Added missing util function

R/utils.R

@@ -8,6 +8,11 @@ check_pacman_dir <- function() {
       return(invisible(FALSE))
     }
   }
+  if (!dir.exists("./.pacman/library")) {
+    if (!dir.create("./.pacman/library")) {
+      return(invisible(FALSE))
+    }
+  }
   invisible(TRUE)
 }
 
@@ -21,4 +26,35 @@ get_cran_repo <- function() {
     repo <- getOption("repos")[[1]]
   }
   repo
+}
+
+#' Displays a menu for the user to select elements from.
+#'
+#' @param choices A character vector of choices the user must choose from
+#' @param title An optional string containing text for a title line above the
+#'    menu
+#' @param msg An optional string containung the text directing the user what to
+#'    do, displayed below the menu
+#' @param default An integer containing the index of the default choice to return
+#'
+#' @return string Selected menu choice
+select_menu <- function(choices, title = NULL, msg = "Enter a number from the menu above, or an empty line to default: ", default = 1) {
+  if (!is.null(title)) {
+    cat(title, "\n", sep = "")
+  }
+
+  nc <- length(choices)
+  op <- paste0(format(seq_len(nc)), ": ", choices)
+  fop <- format(op)
+  cat("", fop, "", sep = "\n")
+  repeat {
+    answer <- readline(msg)
+    answer <- strsplit(answer, "[ ,]+")[[1]]
+    if (length(answer) == 0) {
+      return(choices[default])
+    }
+    if (all(answer %in% seq_along(choices))) {
+      return(choices[as.integer(answer)])
+    }
+  }
 }

man/select_menu.Rd

@@ -0,0 +1,30 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/utils.R
+\name{select_menu}
+\alias{select_menu}
+\title{Displays a menu for the user to select elements from.}
+\usage{
+select_menu(
+  choices,
+  title = NULL,
+  msg = "Enter a number from the menu above, or an empty line to default: ",
+  default = 1
+)
+}
+\arguments{
+\item{choices}{A character vector of choices the user must choose from}
+
+\item{title}{An optional string containing text for a title line above the
+menu}
+
+\item{msg}{An optional string containung the text directing the user what to
+do, displayed below the menu}
+
+\item{default}{An integer containing the index of the default choice to return}
+}
+\value{
+string Selected menu choice
+}
+\description{
+Displays a menu for the user to select elements from.
+}