org.springframework.data.history.RevisionMetadata.java Source code

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Here is the source code for org.springframework.data.history.RevisionMetadata.java

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/*
 * Copyright 2012-2019 the original author or 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
 *
 *      https://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 org.springframework.data.history;

import java.time.Instant;
import java.util.Optional;

/**
 * Metadata about a revision.
 *
 * @author Philipp Huegelmeyer
 * @author Oliver Gierke
 * @author Jens Schauder
 */
public interface RevisionMetadata<N extends Number & Comparable<N>> {

    /**
     * Returns the revision number of the revision.
     *
     * @return will never be {@literal null}.
     */
    Optional<N> getRevisionNumber();

    /**
     * Returns the revision number of the revision, immediately failing on absence.
     *
     * @return will never be {@literal null}.
     * @throws IllegalStateException if no revision number is available.
     */
    default N getRequiredRevisionNumber() {

        return getRevisionNumber().orElseThrow(() -> new IllegalStateException(
                String.format("No revision number found on %s!", this.<Object>getDelegate())));
    }

    /**
     * Returns the timestamp of the revision.
     *
     * @return will never be {@literal null}.
     */
    Optional<Instant> getRevisionInstant();

    /**
     * Returns the time stamp of the revision, immediately failing on absence.
     *
     * @return will never be {@literal null}.
     * @throws IllegalStateException if no revision date is available.
     */
    default Instant getRequiredRevisionInstant() {

        return getRevisionInstant().orElseThrow(() -> new IllegalStateException(
                String.format("No revision date found on %s!", this.<Object>getDelegate())));
    }

    /**
     * Returns the underlying revision metadata which might provider more detailed implementation specific information.
     *
     * @return
     */
    <T> T getDelegate();

    /**
     * Returns the {@link RevisionType} of this change. If the {@link RevisionType} cannot be determined, this method
     * returns {@link RevisionType#UNKNOWN}.
     *
     * @return will never be {@literal null}.
     * @since 2.2.0
     */
    default RevisionType getRevisionType() {
        return RevisionType.UNKNOWN;
    }

    /**
     * The type of a {@link Revision}.
     *
     * @author Jens Schauder
     * @since 2.2.0
     */
    enum RevisionType {

        /** Fallback if the type of a revision cannot be determined. */
        UNKNOWN,

        /** Creation of an instance */
        INSERT,

        /** Change of an instance */
        UPDATE,

        /** Deletion of an instance */
        DELETE
    }
}