Word Scanner in Swift

scanner.swift

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

import Cocoa

let str = "Foo Bar bannana' basa fist ada-2@🚅 afa2-ff 👍🎭-asd👍 adsa😃da\ndas🎉d"

let whitespaceSet = NSCharacterSet.whitespaceAndNewlineCharacterSet()

enum ScanResult<T> {
  case Append(T)
  case End
}

func scanWords<T>(string: String, callback: (String, NSRange) -> (ScanResult<T>)) -> [T] {
  let scanner = NSScanner(string: string)
  var results: [T] = []
  
  while (!scanner.atEnd) {
    var substringMaybe: NSString? = nil
    let scanned = scanner.scanUpToCharactersFromSet(whitespaceSet, intoString: &substringMaybe)
    if (!scanned) {
      return results
    }
    
    if let substring = substringMaybe as String? {
      let range = NSMakeRange(scanner.scanLocation, countElements(substring) )
      let result = callback(substring, range)
      
      switch result {
      case .End:
        return results
      case .Append(let value):
        results.append(value)
      }
    }
  }
  
  return results
}

let result = scanWords(str, { (string: String, range: NSRange) -> ScanResult<String> in
  return .Append(string)
})