//
|
// NullSafe.m
|
//
|
// Version 1.2.2
|
//
|
// Created by Nick Lockwood on 19/12/2012.
|
// Copyright 2012 Charcoal Design
|
//
|
// Distributed under the permissive zlib License
|
// Get the latest version from here:
|
//
|
// https://github.com/nicklockwood/NullSafe
|
//
|
// This software is provided 'as-is', without any express or implied
|
// warranty. In no event will the authors be held liable for any damages
|
// arising from the use of this software.
|
//
|
// Permission is granted to anyone to use this software for any purpose,
|
// including commercial applications, and to alter it and redistribute it
|
// freely, subject to the following restrictions:
|
//
|
// 1. The origin of this software must not be misrepresented; you must not
|
// claim that you wrote the original software. If you use this software
|
// in a product, an acknowledgment in the product documentation would be
|
// appreciated but is not required.
|
//
|
// 2. Altered source versions must be plainly marked as such, and must not be
|
// misrepresented as being the original software.
|
//
|
// 3. This notice may not be removed or altered from any source distribution.
|
//
|
|
#import <objc/runtime.h>
|
#import <Foundation/Foundation.h>
|
|
|
#ifndef NULLSAFE_ENABLED
|
#define NULLSAFE_ENABLED 1
|
#endif
|
|
|
#pragma GCC diagnostic ignored "-Wgnu-conditional-omitted-operand"
|
|
|
@implementation NSNull (NullSafe)
|
|
#if NULLSAFE_ENABLED
|
|
- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector
|
{
|
@synchronized([self class])
|
{
|
//look up method signature
|
NSMethodSignature *signature = [super methodSignatureForSelector:selector];
|
if (!signature)
|
{
|
//not supported by NSNull, search other classes
|
static NSMutableSet *classList = nil;
|
static NSMutableDictionary *signatureCache = nil;
|
if (signatureCache == nil)
|
{
|
classList = [[NSMutableSet alloc] init];
|
signatureCache = [[NSMutableDictionary alloc] init];
|
|
//get class list
|
int numClasses = objc_getClassList(NULL, 0);
|
Class *classes = (Class *)malloc(sizeof(Class) * (unsigned long)numClasses);
|
numClasses = objc_getClassList(classes, numClasses);
|
|
//add to list for checking
|
NSMutableSet *excluded = [NSMutableSet set];
|
for (int i = 0; i < numClasses; i++)
|
{
|
//determine if class has a superclass
|
Class someClass = classes[i];
|
Class superclass = class_getSuperclass(someClass);
|
while (superclass)
|
{
|
if (superclass == [NSObject class])
|
{
|
[classList addObject:someClass];
|
break;
|
}
|
[excluded addObject:NSStringFromClass(superclass)];
|
superclass = class_getSuperclass(superclass);
|
}
|
}
|
|
//remove all classes that have subclasses
|
for (Class someClass in excluded)
|
{
|
[classList removeObject:someClass];
|
}
|
|
//free class list
|
free(classes);
|
}
|
|
//check implementation cache first
|
NSString *selectorString = NSStringFromSelector(selector);
|
signature = signatureCache[selectorString];
|
if (!signature)
|
{
|
//find implementation
|
for (Class someClass in classList)
|
{
|
if ([someClass instancesRespondToSelector:selector])
|
{
|
signature = [someClass instanceMethodSignatureForSelector:selector];
|
break;
|
}
|
}
|
|
//cache for next time
|
signatureCache[selectorString] = signature ?: [NSNull null];
|
}
|
else if ([signature isKindOfClass:[NSNull class]])
|
{
|
signature = nil;
|
}
|
}
|
return signature;
|
}
|
}
|
|
- (void)forwardInvocation:(NSInvocation *)invocation
|
{
|
invocation.target = nil;
|
[invocation invoke];
|
}
|
|
#endif
|
|
@end
|
