use backslashes with findstr on windows

Author: rok-cesnovar

R/read_csv.R

@@ -204,7 +204,8 @@ read_cmdstan_csv <- function(files,
       all_draws <- 1
     }
     if (os_is_windows()) {
-      fread_cmd <- paste0("findstr /b /v '#' ", output_file)
+      output_file_backslashes <- gsub("/", "\\\\", , output_file)
+      fread_cmd <- paste0("findstr /b /v '#' ", output_file_backslashes)
     } else {
       fread_cmd <- paste0("grep -v '^#' ", output_file)
     }
@@ -386,6 +387,7 @@ read_csv_metadata <- function(csv_file) {
   inv_metric_rows <- 0
   parsing_done <- FALSE
   if (os_is_windows()) {
+    csv_file_backslashes <- gsub("/", "\\\\", , csv_file)
     fread_cmd <- paste0("findstr /b '[#a-zA-Z]' ", csv_file)
   } else {
     fread_cmd <- paste0("grep '^[#a-zA-Z]' ", csv_file)