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package cdc.util.enums;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import cdc.util.lang.Introspection;

/**
 * Specialization of AbstractEnumMask dedicated to standard enums.
 * 
 * This class must not (and can not) be specialized to work correctly.

 * If specialization is needed, use AbstractEnumMask directly.
 *
 * @author Damien Carbonne
 *
 * @param  The enum type.
 */
public final class NullableEnumMask> extends AbstractMask, E> {
    private static final Map>, MaskSupport> MAP = new HashMap<>();

    private NullableEnumMask(MaskSupport, E> support,
                             Set values) {
        super(support,
              values);
    }

    /**
     * Creates a Support implementation for a standard enum.
     *
     * @param  The enum type.
     * @param enumClass The enum class.
     * @return A Support implementation.
     */
    public static > MaskSupport, E> newSupport(Class enumClass) {
        final Class> maskClass = Introspection.uncheckedCast(NullableEnumMask.class);
        final Creator, E> creator = NullableEnumMask::new;
        return support(maskClass,
                       creator,
                       enumClass,
                       Nullable.TRUE);
    }

    /**
     * Returns the support associated to an enum class.
     *
     * @param  The enum type.
     * @param enumClass The enum class.
     * @return The support for {@code NullableEnumMask}.
     */
    public static > MaskSupport, E> support(Class enumClass) {
        final MaskSupport tmp;
        tmp = MAP.computeIfAbsent(enumClass, k -> newSupport(enumClass));

        @SuppressWarnings("unchecked")
        final MaskSupport, E> result = (MaskSupport, E>) tmp;
        return result;
    }

    /**
     * @return A set of enums for which a support has been created.
     */
    public static Set>> getEnumClasses() {
        return MAP.keySet();
    }

    /**
     * Returns the empty mask corresponding to an enum.
     *
     * @param  The enum type.
     * @param enumClass The enum class.
     * @return The empty {@code NullableEnumMask}.
     */
    public static > NullableEnumMask empty(Class enumClass) {
        return support(enumClass).empty();
    }

    /**
     * Returns the full mask corresponding to an enum.
     *
     * @param  The enum type.
     * @param enumClass The enum class.
     * @return The full {@code NullableEnumMask}.
     */
    public static > NullableEnumMask full(Class enumClass) {
        return support(enumClass).full();
    }
}