Functional Tokenizer

tokenizer.scala

type Tokenizer = String => Seq[Token]
val tokenizer = new Tokenizer {
  override def apply(input: String): Seq[Token] = input.foldRight(Seq("")) {
    case (c, acc) if Character.isMirrored(c) => Seq("", c.toString) ++ acc
    case (c, acc) => Seq(c + acc.head) ++ acc.tail
  }.map(_.trim).filter(_.nonEmpty).map {
    str => Token(str, str match {
      case "(" | "{" | "[" | "<" => TokenType.LPAREN
      case ")" | "}" | "]" | ">" => TokenType.RPAREN
      case _ => TokenType.STR
    })
  }
}