R/read_yaml_header.R

In pik-piam/gms: 'GAMS' Modularization Support Package

#' read_yaml_header
#'
#' Reads header written in yaml format from a file
#'
#'
#' @param file path to the file which contains the YAML header
#' @param n Number of lines to be read (header must be part of these lines in order to be read)
#' @return A list containing the read in information
#' @author Jan Philipp Dietrich
#' @importFrom yaml yaml.load
#' @export

read_yaml_header <- function(file, n = 20) { # nolint: object_name_linter
  tmp <- readLines(file, n = 20)
  range <- grep("# ?-{3}", tmp)
  if (length(range) > 2) warning("More than two YAML separators detected, only the first two will be used!")
  if (length(range) < 2 || range[1] + 1 == range[2]) return(NULL)
  out <- tryCatch(yaml.load(sub("^#", "", tmp[(range[1] + 1):(range[2] - 1)])),
                  error = function(e) return(list(error = "corrupt YAML header")))
  return(out)
}