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/*
 * Copyright (C) 2011 The Guava 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 com.google.common.base;

import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import java.io.Serializable;
import java.lang.reflect.Field;
import javax.annotation.Nullable;

/**
 *  Utility methods for working with {@link Enum} instances.
 *
 *  @author Steve McKay
 *
 *  @since 9.0
 *
 * @deprecated The Google Guava Core Libraries are deprecated and will not be part of the AEM SDK after April 2023
 */
@GwtCompatible(emulated = true)
@Beta
@Deprecated(since = "2022-12-01")
public final class Enums {

    private Enums() {
    }

    /**
     * Returns the {@link Field} in which {@code enumValue} is defined.
     * For example, to get the {@code Description} annotation on the {@code GOLF}
     * constant of enum {@code Sport}, use
     * {@code Enums.getField(Sport.GOLF).getAnnotation(Description.class)}.
     *
     * @since 12.0
     */
    @GwtIncompatible("reflection")
    public static Field getField(Enum enumValue) {
        Class clazz = enumValue.getDeclaringClass();
        try {
            return clazz.getDeclaredField(enumValue.name());
        } catch (NoSuchFieldException impossible) {
            throw new AssertionError(impossible);
        }
    }

    /**
     * Returns a {@link Function} that maps an {@link Enum} name to the associated
     * {@code Enum} constant. The {@code Function} will return {@code null} if the
     * {@code Enum} constant does not exist.
     *
     * @param enumClass the {@link Class} of the {@code Enum} declaring the
     *     constant values.
     */
    public static > Function valueOfFunction(Class enumClass) {
        return new ValueOfFunction(enumClass);
    }

    /**
     *  A {@link Function} that maps an {@link Enum} name to the associated
     *  constant, or {@code null} if the constant does not exist.
     *
     * @deprecated The Google Guava Core Libraries are deprecated and will not be part of the AEM SDK after April 2023
     */
    @Deprecated(since = "2022-12-01")
    private static final class ValueOfFunction> implements Function, Serializable {

        private final Class enumClass;

        private ValueOfFunction(Class enumClass) {
            this.enumClass = checkNotNull(enumClass);
        }

        @Override
        public T apply(String value) {
            try {
                return Enum.valueOf(enumClass, value);
            } catch (IllegalArgumentException e) {
                return null;
            }
        }

        @Override
        public boolean equals(@Nullable Object obj) {
            return obj instanceof ValueOfFunction && enumClass.equals(((ValueOfFunction) obj).enumClass);
        }

        @Override
        public int hashCode() {
            return enumClass.hashCode();
        }

        @Override
        public String toString() {
            return "Enums.valueOf(" + enumClass + ")";
        }

        private static final long serialVersionUID = 0;
    }

    /**
     * Returns an optional enum constant for the given type, using {@link Enum#valueOf}. If the
     * constant does not exist, {@link Optional#absent} is returned. A common use case is for parsing
     * user input or falling back to a default enum constant. For example,
     * {@code Enums.getIfPresent(Country.class, countryInput).or(Country.DEFAULT);}
     *
     * @since 12.0
     */
    public static > Optional getIfPresent(Class enumClass, String value) {
        checkNotNull(enumClass);
        checkNotNull(value);
        try {
            return Optional.of(Enum.valueOf(enumClass, value));
        } catch (IllegalArgumentException iae) {
            return Optional.absent();
        }
    }
}