TreeViewDemo/Model/ObjCClassWrapper.m

/*
    File: ObjCClassWrapper.m
Abstract: ObjCClassWrapper Implementation
 Version: 1.4
 
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*/
 
#import "ObjCClassWrapper.h"
#import <objc/objc-runtime.h>
 
/* Keeps track of the ObjCClassWrapper instances we create. 
    We create one unique ObjCClassWrapper for each Objective-C "Class" we're asked to wrap.
*/
static NSMapTable *classToWrapperMapTable = nil;
 
/* Compares two ObjCClassWrappers by name, and returns an NSComparisonResult.
*/
static NSInteger CompareClassNames(id classA, id classB, void* context) {
    return [[classA description] compare:[classB description]];
}
 
@implementation ObjCClassWrapper
 
#pragma mark *** Creating Instances ***
 
- initWithWrappedClass:(Class)aClass {
    self = [super init];
    if (self) {
        if (aClass != Nil) {
            wrappedClass = aClass;
            if (classToWrapperMapTable == nil) {
                classToWrapperMapTable = [[NSMapTable weakToStrongObjectsMapTable] retain];
            }
            [classToWrapperMapTable setObject:self forKey:wrappedClass];
        } else {
            [self release];
            return nil;
        }
    }
    return self;
}
 
+ (ObjCClassWrapper *)wrapperForClass:(Class)aClass {
    ObjCClassWrapper *wrapper = [classToWrapperMapTable objectForKey:aClass];
    if (wrapper == nil) {
        wrapper = [[[self alloc] initWithWrappedClass:aClass] autorelease];
    }
    return wrapper;
}
 
+ (ObjCClassWrapper *)wrapperForClassNamed:(NSString *)aClassName {
    return [self wrapperForClass:NSClassFromString(aClassName)];
}
 
 
#pragma mark *** Property Accessors ***
 
- (NSString *)name {
    return NSStringFromClass(wrappedClass);
}
 
- (NSString *)description {
    return [self name];
}
 
- (size_t)wrappedClassInstanceSize {
    return class_getInstanceSize(wrappedClass);
}
 
- (ObjCClassWrapper *)superclassWrapper {
    return [[self class] wrapperForClass:class_getSuperclass(wrappedClass)];
}
 
- (NSArray *)subclasses {
 
    // If we haven't built our array of subclasses yet, do so.
    if (subclassesCache == nil) {
 
        // Iterate over all classes (as described in objc/objc-runtime.h) to find the subclasses of wrappedClass.
        int i;
        int numClasses = 0;
        int newNumClasses = objc_getClassList(NULL, 0);
        Class* classes = NULL;
        while (numClasses < newNumClasses) {
            numClasses = newNumClasses;
            classes = (Class *)realloc(classes, sizeof(Class) * numClasses);
            newNumClasses = objc_getClassList(classes, numClasses);
        }
 
        // Make an array of ObjCClassWrapper instances to represent the classes.
        subclassesCache = [[NSMutableArray alloc] initWithCapacity:numClasses];
        for (i = 0; i < numClasses; i++) {
            if (class_getSuperclass(classes[i]) == wrappedClass) {
                [subclassesCache addObject:[[self class] wrapperForClass:classes[i]]];
            }
        }
        free(classes);
 
        // Sort subclasses by name.
        [subclassesCache sortUsingFunction:CompareClassNames context:NULL];
    }
    return subclassesCache;
}
 
#pragma mark *** TreeViewModelNode Protocol Conformance ***
 
- (id<TreeViewModelNode>)parentModelNode {
    return [self superclassWrapper];
}
 
- (NSArray *)childModelNodes {
    return [self subclasses];
}
 
 
#pragma mark *** Cleanup ***
 
- (void)dealloc {
    [subclassesCache release];
    [super dealloc];
}
 
@end