write_pgfkeys <- function(x, ...) {
  UseMethod("write_pgfkeys")
}

.pgfkey <- function(key, value) {
  str_c("\\pgfkeysetvalue{", key, "}{", value, "}")
}

write_pgfkeys.default <- function(x, path=NULL, root = "/data/", ...) {
  keys <- str_c(root, names(x)) %>%
  # ensure leading and trailing / and no //
    str_replace("^/*", "/") %>%
    str_replace("/*$", "/") %>%
    str_replace("//", "/")

  out <- str_c(map2_chr(keys, as.character(x), .pgfkey), collapse = "\n")
  if (!is.null(path)) {
    cat(out, file = path)
  }
  invisible(out)
}

write_pgfkeys.environment <- function(x, ....) {
  v <- set_names(map_chr(names(x), function(i) as.character(x[[i]])),
                names(x))
  write_pgfkeys.character(v)
}