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JaVers - object auditing and diff framework for Java

There is a newer version: 7.6.2

package org.javers.core.diff.custom;

import org.javers.core.diff.changetype.PropertyChange;
import org.javers.core.diff.changetype.PropertyChangeMetadata;
import org.javers.core.diff.changetype.ValueChange;
import org.javers.core.metamodel.property.Property;
import org.javers.core.metamodel.type.CustomType;
import org.javers.core.metamodel.type.ValueType;

import java.util.Optional;

/**
 * Property-scope comparator bounded to {@link CustomType}.
 * 


 *
 * 
 * Custom Types are not easy to manage, use it as a last resort,

 * only for corner cases like comparing custom Collection types.
 * 


 *
 * Typically, Custom Types are large structures (like Multimap).

 * Implementation should calculate diff between two objects of given Custom Type.
 * 


 *
 * Usage:
 *  * JaversBuilder.javers()
 *              .registerCustomType( Multimap.class, new GuavaCustomComparator())
 *              .build()
 * 
 *
 * @param  Custom Type
 * @param  Concrete type of PropertyChange returned by a comparator
 * @see https://javers.org/documentation/diff-configuration/#custom-comparators
 * @see CustomValueComparator
 */
public interface CustomPropertyComparator extends CustomValueComparator {
    /**
     * Called by JaVers to calculate property-to-property diff
     * between two Custom Type objects. Can calculate any of concrete {@link PropertyChange}.
     *
     * 


     * Implementation of compare() should be consistent with
     * {@link #equals(Object, Object)}.
     * When compare() returns Optional.empty(),
     * equals() should return false.
     *
     * @param left left (or old) value
     * @param right right (or current) value
     * @param metadata call {@link PropertyChangeMetadata#getAffectedCdoId()} to get
     *                 Id of domain object being compared
     * @param property property being compared
     *
     * @return should return Optional.empty() if compared objects are the same
     */
    Optional compare(T left, T right, PropertyChangeMetadata metadata, Property property);
}