Add --wrap=preserve by default

fixes #115

This handles the changes in Pandoc 2.19+ with default wrapping, as it was needed in bookdown

DESCRIPTION

@@ -1,7 +1,7 @@
 Type: Package
 Package: tufte
 Title: Tufte's Styles for R Markdown Documents
-Version: 0.12.1
+Version: 0.12.3
 Authors@R: c(
     person("Yihui", "Xie", role = "aut", email = "xie@yihui.name", comment = c(ORCID = "0000-0003-0645-5666")),
     person("Christophe", "Dervieux", role = c("ctb", "cre"), email = "cderv@rstudio.com", comment = c(ORCID = "0000-0003-4474-2498")),

NEWS.md

@@ -1,5 +1,7 @@
 # CHANGES IN tufte VERSION 0.13
 
+- Fix issue with margin content when using Pandoc 2.19 and later by adding `--wrap preserve` by default (thanks, @TomBen, #115).
+
 # CHANGES IN tufte VERSION 0.12
 
 - Fix footnotes as sidenotes issue with Pandoc 2.15 and later (thanks, @MCMaurer, #108).

R/html.R

@@ -33,6 +33,9 @@ tufte_html <- function(..., tufte_features = c("fonts", "background", "italics")
   format <- html_document2(theme = NULL, ...)
   pandoc2 <- pandoc2.0()
 
+  # add --wrap=preserve to pandoc args for pandoc 2.0:
+  format$pandoc$args <-  add_wrap_preserve(format$pandoc$args, pandoc2)
+
   # when fig.margin = TRUE, set fig.beforecode = TRUE so plots are moved before
   # code blocks, and they can be top-aligned
   ohooks <- knitr::opts_hooks$set(fig.margin = function(options) {

R/utils.R

@@ -76,3 +76,14 @@ template_resources <- function(name, ...) {
 gsub_fixed <- function(...) gsub(..., fixed = TRUE)
 
 pandoc2.0 <- function() rmarkdown::pandoc_available("2.0")
+
+# add --wrap=preserve to pandoc args for pandoc 2.0:
+# https://github.com/rstudio/bookdown/issues/504
+# https://github.com/rstudio/tufte/issues/115
+add_wrap_preserve <- function(args, pandoc2 = pandoc2.0) {
+  if (pandoc2 && !length(grep("--wrap", args))) {
+    c("--wrap", "preserve", args)
+  } else {
+    args
+  }
+}