Past exam of the year 1 of the computer science course of the University of Oxford / 2014 / Imperative programming / 7 / c

Convert lowercase alphabet letters before passing them to the next implementation. Already uppercase letters and other characters pass through unchanged.

trait CapitalisePlugIn extends Doc {
  abstract override def insert(x: Char, pos: Int): Unit = {
    val y = if ('a' <= x && x <= 'z') ('A' + (x - 'a')).toChar else x
    super.insert(y, pos)
  }
}

The character conversion uses the paper's contiguous lowercase and uppercase Latin ranges. Thus