BUG FIX: Work around utils::txtProgressBar(min=0, max=0) not being supported (#108)

Author: HenrikBengtsson

R/handler_txtprogressbar.R

@@ -48,10 +48,15 @@ handler_txtprogressbar <- function(style = 3L, file = stderr(), intrusiveness =
   reporter <- local({
     pb <- NULL
 
-    make_pb <- function(...) {
+    make_pb <- function(max, ...) {
       if (!is.null(pb)) return(pb)
-      args <- c(list(...), backend_args)
-      pb <<- do.call(txtProgressBar, args = args)
+      ## SPECIAL CASE: utils::txtProgressBar() does not support max == min
+      if (max == 0) {
+        pb <<- voidProgressBar()
+      } else {
+        args <- c(list(max = max, ...), backend_args)
+        pb <<- do.call(txtProgressBar, args = args)
+      }
       pb
     }
 
@@ -115,9 +120,17 @@ handler_txtprogressbar <- function(style = 3L, file = stderr(), intrusiveness =
 }
 
 
+#' @importFrom utils txtProgressBar
+voidProgressBar <- function(...) {
+  pb <- txtProgressBar()
+  class(pb) <- c("voidProgressBar", class(pb))
+  pb
+}
+
 
 ## Erase a utils::txtProgressBar()
 eraseTxtProgressBar <- function(pb) {
+  if (inherits(pb, "voidProgressBar")) return()
   pb_env <- environment(pb$getVal)
   with(pb_env, {
     if (style == 1L || style == 2L) {
@@ -136,6 +149,7 @@ eraseTxtProgressBar <- function(pb) {
 
 ## Redraw a utils::txtProgressBar()
 redrawTxtProgressBar <- function(pb) {
+  if (inherits(pb, "voidProgressBar")) return()
   setTxtProgressBar(pb, value = pb$getVal())
 }
 

tests/handler_txtprogressbar.R

@@ -4,19 +4,20 @@ options(progressr.clear = FALSE)
 
 message("txtprogressbar ...")
 
-x <- 1:10
-
 for (style in 1:3) {
   message(sprintf("- style = %d ...", style))
   handlers(handler_txtprogressbar(style = style))
 
-  with_progress({
-    progress <- progressor(along = x)
-    for (ii in x) {
-      Sys.sleep(getOption("progressr.demo.delay", 0.1))
-      progress(message = sprintf("(%s)", paste(letters[1:ii], collapse="")))
-    }
-  })
+  for (x in list(1:10, 1L, integer(0))) {
+    message("length(x): ", length(x))
+    with_progress({
+      progress <- progressor(along = x)
+      for (ii in x) {
+        Sys.sleep(getOption("progressr.demo.delay", 0.1))
+        progress(message = sprintf("(%s)", paste(letters[1:ii], collapse="")))
+      }
+    })
+  }
 
   message(sprintf("- style = %d ... done", style))
 }