Shift bits to the left - Generic version. This is the most advanced Generic function I ever wrote (req: extensions, protocol, funcs)

shift_left_generic

// Playground - noun: a place where people can play

import Foundation

/** Protocol and extensions for integerFromBitsArray. Bit hakish for me, but I can't do it in any other way */
protocol Initiable  {
    init(_ v: Int)
    init(_ v: UInt)
}

extension Int:Initiable {}
extension UInt:Initiable {}

// helper to be able tomake shift operation on T
func <<<T:SignedIntegerType>(lhs: T, rhs: Int) -> Int {
    let a = lhs as Int
    let b = rhs
    return a << b
}

func <<<T:UnsignedIntegerType>(lhs: T, rhs: Int) -> UInt {
    let a = lhs as UInt
    let b = rhs
    return a << b
}

// Generic function itself
func shiftLeft<T: SignedIntegerType where T: Initiable>(value: T, count: Int) -> T {
    if (value == 0) {
        return 0;
    }
    
    var bitsCount = sizeofValue(value) * 8
    var shiftCount = Int(Swift.min(count, bitsCount - 1))
    var shiftedValue:T = 0;
    
    for bitIdx in 0..<bitsCount {
        var bit = T(1 << bitIdx)
        if ((value & bit) == bit) {
            shiftedValue = shiftedValue | T(bit << shiftCount)
        }
    }
    return shiftedValue
}

// for any f*** other Integer type - this part is so non-Generic
func shiftLeft(value: UInt, count: Int) -> UInt {
    return UInt(shiftLeft(UInt(value), count))
}

func shiftLeft(value: UInt8, count: Int) -> UInt8 {
    return UInt8(shiftLeft(UInt(value), count))
}

func shiftLeft(value: UInt16, count: Int) -> UInt16 {
    return UInt16(shiftLeft(UInt(value), count))
}

func shiftLeft(value: UInt32, count: Int) -> UInt32 {
    return UInt32(shiftLeft(UInt(value), count))
}

func shiftLeft(value: UInt64, count: Int) -> UInt64 {
    return UInt64(shiftLeft(UInt(value), count))
}

func shiftLeft(value: Int8, count: Int) -> Int8 {
    return Int8(shiftLeft(Int(value), count))
}

func shiftLeft(value: Int16, count: Int) -> Int16 {
    return Int16(shiftLeft(Int(value), count))
}

func shiftLeft(value: Int32, count: Int) -> Int32 {
    return Int32(shiftLeft(Int(value), count))
}

func shiftLeft(value: Int64, count: Int) -> Int64 {
    return Int64(shiftLeft(Int(value), count))
}

// testing

shiftLeft(1, 2) as UInt
shiftLeft(1, 2) as UInt8
shiftLeft(1, 2) as UInt16
shiftLeft(1, 2) as UInt32
shiftLeft(1, 2) as UInt64

shiftLeft(1, 2) as Int
shiftLeft(1, 2) as Int8
shiftLeft(1, 2) as Int16
shiftLeft(1, 2) as Int32
shiftLeft(1, 2) as Int64