Ternary Swift 3 Operators Example

ternary.swift

import Foundation

precedencegroup GreaterBPrecedence {
    associativity: left
    higherThan: LogicalConjunctionPrecedence
}

precedencegroup EqualBPrecedence {
    associativity: left
    higherThan: GreaterBPrecedence
}

infix operator >==: GreaterBPrecedence
infix operator <==>: EqualBPrecedence

typealias HashCashBitField = [UInt8]

func <==>(lhs: @autoclosure @escaping () -> HashCashBitField, rhs: @autoclosure @escaping () -> HashCashBitField) -> (Int) -> Bool {
    return { (rangeIndexToMatchUpTo: Int) -> Bool in
        let leftBitfield = lhs()
        let rightBitfield = rhs()
        var matchingRange = 0
        
        var counter = 0
        for leftByte in leftBitfield {
            let rightByte = rightBitfield[counter]
            
            let diff = leftByte ^ rightByte
            var checker: UInt8 = 0b10000000
            
            while (checker & diff == 0) {
                matchingRange = matchingRange + 1
                checker = checker >> 1
            }
            
            counter = counter + 1
        }
        
        return matchingRange >= rangeIndexToMatchUpTo
    }
}

func >==(lhs: Int, rhs: (Int) -> Bool) -> Bool {
    return rhs(lhs)
}

let field1: HashCashBitField = [0b01010101]
let field2: HashCashBitField = [0b01011111]

4 >== field1 <==> field2
// => true

5 >== field1 <==> field2
// => false