gellmark wordscount

typealias Counters = (characters: Int, words: Int, lines: Int)

func count(input: String) -> Counters {
    let isWhitespace = { (character: Unicode.Scalar) in CharacterSet.whitespaces.contains(character) }
    let isNewline = { (character: Unicode.Scalar) in CharacterSet.newlines.contains(character) }
    let isAlphanumeric = { (character: Unicode.Scalar) in CharacterSet.alphanumerics.contains(character) }

    var counters = Counters(0, 0, 0)

    var isTrackingWord = false
    var isTrackingLine = false

    for c in input.unicodeScalars {
        counters.characters += 1
        if isWhitespace(c) && isTrackingWord {
            counters.words += 1
        } else if isNewline(c) && isTrackingLine {
            counters.lines += 1
        } else if isAlphanumeric(c) {
            isTrackingLine = true
            isTrackingWord = true
        }
    }

    return counters
}