src/servers/registrar/EventMaskWatcher.cpp

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  22 //      File Name:              EventMaskWatcher.cpp
  23 //      Author:                 Ingo Weinhold (bonefish@users.sf.net)
  24 //      Description:    EventMaskWatcher is a Watcher extended by an event mask.
  25 //                                      EventMaskWatcherFilter filters EventMaskWatchers with
  26 //                                      respect to their event mask and a specific event.
  27 //------------------------------------------------------------------------------
  28
  29 #include "EventMaskWatcher.h"
  30
  31 // EventMaskWatcher
  32
  33 /*!     \class EventMaskWatcher
  34         \brief EventMaskWatcher is a Watcher extended by an event mask.
  35
  36         Each set bit in the watcher's event mask specifies an event the watcher
  37         wants to get notified about.
  38
  39         This class is intended to be used together with EventMaskWatcherFilter.
  40         Such a filter object is created with a certain event and its
  41         EventMaskWatcherFilter::Filter() method only selects those
  42         EventMaskWatchers with an event mask that contains the event.
  43 */
  44
  45 /*!     \var uint32 EventMaskWatcher::fEventMask
  46         \brief The watcher's event mask.
  47 */
  48
  49 // constructor
  50 /*!     \brief Creates a new EventMaskWatcher with a given target and event mask.
  51         \param target The watcher's message target.
  52         \param eventMask the watcher's event mask.
  53 */
  54 EventMaskWatcher::EventMaskWatcher(const BMessenger &target, uint32 eventMask)
  55         : Watcher(target),
  56           fEventMask(eventMask)
  57 {
  58 }
  59
  60 // EventMask
  61 /*!     \brief Returns the watcher's event mask.
  62         \return The watcher's event mask.
  63 */
  64 uint32
  65 EventMaskWatcher::EventMask() const
  66 {
  67         return fEventMask;
  68 }
  69
  70
  71 // EventMaskWatcherFilter
  72
  73 /*!     \class EventMaskWatcherFilter
  74         \brief EventMaskWatcherFilter filters EventMaskWatchers with respect to
  75                    their event mask and a specific event.
  76
  77         This class is intended to be used together with EventMaskWatcher.
  78         A filter object is created with a certain event and its Filter() method
  79         only selects those EventMaskWatchers with an event mask that contains
  80         the event.
  81 */
  82
  83 /*!     \var uint32 EventMaskWatcherFilter::fEvent
  84         \brief The filter's event.
  85
  86         Filter only returns \c true for watchers whose event mask contains the
  87         event.
  88 */
  89
  90 // constructor
  91 /*!     \brief Creates a new EventMaskWatcherFilter with a specified event.
  92
  93         Actually \a event may specify more than one event. Usually each set bit
  94         represents an event.
  95
  96         \param event The event.
  97 */
  98 EventMaskWatcherFilter::EventMaskWatcherFilter(uint32 event)
  99         : WatcherFilter(),
 100           fEvent(event)
 101 {
 102 }
 103
 104 // Filter
 105 /*!     \brief Returns whether the watcher-message pair satisfies the predicate
 106                    represented by this object.
 107
 108         Returns \c true, if the supplied watcher is an EventMaskWatcher and its
 109         event mask contains this filter's event, or more precise the bitwise AND
 110         on event mask and event is not 0.
 111
 112         \param watcher The watcher in question.
 113         \param message The message in question.
 114         \return \c true, if the watcher's event mask contains the filter's event.
 115 */
 116 bool
 117 EventMaskWatcherFilter::Filter(Watcher *watcher, BMessage *message)
 118 {
 119         EventMaskWatcher *emWatcher = dynamic_cast<EventMaskWatcher *>(watcher);
 120         return (emWatcher && (emWatcher->EventMask() & fEvent));
 121 }
 122