    001/*
    002 * Copyright 2001-2004 The Apache Software Foundation.
    003 *
    004 * Licensed under the Apache License, Version 2.0 (the "License");
    005 * you may not use this file except in compliance with the License.
    006 * You may obtain a copy of the License at
    007 *
    008 *      http://www.apache.org/licenses/LICENSE-2.0
    009 *
    010 * Unless required by applicable law or agreed to in writing, software
    011 * distributed under the License is distributed on an "AS IS" BASIS,
    012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    013 * See the License for the specific language governing permissions and
    014 * limitations under the License.
    015 */
    016
    017package org.apache.log4j;
    018
    019import org.slf4j.MDC;
    020
    021import java.util.Stack;
    022
    023/**
    024 * A log4j's NDC implemented in terms of SLF4J MDC primitives.
    025 *
    026 * @since SLF4J 1.6.0
    027 */
    028
    029public class NDC {
    030
    031    public final static String PREFIX = "NDC";
    032
    033    public static void clear() {
    034        int depth = getDepth();
    035        for (int i = 0; i < depth; i++) {
    036            String key = PREFIX + i;
    037            MDC.remove(key);
    038        }
    039    }
    040
    041    @SuppressWarnings("rawtypes")
    042    public static Stack cloneStack() {
    043        return null;
    044    }
    045
    046    @SuppressWarnings("rawtypes")
    047    public static void inherit(Stack stack) {
    048    }
    049
    050    static public String get() {
    051        return null;
    052    }
    053
    054    public static int getDepth() {
    055        int i = 0;
    056        while (true) {
    057            String val = MDC.get(PREFIX + i);
    058            if (val != null) {
    059                i++;
    060            } else {
    061                break;
    062            }
    063        }
    064        return i;
    065    }
    066
    067    public static String pop() {
    068        int next = getDepth();
    069        if (next == 0) {
    070            return "";
    071        }
    072        int last = next - 1;
    073        String key = PREFIX + last;
    074        String val = MDC.get(key);
    075        MDC.remove(key);
    076        return val;
    077    }
    078
    079    public static String peek() {
    080        int next = getDepth();
    081        if (next == 0) {
    082            return "";
    083        }
    084        int last = next - 1;
    085        String key = PREFIX + last;
    086        String val = MDC.get(key);
    087        return val;
    088    }
    089
    090    public static void push(String message) {
    091        int next = getDepth();
    092        MDC.put(PREFIX + next, message);
    093    }
    094
    095    static public void remove() {
    096        clear();
    097    }
    098
    099    static public void setMaxDepth(int maxDepth) {
    100    }
    101
    102}