src/base/listener.h

   1 /*********************                                                        */
   2 /*! \file listener.h
   3  ** \verbatim
   4  ** Original author: Tim King
   5  ** Major contributors: none
   6  ** Minor contributors (to current version): none
   7  ** This file is part of the CVC4 project.
   8  ** Copyright (c) 2009-2016  New York University and The University of Iowa
   9  ** See the file COPYING in the top-level source directory for licensing
  10  ** information.\endverbatim
  11  **
  12  ** \brief Utility classes for listeners and collections of listeners.
  13  **
  14  ** Utilities for the development of a Listener interface class. This class
  15  ** provides a single notification that must be overwritten. This file also
  16  ** provides a utility class for a collection of listeners and an RAII style
  17  ** RegisterListener class for managing the relationship between Listeners
  18  ** and the manager.
  19  **/
  20
  21 #include "cvc4_public.h"
  22
  23 #ifndef __CVC4__LISTENER_H
  24 #define __CVC4__LISTENER_H
  25
  26 #include <list>
  27
  28 namespace CVC4 {
  29
  30 /**
  31  * Listener interface class.
  32  *
  33  * The interface provides a notify() function.
  34  */
  35 class CVC4_PUBLIC Listener {
  36 public:
  37   Listener();
  38   virtual ~Listener();
  39
  40   /** Note that notify may throw arbitrary exceptions. */
  41   virtual void notify() = 0;
  42 };
  43
  44 /**
  45  * ListenerCollection is a list of Listener instances.
  46  * One can add and remove Listeners.
  47  *
  48  * ListenerCollection does not own the memory of the Listeners.
  49  * As a sanity check, it asserted that all of its listeners
  50  * have been removed.
  51  */
  52 class CVC4_PUBLIC ListenerCollection {
  53 public:
  54   typedef std::list<Listener*> ListenerList;
  55   typedef ListenerList::iterator iterator;
  56
  57   ListenerCollection();
  58
  59   ~ListenerCollection();
  60
  61   iterator addListener(Listener* listener);
  62
  63   void removeListener(iterator position);
  64
  65   void notify();
  66
  67   bool empty() const;
  68
  69 private:
  70   ListenerList d_listeners;
  71 };
  72
  73 /**
  74  * RegisterListener is an RAII utility function for using Listener
  75  * with ListenerCollection.
  76  *
  77  * On construction, the RegisterListener takes a ListenerCollection, collection,
  78  * and a Listener*, listener. It takes over the memory for listener. It then
  79  * add listener to collection. On destruction it removes listener and calls
  80  * delete on listener.
  81  *
  82  * Because of this usage, a RegisterListener must be destroyed before
  83  * collection.
  84  */
  85 class CVC4_PUBLIC RegisterListener {
  86 public:
  87   RegisterListener(ListenerCollection* collection, Listener* listener);
  88   ~RegisterListener();
  89
  90 private:
  91   Listener* d_listener;
  92   ListenerCollection::iterator d_position;
  93   ListenerCollection* d_collection;
  94 };
  95
  96
  97 }/* CVC4 namespace */
  98
  99 #endif /* __CVC4__LISTENER_H */