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

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Here is the source code for org.springframework.data.history.Revision.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 static org.springframework.data.util.Optionals.*;

import lombok.AccessLevel;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.Value;

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

import org.springframework.lang.Nullable;

/**
 * Wrapper to contain {@link RevisionMetadata} as well as the revisioned entity.
 *
 * @author Oliver Gierke
 * @author Philipp Huegelmeyer
 * @author Christoph Strobl
 * @author Jens Schauder
 */
@Value
@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
public final class Revision<N extends Number & Comparable<N>, T> implements Comparable<Revision<N, ?>> {

    /**
     * The {@link RevisionMetadata} for the current {@link Revision}.
     */
    @NonNull
    RevisionMetadata<N> metadata;

    /**
     * The underlying entity.
     */
    @NonNull
    T entity;

    /**
     * Creates a new {@link Revision} for the given {@link RevisionMetadata} and entity.
     *
     * @param metadata must not be {@literal null}.
     * @param entity must not be {@literal null}.
     * @return
     */
    public static <N extends Number & Comparable<N>, T> Revision<N, T> of(RevisionMetadata<N> metadata, T entity) {
        return new Revision<>(metadata, entity);
    }

    /**
     * Returns the revision number of the revision.
     *
     * @return the revision number.
     */
    public Optional<N> getRevisionNumber() {
        return metadata.getRevisionNumber();
    }

    /**
     * Returns the revision number of the revision, immediately failing on absence.
     *
     * @return the revision number.
     */
    public N getRequiredRevisionNumber() {
        return metadata.getRequiredRevisionNumber();
    }

    /**
     * Returns the timestamp of the revision.
     *
     * @return Guaranteed to be not {@literal null}.
     */
    public Optional<Instant> getRevisionInstant() {
        return metadata.getRevisionInstant();
    }

    /**
     * Returns the timestamp of the revision, immediately failing on absence.
     *
     * @return the revision {@link Instant}. May be {@literal null}.
     */
    public Instant getRequiredRevisionInstant() {
        return metadata.getRequiredRevisionInstant();
    }

    /*
     * (non-Javadoc)
     * @see java.lang.Comparable#compareTo(java.lang.Object)
     */
    public int compareTo(@Nullable Revision<N, ?> that) {

        if (that == null) {
            return 1;
        }

        return mapIfAllPresent(getRevisionNumber(), that.getRevisionNumber(), //
                Comparable::compareTo).orElse(-1);
    }

    /*
     * (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {

        return String.format("Revision %s of entity %s - Revision metadata %s",
                getRevisionNumber().map(Object::toString).orElse("<unknown>"), entity, metadata);
    }
}