jpa/org.eclipse.persistence.jpa.jpql/src/main/java/org/eclipse/persistence/jpa/jpql/JPAVersion.java

/*
 * Copyright (c) 2006, 2021 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle - initial API and implementation
//
package org.eclipse.persistence.jpa.jpql;

/**
 * An enumeration listing the various releases of the Java Persistence specification.
 * <p>
 * Provisional API: This interface is part of an interim API that is still under development and
 * expected to change significantly before reaching stability. It is available at this early stage
 * to solicit feedback from pioneering adopters on the understanding that any code that uses this
 * API will almost certainly be broken (repeatedly) as the API evolves.
 *
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
public enum JPAVersion {

    /**
     * The constant for the default version used by the parsing system, which is always the latest
     * version of the Java Persistence functional specification, which is version 2.0.
     */
    DEFAULT_VERSION(2.1),

    /**
     * The constant for the Java Persistence specification 1.0.
     */
    VERSION_1_0(1.0),

    /**
     * The constant for the Java Persistence specification 2.0.
     */
    VERSION_2_0(2.0),

    /**
     * The constant for the Java Persistence specification 2.1.
     */
    VERSION_2_1(2.1);

    /**
     * The real version number.
     */
    private double version;

    /**
     * Creates a new <code>JPAVersion</code>.
     *
     * @param version The actual version number
     */
    private JPAVersion(double version) {
        this.version = version;
    }

    /**
     * Retrieves the enumeration constant for the given value. If the value is not known, then
     * {@link #DEFAULT_VERSION} will be returned.
     *
     * @param value The value to retrieve its constant version
     * @return The constant version of the given value
     */
    public static JPAVersion value(String value) {
        for (JPAVersion version : versions()) {
            if (version.getVersion().equals(value)) {
                return version;
            }
        }
        return DEFAULT_VERSION;
    }

    /**
     * Returns the list of {@link JPAVersion} excluding {@link #DEFAULT_VERSION}.
     *
     * @return The list of unique constants
     */
    public static JPAVersion[] versions() {
        JPAVersion[] values = new JPAVersion[3];
        values[0] = VERSION_1_0;
        values[1] = VERSION_2_0;
        values[2] = VERSION_2_1;
        return values;
    }

    /**
     * Returns the real version this constant represents.
     *
     * @return The string value of the version
     */
    public String getVersion() {
        return String.valueOf(version);
    }

    /**
     * Determines whether this constant represents a version that is newer than the given version.
     *
     * @param version The constant to verify if it's representing a version that is older than this one
     * @return <code>true</code> if this constant represents a newer version and the given constant
     * represents a version that is older; <code>false</code> if the given constant represents a
     * newer and this constant represents an older version
     */
    public boolean isNewerThan(JPAVersion version) {
        return this.version > version.version;
    }

    /**
     * Determines whether this constant represents a version that is newer than the given version or
     * if it's the same version.
     *
     * @param version The constant to verify if it's representing a version that is older than this
     * one or if it's the same than this one
     * @return <code>true</code> if this constant represents a newer version and the given constant
     * represents a version that is older or if it's the same constant; <code>false</code> if the
     * given constant represents a newer and this constant represents an older version
     */
    public boolean isNewerThanOrEqual(JPAVersion version) {
        return this.version >= version.version;
    }

    /**
     * Determines whether this constant represents a version that is older than the given version.
     *
     * @param version The constant to verify if it's representing a version that is more recent than
     * this one
     * @return <code>true</code> if this constant represents an earlier version and the given
     * constant represents a version that is more recent; <code>false</code> if the given constant
     * represents an earlier version and this constant represents a more recent version
     */
    public boolean isOlderThan(JPAVersion version) {
        return this.version < version.version;
    }

    /**
     * Determines whether this constant represents a version that is older than the given version or
     * if it's the same version.
     *
     * @param version The constant to verify if it's representing a version that is more recent than
     * this one or if it's the same than this one
     * @return <code>true</code> if this constant represents an earlier version and the given
     * constant represents a version that is more recent or if it's the same constant; <code>false</code>
     * if the given constant represents an earlier version and this constant represents a more recent
     * version
     */
    public boolean isOlderThanOrEqual(JPAVersion version) {
        return this.version <= version.version;
    }

    /**
     * Converts the current constant to one of the known versions, this means if the constant is
     * {@link #DEFAULT_VERSION}, then it will be converted into the actual constant representing that
     * version.
     *
     * @return Either this same constant or the actual version constant
     */
    public JPAVersion toCurrentVersion() {

        if (this == DEFAULT_VERSION) {

            String currentVersion = getVersion();

            for (JPAVersion version : versions()) {
                if (currentVersion.equals(String.valueOf(version.version))) {
                    return version;
                }
            }
        }

        return this;
    }

    @Override
    public String toString() {
        return getVersion();
    }
}