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General data-binding functionality for Jackson: works on core streaming API
There is a newer version: 2.18.1
package com.fasterxml.jackson.databind.util;

import java.util.*;

import com.fasterxml.jackson.core.SerializableString;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.cfg.EnumFeature;
import com.fasterxml.jackson.databind.cfg.MapperConfig;

/**
 * Helper class used for storing String serializations of {@code Enum}s,
 * to match to/from external representations.
 */
public final class EnumValues
    implements java.io.Serializable
{
    private static final long serialVersionUID = 1;

    private final Class> _enumClass;

    private final Enum[] _values;
    private final SerializableString[] _textual;

    private transient EnumMap _asMap;

    private EnumValues(Class> enumClass, SerializableString[] textual)
    {
        _enumClass = enumClass;
        _values = enumClass.getEnumConstants();
        _textual = textual;
    }

    /**
     * NOTE: do NOT call this if configuration may change, and choice between toString()
     *   and name() might change dynamically.
     */
    public static EnumValues construct(SerializationConfig config, Class> enumClass) {
        if (config.isEnabled(SerializationFeature.WRITE_ENUMS_USING_TO_STRING)) {
            return constructFromToString(config, enumClass);
        }
        return constructFromName(config, enumClass);
    }

    public static EnumValues constructFromName(MapperConfig config, Class> enumClass)
    {
        // Enum types with per-instance sub-classes need special handling
        Class> enumCls = ClassUtil.findEnumType(enumClass);
        Enum[] enumValues = enumCls.getEnumConstants();
        if (enumValues == null) {
            throw new IllegalArgumentException("Cannot determine enum constants for Class "+enumClass.getName());
        }
        String[] names = config.getAnnotationIntrospector().findEnumValues(enumCls, enumValues, new String[enumValues.length]);
        SerializableString[] textual = new SerializableString[enumValues.length];
        for (int i = 0, len = enumValues.length; i < len; ++i) {
            Enum en = enumValues[i];
            String name = names[i];
            if (name == null) {
                name = en.name();
            }
            if (config.isEnabled(EnumFeature.WRITE_ENUMS_TO_LOWERCASE)) {
                name = name.toLowerCase();
            }
            textual[en.ordinal()] = config.compileString(name);
        }
        return construct(enumClass, textual);
    }

    public static EnumValues constructFromToString(MapperConfig config, Class> enumClass)
    {
        Class> cls = ClassUtil.findEnumType(enumClass);
        Enum[] values = cls.getEnumConstants();
        if (values == null) { // can this ever occur?
            throw new IllegalArgumentException("Cannot determine enum constants for Class "+enumClass.getName());
        }
        ArrayList external = new ArrayList<>(values.length);
        for (Enum en : values) {
            external.add(en.toString());
        }
        return construct(config, enumClass, external);
    }

    /**
     * Returns String serializations of Enum name using an instance of {@link EnumNamingStrategy}.
     *
     * The output {@link EnumValues} should contain values that are symmetric to
     * {@link EnumResolver#constructUsingEnumNamingStrategy(DeserializationConfig, Class, EnumNamingStrategy)}.
     *
     * @since 2.15
     */
    public static EnumValues constructUsingEnumNamingStrategy(MapperConfig config, Class> enumClass, EnumNamingStrategy namingStrategy) {
        Class> cls = ClassUtil.findEnumType(enumClass);
        Enum[] values = cls.getEnumConstants();
        if (values == null) {
            throw new IllegalArgumentException("Cannot determine enum constants for Class " + enumClass.getName());
        }
        ArrayList external = new ArrayList<>(values.length);
        for (Enum en : values) {
            external.add(namingStrategy.convertEnumToExternalName(en.name()));
        }
        return construct(config, enumClass, external);
    }

    /**
     * @since 2.11
     */
    public static EnumValues construct(MapperConfig config, Class> enumClass,
            List externalValues) {
        final int len = externalValues.size();
        SerializableString[] textual = new SerializableString[len];
        for (int i = 0; i < len; ++i) {
            textual[i] = config.compileString(externalValues.get(i));
        }
        return construct(enumClass, textual);
    }

    /**
     * @since 2.11
     */
    public static EnumValues construct(Class> enumClass,
            SerializableString[] externalValues) {
        return new EnumValues(enumClass, externalValues);
    }

    public SerializableString serializedValueFor(Enum key) {
        return _textual[key.ordinal()];
    }

    public Collection values() {
        return Arrays.asList(_textual);
    }

    /**
     * Convenience accessor for getting raw Enum instances.
     *
     * @since 2.6
     */
    public List> enums() {
        return Arrays.asList(_values);
    }

    /**
     * Method used for serialization and introspection by core Jackson code.
     */
    @SuppressWarnings({ "unchecked", "rawtypes" })
    public EnumMap internalMap() {
        EnumMap result = _asMap;
        if (result == null) {
            // Alas, need to create it in a round-about way, due to typing constraints...
            Map,SerializableString> map = new LinkedHashMap,SerializableString>();
            for (Enum en : _values) {
                map.put(en, _textual[en.ordinal()]);
            }
            result = new EnumMap(map);
        }
        return result;
    }

    /**
     * @since 2.2
     */
    public Class> getEnumClass() { return _enumClass; }
}