//
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// Aspects.h
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// Aspects - A delightful, simple library for aspect oriented programming.
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//
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// Copyright (c) 2014 Peter Steinberger. Licensed under the MIT license.
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//
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#import <Foundation/Foundation.h>
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typedef NS_OPTIONS(NSUInteger, AspectOptions) {
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AspectPositionAfter = 0, /// Called after the original implementation (default)
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AspectPositionInstead = 1, /// Will replace the original implementation.
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AspectPositionBefore = 2, /// Called before the original implementation.
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AspectOptionAutomaticRemoval = 1 << 3 /// Will remove the hook after the first execution.
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};
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/// Opaque Aspect Token that allows to deregister the hook.
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@protocol AspectToken <NSObject>
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/// Deregisters an aspect.
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/// @return YES if deregistration is successful, otherwise NO.
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- (BOOL)remove;
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@end
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/// The AspectInfo protocol is the first parameter of our block syntax.
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@protocol AspectInfo <NSObject>
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/// The instance that is currently hooked.
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- (id)instance;
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/// The original invocation of the hooked method.
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- (NSInvocation *)originalInvocation;
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/// All method arguments, boxed. This is lazily evaluated.
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- (NSArray *)arguments;
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@end
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/**
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Aspects uses Objective-C message forwarding to hook into messages. This will create some overhead. Don't add aspects to methods that are called a lot. Aspects is meant for view/controller code that is not called a 1000 times per second.
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Adding aspects returns an opaque token which can be used to deregister again. All calls are thread safe.
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*/
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@interface NSObject (Aspects)
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/// Adds a block of code before/instead/after the current `selector` for a specific class.
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///
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/// @param block Aspects replicates the type signature of the method being hooked.
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/// The first parameter will be `id<AspectInfo>`, followed by all parameters of the method.
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/// These parameters are optional and will be filled to match the block signature.
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/// You can even use an empty block, or one that simple gets `id<AspectInfo>`.
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///
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/// @note Hooking static methods is not supported.
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/// @return A token which allows to later deregister the aspect.
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+ (id<AspectToken>)aspect_hookSelector:(SEL)selector
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withOptions:(AspectOptions)options
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usingBlock:(id)block
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error:(NSError **)error;
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/// Adds a block of code before/instead/after the current `selector` for a specific instance.
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- (id<AspectToken>)aspect_hookSelector:(SEL)selector
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withOptions:(AspectOptions)options
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usingBlock:(id)block
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error:(NSError **)error;
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@end
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typedef NS_ENUM(NSUInteger, AspectErrorCode) {
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AspectErrorSelectorBlacklisted, /// Selectors like release, retain, autorelease are blacklisted.
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AspectErrorDoesNotRespondToSelector, /// Selector could not be found.
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AspectErrorSelectorDeallocPosition, /// When hooking dealloc, only AspectPositionBefore is allowed.
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AspectErrorSelectorAlreadyHookedInClassHierarchy, /// Statically hooking the same method in subclasses is not allowed.
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AspectErrorFailedToAllocateClassPair, /// The runtime failed creating a class pair.
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AspectErrorMissingBlockSignature, /// The block misses compile time signature info and can't be called.
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AspectErrorIncompatibleBlockSignature, /// The block signature does not match the method or is too large.
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AspectErrorRemoveObjectAlreadyDeallocated = 100 /// (for removing) The object hooked is already deallocated.
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};
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extern NSString *const AspectErrorDomain;
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