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1   /**
2    * Logback: the reliable, generic, fast and flexible logging framework.
3    * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
4    *
5    * This program and the accompanying materials are dual-licensed under
6    * either the terms of the Eclipse Public License v1.0 as published by
7    * the Eclipse Foundation
8    *
9    *   or (per the licensee's choosing)
10   *
11   * under the terms of the GNU Lesser General Public License version 2.1
12   * as published by the Free Software Foundation.
13   */
14  package ch.qos.logback.core;
15  
16  import ch.qos.logback.core.spi.ContextAware;
17  import ch.qos.logback.core.spi.LifeCycle;
18  
19  public interface Layout<E> extends ContextAware, LifeCycle {
20  
21      /**
22       * Transform an event (of type Object) and return it as a String after 
23       * appropriate formatting.
24       * 
25       * <p>Taking in an object and returning a String is the least sophisticated
26       * way of formatting events. However, it is remarkably CPU-effective.
27       * </p>
28       * 
29       * @param event The event to format
30       * @return the event formatted as a String
31       */
32      String doLayout(E event);
33  
34      /**
35       * Return the file header for this layout. The returned value may be null.
36       * @return The header.
37       */
38      String getFileHeader();
39  
40      /**
41       * Return the header of the logging event formatting. The returned value
42       * may be null.
43       * 
44       * @return The header.
45       */
46      String getPresentationHeader();
47  
48      /**
49       * Return the footer of the logging event formatting. The returned value
50       * may be null.
51       * 
52       * @return The footer.
53       */
54  
55      String getPresentationFooter();
56  
57      /**
58       * Return the file footer for this layout. The returned value may be null.
59       * @return The footer.
60       */
61      String getFileFooter();
62  
63      /**
64       * Returns the content type as appropriate for the implementation.
65       *  
66       * @return
67       */
68      String getContentType();
69  
70  }