    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements. See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache license, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License. You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the license for the specific language governing permissions and
    015     * limitations under the license.
    016     */
    017    package org.apache.logging.log4j;
    018
    019    import java.io.Serializable;
    020
    021    /**
    022     *  Markers are objects that are used to add easily filterable information to log messages.
    023     *
    024     *  Markers can be hierarchical - each Marker may have a parent. This allows for broad categories
    025     *  being subdivided into more specific categories. An example might be a Marker named "Error" with
    026     *  children named "SystemError" and "ApplicationError".
    027     */
    028    public interface Marker extends Serializable {
    029
    030        /**
    031         * Returns the name of this Marker.
    032         * @return The name of the Marker.
    033         */
    034        String getName();
    035
    036        /**
    037         * Returns a list of parents of this Marker.
    038         * @return The parent Markers or {@code null} if this Marker has no parents.
    039         */
    040        Marker[] getParents();
    041
    042        /**
    043         * Indicates whether this Marker has references to any other Markers.
    044         * @return {@code true} if the Marker has parent Markers
    045         */
    046        boolean hasParents();
    047
    048        /**
    049         * Checks whether this Marker is an instance of the specified Marker.
    050         * @param m The Marker to check.
    051         * @return {@code true} if this Marker or one of its ancestors is the specified Marker, {@code false} otherwise.
    052         * @throws IllegalArgumentException if the argument is {@code null}
    053         */
    054        boolean isInstanceOf(Marker m);
    055
    056        /**
    057         * Checks whether this Marker is an instance of the specified Marker.
    058         * @param name The name of the Marker.
    059         * @return {@code true} if this Marker or one of its ancestors matches the specified name, {@code false} otherwise.
    060         * @throws IllegalArgumentException if the argument is {@code null}
    061         */
    062        boolean isInstanceOf(String name);
    063
    064        /**
    065         * Adds a Marker as a parent to this Marker.
    066         * @param markers The parent markers to add.
    067         * @return The current Marker object, thus allowing multiple adds to be concatenated.
    068         * @throws IllegalArgumentException if the argument is {@code null}
    069         */
    070        Marker addParents(Marker... markers);
    071
    072        /**
    073         * Replaces the set of parent Markers with the provided Markers.
    074         * @param markers The new set of parent Markers or {@code null} to clear the parents.
    075         * @return The current Marker object.
    076         */
    077        Marker setParents(Marker... markers);
    078
    079        /**
    080         * Removes the specified Marker as a parent of this Marker.
    081         * @param marker The marker to remove.
    082         * @return {@code true} if the marker was removed.
    083         * @throws IllegalArgumentException if the argument is {@code null}
    084         */
    085        boolean remove(Marker marker);
    086    }