R/1-pitch-normalize-notation.R

In flujoo/gm: Create Music with Ease

#' @keywords internal
#' @export
to_Pitch.character <- function(x, ...) {
  if (is.na(x)) {
    structure(x, class = "Pitch")

  } else {
    do.call(Pitch, parse_pitch_notation(x))
  }
}


parse_pitch_notation <- function(pitch) {
  pitch <- trimws(pitch)
  l <- nchar(pitch)

  step <- toupper(substr(pitch, 1, 1))
  accidental <- substr(pitch, 2, l - 1)
  alter <- (-2:2)[accidental == c("--", "-", "", "#", "##")]
  octave <- as.integer(substr(pitch, l, l))

  list(step = step, alter = alter, octave = octave)
}