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	/*
	* Copyright (c) 2003, 2020, 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.lang;

	import java.io.IOException;
	import java.io.InvalidObjectException;
	import java.io.ObjectInputStream;
	import java.io.ObjectStreamException;
	import java.io.Serializable;
	import java.lang.constant.ClassDesc;
	import java.lang.constant.Constable;
	import java.lang.constant.ConstantDescs;
	import java.lang.constant.DynamicConstantDesc;
	import java.lang.invoke.MethodHandles;
	import java.util.Optional;

	import static java.util.Objects.requireNonNull;

	/**
	* This is the common base class of all Java language enumeration classes.
	*
	* More information about enums, including descriptions of the
	* implicitly declared methods synthesized by the compiler, can be
	* found in section {@jls 8.9} of <cite>The Java Language
	* Specification</cite>.
	*
	* Enumeration classes are all serializable and receive special handling
	* by the serialization mechanism. The serialized representation used
	* for enum constants cannot be customized. Declarations of methods
	* and fields that would otherwise interact with serialization are
	* ignored, including {@code serialVersionUID}; see the <cite>Java
	* Object Serialization Specification</cite> for details.
	*
	* <p> Note that when using an enumeration type as the type of a set
	* or as the type of the keys in a map, specialized and efficient
	* {@linkplain java.util.EnumSet set} and {@linkplain
	* java.util.EnumMap map} implementations are available.
	*
	* @param <E> The type of the enum subclass
	* @serial exclude
	* @author Josh Bloch
	* @author Neal Gafter
	* @see Class#getEnumConstants()
	* @see java.util.EnumSet
	* @see java.util.EnumMap
	* @jls 8.9 Enum Classes
	* @jls 8.9.3 Enum Members
	* @since 1.5
	*/
	@SuppressWarnings("serial") // No serialVersionUID needed due to
	// special-casing of enum classes.
	public abstract class Enum<E extends Enum<E>>
	implements Constable, Comparable<E>, Serializable {
	/**
	* The name of this enum constant, as declared in the enum declaration.
	* Most programmers should use the {@link #toString} method rather than
	* accessing this field.
	*/
	private final String name;

	/**
	* Returns the name of this enum constant, exactly as declared in its
	* enum declaration.
	*
	* <b>Most programmers should use the {@link #toString} method in
	* preference to this one, as the toString method may return
	* a more user-friendly name.</b> This method is designed primarily for
	* use in specialized situations where correctness depends on getting the
	* exact name, which will not vary from release to release.
	*
	* @return the name of this enum constant
	*/
	public final String name() {
	return name;
	}

	/**
	* The ordinal of this enumeration constant (its position
	* in the enum declaration, where the initial constant is assigned
	* an ordinal of zero).
	*
	* Most programmers will have no use for this field. It is designed
	* for use by sophisticated enum-based data structures, such as
	* {@link java.util.EnumSet} and {@link java.util.EnumMap}.
	*/
	private final int ordinal;

	/**
	* Returns the ordinal of this enumeration constant (its position
	* in its enum declaration, where the initial constant is assigned
	* an ordinal of zero).
	*
	* Most programmers will have no use for this method. It is
	* designed for use by sophisticated enum-based data structures, such
	* as {@link java.util.EnumSet} and {@link java.util.EnumMap}.
	*
	* @return the ordinal of this enumeration constant
	*/
	public final int ordinal() {
	return ordinal;
	}

	/**
	* Sole constructor. Programmers cannot invoke this constructor.
	* It is for use by code emitted by the compiler in response to
	* enum class declarations.
	*
	* @param name - The name of this enum constant, which is the identifier
	* used to declare it.
	* @param ordinal - The ordinal of this enumeration constant (its position
	* in the enum declaration, where the initial constant is assigned
	* an ordinal of zero).
	*/
	protected Enum(String name, int ordinal) {
	this.name = name;
	this.ordinal = ordinal;
	}

	/**
	* Returns the name of this enum constant, as contained in the
	* declaration. This method may be overridden, though it typically
	* isn't necessary or desirable. An enum class should override this
	* method when a more "programmer-friendly" string form exists.
	*
	* @return the name of this enum constant
	*/
	public String toString() {
	return name;
	}

	/**
	* Returns true if the specified object is equal to this
	* enum constant.
	*
	* @param other the object to be compared for equality with this object.
	* @return true if the specified object is equal to this
	* enum constant.
	*/
	public final boolean equals(Object other) {
	return this==other;
	}

	/**
	* Returns a hash code for this enum constant.
	*
	* @return a hash code for this enum constant.
	*/
	public final int hashCode() {
	return super.hashCode();
	}

	/**
	* Throws CloneNotSupportedException. This guarantees that enums
	* are never cloned, which is necessary to preserve their "singleton"
	* status.
	*
	* @return (never returns)
	*/
	protected final Object clone() throws CloneNotSupportedException {
	throw new CloneNotSupportedException();
	}

	/**
	* Compares this enum with the specified object for order. Returns a
	* negative integer, zero, or a positive integer as this object is less
	* than, equal to, or greater than the specified object.
	*
	* Enum constants are only comparable to other enum constants of the
	* same enum type. The natural order implemented by this
	* method is the order in which the constants are declared.
	*/
	public final int compareTo(E o) {
	Enum<?> other = (Enum<?>)o;
	Enum<E> self = this;
	if (self.getClass() != other.getClass() && // optimization
	self.getDeclaringClass() != other.getDeclaringClass())
	throw new ClassCastException();
	return self.ordinal - other.ordinal;
	}

	/**
	* Returns the Class object corresponding to this enum constant's
	* enum type. Two enum constants e1 and e2 are of the
	* same enum type if and only if
	* e1.getDeclaringClass() == e2.getDeclaringClass().
	* (The value returned by this method may differ from the one returned
	* by the {@link Object#getClass} method for enum constants with
	* constant-specific class bodies.)
	*
	* @return the Class object corresponding to this enum constant's
	* enum type
	*/
	@SuppressWarnings("unchecked")
	public final Class<E> getDeclaringClass() {
	Class<?> clazz = getClass();
	Class<?> zuper = clazz.getSuperclass();
	return (zuper == Enum.class) ? (Class<E>)clazz : (Class<E>)zuper;
	}

	/**
	* Returns an enum descriptor {@code EnumDesc} for this instance, if one can be
	* constructed, or an empty {@link Optional} if one cannot be.
	*
	* @return An {@link Optional} containing the resulting nominal descriptor,
	* or an empty {@link Optional} if one cannot be constructed.
	* @since 12
	*/
	@Override
	public final Optional<EnumDesc<E>> describeConstable() {
	return getDeclaringClass()
	.describeConstable()
	.map(c -> EnumDesc.of(c, name));
	}

	/**
	* Returns the enum constant of the specified enum class with the
	* specified name. The name must match exactly an identifier used
	* to declare an enum constant in this class. (Extraneous whitespace
	* characters are not permitted.)
	*
	* <p>Note that for a particular enum class {@code T}, the
	* implicitly declared {@code public static T valueOf(String)}
	* method on that enum may be used instead of this method to map
	* from a name to the corresponding enum constant. All the
	* constants of an enum class can be obtained by calling the
	* implicit {@code public static T[] values()} method of that
	* class.
	*
	* @param <T> The enum class whose constant is to be returned
	* @param enumClass the {@code Class} object of the enum class from which
	* to return a constant
	* @param name the name of the constant to return
	* @return the enum constant of the specified enum class with the
	* specified name
	* @throws IllegalArgumentException if the specified enum class has
	* no constant with the specified name, or the specified
	* class object does not represent an enum class
	* @throws NullPointerException if {@code enumClass} or {@code name}
	* is null
	* @since 1.5
	*/
	public static <T extends Enum<T>> T valueOf(Class<T> enumClass,
	String name) {
	T result = enumClass.enumConstantDirectory().get(name);
	if (result != null)
	return result;
	if (name == null)
	throw new NullPointerException("Name is null");
	throw new IllegalArgumentException(
	"No enum constant " + enumClass.getCanonicalName() + "." + name);
	}

	/**
	* enum classes cannot have finalize methods.
	*/
	@SuppressWarnings("deprecation")
	protected final void finalize() { }

	/**
	* prevent default deserialization
	*/
	@java.io.Serial
	private void readObject(ObjectInputStream in) throws IOException,
	ClassNotFoundException {
	throw new InvalidObjectException("can't deserialize enum");
	}

	@java.io.Serial
	private void readObjectNoData() throws ObjectStreamException {
	throw new InvalidObjectException("can't deserialize enum");
	}

	/**
	* A <a href="{@docRoot}/java.base/java/lang/constant/package-summary.html#nominal">nominal descriptor</a> for an
	* {@code enum} constant.
	*
	* @param <E> the type of the enum constant
	*
	* @since 12
	*/
	public static final class EnumDesc<E extends Enum<E>>
	extends DynamicConstantDesc<E> {

	/**
	* Constructs a nominal descriptor for the specified {@code enum} class and name.
	*
	* @param constantClass a {@link ClassDesc} describing the {@code enum} class
	* @param constantName the unqualified name of the enum constant
	* @throws NullPointerException if any argument is null
	* @jvms 4.2.2 Unqualified Names
	*/
	private EnumDesc(ClassDesc constantClass, String constantName) {
	super(ConstantDescs.BSM_ENUM_CONSTANT, requireNonNull(constantName), requireNonNull(constantClass));
	}

	/**
	* Returns a nominal descriptor for the specified {@code enum} class and name
	*
	* @param <E> the type of the enum constant
	* @param enumClass a {@link ClassDesc} describing the {@code enum} class
	* @param constantName the unqualified name of the enum constant
	* @return the nominal descriptor
	* @throws NullPointerException if any argument is null
	* @jvms 4.2.2 Unqualified Names
	* @since 12
	*/
	public static<E extends Enum<E>> EnumDesc<E> of(ClassDesc enumClass,
	String constantName) {
	return new EnumDesc<>(enumClass, constantName);
	}

	@Override
	@SuppressWarnings("unchecked")
	public E resolveConstantDesc(MethodHandles.Lookup lookup)
	throws ReflectiveOperationException {
	return Enum.valueOf((Class<E>) constantType().resolveConstantDesc(lookup), constantName());
	}

	@Override
	public String toString() {
	return String.format("EnumDesc[%s.%s]", constantType().displayName(), constantName());
	}
	}
	}

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