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//
// GTMNSObject+KeyValueObserving.h
//
// Copyright 2009 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//
//
// MAKVONotificationCenter.m
// MAKVONotificationCenter
//
// Created by Michael Ash on 10/15/08.
//
// This code is based on code by Michael Ash.
// See comment in header.
#import "GTMNSObject+KeyValueObserving.h"
#import <libkern/OSAtomic.h>
#import "GTMDefines.h"
#import "GTMDebugSelectorValidation.h"
#import "GTMObjC2Runtime.h"
// A singleton that works as a dispatch center for KVO
// -[NSObject observeValueForKeyPath:ofObject:change:context:] and turns them
// into selector dispatches. It stores a collection of
// GTMKeyValueObservingHelpers, and keys them via the key generated by
// -dictionaryKeyForObserver:ofObject:forKeyPath:selector.
@interface GTMKeyValueObservingCenter : NSObject {
@private
NSMutableDictionary *observerHelpers_;
}
+ (id)defaultCenter;
- (void)addObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options;
- (void)removeObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector;
- (id)dictionaryKeyForObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector;
@end
@interface GTMKeyValueObservingHelper : NSObject {
@private
__weak id observer_;
SEL selector_;
id userInfo_;
id target_;
NSString* keyPath_;
}
- (id)initWithObserver:(id)observer
object:(id)target
keyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options;
- (void)deregister;
@end
@interface GTMKeyValueChangeNotification ()
- (id)initWithKeyPath:(NSString *)keyPath ofObject:(id)object
userInfo:(id)userInfo change:(NSDictionary *)change;
@end
@implementation GTMKeyValueObservingHelper
// For info how and why we use these statics:
// http://lists.apple.com/archives/cocoa-dev/2006/Jul/msg01038.html
static char GTMKeyValueObservingHelperContextData;
static char* GTMKeyValueObservingHelperContext
= >MKeyValueObservingHelperContextData;
- (id)initWithObserver:(id)observer
object:(id)target
keyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options {
if((self = [super init])) {
observer_ = observer;
selector_ = selector;
userInfo_ = [userInfo retain];
target_ = target;
keyPath_ = [keyPath retain];
[target addObserver:self
forKeyPath:keyPath
options:options
context:GTMKeyValueObservingHelperContext];
}
return self;
}
- (void)dealloc {
[userInfo_ release];
[keyPath_ release];
[super dealloc];
}
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context {
if(context == GTMKeyValueObservingHelperContext) {
GTMKeyValueChangeNotification *notification
= [[GTMKeyValueChangeNotification alloc] initWithKeyPath:keyPath
ofObject:object
userInfo:userInfo_
change:change];
[observer_ performSelector:selector_ withObject:notification];
[notification release];
} else {
// COV_NF_START
// There's no way this should ever be called.
// If it is, the call will go up to NSObject which will assert.
[super observeValueForKeyPath:keyPath
ofObject:object
change:change
context:context];
// COV_NF_END
}
}
- (void)deregister {
[target_ removeObserver:self forKeyPath:keyPath_];
}
@end
@implementation GTMKeyValueObservingCenter
+ (id)defaultCenter {
static GTMKeyValueObservingCenter *center = nil;
if(!center) {
// do a bit of clever atomic setting to make this thread safe
// if two threads try to set simultaneously, one will fail
// and the other will set things up so that the failing thread
// gets the shared center
GTMKeyValueObservingCenter *newCenter = [[self alloc] init];
if(!objc_atomicCompareAndSwapGlobalBarrier(nil,
newCenter,
(void *)¢er)) {
[newCenter release]; // COV_NF_LINE no guarantee we'll hit this line
}
}
return center;
}
- (id)init {
if((self = [super init])) {
observerHelpers_ = [[NSMutableDictionary alloc] init];
}
return self;
}
// COV_NF_START
// Singletons don't get deallocated
- (void)dealloc {
[observerHelpers_ release];
[super dealloc];
}
// COV_NF_END
- (id)dictionaryKeyForObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector {
NSString *key = [NSString stringWithFormat:@"%p:%p:%@:%p",
observer, target, keyPath, selector];
return key;
}
- (void)addObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options {
GTMKeyValueObservingHelper *helper
= [[GTMKeyValueObservingHelper alloc] initWithObserver:observer
object:target
keyPath:keyPath
selector:selector
userInfo:userInfo
options:options];
id key = [self dictionaryKeyForObserver:observer
ofObject:target
forKeyPath:keyPath
selector:selector];
@synchronized(self) {
#if DEBUG
GTMKeyValueObservingHelper *oldHelper = [observerHelpers_ objectForKey:key];
if (oldHelper) {
_GTMDevLog(@"%@ already observing %@ forKeyPath %@",
observer, target, keyPath);
}
#endif // DEBUG
[observerHelpers_ setObject:helper forKey:key];
}
[helper release];
}
- (void)removeObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector {
id key = [self dictionaryKeyForObserver:observer
ofObject:target
forKeyPath:keyPath
selector:selector];
GTMKeyValueObservingHelper *helper = nil;
@synchronized(self) {
helper = [[observerHelpers_ objectForKey:key] retain];
#if DEBUG
if (!helper) {
_GTMDevLog(@"%@ was not observing %@ with keypath %@",
observer, target, keyPath);
}
#endif // DEBUG
[observerHelpers_ removeObjectForKey:key];
}
[helper deregister];
[helper release];
}
@end
@implementation NSObject (GTMKeyValueObservingAdditions)
- (void)gtm_addObserver:(id)observer
forKeyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options {
_GTMDevAssert(observer && [keyPath length] && selector,
@"Missing observer, keyPath, or selector");
GTMKeyValueObservingCenter *center
= [GTMKeyValueObservingCenter defaultCenter];
GTMAssertSelectorNilOrImplementedWithArguments(observer,
selector,
@encode(GTMKeyValueChangeNotification *),
NULL);
[center addObserver:observer
ofObject:self
forKeyPath:keyPath
selector:selector
userInfo:userInfo
options:options];
}
- (void)gtm_removeObserver:(id)observer
forKeyPath:(NSString *)keyPath
selector:(SEL)selector {
_GTMDevAssert(observer && [keyPath length] && selector,
@"Missing observer, keyPath, or selector");
GTMKeyValueObservingCenter *center
= [GTMKeyValueObservingCenter defaultCenter];
GTMAssertSelectorNilOrImplementedWithArguments(observer,
selector,
@encode(GTMKeyValueChangeNotification *),
NULL);
[center removeObserver:observer
ofObject:self
forKeyPath:keyPath
selector:selector];
}
@end
@implementation GTMKeyValueChangeNotification
- (id)initWithKeyPath:(NSString *)keyPath ofObject:(id)object
userInfo:(id)userInfo change:(NSDictionary *)change {
if ((self = [super init])) {
keyPath_ = [keyPath copy];
object_ = [object retain];
userInfo_ = [userInfo retain];
change_ = [change retain];
}
return self;
}
- (void)dealloc {
[keyPath_ release];
[object_ release];
[userInfo_ release];
[change_ release];
[super dealloc];
}
- (id)copyWithZone:(NSZone *)zone {
return [[[self class] allocWithZone:zone] initWithKeyPath:keyPath_
ofObject:object_
userInfo:userInfo_
change:change_];
}
- (BOOL)isEqual:(id)object {
return ([keyPath_ isEqualToString:[object keyPath]]
&& [object_ isEqual:[object object]]
&& [userInfo_ isEqual:[object userInfo]]
&& [change_ isEqual:[object change]]);
}
- (NSUInteger)hash {
return [keyPath_ hash] + [object_ hash] + [userInfo_ hash] + [change_ hash];
}
- (NSString *)keyPath {
return keyPath_;
}
- (id)object {
return object_;
}
- (id)userInfo {
return userInfo_;
}
- (NSDictionary *)change {
return change_;
}
@end
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