/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
 * or http://forgerock.org/license/CDDLv1.0.html.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at legal-notices/CDDLv1_0.txt.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information:
 *      Portions Copyright [yyyy] [name of copyright owner]
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 * CDDL HEADER END
 *
 *
 *      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.
    }

}