net.bytebuddy.utility.QueueFactory Maven / Gradle / Ivy
/*
* Copyright 2014 - Present Rafael Winterhalter
*
* 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 net.bytebuddy.utility;
import net.bytebuddy.build.AccessControllerPlugin;
import net.bytebuddy.build.HashCodeAndEqualsPlugin;
import net.bytebuddy.utility.dispatcher.JavaDispatcher;
import net.bytebuddy.utility.nullability.MaybeNull;
import java.security.PrivilegedAction;
import java.util.Collection;
import java.util.LinkedList;
import java.util.Queue;
/**
* A factory for creating a {@link Queue}. For Java 5, a {@link LinkedList} is created whereas a
* {@code java.util.ArrayDeque} is used for any future JVM version.
*/
@HashCodeAndEqualsPlugin.Enhance
public class QueueFactory {
/**
* The singleton instance.
*/
private static final QueueFactory INSTANCE = new QueueFactory();
/**
* The dispatcher to use.
*/
private final Dispatcher dispatcher;
/**
* Creates a new queue factory.
*/
private QueueFactory() {
dispatcher = doPrivileged(JavaDispatcher.of(Dispatcher.class));
}
/**
* Creates a new queue.
*
* @param The type of the queue elements.
* @return An appropriate queue.
*/
public static Queue make() {
Queue queue = INSTANCE.dispatcher.arrayDeque();
return queue == null
? new LinkedList()
: queue;
}
/**
* Creates a new queue.
*
* @param The type of the queue elements.
* @param elements The elements to provide to the queue constructor.
* @return An appropriate queue.
*/
public static Queue make(Collection elements) {
Queue queue = INSTANCE.dispatcher.arrayDeque(elements);
return queue == null
? new LinkedList(elements)
: queue;
}
/**
* A proxy for {@code java.security.AccessController#doPrivileged} that is activated if available.
*
* @param action The action to execute from a privileged context.
* @param The type of the action's resolved value.
* @return The action's resolved value.
*/
@AccessControllerPlugin.Enhance
private static T doPrivileged(PrivilegedAction action) {
return action.run();
}
/**
* A dispatcher for creating an {@code java.util.ArrayDeque}.
*/
@JavaDispatcher.Defaults
@JavaDispatcher.Proxied("java.util.ArrayDeque")
protected interface Dispatcher {
/**
* Creates a new array deque.
*
* @param The type of the action's resolved value.
* @return An array deque or {@code null} if this class is not supplied by the current VM.
*/
@MaybeNull
@JavaDispatcher.IsConstructor
Queue arrayDeque();
/**
* Creates a new array deque.
*
* @param The type of the action's resolved value.
* @param elements The elements to provide to the queue constructor.
* @return An array deque or {@code null} if this class is not supplied by the current VM.
*/
@MaybeNull
@JavaDispatcher.IsConstructor
Queue arrayDeque(Collection elements);
}
}