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package org.apache.cayenne;

import java.io.Serializable;

/**
 * Represents a placeholder for an unresolved relationship from a source object. Fault is
 * resolved via {@link #resolveFault(Persistent, String)}. Depending on the type of fault
 * it is resolved differently. Each type of fault is a singleton that can be obtained via
 * corresponding static method.
 * 
 * @since 1.1
 * @author Andrei Adamchik
 */
// TODO: serialization of faults should take into account the fact that
// they are used as singletons to avoid duplicate creation on deserialization
public abstract class Fault implements Serializable {

    protected static Fault toOneFault;
    protected static Fault toManyFault;

    public static Fault getToOneFault() {
        return toOneFault;
    }

    public static Fault getToManyFault() {
        return toManyFault;
    }

    protected Fault() {
    }

    /**
     * Returns an object for a given source object and relationship.
     */
    public abstract Object resolveFault(Persistent sourceObject, String relationshipName);
}
