/**

 *******************************************************************************

 * Copyright (C) 2001-2004, International Business Machines Corporation and    *

 * others. All Rights Reserved.                                                *

 *******************************************************************************

 */

#ifndef ICUNOTIF_H

#define ICUNOTIF_H

#include "unicode/utypes.h"

#if UCONFIG_NO_SERVICE

U_NAMESPACE_BEGIN

/*

 * Allow the declaration of APIs with pointers to BreakIterator

 * even when break iteration is removed from the build.

 */

class ICUNotifier;

U_NAMESPACE_END

#else

#include "unicode/uobject.h"

#include "unicode/unistr.h"

#include "mutex.h"

#include "uvector.h"

U_NAMESPACE_BEGIN

class U_COMMON_API EventListener : public UObject {

public: 

    virtual ~EventListener();

public:

    static UClassID U_EXPORT2 getStaticClassID();

    virtual UClassID getDynamicClassID() const;

public:

#ifdef SERVICE_DEBUG

    virtual UnicodeString& debug(UnicodeString& result) const {

      return debugClass(result);

    }

    virtual UnicodeString& debugClass(UnicodeString& result) const {

      return result.append("Key");

    }

#endif

};

/**

 * <p>Abstract implementation of a notification facility.  Clients add

 * EventListeners with addListener and remove them with removeListener.

 * Notifiers call notifyChanged when they wish to notify listeners.

 * This queues the listener list on the notification thread, which

 * eventually dequeues the list and calls notifyListener on each

 * listener in the list.</p>

 *

 * <p>Subclasses override acceptsListener and notifyListener 

 * to add type-safe notification.  AcceptsListener should return

 * true if the listener is of the appropriate type; ICUNotifier

 * itself will ensure the listener is non-null and that the

 * identical listener is not already registered with the Notifier.

 * NotifyListener should cast the listener to the appropriate 

 * type and call the appropriate method on the listener.

 */

class U_COMMON_API ICUNotifier : public UMemory  {

private: UMTX notifyLock;

private: UVector* listeners;

public: 

    ICUNotifier(void);

    virtual ~ICUNotifier(void);

    /**

     * Add a listener to be notified when notifyChanged is called.

     * The listener must not be null. AcceptsListener must return

     * true for the listener.  Attempts to concurrently

     * register the identical listener more than once will be

     * silently ignored.  

     */

    virtual void addListener(const EventListener* l, UErrorCode& status);

    /**

     * Stop notifying this listener.  The listener must

     * not be null.  Attemps to remove a listener that is

     * not registered will be silently ignored.

     */

    virtual void removeListener(const EventListener* l, UErrorCode& status);

    /**

     * ICU doesn't spawn its own threads.  All listeners are notified in

     * the thread of the caller.  Misbehaved listeners can therefore

     * indefinitely block the calling thread.  Callers should beware of

     * deadlock situations.  

     */

    virtual void notifyChanged(void);

protected: 

    /**

     * Subclasses implement this to return TRUE if the listener is

     * of the appropriate type.

     */

    virtual UBool acceptsListener(const EventListener& l) const = 0;

    /**

     * Subclasses implement this to notify the listener.

     */

    virtual void notifyListener(EventListener& l) const = 0;

};

U_NAMESPACE_END

/* UCONFIG_NO_SERVICE */

#endif

/* ICUNOTIF_H */

#endif