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    1   /*
    2    * Copyright 2001-2004 The Apache Software Foundation.
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    *      http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16
    17  package org.apache.log4j;
    18
    19  import org.slf4j.MDC;
    20
    21  import java.util.Stack;
    22
    23  /**
    24   * A log4j's NDC implemented in terms of SLF4J MDC primitives.
    25   *
    26   * @since SLF4J 1.6.0
    27   */
    28
    29  public class NDC {
    30
    31      public final static String PREFIX = "NDC";
    32
    33      public static void clear() {
    34          int depth = getDepth();
    35          for (int i = 0; i < depth; i++) {
    36              String key = PREFIX + i;
    37              MDC.remove(key);
    38          }
    39      }
    40
    41      @SuppressWarnings("rawtypes")
    42      public static Stack cloneStack() {
    43          return null;
    44      }
    45
    46      @SuppressWarnings("rawtypes")
    47      public static void inherit(Stack stack) {
    48      }
    49
    50      static public String get() {
    51          return null;
    52      }
    53
    54      public static int getDepth() {
    55          int i = 0;
    56          while (true) {
    57              String val = MDC.get(PREFIX + i);
    58              if (val != null) {
    59                  i++;
    60              } else {
    61                  break;
    62              }
    63          }
    64          return i;
    65      }
    66
    67      public static String pop() {
    68          int next = getDepth();
    69          if (next == 0) {
    70              return "";
    71          }
    72          int last = next - 1;
    73          String key = PREFIX + last;
    74          String val = MDC.get(key);
    75          MDC.remove(key);
    76          return val;
    77      }
    78
    79      public static String peek() {
    80          int next = getDepth();
    81          if (next == 0) {
    82              return "";
    83          }
    84          int last = next - 1;
    85          String key = PREFIX + last;
    86          String val = MDC.get(key);
    87          return val;
    88      }
    89
    90      public static void push(String message) {
    91          int next = getDepth();
    92          MDC.put(PREFIX + next, message);
    93      }
    94
    95      static public void remove() {
    96          clear();
    97      }
    98
    99      static public void setMaxDepth(int maxDepth) {
    100     }
    101
    102 }