RestKit/Code/ObjectMapping/RKObjectUtilities.m

//
//  RKObjectUtilities.m
//  RestKit
//
//  Created by Blake Watters on 9/30/12.
//  Copyright (c) 2012 RestKit. All rights reserved.
//
//  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 <objc/message.h>
#import "RKObjectUtilities.h"

BOOL RKObjectIsEqualToObject(id object, id anotherObject) {
    NSCAssert(object, @"Expected object not to be nil");
    NSCAssert(anotherObject, @"Expected anotherObject not to be nil");
    
    SEL comparisonSelector;
    if ([object isKindOfClass:[NSString class]] && [anotherObject isKindOfClass:[NSString class]]) {
        comparisonSelector = @selector(isEqualToString:);
    } else if ([object isKindOfClass:[NSNumber class]] && [anotherObject isKindOfClass:[NSNumber class]]) {
        comparisonSelector = @selector(isEqualToNumber:);
    } else if ([object isKindOfClass:[NSDate class]] && [anotherObject isKindOfClass:[NSDate class]]) {
        comparisonSelector = @selector(isEqualToDate:);
    } else if ([object isKindOfClass:[NSArray class]] && [anotherObject isKindOfClass:[NSArray class]]) {
        comparisonSelector = @selector(isEqualToArray:);
    } else if ([object isKindOfClass:[NSDictionary class]] && [anotherObject isKindOfClass:[NSDictionary class]]) {
        comparisonSelector = @selector(isEqualToDictionary:);
    } else if ([object isKindOfClass:[NSSet class]] && [anotherObject isKindOfClass:[NSSet class]]) {
        comparisonSelector = @selector(isEqualToSet:);
    } else {
        comparisonSelector = @selector(isEqual:);
    }
    
    // Comparison magic using function pointers. See this page for details: http://www.red-sweater.com/blog/320/abusing-objective-c-with-class
    // Original code courtesy of Greg Parker
    // This is necessary because isEqualToNumber will return negative integer values that aren't coercable directly to BOOL's without help [sbw]
    BOOL (*ComparisonSender)(id, SEL, id) = (BOOL (*)(id, SEL, id))objc_msgSend;
    return ComparisonSender(object, comparisonSelector, anotherObject);
}

BOOL RKClassIsCollection(Class aClass)
{
    return (aClass && ([aClass isSubclassOfClass:[NSSet class]] ||
                       [aClass isSubclassOfClass:[NSArray class]] ||
                       [aClass isSubclassOfClass:[NSOrderedSet class]]));
}

BOOL RKObjectIsCollection(id object)
{
    return RKClassIsCollection([object class]);
}

BOOL RKObjectIsCollectionContainingOnlyManagedObjects(id object)
{
    if (! RKObjectIsCollection(object)) return NO;
    Class managedObjectClass = NSClassFromString(@"NSManagedObject");
    if (! managedObjectClass) return NO;
    for (id instance in object) {
        if (! [instance isKindOfClass:managedObjectClass]) return NO;
    }
    return YES;
}

BOOL RKObjectIsCollectionOfCollections(id object)
{
    if (! RKObjectIsCollection(object)) return NO;
    id collectionSanityCheckObject = nil;
    if ([object respondsToSelector:@selector(anyObject)]) collectionSanityCheckObject = [object anyObject];
    if ([object respondsToSelector:@selector(lastObject)]) collectionSanityCheckObject = [object lastObject];
    return RKObjectIsCollection(collectionSanityCheckObject);
}

Class RKKeyValueCodingClassForObjCType(const char *type)
{
    if (type) {
        // https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtTypeEncodings.html
        switch (type[0]) {
            case '@': {
                char *openingQuoteLoc = strchr(type, '"');
                if (openingQuoteLoc) {
                    char *closingQuoteLoc = strchr(openingQuoteLoc+1, '"');
                    if (closingQuoteLoc) {
                        size_t classNameStrLen = closingQuoteLoc-openingQuoteLoc;
                        char className[classNameStrLen];
                        memcpy(className, openingQuoteLoc+1, classNameStrLen-1);
                        // Null-terminate the array to stringify
                        className[classNameStrLen-1] = '\0';
                        return objc_getClass(className);
                    }
                }
                // If there is no quoted class type (id), it can be used as-is.
                return Nil;
            }
                
            case 'c': // char
            case 'C': // unsigned char
            case 's': // short
            case 'S': // unsigned short
            case 'i': // int
            case 'I': // unsigned int
            case 'l': // long
            case 'L': // unsigned long
            case 'q': // long long
            case 'Q': // unsigned long long
            case 'f': // float
            case 'd': // double
                return [NSNumber class];
                
            case 'B': // C++ bool or C99 _Bool
                return objc_getClass("NSCFBoolean")
                ?: objc_getClass("__NSCFBoolean")
                ?: [NSNumber class];
                
            case '{': // struct
            case 'b': // bitfield
            case '(': // union
                return [NSValue class];
                
            case '[': // c array
            case '^': // pointer
            case 'v': // void
            case '*': // char *
            case '#': // Class
            case ':': // selector
            case '?': // unknown type (function pointer, etc)
            default:
                break;
        }
    }
    return Nil;
}

Class RKKeyValueCodingClassFromPropertyAttributes(const char *attr)
{
    if (attr) {
        const char *typeIdentifierLoc = strchr(attr, 'T');
        if (typeIdentifierLoc) {
            return RKKeyValueCodingClassForObjCType(typeIdentifierLoc+1);
        }
    }
    return Nil;
}

NSString *RKPropertyTypeFromAttributeString(NSString *attributeString)
{
    NSString *type = [NSString string];
    NSScanner *typeScanner = [NSScanner scannerWithString:attributeString];
    [typeScanner scanUpToCharactersFromSet:[NSCharacterSet characterSetWithCharactersInString:@"@"] intoString:NULL];
    
    // we are not dealing with an object
    if ([typeScanner isAtEnd]) {
        return @"NULL";
    }
    [typeScanner scanCharactersFromSet:[NSCharacterSet characterSetWithCharactersInString:@"\"@"] intoString:NULL];
    // this gets the actual object type
    [typeScanner scanUpToCharactersFromSet:[NSCharacterSet characterSetWithCharactersInString:@"\""] intoString:&type];
    return type;
}