use litedown for rendering vignettes (#6583)

* add first steps

* add litedown R CMD check occasional

* remove knitr::opts_chunk

* set comment char

* add error option

* update comment char

* adjust print

* remove space

* fix namespace

* Update vignettes/datatable-benchmarking.Rmd

Co-authored-by: Yihui Xie <xie@yihui.name>

* use yihuis suggestions

* upd translation script and r -> {r} code blocks

* move knitr tests

* Enhances: knitr

Since we register a method for knitr::knit_print, keep it mentioned in
the DESCRIPTION.

* Register xfun::record_print method for data.table

As with knit_print, avoid printing x when !shouldPrint(x). Use the
overloaded method in the vignettes instead of relying on the
auto-printing detection in print.data.table.

* add nocov

* add nocov for knitr_print

* nocov range

* Add missing periods.

* Fix footnote

* Fix remaining `r ...` expressions

* update joins vignette

* set/unset threads

* sys.date

* add xfun to enhances

* add litedown mock

* fix translation links

* more translation links

* remove knitr in fread and fwrite vignette

* add NEWS

---------

Co-authored-by: Yihui Xie <xie@yihui.name>
Co-authored-by: Ricardo Villalba <rikivillalba@gmail.com>
Co-authored-by: Ivan K <krylov.r00t@gmail.com>
Co-authored-by: Michael Chirico <chiricom@google.com>
Co-authored-by: Christian Wia <w9204-gi@yahoo.com>

Author: 6 people

.dev/CRAN_Release.cmd

@@ -323,7 +323,7 @@ Rdevel-strict-[gcc|clang] CMD check data.table_1.16.99.tar.gz
 Rdevel-strict-[gcc|clang]
 isTRUE(.Machine$sizeof.longdouble==0)  # check noLD is being tested
 options(repos = "http://cloud.r-project.org")
-install.packages(c("bit64", "bit", "R.utils", "xts", "zoo", "yaml", "knitr", "markdown"),
+install.packages(c("bit64", "bit", "R.utils", "xts", "zoo", "yaml", "litedown"),
                  Ncpus=4)
 # Issue #5491 showed that CRAN is running UBSAN on .Rd examples which found an error so we now run full R CMD check
 q("no")

.github/workflows/R-CMD-check-occasional.yaml

@@ -111,7 +111,7 @@ jobs:
             TEST_DATA_TABLE_WITH_OTHER_PACKAGES=as.character(run_other)
           )
 
-          do_vignettes = requireNamespace("knitr", quietly=TRUE)
+          do_vignettes = requireNamespace("litedown", quietly=TRUE)
 
           build_args = NULL
           check_args = c("--no-manual", "--as-cran")

DESCRIPTION

@@ -3,12 +3,13 @@ Version: 1.18.99
 Title: Extension of `data.frame`
 Depends: R (>= 3.5.0)
 Imports: methods
-Suggests: bit64 (>= 4.0.0), bit (>= 4.0.4), R.utils (>= 2.13.0), xts, zoo (>= 1.8-1), yaml, knitr, markdown
+Suggests: bit64 (>= 4.0.0), bit (>= 4.0.4), R.utils, xts, zoo (>= 1.8-1), yaml, litedown
+Enhances: knitr, xfun
 Description: Fast aggregation of large data (e.g. 100GB in RAM), fast ordered joins, fast add/modify/delete of columns by group using no copies at all, list columns, friendly and fast character-separated-value read/write. Offers a natural and flexible syntax, for faster development.
 License: MPL-2.0 | file LICENSE
 URL: https://r-datatable.com, https://Rdatatable.gitlab.io/data.table, https://github.com/Rdatatable/data.table
 BugReports: https://github.com/Rdatatable/data.table/issues
-VignetteBuilder: knitr
+VignetteBuilder: litedown
 Encoding: UTF-8
 ByteCompile: TRUE
 Authors@R: c(

NAMESPACE

@@ -114,7 +114,10 @@ if (getRversion() >= "4.0.0") {
   # version of R (and that is checked in .onLoad with error if not).
   export(.rbind.data.table) # only export in R<4.0.0 where it is still used; R-devel now detects it is missing doc, #5600
 }
-if (getRversion() >= "3.6.0") S3method(knitr::knit_print, data.table) # else manual delayed registration from the onLoad hook
+if (getRversion() >= "3.6.0") {
+  S3method(knitr::knit_print, data.table)
+  S3method(xfun::record_print, data.table)
+} # else manual delayed registration from the onLoad hook
 S3method(dim, data.table)
 S3method(dimnames, data.table)
 S3method("dimnames<-", data.table)

NEWS.md

@@ -10,6 +10,8 @@
 
 2. pydatatable compatibility layer in `fread()` and `fwrite()` has been removed, [#7069](https://github.com/Rdatatable/data.table/issues/7069). Thanks @badasahog for the report and the PR.
 
+3. Vignettes are now built using `litedown` instead of `knitr`, [#6394](https://github.com/Rdatatable/data.table/issues/6394). Thanks @jangorecki for the suggestion and @ben-schwen and @aitap for the implementation.
+
 ### BUG FIXES
 
 1. `fread()` with `skip=0` and `(header=TRUE|FALSE)` no longer skips the first row when it has fewer fields than subsequent rows, [#7463](https://github.com/Rdatatable/data.table/issues/7463). Thanks @emayerhofer for the report and @ben-schwen for the fix.

R/onLoad.R

@@ -67,6 +67,12 @@
     setHook(packageEvent("knitr", "onLoad"), function(...) {
       registerS3method("knit_print", "data.table", knit_print.data.table, envir = asNamespace("knitr"))
     })
+    if (isNamespaceLoaded("xfun")) {
+      registerS3method("record_print", "data.table", record_print.data.table, envir = asNamespace("xfun"))
+    }
+    setHook(packageEvent("xfun", "onLoad"), function(...) {
+      registerS3method("record_print", "data.table", record_print.data.table, envir = asNamespace("xfun"))
+    })
   }
 
   # Set options for the speed boost in v1.8.0 by avoiding 'default' arg of getOption(,default=)

R/print.data.table.R

@@ -294,7 +294,13 @@ trunc_cols_message = function(not_printed, abbs, class, col.names){
 }
 
 # Maybe add a method for repr::repr_text.  See https://github.com/Rdatatable/data.table/issues/933#issuecomment-220237965
+# nocov start
 knit_print.data.table = function(x, ...) {
   if (!shouldPrint(x)) return(invisible(x))
   NextMethod()
 }
+record_print.data.table = function(x, ...) {
+  if (!shouldPrint(x)) return(character())
+  NextMethod()
+}
+# nocov end

inst/tests/other.Rraw

@@ -182,6 +182,9 @@ if (loaded[["knitr"]]) {
   # Which is fine and works thanks to cedta().
   DT = data.table(x=1, y=2)
   test(11, kable(DT), output="x.*y.*1.*2")
+  invisible(knit(testDir("knitr.Rmd"), quiet=TRUE))
+  cat(readLines("knitr.md"), sep="\n")
+  invisible(file.remove("knitr.md"))
 }
 
 if (loaded[["parallel"]]) {