethodHandles.class.getMethod("privateLookupIn",
Class.class, MethodHandles.Lookup.class);
final MethodHandles.Lookup lookup = MethodHandles.lookup();
return privateLookupMethod.invoke(null, clazz, lookup);
} catch (NoSuchMethodException e) {
return privateLookupJdk8(clazz);
}
}
return null;
});
}
/** Emulates MethodHandles.privateLookupIn on JDK 8;
* in later JDK versions, throws. */
@SuppressWarnings("deprecation")
static MethodHandles.Lookup privateLookupJdk8(Class clazz) {
try {
final Constructor constructor =
MethodHandles.Lookup.class.getDeclaredConstructor(Class.class,
int.class);
if (!constructor.isAccessible()) {
constructor.setAccessible(true);
}
return constructor.newInstance(clazz, MethodHandles.Lookup.PRIVATE);
} catch (InstantiationException | IllegalAccessException
| InvocationTargetException | NoSuchMethodException e) {
throw new RuntimeException(e);
}
}
}
}