OGKeyPath.h

//
//  OGKeyPath.h
//
//  Created by Jim on 3/11/10.
//  
//  Copyright (c) 2010 Jim Kang/Phalange Software.
//  
//  Permission is hereby granted, free of charge, to any person
//  obtaining a copy of this software and associated documentation
//  files (the "Software"), to deal in the Software without
//  restriction, including without limitation the rights to use,
//  copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the
//  Software is furnished to do so, subject to the following
//  conditions:
//  
//  The above copyright notice and this permission notice shall be
//  included in all copies or substantial portions of the Software.
//  
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
//  OTHER DEALINGS IN THE SOFTWARE.

#import <Foundation/Foundation.h>


@interface OGKeyPath : NSObject 
{
}

// Cocoa KVC key paths let you get at elements with an object hierarchy, provided 
// everything in your desired path is KVC-compliant. Unfortunately, NSArray 
// elements cannot be referenced in key path strings.
// OGKeyPath provides a way to traverse those hierarchies containing arrays.

// "Extended key path" arguments for OGKeyPath methods are like KVC key paths but are 
// arrays instead of strings. A key path segment may be a NSNumber representing an index 
// in an NSArray or an NSString representing a property of an object.
// 
// e.g. This extended key path 
// 
// [@"configs", [NSNumber numberWithInt:3], @"color", @"alpha"] 
// 
// would map to the value 0.5 on the hierarchy in the diagram below, which has "foo" at 
// the top level:
// 
// foo
// {
//      users: { ... },
//      something: "whatever",
//      configs:
//      [
//          config1: { ... },
//          config2: { ... },
//          config3: { ... },
//          config4: 
//          {
//              size: 50,
//              color: 
//              {
//                  r: 0,
//                  g: 255,
//                  b: 255,
//                  alpha: 0.5 (*)
//              }
//          }
//      ]
//}

// Example: 
// [OGKeyPath set:myObject value:[NSNumber numberWithFloat:1.0f] forExtendedKeyPath:
//  [NSArray arrayWithObjects:@"configs", [NSNumber numberWithInt:3], @"color", @"alpha", nil]]; 
+ (void)set:(id)kvcObject value:(id)value forExtendedKeyPath:(NSArray *)path;

// Alternate version that puts the array together for you.
// Example: 
// [OGKeyPath set:myObject value:[NSNumber numberWithFloat:1.0f] forExtendedKeyPathWithObjects:
//  @"configs", [NSNumber numberWithInt:3], @"color", @"alpha", nil]; 
+ (void)set:(id)kvcObject value:(id)value forExtendedKeyPathWithObjects:(id)firstPathSegment, ...;

// Example: 
// [OGKeyPath valueFrom:myObject forExtendedKeyPath:
//  [NSArray arrayWithObjects:@"configs", [NSNumber numberWithInt:3], @"color", @"alpha", nil]]; 
+ (id)valueFrom:(id)kvcObject forExtendedKeyPath:(NSArray *)path;

// Alternate version that puts the array together for you. 
// Example: 
// [OGKeyPath valueFrom:myObject forExtendedKeyPathWithObjects:
//  @"configs", [NSNumber numberWithInt:3], @"color", @"alpha", nil]; 
+ (id)valueFrom:(id)kvcObject forExtendedKeyPathWithObjects:(id)firstPathSegment, ...;

@end

OGKeyPath.m

//
//  OGKeyPath.m
//
//  Created by Jim on 3/11/10.
//  
//  Copyright (c) 2010 Jim Kang/Phalange Software.
//  
//  Permission is hereby granted, free of charge, to any person
//  obtaining a copy of this software and associated documentation
//  files (the "Software"), to deal in the Software without
//  restriction, including without limitation the rights to use,
//  copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the
//  Software is furnished to do so, subject to the following
//  conditions:
//  
//  The above copyright notice and this permission notice shall be
//  included in all copies or substantial portions of the Software.
//  
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
//  OTHER DEALINGS IN THE SOFTWARE.

#import "OGKeyPath.h"


@implementation OGKeyPath

+ (void)set:(id)kvcObject value:(id)value forExtendedKeyPathWithObjects:(id)object, ... 
{
    NSMutableArray* path = [NSMutableArray array];
    va_list ap;
    va_start(ap, object);
    while (object) 
    {
        [path addObject:object];
        object = va_arg(ap, id);
    }
    va_end(ap);
    [OGKeyPath set:kvcObject value:value forExtendedKeyPath:path];
}
    
+ (void)set:(id)kvcObject value:(id)value forExtendedKeyPath:(NSArray *)path
{
    if ([path isKindOfClass:[NSArray class]] && [path count] > 0)
    {
        NSArray *penultimatePath = [path subarrayWithRange:NSMakeRange(0, [path count] - 1)];
        id objectAtPenultimatePath = [OGKeyPath valueFrom:kvcObject forExtendedKeyPath:penultimatePath];
        id lastPathSegment = [path objectAtIndex:[path count] - 1];
        if ([lastPathSegment isKindOfClass:[NSString class]])
        {
			if ([objectAtPenultimatePath isKindOfClass:[NSMutableArray class]] && 
				([lastPathSegment intValue] < [objectAtPenultimatePath count]))
			{
				[objectAtPenultimatePath replaceObjectAtIndex:[lastPathSegment intValue] withObject:value];
			}
			else 
			{
				[objectAtPenultimatePath setValue:value forKey:lastPathSegment];
			}
        }
        else if ([lastPathSegment isKindOfClass:[NSNumber class]])
        {
            if ([lastPathSegment isKindOfClass:[NSMutableArray class]])
            {
                [objectAtPenultimatePath replaceObjectAtIndex:[lastPathSegment intValue] withObject:value];
            }
            else 
            {
                NSLog(@"set:value:forExtendedKeyPath: is in the position of applying an array index %d \
                      to a non-mutable-array object, which it can't do.", [lastPathSegment intValue]);
            }
        }
        else 
        {
            NSLog(@"set:value:forExtendedKeyPath: encountered a path segment it can't handle.");
        }        
    }
}

+ (id)valueFrom:(id)kvcObject forExtendedKeyPath:(NSArray *)path
{
    id currentValue = kvcObject;
    for (id pathSegment in path) 
    {
        if ([pathSegment isKindOfClass:[NSString class]])
        {
            currentValue = [currentValue valueForKey:pathSegment];
        }
        else if ([pathSegment isKindOfClass:[NSNumber class]])
        {
            if ([currentValue isKindOfClass:[NSArray class]])
            {
                currentValue = [currentValue objectAtIndex:[currentValue intValue]];
            }
            else 
            {
                NSLog(@"valueFrom:forExtendedKeyPath: is in the position of applying an array index %d \
                      to a non-array object, which it can't do.", [currentValue intValue]);
                break;
            }
        }
        else 
        {
            NSLog(@"valueFrom:forExtendedKeyPath: encountered a path segment it can't handle.");
            break;
        }        
    }
    
    return currentValue;
}

+ (id)valueFrom:(id)kvcObject forExtendedKeyPathWithObjects:(id)object, ...
{
    NSMutableArray* path = [NSMutableArray array];
    va_list ap;
    va_start(ap, object);
    while (object) 
    {
        [path addObject:object];
        object = va_arg(ap, id);
    }
    va_end(ap);
    return [OGKeyPath valueFrom:kvcObject forExtendedKeyPath:path];
}

@end

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