package rac;

/**
 * The installable policy for a RAC (Restricted Access Container).  This class
 * provides the store(), retrieve() and init() methods that the RAC uses.
 * @author S. Wong
 */
public abstract class ARACPolicy {
    /**
     * The RACont will dispatch its store(data) method through this method to
     * perform the data store operation.
     * @param data The data to be stored in the RACont.
     * @param stopNode The RACStopNode that is the head/tail of this internal
     * doubly-linked circular data list of the RACont.
     */
    public abstract void store(Object data, RACStopNode stopNode);

    /**
     * The RACont will dispatch its retrieve() method through this method to
     * perform the data retrieval operation.
     * @param stopNode The RACStopNode that is the head/tail of this internal
     * doubly-linked circular data list of the RACont.
     * @return The data value found.
     */
    public abstract Object retrieve(RACStopNode stopNode);

    /**
     * This method is called when a ARACPolicy is installed in the RACont. The
     * policy cannot assume that the data in the RACont is in any particular
     * order, nor that the data are all valid, acceptible types.    It is the
     * responsibility of the policy's init() method to prepare the data for use
     * by the policy. By default, the init() method does nothing.
     * @param stopNode The RACStopNode that is the head/tail of this internal
     * doubly-linked circular data list of the RACont.
     */
    public void init(RACStopNode stopNode) {
    }
}