Castable

Castable.swift

import Foundation

infix operator ->>: DefaultPrecedence

public protocol Castable {

    func forceCast<U>(to type: U.Type) -> U

    func AS<U>(to type: U.Type) -> U?

    func cast<U>(to type: U.Type) -> U?

    func unsafeBitCast<U>(to type: U.Type) throws -> U

    func unsafeDownCast<U>(to type: U.Type) throws -> U where U: AnyObject

    static func ->> <U>(lhs: Self, rhs: U.Type) -> U?

}

public extension Castable where Self: AnyObject {

    func unsafeDownCast<U>(to type: U.Type) throws -> U where U: AnyObject {
        Swift.unsafeDowncast(self, to: type.self)
    }
}

public extension Castable {

    func isReferenceType() -> Bool {
        return Swift.type(of: self) is AnyClass
    }

    static func ->> <U>(lhs: Self, rhs: U.Type) -> U? {
        lhs as? U
    }

    func forceCast<U>(to type: U.Type) -> U {
        self as! U
    }

    func AS<U>(to type: U.Type) -> U? {
        self as? U
    }

    func cast<U>(to type: U.Type) -> U? {
        self as? U
    }

    func unsafeBitCast<U>(to type: U.Type) throws -> U {
        if MemoryLayout<Self>.size != MemoryLayout<U>.size {
            throw ProtoError.castingError(reason: .bitcastTwoVariableWithDifferentBitCount)
        }

        return Swift.unsafeBitCast(self, to: U.self)
    }

    func unsafeDownCast<U>(to type: U.Type) throws -> U where U: AnyObject {
        throw ProtoError.castingError(reason: .downCastingNonRefrencableVariable)
    }
}

extension NSObject: Castable {}