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1   /**
2    * Copyright (c) 2004-2011 QOS.ch
3    * All rights reserved.
4    *
5    * Permission is hereby granted, free  of charge, to any person obtaining
6    * a  copy  of this  software  and  associated  documentation files  (the
7    * "Software"), to  deal in  the Software without  restriction, including
8    * without limitation  the rights to  use, copy, modify,  merge, publish,
9    * distribute,  sublicense, and/or sell  copies of  the Software,  and to
10   * permit persons to whom the Software  is furnished to do so, subject to
11   * the following conditions:
12   *
13   * The  above  copyright  notice  and  this permission  notice  shall  be
14   * included in all copies or substantial portions of the Software.
15   *
16   * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
17   * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
18   * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
19   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21   * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
22   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23   *
24   */
25  package org.slf4j;
26  
27  import org.slf4j.MDC;
28  
29  public class NDC {
30      public final static String PREFIX = "NDC";
31  
32      private static int size() {
33          int i = 0;
34          while (true) {
35              String val = MDC.get(PREFIX + i);
36              if (val != null) {
37                  i++;
38              } else {
39                  break;
40              }
41          }
42          return i;
43      }
44  
45      public static void push(String val) {
46          int next = size();
47          MDC.put(PREFIX + next, val);
48      }
49  
50      public static String pop() {
51          int next = size();
52          if (next == 0) {
53              return "";
54          }
55          int last = next - 1;
56          String key = PREFIX + last;
57          String val = MDC.get(key);
58          MDC.remove(key);
59          return val;
60      }
61  
62  }