Swift-JSONを自分なりに書いてみる練習 (書きかけ)

json.swift

import Cocoa

let JSONErrorDomain: String = "JSONErrorDomain"

enum JSONErrorCode: Int {
    case InvalidData = 0
}

@objc class JSON: NSObject {
    
    private(set) var object: AnyObject?
    
    @objc(isValid) var valid: Bool {
        get {
            if object != nil {
                return NSJSONSerialization.isValidJSONObject(object!)
            } else {
                return false
            }
        }
    }
    
    init(object: AnyObject?) {
        super.init()
        
        self.object = object
    }
    
    convenience init(data: NSData, error: NSErrorPointer) {
        self.init(object: NSJSONSerialization.JSONObjectWithData(data, options: nil, error: error))
    }
    
    convenience init(string: String, error: NSErrorPointer) {
        if let data = string.dataUsingEncoding(NSUTF8StringEncoding) {
            self.init(object: NSJSONSerialization.JSONObjectWithData(data, options: nil, error: error))
        } else {
            self.init(object: nil)
            
            error.memory = NSError(
                domain: JSONErrorDomain,
                code: JSONErrorCode.InvalidData.toRaw(),
                userInfo: nil
            )
        }
    }
    
}

extension JSON {
    
    override var description: String {
        if object != nil {
            return "\(object!)"
        } else {
            return "nil"
        }
    }
    
}

extension JSON {
    
    subscript(key: NSCopying) -> JSON {
        if let dictionary = object as? NSDictionary {
            if let object: AnyObject = dictionary[key] {
                return JSON(object: object)
            }
        }
        
        return JSON(object: nil)
    }
    
    subscript(index: UInt) -> JSON {
        if let array = object as? NSArray {
            return JSON(object: array[Int(index)])
        }
        
        return JSON(object: nil)
    }
    
}

extension JSON {
    
    var isNil: Bool { return object == nil }
    
    var asArray: NSArray { return object as NSArray }
    var asDictionary: NSDictionary { return object as NSDictionary }
    var asString: String { return object as String }
    var asInt: Int { return object as Int }
    var asBool: Bool { return object as Bool }
    
}