OpenStructure
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Properties Friends Macros Groups Pages
data_observer.hh
Go to the documentation of this file.
1 //------------------------------------------------------------------------------
2 // This file is part of the OpenStructure project <www.openstructure.org>
3 //
4 // Copyright (C) 2008-2011 by the OpenStructure authors
5 // Copyright (C) 2003-2010 by the IPLT authors
6 //
7 // This library is free software; you can redistribute it and/or modify it under
8 // the terms of the GNU Lesser General Public License as published by the Free
9 // Software Foundation; either version 3.0 of the License, or (at your option)
10 // any later version.
11 // This library is distributed in the hope that it will be useful, but WITHOUT
12 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13 // FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
14 // details.
15 //
16 // You should have received a copy of the GNU Lesser General Public License
17 // along with this library; if not, write to the Free Software Foundation, Inc.,
18 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 //------------------------------------------------------------------------------
20 
21 /*
22  data observer
23 
24  Author: Ansgar Philippsen
25 */
26 
27 #ifndef IMG_DATA_OBSERVER
28 #define IMG_DATA_OBSERVER
29 
30 #include <boost/ref.hpp>
31 
32 #include "data.hh"
33 
34 namespace ost { namespace img {
35 
36 
37 class DLLEXPORT InvalidObserver: public Error {
38 public:
39  InvalidObserver(const String& s = String("unknown")):
40  Error(String("InvalidObserver exception occured: ") + s)
41  {}
42 };
43 
45 /*
46  Based on the pattern of same name (293). The expression Observer or
47  Observed is part of the method names in purpose, in order to avoid
48  conflict with other interfaces (such as in wxWidgets)
49 
50  ObserverUpdate() and ObserverRelease() are the abstract methods and
51  must be implemented by a derived class. It is important to note that
52  the reference to Data given to the ctor should not be saved in the
53  derived class, but rather the GetObservedData method should be used.
54 
55  If the observed data goes out-of-scope, a call to ObserverRelease will
56  be followed by a call to ObserverInvalidate, which will mark the data
57  reference as invalidated. A further call to GetObserved Data will throw
58  an InvalidObserver exception!
59 */
61  public:
63 
66  DataObserver(const Data& d);
67 
68  DataObserver(const DataObserver& o);
69 
70  DataObserver& operator=(const DataObserver& o);
71 
72  virtual ~DataObserver();
73 
75  virtual void ObserverUpdate();
76 
78  virtual void ObserverUpdate(const Extent&);
79 
81  virtual void ObserverUpdate(const Point&);
82 
84  virtual void ObserverRelease() = 0;
85 
87  /*
88  This will automatically invalidate the observer so that
89  a next call to GetData() will throw an InvalidObserver
90  exception
91  */
92  void ObserverInvalidate();
93 
95  virtual const Data& GetObservedData() const;
96 
97  bool IsDataValid() const {return is_valid();}
98 
99  protected:
100 
102 
105  void SetObservedData(const Data& d);
106 
107  bool is_valid() const;
108 
109 private:
110  boost::reference_wrapper<const Data> data_;
111 
112 };
113 
114 }} // namespace img
115 
116 #endif
117