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//
// GTMLightweightProxy.m
//
// Copyright 2006-2008 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.
//
#import "GTMLightweightProxy.h"
#import "GTMDefines.h"
@implementation GTMLightweightProxy
- (id)initWithRepresentedObject:(id)object {
// it's weak, we don't retain
representedObject_ = object;
return self;
}
- (id)init {
return [self initWithRepresentedObject:nil];
}
- (void)dealloc {
// it's weak, we don't release
representedObject_ = nil;
[super dealloc];
}
- (id)representedObject {
// Use a local variable to avoid a bogus compiler warning.
id repObject = nil;
@synchronized(self) {
// Even though we don't retain this object, we hang it on the lifetime
// of the calling threads pool so it's lifetime is safe for at least that
// long.
repObject = [representedObject_ retain];
}
return [repObject autorelease];
}
- (void)setRepresentedObject:(id)object {
@synchronized(self) {
representedObject_ = object;
}
}
// Passes any unhandled method to the represented object if it responds to that
// method.
- (void)forwardInvocation:(NSInvocation*)invocation {
id target = [self representedObject];
// Silently discard all messages when there's no represented object
if (!target)
return;
SEL aSelector = [invocation selector];
if ([target respondsToSelector:aSelector])
[invocation invokeWithTarget:target];
}
// Gets the represented object's method signature for |selector|; necessary for
// forwardInvocation.
- (NSMethodSignature*)methodSignatureForSelector:(SEL)selector {
id target = [self representedObject];
if (target) {
return [target methodSignatureForSelector:selector];
} else {
// Apple's underlying forwarding code crashes if we return nil here.
// Since we are not going to use the invocation being constructed
// if there's no representedObject, a random valid NSMethodSignature is fine.
return [NSObject methodSignatureForSelector:@selector(alloc)];
}
}
// Prevents exceptions from unknown selectors if there is no represented
// object, and makes the exception come from the right place if there is one.
- (void)doesNotRecognizeSelector:(SEL)selector {
id target = [self representedObject];
if (target)
[target doesNotRecognizeSelector:selector];
}
// Checks the represented object's selectors to allow clients of the proxy to
// do respondsToSelector: tests.
- (BOOL)respondsToSelector:(SEL)selector {
if ([super respondsToSelector:selector] ||
selector == @selector(initWithRepresentedObject:) ||
selector == @selector(representedObject) ||
selector == @selector(setRepresentedObject:))
{
return YES;
}
id target = [self representedObject];
return target && [target respondsToSelector:selector];
}
@end
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