/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2008 Sun Microsystems, Inc.
 */
package org.forgerock.opendj.config;

/**
 * An interface for determining the default behavior of a property. A property
 * exhibits default behavior when it has no values defined. There are four
 * different types of default behavior:
 * <ol>
 * <li>there is no default behavior - e.g. leaving a "description" unset has no
 * side-effects. This default behavior is represented using the
 * {@link UndefinedDefaultBehaviorProvider} implementation
 * <li>the property defaults to one or more real values of the property. This
 * default behavior is represented using the
 * {@link DefinedDefaultBehaviorProvider} implementation
 * <li>the property defaults to some special behavior that cannot be represented
 * using real property values. This default behavior is represented using the
 * {@link AliasDefaultBehaviorProvider} implementation
 * <li>the property inherits its values from property held in another managed
 * object (e.g. the parent managed object). This default behavior is represented
 * using the {@link AbsoluteInheritedDefaultBehaviorProvider} and
 * {@link RelativeInheritedDefaultBehaviorProvider} implementations.
 * </ol>
 * An application can perform actions based on the type of the default behavior
 * by implementing the {@link DefaultBehaviorProviderVisitor} interface.
 *
 * @param <T>
 *            The type of values represented by this provider.
 */
public abstract class DefaultBehaviorProvider<T> {

    /**
     * Creates a new default behavior provider.
     */
    protected DefaultBehaviorProvider() {
        // No implementation required.
    }

    /**
     * Apply a visitor to this default behavior provider.
     *
     * @param <R>
     *            The return type of the visitor's methods.
     * @param <P>
     *            The type of the additional parameters to the visitor's
     *            methods.
     * @param v
     *            The default behavior visitor.
     * @param p
     *            Optional additional visitor parameter.
     * @return Returns a result as specified by the visitor.
     */
    public abstract <R, P> R accept(DefaultBehaviorProviderVisitor<T, R, P> v, P p);

    /**
     * Performs any run-time initialization required by this default behavior
     * provider. This may include resolving managed object paths and property
     * names.
     * <p>
     * The default implementation is to do nothing.
     *
     * @throws Exception
     *             If this default behavior provider could not be initialized.
     */
    protected void initialize() throws Exception {
        // Default implementation is to do nothing.
    }

}