Add support for # %% for chunk demarcation in knitr::spin

NEWS.md

@@ -4,6 +4,8 @@
 
 - Added a new chunk option `tab.cap` to specify the table caption for `kable()` (thanks, @ulyngs, #1679). Previously, the caption could only be specified via the `caption` argument of `kable()`. Now you can set it in the chunk header if you want. Please note that this chunk option only works with a single `kable()` in each code chunk, and its value must be of length 1.
 
+- `knitr::spin()` now recognizes `# %%` as a valid code chunk delimiter (thanks, @kylebutts, #2307).
+
 ## BUG FIXES
 
 - `write_bib()` generated empty entries for packages without URLs (thanks, @bastistician, #2304).

R/spin.R

@@ -3,8 +3,8 @@
 #' This function takes a specially formatted R script and converts it to a
 #' literate programming document. By default normal text (documentation) should
 #' be written after the roxygen comment (\code{#'}) and code chunk options are
-#' written after \code{#+} or \code{#-} or \code{# ----} or any of these
-#' combinations replacing \code{#} with \code{--}.
+#' written after \code{#+} or \code{# \%\%} or \code{#-} or \code{# ----} or
+#' any of these combinations replacing \code{#} with \code{--}.
 #'
 #' Obviously the goat's hair is the original R script, and the wool is the
 #' literate programming document (ready to be knitted).
@@ -90,7 +90,8 @@ spin = function(
       # R code; #+/- indicates chunk options
       block = strip_white(block) # rm white lines in beginning and end
       if (!length(block)) next
-      if (length(opt <- grep(rc <- '^(#|--)+(\\+|-| ----+| @knitr)', block))) {
+      rc <- '^(#|--)+(\\+|-|\\s+%%| ----+| @knitr)'
+      if (length(opt <- grep(rc, block))) {
         opts = gsub(paste0(rc, '\\s*|-*\\s*$'), '', block[opt])
         opts = paste0(ifelse(opts == '', '', ' '), opts)
         block[opt] = paste0(p[1L], opts, p[2L])