1 // Copyright 2014 The Chromium Authors 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_IOS_CRB_PROTOCOL_OBSERVERS_H_ 6 #define BASE_IOS_CRB_PROTOCOL_OBSERVERS_H_ 7 8 #import <Foundation/Foundation.h> 9 10 typedef void (^ExecutionWithObserverBlock)(id); 11 12 // Implements a container for observers that implement a specific Objective-C 13 // protocol. The container forwards method invocations to its contained 14 // observers, so that sending a message to all the observers is as simple as 15 // sending the message to the container. 16 // It is safe for an observer to remove itself or another observer while being 17 // notified. It is also safe to add an other observer while being notified but 18 // the newly added observer will not be notified as part of the current 19 // notification dispatch. 20 @interface CRBProtocolObservers : NSObject 21 22 // The Objective-C protocol that the observers in this container conform to. 23 @property(nonatomic, readonly) Protocol* protocol; 24 25 // Returns a CRBProtocolObservers container for observers that conform to 26 // |protocol|. 27 + (instancetype)observersWithProtocol:(Protocol*)protocol; 28 29 // Adds |observer| to this container. 30 - (void)addObserver:(id)observer; 31 32 // Remove |observer| from this container. 33 - (void)removeObserver:(id)observer; 34 35 // Returns true if there are currently no observers. 36 - (BOOL)empty; 37 38 // Executes callback on every observer. |callback| cannot be nil. 39 - (void)executeOnObservers:(ExecutionWithObserverBlock)callback; 40 41 @end 42 43 #endif // BASE_IOS_CRB_PROTOCOL_OBSERVERS_H_ 44