Remove obsolete backports (#1882)

R/utils.R

@@ -9,31 +9,12 @@ escape_regex <- function(x) {
   gsub(paste0("([\\", paste0(collapse = "\\", chars), "])"), "\\\\\\1", x, perl = TRUE)
 }
 
-# For R 3.1
-dir.exists <- function(paths) {
-  file.exists(paths) & file.info(paths)$isdir
-}
-
 maybe_restart <- function(restart) {
   if (!is.null(findRestart(restart))) {
     invokeRestart(restart)
   }
 }
 
-# Backport for R 3.2
-strrep <- function(x, times) {
-  x = as.character(x)
-  if (length(x) == 0L)
-    return(x)
-  unlist(.mapply(function(x, times) {
-    if (is.na(x) || is.na(times))
-      return(NA_character_)
-    if (times <= 0L)
-      return("")
-    paste0(replicate(times, x), collapse = "")
-  }, list(x = x, times = times), MoreArgs = list()), use.names = FALSE)
-}
-
 # Backport for R < 4.0
 deparse1 <- function(expr, ...) paste(deparse(expr, ...), collapse = "\n")