icuSources/common/servnotf.h

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 /**
   4  *******************************************************************************
   5  * Copyright (C) 2001-2014, International Business Machines Corporation and    *
   6  * others. All Rights Reserved.                                                *
   7  *******************************************************************************
   8  */
   9 #ifndef ICUNOTIF_H
  10 #define ICUNOTIF_H
  11
  12 #include "unicode/utypes.h"
  13
  14 #if UCONFIG_NO_SERVICE
  15
  16 U_NAMESPACE_BEGIN
  17
  18 /*
  19  * Allow the declaration of APIs with pointers to BreakIterator
  20  * even when break iteration is removed from the build.
  21  */
  22 class ICUNotifier;
  23
  24 U_NAMESPACE_END
  25
  26 #else
  27
  28 #include "unicode/uobject.h"
  29 #include "unicode/unistr.h"
  30
  31 #include "mutex.h"
  32 #include "uvector.h"
  33
  34 U_NAMESPACE_BEGIN
  35
  36 class U_COMMON_API EventListener : public UObject {
  37 public:
  38     virtual ~EventListener();
  39
  40 public:
  41     static UClassID U_EXPORT2 getStaticClassID();
  42
  43     virtual UClassID getDynamicClassID() const;
  44
  45 public:
  46 #ifdef SERVICE_DEBUG
  47     virtual UnicodeString& debug(UnicodeString& result) const {
  48       return debugClass(result);
  49     }
  50
  51     virtual UnicodeString& debugClass(UnicodeString& result) const {
  52       return result.append((UnicodeString)"Key");
  53     }
  54 #endif
  55 };
  56
  57 /**
  58  * <p>Abstract implementation of a notification facility.  Clients add
  59  * EventListeners with addListener and remove them with removeListener.
  60  * Notifiers call notifyChanged when they wish to notify listeners.
  61  * This queues the listener list on the notification thread, which
  62  * eventually dequeues the list and calls notifyListener on each
  63  * listener in the list.</p>
  64  *
  65  * <p>Subclasses override acceptsListener and notifyListener
  66  * to add type-safe notification.  AcceptsListener should return
  67  * true if the listener is of the appropriate type; ICUNotifier
  68  * itself will ensure the listener is non-null and that the
  69  * identical listener is not already registered with the Notifier.
  70  * NotifyListener should cast the listener to the appropriate
  71  * type and call the appropriate method on the listener.
  72  */
  73
  74 class U_COMMON_API ICUNotifier : public UMemory  {
  75 private: UVector* listeners;
  76
  77 public:
  78     ICUNotifier(void);
  79
  80     virtual ~ICUNotifier(void);
  81
  82     /**
  83      * Add a listener to be notified when notifyChanged is called.
  84      * The listener must not be null. AcceptsListener must return
  85      * true for the listener.  Attempts to concurrently
  86      * register the identical listener more than once will be
  87      * silently ignored.
  88      */
  89     virtual void addListener(const EventListener* l, UErrorCode& status);
  90
  91     /**
  92      * Stop notifying this listener.  The listener must
  93      * not be null.  Attemps to remove a listener that is
  94      * not registered will be silently ignored.
  95      */
  96     virtual void removeListener(const EventListener* l, UErrorCode& status);
  97
  98     /**
  99      * ICU doesn't spawn its own threads.  All listeners are notified in
 100      * the thread of the caller.  Misbehaved listeners can therefore
 101      * indefinitely block the calling thread.  Callers should beware of
 102      * deadlock situations.
 103      */
 104     virtual void notifyChanged(void);
 105
 106 protected:
 107     /**
 108      * Subclasses implement this to return TRUE if the listener is
 109      * of the appropriate type.
 110      */
 111     virtual UBool acceptsListener(const EventListener& l) const = 0;
 112
 113     /**
 114      * Subclasses implement this to notify the listener.
 115      */
 116     virtual void notifyListener(EventListener& l) const = 0;
 117 };
 118
 119 U_NAMESPACE_END
 120
 121 /* UCONFIG_NO_SERVICE */
 122 #endif
 123
 124 /* ICUNOTIF_H */
 125 #endif