TypeDictionary

TypeDictionary.swift

private struct TypeDescriptor: Hashable, CustomStringConvertible {
    private let type: Any.Type
    internal init(_ type: Any.Type) {
        self.type = type
    }
    
    public var hashValue: Int {
        return String(describing: type).hashValue
    }
    public static func ==(lhs: TypeDescriptor, rhs: TypeDescriptor) -> Bool {
        return lhs.type == rhs.type
    }
    
    public var description: String {
        return String(describing: type)
    }
}

public struct TypeDictionary: ExpressibleByArrayLiteral, CustomStringConvertible {
    private var backing: [TypeDescriptor : Any] = [:]
        
    public mutating func insert(_ value: Any) {
        self.backing[TypeDescriptor(type(of: value))] = value
    }
    public subscript(type: Any.Type) -> Any? {
        return self.backing[TypeDescriptor(type)]
    }
    
    public subscript<T>(type: T.Type) -> T? {
        get {
            guard let value = backing[TypeDescriptor(type)] else { return nil }
            return (value as! T)
        }
        set {
            guard let newValue = newValue else {
                backing[TypeDescriptor(type)] = nil
                return
            }
            backing[TypeDescriptor(type)] = newValue
        }
    }
    
    public init(arrayLiteral: Any...) {
        for value in arrayLiteral {
            self.insert(value)
        }
    }
    
    public var description: String {
        return self.backing.description
    }
}