petejkim · July 2, 2013 07:27 · Jan 6, 2010
diff --git a/NSObject+ProcObservation.h b/NSObject+ProcObservation.h
@@ -0,0 +1,41 @@
+//
+//  NSObject+ProcObservation.h
+//  Version 1.0
+//
+//  Andy Matuschak
+//  [email protected]
+//  Public domain because I love you. Let me know how you use it.
+//
+//  NTW 2009-Oct-21: Added selectors with an options argument.
+//  NTW 2009-Oct-30: Transplanted new observation key from MYUtilities's KVUtils.
+//  NTW 2010-Jan-06: Changed to accept Ruby proc instead of C block. Got rid of block token typedef so MacRuby isn't confused. See NSObject_ProcObservation.rb for handy Ruby interface.
+
+#import <Cocoa/Cocoa.h>
+
+// Or MYKeyValueObservingOptionOnce with your observation options to cause the 
+// observer to remove itself upon the first change notification.
+// Idea and line of code from MYUtilities.
+enum {
+    MYKeyValueObservingOptionOnce = 1<<31
+};
+
+@interface NSObject (AMRubyBlockObservation)
+
+- (NSString *)addObserverForKeyPath:(NSString *)keyPath proc:(id)proc;
+
+- (NSString*)addObserverForKeyPath:(NSString*)keyPath
+                           options:(NSKeyValueObservingOptions)options
+                              proc:(id)proc;
+
+- (NSString*)addObserverForKeyPath:(NSString*)keyPath
+                           onQueue:(NSOperationQueue*)queue
+                              proc:(id)proc;
+
+- (NSString*)addObserverForKeyPath:(NSString*)keyPath
+                           options:(NSKeyValueObservingOptions)options
+                           onQueue:(NSOperationQueue*)queue
+                              proc:(id)proc;
+
+- (void)removeObserverWithProcToken:(NSString *)token;
+
+@end
diff --git a/NSObject+ProcObservation.m b/NSObject+ProcObservation.m
@@ -0,0 +1,156 @@
+//
+//  NSObject+ProcObservation.m
+//  Version 1.0
+//
+//  Andy Matuschak
+//  [email protected]
+//  Public domain because I love you. Let me know how you use it.
+//
+
+#import "NSObject+ProcObservation.h"
+#import <dispatch/dispatch.h>
+#import <objc/runtime.h>
+#import <macruby/macruby.h>
+
+@interface AMRubyObserverTrampoline : NSObject
+{
+	__weak id observee;
+	NSString *keyPath;
+	id proc;
+	NSOperationQueue *queue;
+  NSKeyValueObservingOptions options;
+}
+
+- (AMRubyObserverTrampoline*)initObservingObject:(id)obj
+                                         keyPath:(NSString*)newKeyPath
+                                         options:(NSKeyValueObservingOptions)newOptions
+                                         onQueue:(NSOperationQueue*)newQueue
+                                            proc:(id)newProc;
+
+- (void)cancelObservation;
+
+@end
+
+
+@implementation AMRubyObserverTrampoline
+
+static NSString *AMRubyObserverTrampolineContext = @"AMRubyObserverTrampolineContext";
+
+- (AMRubyObserverTrampoline*)initObservingObject:(id)obj
+                                     keyPath:(NSString*)newKeyPath
+                                     options:(NSKeyValueObservingOptions)newOptions
+                                     onQueue:(NSOperationQueue*)newQueue
+                                        proc:(id)newProc
+{
+  self = [super init];
+  if (self != nil)
+  {
+  	proc = newProc;
+  	keyPath = [newKeyPath copy];
+  	queue = [newQueue retain];
+  	observee = obj;
+    options = newOptions;
+
+  	// Clear out our customized options before passing them on.
+  	// From MYUtilities.
+    newOptions &= ~MYKeyValueObservingOptionOnce;
+
+  	[observee addObserver:self
+               forKeyPath:keyPath
+                  options:newOptions
+                  context:AMRubyObserverTrampolineContext];
+	}
+	return self;
+}
+
+- (void)observeValueForKeyPath:(NSString*)aKeyPath
+                      ofObject:(id)object
+                        change:(NSDictionary*)change
+                       context:(void*)context
+{
+  if (context != AMRubyObserverTrampolineContext)
+	{
+		[super observeValueForKeyPath:aKeyPath ofObject:object change:change context:context];
+    return;
+  }
+
+	// Not sure if we really need this on the next run loop iteration. Seemed right.
+	if (options & MYKeyValueObservingOptionOnce)
+    [self performSelector:@selector(cancelObservation) withObject:nil afterDelay:0.0];
+
+	if (queue)
+		[queue addOperationWithBlock:^{ [proc performRubySelector:@selector(call:) withArguments:object, change]; }];
+	else
+    [proc performRubySelector:@selector(call:) withArguments:object, change];
+}
+
+- (void)cancelObservation
+{
+	[observee removeObserver:self forKeyPath:keyPath];
+}
+
+- (void)dealloc
+{
+	[self cancelObservation];
+	[proc release];
+	[keyPath release];
+	[queue release];
+	[super dealloc];
+}
+
+@end
+
+
+static NSString *AMRubyObserverMapKey = @"org.andymatuschak.observerMapRuby";
+
+
+@implementation NSObject (AMRubyBlockObservation)
+
+- (NSString *)addObserverForKeyPath:(NSString *)keyPath proc:(id)proc
+{
+	return [self addObserverForKeyPath:keyPath options:0 onQueue:nil proc:proc];
+}
+
+- (NSString*)addObserverForKeyPath:(NSString*)keyPath
+                               options:(NSKeyValueObservingOptions)options
+                                  proc:(id)proc
+{
+  return [self addObserverForKeyPath:keyPath options:options onQueue:nil proc:proc];
+}
+
+- (NSString*)addObserverForKeyPath:(NSString*)keyPath
+                               onQueue:(NSOperationQueue*)queue
+                                  proc:(id)proc
+{
+  return [self addObserverForKeyPath:keyPath options:0 onQueue:queue proc:proc];
+}
+
+- (NSString*)addObserverForKeyPath:(NSString*)keyPath
+                               options:(NSKeyValueObservingOptions)options
+                               onQueue:(NSOperationQueue*)queue
+                                  proc:(id)proc
+{
+	NSString *token = [[NSProcessInfo processInfo] globallyUniqueString];
+	dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+		if (!objc_getAssociatedObject(self, AMRubyObserverMapKey))
+			objc_setAssociatedObject(self, AMRubyObserverMapKey, [NSMutableDictionary dictionary], OBJC_ASSOCIATION_RETAIN);
+		AMRubyObserverTrampoline *trampoline = [[[AMRubyObserverTrampoline alloc] initObservingObject:self keyPath:keyPath options:options onQueue:queue proc:proc] autorelease];
+		[objc_getAssociatedObject(self, AMRubyObserverMapKey) setObject:trampoline forKey:token];
+	});
+	return token;
+}
+
+- (void)removeObserverWithProcToken:(NSString *)token
+{
+	NSMutableDictionary *observationDictionary = objc_getAssociatedObject(self, AMRubyObserverMapKey);
+	AMRubyObserverTrampoline *trampoline = [observationDictionary objectForKey:token];
+	if (!trampoline)
+	{
+		NSLog(@"Tried to remove non-existent observer on %@ for token %@", self, token);
+		return;
+	}
+	[trampoline cancelObservation];
+	[observationDictionary removeObjectForKey:token];
+}
+
+@end
diff --git a/NSObject+ProcObservation.rb b/NSObject+ProcObservation.rb
@@ -0,0 +1,18 @@
+# NSObject+ProcObservation.rb
+# Public Domain
+#
+# Created by Nolan Waite on 10-01-06.
+# Copyright 2010 Nolan Waite. All rights reserved.
+
+
+# Replicated from NSObject+ProcObservation.h
+MYKeyValueObservingOptionsOnce = 1<<31
+
+class NSObject
+  def observe(keyPath, options=0, &block)
+    self.addObserverForKeyPath(keyPath, options:options, proc:block)
+  end
+  def stopObserving(token)
+    self.removeObserverWithProcToken token
+  end
+end
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