R/ConfEnv-R6.R

In obarisk/rconf: rconf is an R package that works with configuration files

#' Conf Environment
#' 
#' A Conf Environment Class.
#'
#'
#' @section Usage:
#' \preformatted{
#'   Conf = ConfEnv$new(system.file("extdata/example.yml", package="rconf"))
#'   Conf$configuration
#'   Conf$getorstop("config")
#'   Conf$getorstop("db.host")
#'   Conf$getornull("config")
#'   Conf$getornull("db.user")
#' }
#'
#' @section Arguments:
#' \code{filename} The filename of configuration file
#' \code{filetype} The filetype of configuration file values should be one of "" "yml", "json",
#' "ini", default is "" which autodetect filetype by file extension
#'
#' @section Methods:
#' \code{$new} Initialize a Conf interface
#' \code{$load} Load a configuration file
#' \code{$getornull} get value of configuration file by path, if does not exists return null.
#' the path is seperate by . as default. modify it by specify sep parameter.
#' \code{$getorstop} get value of configuration file by path, if does not exists stop program,
#' the path is seperate by . as default. modify it by specify sep parameter.
#' @name ConfEnv
NULL

#' @export
ConfEnv <- R6Class(
  "Conf",
  public=list(
    filename = NULL,
    filetype = "",
    configuration = NULL,
    initialize = function(filename=NA, filetype="") {
      self$filename <- filename
      self$load(filename = self$filename, filetype = self$filetype)
    },
    load=function(filename, filetype) {
      private$setfiletype(filename, filetype)
      self$configuration <- switch(
        self$filetype,
        yml = yaml::yaml.load_file(filename),
        json = jsonlite::fromJSON(filename),
        ini = ini::read.ini(filename)
      )
      invisible(0)
    },
    getornull=function(path, sep="\\.") {
      if (is.null(self$configuration)) {
        stop("please load configuration first")
      }
      return(self$getconf(self$configuration, path, sep))
    },
    getorstop = function(path, sep="\\.") {
      if (is.null(self$configuration)) {
        stop("please load configuration first")
      }
      value <- self$getconf(self$configuration, path, sep)
      if (is.null(value)) {
        stop("no such configuration")
      }
      return(value)
    },
    getconf=function(conflist, path, sep="\\.") {
      p <- strsplit(path, sep)[[1]]
      if (length(p) <= 1) {
        p <- path
        if (p %in% names(conflist)) {
          return(list.extract(conflist, p))
        }else{
          return(NULL)
        }
      } else {
        return(self$getconf(list.extract(conflist, p[1]), p[2]))
      }
    }
  ),
  private=list(
    setfiletype = function(filename, filetype) {
      if (filetype != "" && filetype %in% c("ini", "yml", "json")) {
        filetype <- filetype
      }else if ( grepl("\\.ya*ml$", filename) ) {
        filetype <- "yml"
      }else if ( grepl("\\.json$", filename) ) {
        filetype <- "json"
      }else if ( grepl("\\.ini$", filename) ) {
        filetype <- "ini"
      }else{
        stop("rconf only supports ya*ml, json, and ini.")
      }
      self$filetype <- filetype
    }
  )
)