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	/*
	* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.util;

	import jdk.internal.misc.SharedSecrets;

	/**
	* A specialized {@link Set} implementation for use with enum types. All of
	* the elements in an enum set must come from a single enum type that is
	* specified, explicitly or implicitly, when the set is created. Enum sets
	* are represented internally as bit vectors. This representation is
	* extremely compact and efficient. The space and time performance of this
	* class should be good enough to allow its use as a high-quality, typesafe
	* alternative to traditional {@code int}-based "bit flags." Even bulk
	* operations (such as {@code containsAll} and {@code retainAll}) should
	* run very quickly if their argument is also an enum set.
	*
	* <p>The iterator returned by the {@code iterator} method traverses the
	* elements in their <i>natural order</i> (the order in which the enum
	* constants are declared). The returned iterator is <i>weakly
	* consistent</i>: it will never throw {@link ConcurrentModificationException}
	* and it may or may not show the effects of any modifications to the set that
	* occur while the iteration is in progress.
	*
	* <p>Null elements are not permitted. Attempts to insert a null element
	* will throw {@link NullPointerException}. Attempts to test for the
	* presence of a null element or to remove one will, however, function
	* properly.
	*
	* <P>Like most collection implementations, {@code EnumSet} is not
	* synchronized. If multiple threads access an enum set concurrently, and at
	* least one of the threads modifies the set, it should be synchronized
	* externally. This is typically accomplished by synchronizing on some
	* object that naturally encapsulates the enum set. If no such object exists,
	* the set should be "wrapped" using the {@link Collections#synchronizedSet}
	* method. This is best done at creation time, to prevent accidental
	* unsynchronized access:
	*
	* <pre>
	* Set<MyEnum> s = Collections.synchronizedSet(EnumSet.noneOf(MyEnum.class));
	* </pre>
	*
	* <p>Implementation note: All basic operations execute in constant time.
	* They are likely (though not guaranteed) to be much faster than their
	* {@link HashSet} counterparts. Even bulk operations execute in
	* constant time if their argument is also an enum set.
	*
	* <p>This class is a member of the
	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
	* Java Collections Framework</a>.
	*
	* @author Josh Bloch
	* @since 1.5
	* @see EnumMap
	*/
	@SuppressWarnings("serial") // No serialVersionUID due to usage of
	// serial proxy pattern
	public abstract class EnumSet<E extends Enum<E>> extends AbstractSet<E>
	implements Cloneable, java.io.Serializable
	{
	/**
	* The class of all the elements of this set.
	*/
	final transient Class<E> elementType;

	/**
	* All of the values comprising E. (Cached for performance.)
	*/
	final transient Enum<?>[] universe;

	EnumSet(Class<E>elementType, Enum<?>[] universe) {
	this.elementType = elementType;
	this.universe = universe;
	}

	/**
	* Creates an empty enum set with the specified element type.
	*
	* @param <E> The class of the elements in the set
	* @param elementType the class object of the element type for this enum
	* set
	* @return An empty enum set of the specified type.
	* @throws NullPointerException if {@code elementType} is null
	*/
	public static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> elementType) {
	Enum<?>[] universe = getUniverse(elementType);
	if (universe == null)
	throw new ClassCastException(elementType + " not an enum");

	if (universe.length <= 64)
	return new RegularEnumSet<>(elementType, universe);
	else
	return new JumboEnumSet<>(elementType, universe);
	}

	/**
	* Creates an enum set containing all of the elements in the specified
	* element type.
	*
	* @param <E> The class of the elements in the set
	* @param elementType the class object of the element type for this enum
	* set
	* @return An enum set containing all the elements in the specified type.
	* @throws NullPointerException if {@code elementType} is null
	*/
	public static <E extends Enum<E>> EnumSet<E> allOf(Class<E> elementType) {
	EnumSet<E> result = noneOf(elementType);
	result.addAll();
	return result;
	}

	/**
	* Adds all of the elements from the appropriate enum type to this enum
	* set, which is empty prior to the call.
	*/
	abstract void addAll();

	/**
	* Creates an enum set with the same element type as the specified enum
	* set, initially containing the same elements (if any).
	*
	* @param <E> The class of the elements in the set
	* @param s the enum set from which to initialize this enum set
	* @return A copy of the specified enum set.
	* @throws NullPointerException if {@code s} is null
	*/
	public static <E extends Enum<E>> EnumSet<E> copyOf(EnumSet<E> s) {
	return s.clone();
	}

	/**
	* Creates an enum set initialized from the specified collection. If
	* the specified collection is an {@code EnumSet} instance, this static
	* factory method behaves identically to {@link #copyOf(EnumSet)}.
	* Otherwise, the specified collection must contain at least one element
	* (in order to determine the new enum set's element type).
	*
	* @param <E> The class of the elements in the collection
	* @param c the collection from which to initialize this enum set
	* @return An enum set initialized from the given collection.
	* @throws IllegalArgumentException if {@code c} is not an
	* {@code EnumSet} instance and contains no elements
	* @throws NullPointerException if {@code c} is null
	*/
	public static <E extends Enum<E>> EnumSet<E> copyOf(Collection<E> c) {
	if (c instanceof EnumSet) {
	return ((EnumSet<E>)c).clone();
	} else {
	if (c.isEmpty())
	throw new IllegalArgumentException("Collection is empty");
	Iterator<E> i = c.iterator();
	E first = i.next();
	EnumSet<E> result = EnumSet.of(first);
	while (i.hasNext())
	result.add(i.next());
	return result;
	}
	}

	/**
	* Creates an enum set with the same element type as the specified enum
	* set, initially containing all the elements of this type that are
	* <i>not</i> contained in the specified set.
	*
	* @param <E> The class of the elements in the enum set
	* @param s the enum set from whose complement to initialize this enum set
	* @return The complement of the specified set in this set
	* @throws NullPointerException if {@code s} is null
	*/
	public static <E extends Enum<E>> EnumSet<E> complementOf(EnumSet<E> s) {
	EnumSet<E> result = copyOf(s);
	result.complement();
	return result;
	}

	/**
	* Creates an enum set initially containing the specified element.
	*
	* Overloadings of this method exist to initialize an enum set with
	* one through five elements. A sixth overloading is provided that
	* uses the varargs feature. This overloading may be used to create
	* an enum set initially containing an arbitrary number of elements, but
	* is likely to run slower than the overloadings that do not use varargs.
	*
	* @param <E> The class of the specified element and of the set
	* @param e the element that this set is to contain initially
	* @throws NullPointerException if {@code e} is null
	* @return an enum set initially containing the specified element
	*/
	public static <E extends Enum<E>> EnumSet<E> of(E e) {
	EnumSet<E> result = noneOf(e.getDeclaringClass());
	result.add(e);
	return result;
	}

	/**
	* Creates an enum set initially containing the specified elements.
	*
	* Overloadings of this method exist to initialize an enum set with
	* one through five elements. A sixth overloading is provided that
	* uses the varargs feature. This overloading may be used to create
	* an enum set initially containing an arbitrary number of elements, but
	* is likely to run slower than the overloadings that do not use varargs.
	*
	* @param <E> The class of the parameter elements and of the set
	* @param e1 an element that this set is to contain initially
	* @param e2 another element that this set is to contain initially
	* @throws NullPointerException if any parameters are null
	* @return an enum set initially containing the specified elements
	*/
	public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2) {
	EnumSet<E> result = noneOf(e1.getDeclaringClass());
	result.add(e1);
	result.add(e2);
	return result;
	}

	/**
	* Creates an enum set initially containing the specified elements.
	*
	* Overloadings of this method exist to initialize an enum set with
	* one through five elements. A sixth overloading is provided that
	* uses the varargs feature. This overloading may be used to create
	* an enum set initially containing an arbitrary number of elements, but
	* is likely to run slower than the overloadings that do not use varargs.
	*
	* @param <E> The class of the parameter elements and of the set
	* @param e1 an element that this set is to contain initially
	* @param e2 another element that this set is to contain initially
	* @param e3 another element that this set is to contain initially
	* @throws NullPointerException if any parameters are null
	* @return an enum set initially containing the specified elements
	*/
	public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3) {
	EnumSet<E> result = noneOf(e1.getDeclaringClass());
	result.add(e1);
	result.add(e2);
	result.add(e3);
	return result;
	}

	/**
	* Creates an enum set initially containing the specified elements.
	*
	* Overloadings of this method exist to initialize an enum set with
	* one through five elements. A sixth overloading is provided that
	* uses the varargs feature. This overloading may be used to create
	* an enum set initially containing an arbitrary number of elements, but
	* is likely to run slower than the overloadings that do not use varargs.
	*
	* @param <E> The class of the parameter elements and of the set
	* @param e1 an element that this set is to contain initially
	* @param e2 another element that this set is to contain initially
	* @param e3 another element that this set is to contain initially
	* @param e4 another element that this set is to contain initially
	* @throws NullPointerException if any parameters are null
	* @return an enum set initially containing the specified elements
	*/
	public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4) {
	EnumSet<E> result = noneOf(e1.getDeclaringClass());
	result.add(e1);
	result.add(e2);
	result.add(e3);
	result.add(e4);
	return result;
	}

	/**
	* Creates an enum set initially containing the specified elements.
	*
	* Overloadings of this method exist to initialize an enum set with
	* one through five elements. A sixth overloading is provided that
	* uses the varargs feature. This overloading may be used to create
	* an enum set initially containing an arbitrary number of elements, but
	* is likely to run slower than the overloadings that do not use varargs.
	*
	* @param <E> The class of the parameter elements and of the set
	* @param e1 an element that this set is to contain initially
	* @param e2 another element that this set is to contain initially
	* @param e3 another element that this set is to contain initially
	* @param e4 another element that this set is to contain initially
	* @param e5 another element that this set is to contain initially
	* @throws NullPointerException if any parameters are null
	* @return an enum set initially containing the specified elements
	*/
	public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4,
	E e5)
	{
	EnumSet<E> result = noneOf(e1.getDeclaringClass());
	result.add(e1);
	result.add(e2);
	result.add(e3);
	result.add(e4);
	result.add(e5);
	return result;
	}

	/**
	* Creates an enum set initially containing the specified elements.
	* This factory, whose parameter list uses the varargs feature, may
	* be used to create an enum set initially containing an arbitrary
	* number of elements, but it is likely to run slower than the overloadings
	* that do not use varargs.
	*
	* @param <E> The class of the parameter elements and of the set
	* @param first an element that the set is to contain initially
	* @param rest the remaining elements the set is to contain initially
	* @throws NullPointerException if any of the specified elements are null,
	* or if {@code rest} is null
	* @return an enum set initially containing the specified elements
	*/
	@SafeVarargs
	public static <E extends Enum<E>> EnumSet<E> of(E first, E... rest) {
	EnumSet<E> result = noneOf(first.getDeclaringClass());
	result.add(first);
	for (E e : rest)
	result.add(e);
	return result;
	}

	/**
	* Creates an enum set initially containing all of the elements in the
	* range defined by the two specified endpoints. The returned set will
	* contain the endpoints themselves, which may be identical but must not
	* be out of order.
	*
	* @param <E> The class of the parameter elements and of the set
	* @param from the first element in the range
	* @param to the last element in the range
	* @throws NullPointerException if {@code from} or {@code to} are null
	* @throws IllegalArgumentException if {@code from.compareTo(to) > 0}
	* @return an enum set initially containing all of the elements in the
	* range defined by the two specified endpoints
	*/
	public static <E extends Enum<E>> EnumSet<E> range(E from, E to) {
	if (from.compareTo(to) > 0)
	throw new IllegalArgumentException(from + " > " + to);
	EnumSet<E> result = noneOf(from.getDeclaringClass());
	result.addRange(from, to);
	return result;
	}

	/**
	* Adds the specified range to this enum set, which is empty prior
	* to the call.
	*/
	abstract void addRange(E from, E to);

	/**
	* Returns a copy of this set.
	*
	* @return a copy of this set
	*/
	@SuppressWarnings("unchecked")
	public EnumSet<E> clone() {
	try {
	return (EnumSet<E>) super.clone();
	} catch(CloneNotSupportedException e) {
	throw new AssertionError(e);
	}
	}

	/**
	* Complements the contents of this enum set.
	*/
	abstract void complement();

	/**
	* Throws an exception if e is not of the correct type for this enum set.
	*/
	final void typeCheck(E e) {
	Class<?> eClass = e.getClass();
	if (eClass != elementType && eClass.getSuperclass() != elementType)
	throw new ClassCastException(eClass + " != " + elementType);
	}

	/**
	* Returns all of the values comprising E.
	* The result is uncloned, cached, and shared by all callers.
	*/
	private static <E extends Enum<E>> E[] getUniverse(Class<E> elementType) {
	return SharedSecrets.getJavaLangAccess()
	.getEnumConstantsShared(elementType);
	}

	/**
	* This class is used to serialize all EnumSet instances, regardless of
	* implementation type. It captures their "logical contents" and they
	* are reconstructed using public static factories. This is necessary
	* to ensure that the existence of a particular implementation type is
	* an implementation detail.
	*
	* @serial include
	*/
	private static class SerializationProxy<E extends Enum<E>>
	implements java.io.Serializable
	{

	private static final Enum<?>[] ZERO_LENGTH_ENUM_ARRAY = new Enum<?>[0];

	/**
	* The element type of this enum set.
	*
	* @serial
	*/
	private final Class<E> elementType;

	/**
	* The elements contained in this enum set.
	*
	* @serial
	*/
	private final Enum<?>[] elements;

	SerializationProxy(EnumSet<E> set) {
	elementType = set.elementType;
	elements = set.toArray(ZERO_LENGTH_ENUM_ARRAY);
	}

	/**
	* Returns an {@code EnumSet} object with initial state
	* held by this proxy.
	*
	* @return a {@code EnumSet} object with initial state
	* held by this proxy
	*/
	@SuppressWarnings("unchecked")
	private Object readResolve() {
	// instead of cast to E, we should perhaps use elementType.cast()
	// to avoid injection of forged stream, but it will slow the
	// implementation
	EnumSet<E> result = EnumSet.noneOf(elementType);
	for (Enum<?> e : elements)
	result.add((E)e);
	return result;
	}

	private static final long serialVersionUID = 362491234563181265L;
	}

	/**
	* Returns a
	* <a href="../../serialized-form.html#java.util.EnumSet.SerializationProxy">
	* SerializationProxy</a>
	* representing the state of this instance.
	*
	* @return a {@link SerializationProxy}
	* representing the state of this instance
	*/
	Object writeReplace() {
	return new SerializationProxy<>(this);
	}

	/**
	* @param s the stream
	* @throws java.io.InvalidObjectException always
	*/
	private void readObject(java.io.ObjectInputStream s)
	throws java.io.InvalidObjectException {
	throw new java.io.InvalidObjectException("Proxy required");
	}
	}

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