R/envvar_get_list.R

In envvar: Make Working with Environment Variables Easier and More Consistent

#' @rdname list
#' @title Environment variables containing lists
#'
#' @description `envvar_get_list() ` gets lists from environment variables. At
#'   the moment, only unnamed lists are supported.
#'
#' @inheritParams envvar_get
#' @param pattern String specifying the pattern used to separate elements in the
#'   list.
#' @param ... Additional arguments passed to [strsplit]

#'
#' @return A list
#' @export
#'
#' @examples
#' # Get the value of `$PATH`, creating a list with elements for each directory
#' envvar_get_list("PATH")
#'
#' # Parse an list separated by `|`
#' envvar_set("ROOMMATES" = "nandor|laszlo|nadja|guillermo|colin")
#' envvar_get_psv("ROOMMATES")
envvar_get_list <- function(x,
                            pattern = ":",
                            default = NULL,
                            validate = NULL,
                            warn_default = TRUE,
                            ...) {
  assert_scalar_string(pattern)
  # TODO: validate `default`
  rlang::check_dots_used()

  envvar_get(
    x,
    default = default,
    transform = function(x) {
      strsplit(x, split = pattern, ...)[[1]]
    },
    validate = validate,
    warn_default = warn_default
  )
}


#' @rdname list
#' @description  `envvar_get_csv()` and `envvar_get_psv()` are an easy way to
#' use `envvar_get_list()` with comma or pipe separators.
#' @export
#'
envvar_get_csv <- function(x,
                           default = NA,
                           validate = NULL,
                           warn_default = TRUE) {
  envvar_get_list(
    x,
    pattern = "\\s*,\\s*",
    default = default,
    validate = validate,
    warn_default = warn_default
  )
}


#' @rdname list
#' @export
#'
envvar_get_psv <- function(x,
                           default = NA,
                           validate = NULL,
                           warn_default = TRUE) {
  envvar_get_list(
    x,
    pattern = "\\s*\\|\\s*",
    default = default,
    validate = validate,
    warn_default = warn_default
  )
}