//
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// Aspects.m
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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 "Aspects.h"
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#import <libkern/OSAtomic.h>
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#import <objc/runtime.h>
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#import <objc/message.h>
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#define AspectLog(...)
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//#define AspectLog(...) do { NSLog(__VA_ARGS__); }while(0)
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#define AspectLogError(...) do { NSLog(__VA_ARGS__); }while(0)
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// Block internals.
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typedef NS_OPTIONS(int, AspectBlockFlags) {
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AspectBlockFlagsHasCopyDisposeHelpers = (1 << 25),
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AspectBlockFlagsHasSignature = (1 << 30)
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};
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typedef struct _AspectBlock {
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__unused Class isa;
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AspectBlockFlags flags;
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__unused int reserved;
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void (__unused *invoke)(struct _AspectBlock *block, ...);
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struct {
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unsigned long int reserved;
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unsigned long int size;
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// requires AspectBlockFlagsHasCopyDisposeHelpers
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void (*copy)(void *dst, const void *src);
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void (*dispose)(const void *);
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// requires AspectBlockFlagsHasSignature
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const char *signature;
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const char *layout;
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} *descriptor;
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// imported variables
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} *AspectBlockRef;
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@interface AspectInfo : NSObject <AspectInfo>
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- (id)initWithInstance:(__unsafe_unretained id)instance invocation:(NSInvocation *)invocation;
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@property (nonatomic, unsafe_unretained, readonly) id instance;
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@property (nonatomic, strong, readonly) NSArray *arguments;
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@property (nonatomic, strong, readonly) NSInvocation *originalInvocation;
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@end
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// Tracks a single aspect.
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@interface AspectIdentifier : NSObject
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+ (instancetype)identifierWithSelector:(SEL)selector object:(id)object options:(AspectOptions)options block:(id)block error:(NSError **)error;
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- (BOOL)invokeWithInfo:(id<AspectInfo>)info;
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@property (nonatomic, assign) SEL selector;
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@property (nonatomic, strong) id block;
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@property (nonatomic, strong) NSMethodSignature *blockSignature;
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@property (nonatomic, weak) id object;
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@property (nonatomic, assign) AspectOptions options;
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@end
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// Tracks all aspects for an object/class.
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@interface AspectsContainer : NSObject
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- (void)addAspect:(AspectIdentifier *)aspect withOptions:(AspectOptions)injectPosition;
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- (BOOL)removeAspect:(id)aspect;
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- (BOOL)hasAspects;
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@property (atomic, copy) NSArray *beforeAspects;
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@property (atomic, copy) NSArray *insteadAspects;
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@property (atomic, copy) NSArray *afterAspects;
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@end
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@interface AspectTracker : NSObject
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- (id)initWithTrackedClass:(Class)trackedClass;
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@property (nonatomic, strong) Class trackedClass;
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@property (nonatomic, readonly) NSString *trackedClassName;
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@property (nonatomic, strong) NSMutableSet *selectorNames;
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@property (nonatomic, strong) NSMutableDictionary *selectorNamesToSubclassTrackers;
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- (void)addSubclassTracker:(AspectTracker *)subclassTracker hookingSelectorName:(NSString *)selectorName;
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- (void)removeSubclassTracker:(AspectTracker *)subclassTracker hookingSelectorName:(NSString *)selectorName;
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- (BOOL)subclassHasHookedSelectorName:(NSString *)selectorName;
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- (NSSet *)subclassTrackersHookingSelectorName:(NSString *)selectorName;
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@end
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@interface NSInvocation (Aspects)
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- (NSArray *)aspects_arguments;
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@end
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#define AspectPositionFilter 0x07
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#define AspectError(errorCode, errorDescription) do { \
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AspectLogError(@"Aspects: %@", errorDescription); \
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if (error) { *error = [NSError errorWithDomain:AspectErrorDomain code:errorCode userInfo:@{NSLocalizedDescriptionKey: errorDescription}]; }}while(0)
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NSString *const AspectErrorDomain = @"AspectErrorDomain";
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static NSString *const AspectsSubclassSuffix = @"_Aspects_";
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static NSString *const AspectsMessagePrefix = @"aspects_";
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@implementation NSObject (Aspects)
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///////////////////////////////////////////////////////////////////////////////////////////
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#pragma mark - Public Aspects API
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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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return aspect_add((id)self, selector, options, block, error);
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}
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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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return aspect_add(self, selector, options, block, error);
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}
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///////////////////////////////////////////////////////////////////////////////////////////
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#pragma mark - Private Helper
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static id aspect_add(id self, SEL selector, AspectOptions options, id block, NSError **error) {
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NSCParameterAssert(self);
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NSCParameterAssert(selector);
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NSCParameterAssert(block);
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__block AspectIdentifier *identifier = nil;
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aspect_performLocked(^{
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if (aspect_isSelectorAllowedAndTrack(self, selector, options, error)) {
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AspectsContainer *aspectContainer = aspect_getContainerForObject(self, selector);
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identifier = [AspectIdentifier identifierWithSelector:selector object:self options:options block:block error:error];
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if (identifier) {
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[aspectContainer addAspect:identifier withOptions:options];
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// Modify the class to allow message interception.
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aspect_prepareClassAndHookSelector(self, selector, error);
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}
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}
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});
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return identifier;
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}
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static BOOL aspect_remove(AspectIdentifier *aspect, NSError **error) {
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NSCAssert([aspect isKindOfClass:AspectIdentifier.class], @"Must have correct type.");
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__block BOOL success = NO;
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aspect_performLocked(^{
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id self = aspect.object; // strongify
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if (self) {
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AspectsContainer *aspectContainer = aspect_getContainerForObject(self, aspect.selector);
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success = [aspectContainer removeAspect:aspect];
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aspect_cleanupHookedClassAndSelector(self, aspect.selector);
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// destroy token
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aspect.object = nil;
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aspect.block = nil;
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aspect.selector = NULL;
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}else {
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NSString *errrorDesc = [NSString stringWithFormat:@"Unable to deregister hook. Object already deallocated: %@", aspect];
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AspectError(AspectErrorRemoveObjectAlreadyDeallocated, errrorDesc);
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}
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});
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return success;
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}
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static void aspect_performLocked(dispatch_block_t block) {
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static OSSpinLock aspect_lock = OS_SPINLOCK_INIT;
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OSSpinLockLock(&aspect_lock);
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block();
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OSSpinLockUnlock(&aspect_lock);
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}
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static SEL aspect_aliasForSelector(SEL selector) {
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NSCParameterAssert(selector);
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return NSSelectorFromString([AspectsMessagePrefix stringByAppendingFormat:@"_%@", NSStringFromSelector(selector)]);
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}
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static NSMethodSignature *aspect_blockMethodSignature(id block, NSError **error) {
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AspectBlockRef layout = (__bridge void *)block;
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if (!(layout->flags & AspectBlockFlagsHasSignature)) {
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NSString *description = [NSString stringWithFormat:@"The block %@ doesn't contain a type signature.", block];
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AspectError(AspectErrorMissingBlockSignature, description);
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return nil;
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}
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void *desc = layout->descriptor;
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desc += 2 * sizeof(unsigned long int);
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if (layout->flags & AspectBlockFlagsHasCopyDisposeHelpers) {
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desc += 2 * sizeof(void *);
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}
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if (!desc) {
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NSString *description = [NSString stringWithFormat:@"The block %@ doesn't has a type signature.", block];
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AspectError(AspectErrorMissingBlockSignature, description);
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return nil;
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}
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const char *signature = (*(const char **)desc);
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return [NSMethodSignature signatureWithObjCTypes:signature];
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}
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static BOOL aspect_isCompatibleBlockSignature(NSMethodSignature *blockSignature, id object, SEL selector, NSError **error) {
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NSCParameterAssert(blockSignature);
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NSCParameterAssert(object);
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NSCParameterAssert(selector);
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BOOL signaturesMatch = YES;
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NSMethodSignature *methodSignature = [[object class] instanceMethodSignatureForSelector:selector];
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if (blockSignature.numberOfArguments > methodSignature.numberOfArguments) {
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signaturesMatch = NO;
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}else {
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if (blockSignature.numberOfArguments > 1) {
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const char *blockType = [blockSignature getArgumentTypeAtIndex:1];
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if (blockType[0] != '@') {
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signaturesMatch = NO;
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}
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}
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// Argument 0 is self/block, argument 1 is SEL or id<AspectInfo>. We start comparing at argument 2.
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// The block can have less arguments than the method, that's ok.
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if (signaturesMatch) {
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for (NSUInteger idx = 2; idx < blockSignature.numberOfArguments; idx++) {
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const char *methodType = [methodSignature getArgumentTypeAtIndex:idx];
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const char *blockType = [blockSignature getArgumentTypeAtIndex:idx];
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// Only compare parameter, not the optional type data.
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if (!methodType || !blockType || methodType[0] != blockType[0]) {
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signaturesMatch = NO; break;
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}
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}
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}
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}
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if (!signaturesMatch) {
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NSString *description = [NSString stringWithFormat:@"Block signature %@ doesn't match %@.", blockSignature, methodSignature];
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AspectError(AspectErrorIncompatibleBlockSignature, description);
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return NO;
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}
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return YES;
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}
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///////////////////////////////////////////////////////////////////////////////////////////
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#pragma mark - Class + Selector Preparation
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static BOOL aspect_isMsgForwardIMP(IMP impl) {
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return impl == _objc_msgForward
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#if !defined(__arm64__)
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|| impl == (IMP)_objc_msgForward_stret
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#endif
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;
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}
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static IMP aspect_getMsgForwardIMP(NSObject *self, SEL selector) {
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IMP msgForwardIMP = _objc_msgForward;
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#if !defined(__arm64__)
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// As an ugly internal runtime implementation detail in the 32bit runtime, we need to determine of the method we hook returns a struct or anything larger than id.
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// https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/LowLevelABI/000-Introduction/introduction.html
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// https://github.com/ReactiveCocoa/ReactiveCocoa/issues/783
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// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042e/IHI0042E_aapcs.pdf (Section 5.4)
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Method method = class_getInstanceMethod(self.class, selector);
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const char *encoding = method_getTypeEncoding(method);
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BOOL methodReturnsStructValue = encoding[0] == _C_STRUCT_B;
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if (methodReturnsStructValue) {
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@try {
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NSUInteger valueSize = 0;
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NSGetSizeAndAlignment(encoding, &valueSize, NULL);
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if (valueSize == 1 || valueSize == 2 || valueSize == 4 || valueSize == 8) {
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methodReturnsStructValue = NO;
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}
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} @catch (__unused NSException *e) {}
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}
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if (methodReturnsStructValue) {
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msgForwardIMP = (IMP)_objc_msgForward_stret;
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}
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#endif
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return msgForwardIMP;
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}
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static void aspect_prepareClassAndHookSelector(NSObject *self, SEL selector, NSError **error) {
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NSCParameterAssert(selector);
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Class klass = aspect_hookClass(self, error);
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Method targetMethod = class_getInstanceMethod(klass, selector);
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IMP targetMethodIMP = method_getImplementation(targetMethod);
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if (!aspect_isMsgForwardIMP(targetMethodIMP)) {
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// Make a method alias for the existing method implementation, it not already copied.
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const char *typeEncoding = method_getTypeEncoding(targetMethod);
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SEL aliasSelector = aspect_aliasForSelector(selector);
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if (![klass instancesRespondToSelector:aliasSelector]) {
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__unused BOOL addedAlias = class_addMethod(klass, aliasSelector, method_getImplementation(targetMethod), typeEncoding);
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NSCAssert(addedAlias, @"Original implementation for %@ is already copied to %@ on %@", NSStringFromSelector(selector), NSStringFromSelector(aliasSelector), klass);
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}
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// We use forwardInvocation to hook in.
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class_replaceMethod(klass, selector, aspect_getMsgForwardIMP(self, selector), typeEncoding);
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AspectLog(@"Aspects: Installed hook for -[%@ %@].", klass, NSStringFromSelector(selector));
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}
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}
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// Will undo the runtime changes made.
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static void aspect_cleanupHookedClassAndSelector(NSObject *self, SEL selector) {
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NSCParameterAssert(self);
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NSCParameterAssert(selector);
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Class klass = object_getClass(self);
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BOOL isMetaClass = class_isMetaClass(klass);
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if (isMetaClass) {
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klass = (Class)self;
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}
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// Check if the method is marked as forwarded and undo that.
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Method targetMethod = class_getInstanceMethod(klass, selector);
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IMP targetMethodIMP = method_getImplementation(targetMethod);
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if (aspect_isMsgForwardIMP(targetMethodIMP)) {
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// Restore the original method implementation.
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const char *typeEncoding = method_getTypeEncoding(targetMethod);
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SEL aliasSelector = aspect_aliasForSelector(selector);
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Method originalMethod = class_getInstanceMethod(klass, aliasSelector);
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IMP originalIMP = method_getImplementation(originalMethod);
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NSCAssert(originalMethod, @"Original implementation for %@ not found %@ on %@", NSStringFromSelector(selector), NSStringFromSelector(aliasSelector), klass);
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class_replaceMethod(klass, selector, originalIMP, typeEncoding);
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AspectLog(@"Aspects: Removed hook for -[%@ %@].", klass, NSStringFromSelector(selector));
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}
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// Deregister global tracked selector
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aspect_deregisterTrackedSelector(self, selector);
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// Get the aspect container and check if there are any hooks remaining. Clean up if there are not.
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AspectsContainer *container = aspect_getContainerForObject(self, selector);
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if (!container.hasAspects) {
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// Destroy the container
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aspect_destroyContainerForObject(self, selector);
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// Figure out how the class was modified to undo the changes.
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NSString *className = NSStringFromClass(klass);
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if ([className hasSuffix:AspectsSubclassSuffix]) {
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Class originalClass = NSClassFromString([className stringByReplacingOccurrencesOfString:AspectsSubclassSuffix withString:@""]);
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NSCAssert(originalClass != nil, @"Original class must exist");
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object_setClass(self, originalClass);
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AspectLog(@"Aspects: %@ has been restored.", NSStringFromClass(originalClass));
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// We can only dispose the class pair if we can ensure that no instances exist using our subclass.
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// Since we don't globally track this, we can't ensure this - but there's also not much overhead in keeping it around.
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//objc_disposeClassPair(object.class);
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}else {
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// Class is most likely swizzled in place. Undo that.
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if (isMetaClass) {
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aspect_undoSwizzleClassInPlace((Class)self);
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}else if (self.class != klass) {
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aspect_undoSwizzleClassInPlace(klass);
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}
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}
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}
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}
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///////////////////////////////////////////////////////////////////////////////////////////
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#pragma mark - Hook Class
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static Class aspect_hookClass(NSObject *self, NSError **error) {
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NSCParameterAssert(self);
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Class statedClass = self.class;
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Class baseClass = object_getClass(self);
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NSString *className = NSStringFromClass(baseClass);
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// Already subclassed
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if ([className hasSuffix:AspectsSubclassSuffix]) {
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return baseClass;
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// We swizzle a class object, not a single object.
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}else if (class_isMetaClass(baseClass)) {
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return aspect_swizzleClassInPlace((Class)self);
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// Probably a KVO'ed class. Swizzle in place. Also swizzle meta classes in place.
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}else if (statedClass != baseClass) {
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return aspect_swizzleClassInPlace(baseClass);
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}
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// Default case. Create dynamic subclass.
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const char *subclassName = [className stringByAppendingString:AspectsSubclassSuffix].UTF8String;
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Class subclass = objc_getClass(subclassName);
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if (subclass == nil) {
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subclass = objc_allocateClassPair(baseClass, subclassName, 0);
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if (subclass == nil) {
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NSString *errrorDesc = [NSString stringWithFormat:@"objc_allocateClassPair failed to allocate class %s.", subclassName];
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AspectError(AspectErrorFailedToAllocateClassPair, errrorDesc);
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return nil;
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}
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aspect_swizzleForwardInvocation(subclass);
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aspect_hookedGetClass(subclass, statedClass);
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aspect_hookedGetClass(object_getClass(subclass), statedClass);
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objc_registerClassPair(subclass);
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}
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object_setClass(self, subclass);
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return subclass;
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}
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static NSString *const AspectsForwardInvocationSelectorName = @"__aspects_forwardInvocation:";
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static void aspect_swizzleForwardInvocation(Class klass) {
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NSCParameterAssert(klass);
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// If there is no method, replace will act like class_addMethod.
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IMP originalImplementation = class_replaceMethod(klass, @selector(forwardInvocation:), (IMP)__ASPECTS_ARE_BEING_CALLED__, "v@:@");
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if (originalImplementation) {
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class_addMethod(klass, NSSelectorFromString(AspectsForwardInvocationSelectorName), originalImplementation, "v@:@");
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}
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AspectLog(@"Aspects: %@ is now aspect aware.", NSStringFromClass(klass));
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}
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static void aspect_undoSwizzleForwardInvocation(Class klass) {
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NSCParameterAssert(klass);
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Method originalMethod = class_getInstanceMethod(klass, NSSelectorFromString(AspectsForwardInvocationSelectorName));
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Method objectMethod = class_getInstanceMethod(NSObject.class, @selector(forwardInvocation:));
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// There is no class_removeMethod, so the best we can do is to retore the original implementation, or use a dummy.
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IMP originalImplementation = method_getImplementation(originalMethod ?: objectMethod);
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class_replaceMethod(klass, @selector(forwardInvocation:), originalImplementation, "v@:@");
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AspectLog(@"Aspects: %@ has been restored.", NSStringFromClass(klass));
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}
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static void aspect_hookedGetClass(Class class, Class statedClass) {
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NSCParameterAssert(class);
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NSCParameterAssert(statedClass);
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Method method = class_getInstanceMethod(class, @selector(class));
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IMP newIMP = imp_implementationWithBlock(^(id self) {
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return statedClass;
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});
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class_replaceMethod(class, @selector(class), newIMP, method_getTypeEncoding(method));
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}
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///////////////////////////////////////////////////////////////////////////////////////////
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#pragma mark - Swizzle Class In Place
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static void _aspect_modifySwizzledClasses(void (^block)(NSMutableSet *swizzledClasses)) {
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static NSMutableSet *swizzledClasses;
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static dispatch_once_t pred;
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dispatch_once(&pred, ^{
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swizzledClasses = [NSMutableSet new];
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});
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@synchronized(swizzledClasses) {
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block(swizzledClasses);
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}
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}
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static Class aspect_swizzleClassInPlace(Class klass) {
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NSCParameterAssert(klass);
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NSString *className = NSStringFromClass(klass);
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_aspect_modifySwizzledClasses(^(NSMutableSet *swizzledClasses) {
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if (![swizzledClasses containsObject:className]) {
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aspect_swizzleForwardInvocation(klass);
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[swizzledClasses addObject:className];
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}
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});
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return klass;
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}
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static void aspect_undoSwizzleClassInPlace(Class klass) {
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NSCParameterAssert(klass);
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NSString *className = NSStringFromClass(klass);
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_aspect_modifySwizzledClasses(^(NSMutableSet *swizzledClasses) {
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if ([swizzledClasses containsObject:className]) {
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aspect_undoSwizzleForwardInvocation(klass);
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[swizzledClasses removeObject:className];
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}
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});
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}
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///////////////////////////////////////////////////////////////////////////////////////////
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#pragma mark - Aspect Invoke Point
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|
// This is a macro so we get a cleaner stack trace.
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#define aspect_invoke(aspects, info) \
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for (AspectIdentifier *aspect in aspects) {\
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[aspect invokeWithInfo:info];\
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if (aspect.options & AspectOptionAutomaticRemoval) { \
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aspectsToRemove = [aspectsToRemove?:@[] arrayByAddingObject:aspect]; \
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} \
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}
|
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// This is the swizzled forwardInvocation: method.
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static void __ASPECTS_ARE_BEING_CALLED__(__unsafe_unretained NSObject *self, SEL selector, NSInvocation *invocation) {
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NSCParameterAssert(self);
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NSCParameterAssert(invocation);
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SEL originalSelector = invocation.selector;
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SEL aliasSelector = aspect_aliasForSelector(invocation.selector);
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invocation.selector = aliasSelector;
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AspectsContainer *objectContainer = objc_getAssociatedObject(self, aliasSelector);
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AspectsContainer *classContainer = aspect_getContainerForClass(object_getClass(self), aliasSelector);
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AspectInfo *info = [[AspectInfo alloc] initWithInstance:self invocation:invocation];
|
NSArray *aspectsToRemove = nil;
|
|
// Before hooks.
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aspect_invoke(classContainer.beforeAspects, info);
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aspect_invoke(objectContainer.beforeAspects, info);
|
|
// Instead hooks.
|
BOOL respondsToAlias = YES;
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if (objectContainer.insteadAspects.count || classContainer.insteadAspects.count) {
|
aspect_invoke(classContainer.insteadAspects, info);
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aspect_invoke(objectContainer.insteadAspects, info);
|
}else {
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Class klass = object_getClass(invocation.target);
|
do {
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if ((respondsToAlias = [klass instancesRespondToSelector:aliasSelector])) {
|
[invocation invoke];
|
break;
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}
|
}while (!respondsToAlias && (klass = class_getSuperclass(klass)));
|
}
|
|
// After hooks.
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aspect_invoke(classContainer.afterAspects, info);
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aspect_invoke(objectContainer.afterAspects, info);
|
|
// If no hooks are installed, call original implementation (usually to throw an exception)
|
if (!respondsToAlias) {
|
invocation.selector = originalSelector;
|
SEL originalForwardInvocationSEL = NSSelectorFromString(AspectsForwardInvocationSelectorName);
|
if ([self respondsToSelector:originalForwardInvocationSEL]) {
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((void( *)(id, SEL, NSInvocation *))objc_msgSend)(self, originalForwardInvocationSEL, invocation);
|
}else {
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[self doesNotRecognizeSelector:invocation.selector];
|
}
|
}
|
|
// Remove any hooks that are queued for deregistration.
|
[aspectsToRemove makeObjectsPerformSelector:@selector(remove)];
|
}
|
#undef aspect_invoke
|
|
///////////////////////////////////////////////////////////////////////////////////////////
|
#pragma mark - Aspect Container Management
|
|
// Loads or creates the aspect container.
|
static AspectsContainer *aspect_getContainerForObject(NSObject *self, SEL selector) {
|
NSCParameterAssert(self);
|
SEL aliasSelector = aspect_aliasForSelector(selector);
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AspectsContainer *aspectContainer = objc_getAssociatedObject(self, aliasSelector);
|
if (!aspectContainer) {
|
aspectContainer = [AspectsContainer new];
|
objc_setAssociatedObject(self, aliasSelector, aspectContainer, OBJC_ASSOCIATION_RETAIN);
|
}
|
return aspectContainer;
|
}
|
|
static AspectsContainer *aspect_getContainerForClass(Class klass, SEL selector) {
|
NSCParameterAssert(klass);
|
AspectsContainer *classContainer = nil;
|
do {
|
classContainer = objc_getAssociatedObject(klass, selector);
|
if (classContainer.hasAspects) break;
|
}while ((klass = class_getSuperclass(klass)));
|
|
return classContainer;
|
}
|
|
static void aspect_destroyContainerForObject(id<NSObject> self, SEL selector) {
|
NSCParameterAssert(self);
|
SEL aliasSelector = aspect_aliasForSelector(selector);
|
objc_setAssociatedObject(self, aliasSelector, nil, OBJC_ASSOCIATION_RETAIN);
|
}
|
|
///////////////////////////////////////////////////////////////////////////////////////////
|
#pragma mark - Selector Blacklist Checking
|
|
static NSMutableDictionary *aspect_getSwizzledClassesDict() {
|
static NSMutableDictionary *swizzledClassesDict;
|
static dispatch_once_t pred;
|
dispatch_once(&pred, ^{
|
swizzledClassesDict = [NSMutableDictionary new];
|
});
|
return swizzledClassesDict;
|
}
|
|
static BOOL aspect_isSelectorAllowedAndTrack(NSObject *self, SEL selector, AspectOptions options, NSError **error) {
|
static NSSet *disallowedSelectorList;
|
static dispatch_once_t pred;
|
dispatch_once(&pred, ^{
|
disallowedSelectorList = [NSSet setWithObjects:@"retain", @"release", @"autorelease", @"forwardInvocation:", nil];
|
});
|
|
// Check against the blacklist.
|
NSString *selectorName = NSStringFromSelector(selector);
|
if ([disallowedSelectorList containsObject:selectorName]) {
|
NSString *errorDescription = [NSString stringWithFormat:@"Selector %@ is blacklisted.", selectorName];
|
AspectError(AspectErrorSelectorBlacklisted, errorDescription);
|
return NO;
|
}
|
|
// Additional checks.
|
AspectOptions position = options&AspectPositionFilter;
|
if ([selectorName isEqualToString:@"dealloc"] && position != AspectPositionBefore) {
|
NSString *errorDesc = @"AspectPositionBefore is the only valid position when hooking dealloc.";
|
AspectError(AspectErrorSelectorDeallocPosition, errorDesc);
|
return NO;
|
}
|
|
if (![self respondsToSelector:selector] && ![self.class instancesRespondToSelector:selector]) {
|
NSString *errorDesc = [NSString stringWithFormat:@"Unable to find selector -[%@ %@].", NSStringFromClass(self.class), selectorName];
|
AspectError(AspectErrorDoesNotRespondToSelector, errorDesc);
|
return NO;
|
}
|
|
// Search for the current class and the class hierarchy IF we are modifying a class object
|
if (class_isMetaClass(object_getClass(self))) {
|
Class klass = [self class];
|
NSMutableDictionary *swizzledClassesDict = aspect_getSwizzledClassesDict();
|
Class currentClass = [self class];
|
|
AspectTracker *tracker = swizzledClassesDict[currentClass];
|
if ([tracker subclassHasHookedSelectorName:selectorName]) {
|
NSSet *subclassTracker = [tracker subclassTrackersHookingSelectorName:selectorName];
|
NSSet *subclassNames = [subclassTracker valueForKey:@"trackedClassName"];
|
NSString *errorDescription = [NSString stringWithFormat:@"Error: %@ already hooked subclasses: %@. A method can only be hooked once per class hierarchy.", selectorName, subclassNames];
|
AspectError(AspectErrorSelectorAlreadyHookedInClassHierarchy, errorDescription);
|
return NO;
|
}
|
|
do {
|
tracker = swizzledClassesDict[currentClass];
|
if ([tracker.selectorNames containsObject:selectorName]) {
|
if (klass == currentClass) {
|
// Already modified and topmost!
|
return YES;
|
}
|
NSString *errorDescription = [NSString stringWithFormat:@"Error: %@ already hooked in %@. A method can only be hooked once per class hierarchy.", selectorName, NSStringFromClass(currentClass)];
|
AspectError(AspectErrorSelectorAlreadyHookedInClassHierarchy, errorDescription);
|
return NO;
|
}
|
} while ((currentClass = class_getSuperclass(currentClass)));
|
|
// Add the selector as being modified.
|
currentClass = klass;
|
AspectTracker *subclassTracker = nil;
|
do {
|
tracker = swizzledClassesDict[currentClass];
|
if (!tracker) {
|
tracker = [[AspectTracker alloc] initWithTrackedClass:currentClass];
|
swizzledClassesDict[(id<NSCopying>)currentClass] = tracker;
|
}
|
if (subclassTracker) {
|
[tracker addSubclassTracker:subclassTracker hookingSelectorName:selectorName];
|
} else {
|
[tracker.selectorNames addObject:selectorName];
|
}
|
|
// All superclasses get marked as having a subclass that is modified.
|
subclassTracker = tracker;
|
}while ((currentClass = class_getSuperclass(currentClass)));
|
} else {
|
return YES;
|
}
|
|
return YES;
|
}
|
|
static void aspect_deregisterTrackedSelector(id self, SEL selector) {
|
if (!class_isMetaClass(object_getClass(self))) return;
|
|
NSMutableDictionary *swizzledClassesDict = aspect_getSwizzledClassesDict();
|
NSString *selectorName = NSStringFromSelector(selector);
|
Class currentClass = [self class];
|
AspectTracker *subclassTracker = nil;
|
do {
|
AspectTracker *tracker = swizzledClassesDict[currentClass];
|
if (subclassTracker) {
|
[tracker removeSubclassTracker:subclassTracker hookingSelectorName:selectorName];
|
} else {
|
[tracker.selectorNames removeObject:selectorName];
|
}
|
if (tracker.selectorNames.count == 0 && tracker.selectorNamesToSubclassTrackers) {
|
[swizzledClassesDict removeObjectForKey:currentClass];
|
}
|
subclassTracker = tracker;
|
}while ((currentClass = class_getSuperclass(currentClass)));
|
}
|
|
@end
|
|
@implementation AspectTracker
|
|
- (id)initWithTrackedClass:(Class)trackedClass {
|
if (self = [super init]) {
|
_trackedClass = trackedClass;
|
_selectorNames = [NSMutableSet new];
|
_selectorNamesToSubclassTrackers = [NSMutableDictionary new];
|
}
|
return self;
|
}
|
|
- (BOOL)subclassHasHookedSelectorName:(NSString *)selectorName {
|
return self.selectorNamesToSubclassTrackers[selectorName] != nil;
|
}
|
|
- (void)addSubclassTracker:(AspectTracker *)subclassTracker hookingSelectorName:(NSString *)selectorName {
|
NSMutableSet *trackerSet = self.selectorNamesToSubclassTrackers[selectorName];
|
if (!trackerSet) {
|
trackerSet = [NSMutableSet new];
|
self.selectorNamesToSubclassTrackers[selectorName] = trackerSet;
|
}
|
[trackerSet addObject:subclassTracker];
|
}
|
- (void)removeSubclassTracker:(AspectTracker *)subclassTracker hookingSelectorName:(NSString *)selectorName {
|
NSMutableSet *trackerSet = self.selectorNamesToSubclassTrackers[selectorName];
|
[trackerSet removeObject:subclassTracker];
|
if (trackerSet.count == 0) {
|
[self.selectorNamesToSubclassTrackers removeObjectForKey:selectorName];
|
}
|
}
|
- (NSSet *)subclassTrackersHookingSelectorName:(NSString *)selectorName {
|
NSMutableSet *hookingSubclassTrackers = [NSMutableSet new];
|
for (AspectTracker *tracker in self.selectorNamesToSubclassTrackers[selectorName]) {
|
if ([tracker.selectorNames containsObject:selectorName]) {
|
[hookingSubclassTrackers addObject:tracker];
|
}
|
[hookingSubclassTrackers unionSet:[tracker subclassTrackersHookingSelectorName:selectorName]];
|
}
|
return hookingSubclassTrackers;
|
}
|
- (NSString *)trackedClassName {
|
return NSStringFromClass(self.trackedClass);
|
}
|
|
- (NSString *)description {
|
return [NSString stringWithFormat:@"<%@: %@, trackedClass: %@, selectorNames:%@, subclass selector names: %@>", self.class, self, NSStringFromClass(self.trackedClass), self.selectorNames, self.selectorNamesToSubclassTrackers.allKeys];
|
}
|
|
@end
|
|
///////////////////////////////////////////////////////////////////////////////////////////
|
#pragma mark - NSInvocation (Aspects)
|
|
@implementation NSInvocation (Aspects)
|
|
// Thanks to the ReactiveCocoa team for providing a generic solution for this.
|
- (id)aspect_argumentAtIndex:(NSUInteger)index {
|
const char *argType = [self.methodSignature getArgumentTypeAtIndex:index];
|
// Skip const type qualifier.
|
if (argType[0] == _C_CONST) argType++;
|
|
#define WRAP_AND_RETURN(type) do { type val = 0; [self getArgument:&val atIndex:(NSInteger)index]; return @(val); } while (0)
|
if (strcmp(argType, @encode(id)) == 0 || strcmp(argType, @encode(Class)) == 0) {
|
__autoreleasing id returnObj;
|
[self getArgument:&returnObj atIndex:(NSInteger)index];
|
return returnObj;
|
} else if (strcmp(argType, @encode(SEL)) == 0) {
|
SEL selector = 0;
|
[self getArgument:&selector atIndex:(NSInteger)index];
|
return NSStringFromSelector(selector);
|
} else if (strcmp(argType, @encode(Class)) == 0) {
|
__autoreleasing Class theClass = Nil;
|
[self getArgument:&theClass atIndex:(NSInteger)index];
|
return theClass;
|
// Using this list will box the number with the appropriate constructor, instead of the generic NSValue.
|
} else if (strcmp(argType, @encode(char)) == 0) {
|
WRAP_AND_RETURN(char);
|
} else if (strcmp(argType, @encode(int)) == 0) {
|
WRAP_AND_RETURN(int);
|
} else if (strcmp(argType, @encode(short)) == 0) {
|
WRAP_AND_RETURN(short);
|
} else if (strcmp(argType, @encode(long)) == 0) {
|
WRAP_AND_RETURN(long);
|
} else if (strcmp(argType, @encode(long long)) == 0) {
|
WRAP_AND_RETURN(long long);
|
} else if (strcmp(argType, @encode(unsigned char)) == 0) {
|
WRAP_AND_RETURN(unsigned char);
|
} else if (strcmp(argType, @encode(unsigned int)) == 0) {
|
WRAP_AND_RETURN(unsigned int);
|
} else if (strcmp(argType, @encode(unsigned short)) == 0) {
|
WRAP_AND_RETURN(unsigned short);
|
} else if (strcmp(argType, @encode(unsigned long)) == 0) {
|
WRAP_AND_RETURN(unsigned long);
|
} else if (strcmp(argType, @encode(unsigned long long)) == 0) {
|
WRAP_AND_RETURN(unsigned long long);
|
} else if (strcmp(argType, @encode(float)) == 0) {
|
WRAP_AND_RETURN(float);
|
} else if (strcmp(argType, @encode(double)) == 0) {
|
WRAP_AND_RETURN(double);
|
} else if (strcmp(argType, @encode(BOOL)) == 0) {
|
WRAP_AND_RETURN(BOOL);
|
} else if (strcmp(argType, @encode(bool)) == 0) {
|
WRAP_AND_RETURN(BOOL);
|
} else if (strcmp(argType, @encode(char *)) == 0) {
|
WRAP_AND_RETURN(const char *);
|
} else if (strcmp(argType, @encode(void (^)(void))) == 0) {
|
__unsafe_unretained id block = nil;
|
[self getArgument:&block atIndex:(NSInteger)index];
|
return [block copy];
|
} else {
|
NSUInteger valueSize = 0;
|
NSGetSizeAndAlignment(argType, &valueSize, NULL);
|
|
unsigned char valueBytes[valueSize];
|
[self getArgument:valueBytes atIndex:(NSInteger)index];
|
|
return [NSValue valueWithBytes:valueBytes objCType:argType];
|
}
|
return nil;
|
#undef WRAP_AND_RETURN
|
}
|
|
- (NSArray *)aspects_arguments {
|
NSMutableArray *argumentsArray = [NSMutableArray array];
|
for (NSUInteger idx = 2; idx < self.methodSignature.numberOfArguments; idx++) {
|
[argumentsArray addObject:[self aspect_argumentAtIndex:idx] ?: NSNull.null];
|
}
|
return [argumentsArray copy];
|
}
|
|
@end
|
|
///////////////////////////////////////////////////////////////////////////////////////////
|
#pragma mark - AspectIdentifier
|
|
@implementation AspectIdentifier
|
|
+ (instancetype)identifierWithSelector:(SEL)selector object:(id)object options:(AspectOptions)options block:(id)block error:(NSError **)error {
|
NSCParameterAssert(block);
|
NSCParameterAssert(selector);
|
NSMethodSignature *blockSignature = aspect_blockMethodSignature(block, error); // TODO: check signature compatibility, etc.
|
if (!aspect_isCompatibleBlockSignature(blockSignature, object, selector, error)) {
|
return nil;
|
}
|
|
AspectIdentifier *identifier = nil;
|
if (blockSignature) {
|
identifier = [AspectIdentifier new];
|
identifier.selector = selector;
|
identifier.block = block;
|
identifier.blockSignature = blockSignature;
|
identifier.options = options;
|
identifier.object = object; // weak
|
}
|
return identifier;
|
}
|
|
- (BOOL)invokeWithInfo:(id<AspectInfo>)info {
|
NSInvocation *blockInvocation = [NSInvocation invocationWithMethodSignature:self.blockSignature];
|
NSInvocation *originalInvocation = info.originalInvocation;
|
NSUInteger numberOfArguments = self.blockSignature.numberOfArguments;
|
|
// Be extra paranoid. We already check that on hook registration.
|
if (numberOfArguments > originalInvocation.methodSignature.numberOfArguments) {
|
AspectLogError(@"Block has too many arguments. Not calling %@", info);
|
return NO;
|
}
|
|
// The `self` of the block will be the AspectInfo. Optional.
|
if (numberOfArguments > 1) {
|
[blockInvocation setArgument:&info atIndex:1];
|
}
|
|
void *argBuf = NULL;
|
for (NSUInteger idx = 2; idx < numberOfArguments; idx++) {
|
const char *type = [originalInvocation.methodSignature getArgumentTypeAtIndex:idx];
|
NSUInteger argSize;
|
NSGetSizeAndAlignment(type, &argSize, NULL);
|
|
if (!(argBuf = reallocf(argBuf, argSize))) {
|
AspectLogError(@"Failed to allocate memory for block invocation.");
|
return NO;
|
}
|
|
[originalInvocation getArgument:argBuf atIndex:idx];
|
[blockInvocation setArgument:argBuf atIndex:idx];
|
}
|
|
[blockInvocation invokeWithTarget:self.block];
|
|
if (argBuf != NULL) {
|
free(argBuf);
|
}
|
return YES;
|
}
|
|
- (NSString *)description {
|
return [NSString stringWithFormat:@"<%@: %p, SEL:%@ object:%@ options:%tu block:%@ (#%tu args)>", self.class, self, NSStringFromSelector(self.selector), self.object, self.options, self.block, self.blockSignature.numberOfArguments];
|
}
|
|
- (BOOL)remove {
|
return aspect_remove(self, NULL);
|
}
|
|
@end
|
|
///////////////////////////////////////////////////////////////////////////////////////////
|
#pragma mark - AspectsContainer
|
|
@implementation AspectsContainer
|
|
- (BOOL)hasAspects {
|
return self.beforeAspects.count > 0 || self.insteadAspects.count > 0 || self.afterAspects.count > 0;
|
}
|
|
- (void)addAspect:(AspectIdentifier *)aspect withOptions:(AspectOptions)options {
|
NSParameterAssert(aspect);
|
NSUInteger position = options&AspectPositionFilter;
|
switch (position) {
|
case AspectPositionBefore: self.beforeAspects = [(self.beforeAspects ?:@[]) arrayByAddingObject:aspect]; break;
|
case AspectPositionInstead: self.insteadAspects = [(self.insteadAspects?:@[]) arrayByAddingObject:aspect]; break;
|
case AspectPositionAfter: self.afterAspects = [(self.afterAspects ?:@[]) arrayByAddingObject:aspect]; break;
|
}
|
}
|
|
- (BOOL)removeAspect:(id)aspect {
|
for (NSString *aspectArrayName in @[NSStringFromSelector(@selector(beforeAspects)),
|
NSStringFromSelector(@selector(insteadAspects)),
|
NSStringFromSelector(@selector(afterAspects))]) {
|
NSArray *array = [self valueForKey:aspectArrayName];
|
NSUInteger index = [array indexOfObjectIdenticalTo:aspect];
|
if (array && index != NSNotFound) {
|
NSMutableArray *newArray = [NSMutableArray arrayWithArray:array];
|
[newArray removeObjectAtIndex:index];
|
[self setValue:newArray forKey:aspectArrayName];
|
return YES;
|
}
|
}
|
return NO;
|
}
|
|
- (NSString *)description {
|
return [NSString stringWithFormat:@"<%@: %p, before:%@, instead:%@, after:%@>", self.class, self, self.beforeAspects, self.insteadAspects, self.afterAspects];
|
}
|
|
@end
|
|
///////////////////////////////////////////////////////////////////////////////////////////
|
#pragma mark - AspectInfo
|
|
@implementation AspectInfo
|
|
@synthesize arguments = _arguments;
|
|
- (id)initWithInstance:(__unsafe_unretained id)instance invocation:(NSInvocation *)invocation {
|
NSCParameterAssert(instance);
|
NSCParameterAssert(invocation);
|
if (self = [super init]) {
|
_instance = instance;
|
_originalInvocation = invocation;
|
}
|
return self;
|
}
|
|
- (NSArray *)arguments {
|
// Lazily evaluate arguments, boxing is expensive.
|
if (!_arguments) {
|
_arguments = self.originalInvocation.aspects_arguments;
|
}
|
return _arguments;
|
}
|
|
@end
|
