R/s3-constructive_options.R

In constructive: Display Idiomatic Code to Construct Most R Objects

#' Constructive options for the class `constructive_options`
#'
#' These options will be used on objects of class `constructive_options`.
#'
#' Depending on `constructor`, we construct the object as follows:
#' * `"opts"` : Use the relevant `constructive::opts_?()` function.
#' * `"next"` : Use the constructor for the next supported class. Call `.class2()`
#'   on the object to see in which order the methods will be tried.
#'
#' @param constructor String. Name of the function used to construct the object, see Details section.
#' @inheritParams opts_atomic
#' @return An object of class <constructive_options/constructive_options_constructive_options>
#' @export
opts_constructive_options <- function(constructor = c("opts", "next"), ...) {
  .cstr_options("constructive_options", constructor = constructor[[1]], ...)
}

#' @export
#' @method .cstr_construct constructive_options
.cstr_construct.constructive_options <- function(x, ...) {
  opts <- list(...)$opts$constructive_options %||% opts_constructive_options()
  if (is_corrupted_constructive_options(x) || opts$constructor == "next") return(NextMethod())
  UseMethod(".cstr_construct.constructive_options", structure(NA, class = opts$constructor))
}

is_corrupted_constructive_options <- function(x) {
  # TODO
  FALSE
}

#' @export
#' @method .cstr_construct.constructive_options opts
.cstr_construct.constructive_options.opts <- function(x, ...) {
  pattern <- "^constructive_options_(.*)$"
  suffix <- sub(pattern, "\\1", grep(pattern, class(x), value = TRUE))
  # FIXME: there should be 1 and only 1, else it's a corrupted object
  # and we should fall back on list constructor
  fun <- paste0("constructive::opts_", suffix)
  # don't name the constructor arg, and don't provide if it's the default
  constructor_pos <- which("constructor" == rlang::names2(x))
  x_bkp <- x
  if (length(constructor_pos)) {
    names(x)[[constructor_pos]] <- ""
    if (x[[constructor_pos]] == as.list(eval(parse(text = fun)))$constructor[[2]]) {
      x[[constructor_pos]] <- NULL
    }
  }
  code <- .cstr_apply(x, fun, ...)
  repair_attributes_constructive_options(x_bkp, code, ...)
}

repair_attributes_constructive_options <- function(x, code, ..., pipe = NULL) {
  .cstr_repair_attributes(
    x, code, ...,
    idiomatic_class = grep("^constructive_options", class(x), value = TRUE)
  )
}