Function Wrapper Concept

FunctionWrapper.swift

/// Implementation

typealias AnyFunction = ((Any?, ((Any?) -> (Any?))?) -> (Any?))

@functionWrapper
struct Logging {
    let value: AnyFunction

    @discardableResult
    func wrappedFunction(_ arguments: Any?, _ completion: ((Any?) -> (Any?))? = nil) -> Any? {
        let start = mach_absolute_time()
        print("[\(#function)][start]\t\t\(seconds(start))")
        
        if let completion = completion {
            return value(arguments, { result in
                print("[\(#function)][elapsed]\t\t\(seconds(mach_absolute_time() - start))")
                return completion(result)
            })
        } else {
            let result = value(arguments, nil)
            print("[\(#function)][elapsed]\t\t\(seconds(mach_absolute_time() - start))")
            return result
        }
    }

    init(_ value: @escaping AnyFunction) {
        self.value = value
        mach_timebase_info(&timebase)
    }
    
    private var timebase = mach_timebase_info_data_t()
    private func seconds(_ mach: UInt64) -> Double {
        (Double(mach * UInt64(timebase.numer)) / Double(timebase.denom)) / 1.0e9
    }
}

/// Examples

@Logging
func syncFactorAllPrimes(_ input: UInt64) -> [UInt64] {
    // Do very difficult math problem
    let result: [UInt64] = [1, 13, 19]
    print("[\(#function)][result]\t\t\(result)")
    return result
    /**
     Console Output
     -------------------------------------------------------
     [syncFactorAllPrimes(_:)][start]       1629735701
     [syncFactorAllPrimes(_:)][result]      [1, 13, 19]
     [syncFactorAllPrimes(_:)][elapsed]     682ms
     -------------------------------------------------------
     */
}

@Logging
func updateServer(_ completion: @escaping (Bool) -> Void) {
    makePostRequest { didSucceed in completion(didSucceed) }
    /**
     Console Output
     -------------------------------------------------------
     [updateServer(_:)][start]       1629737925
     [updateServer(_:)][elapsed]     93ms
     -------------------------------------------------------
     */
}