Fix conflict between collapse=TRUE and htmlwidgets

NEWS.md

@@ -1,5 +1,9 @@
 # CHANGES IN knitr VERSION 1.43
 
+## BUG FIXES
+
+- The chunk option `collapse = TRUE` works with HTML widgets now (thanks, @dmurdoch, #2212).
+
 ## MINOR CHANGES
 
 - For `.Rnw` documents, dots in figure file paths are no longer sanitized to underscores (thanks, @otoomet, #2213). Other special characters are still sanitized, but this feature can be turned off via `options(knitr.sanitize.paths = FALSE)`.

R/hooks-md.R

@@ -214,6 +214,7 @@ hooks_markdown = function(strict = FALSE, fence_char = '`') {
       if (isTRUE(options$collapse)) {
         r = sprintf('\n([%s]{3,})\n+\\1((\\{[.])?%s[^\n]*)?\n', fence_char, tolower(options$engine))
         x = gsub(r, '\n', x)
+        x = gsub(asis_token, '', x, fixed = TRUE)
       }
       x = pandoc_div(x, options[['attr.chunk']], options[['class.chunk']])
       if (is.null(s <- options$indent)) return(x)

R/output.R

@@ -464,6 +464,16 @@ sew.character = function(x, options, ...) {
   knit_hooks$get('output')(x, options)
 }
 
+asis_token = '<!-- KNITR_ASIS_OUTPUT_TOKEN -->'
+wrap_asis = function(x, options) {
+  x = as.character(x)
+  if ((n <- length(x)) == 0 || !out_format('markdown') || !isTRUE(options$collapse))
+    return(x)
+  x[1] = paste0(asis_token, x[1])
+  x[n] = paste0(x[n], asis_token)
+  x
+}
+
 # If you provide a custom print function that returns a character object of
 # class 'knit_asis', it will be written as is.
 #' @export
@@ -481,10 +491,10 @@ sew.knit_asis = function(x, options, inline = FALSE, ...) {
     if (inherits(x, 'knit_asis_htmlwidget')) {
       options$fig.cur = plot_counter()
       options = reduce_plot_opts(options)
-      return(add_html_caption(options, x))
+      return(add_html_caption(options, wrap_asis(x, options)))
     }
   }
-  x = as.character(x)
+  x = wrap_asis(x, options)
   if (!out_format('latex') || inline) return(x)
   # latex output need the \end{kframe} trick
   options$results = 'asis'

tests/testit/test-hooks-md.R

@@ -29,7 +29,7 @@ assert('include_graphics() includes custom images correctly', {
 hook_src = knit_hooks$get("source")
 options_ = list(engine = "r", prompt = FALSE, highlight = TRUE)
 
-assert('Lengh of fences are satisfied', {
+assert('Length of fences are satisfied', {
   (hook_src("", options_) %==% "\n\n```r\n\n```\n\n")
   (hook_src("```", options_) %==% "\n\n````r\n```\n````\n\n")
 })
@@ -54,7 +54,7 @@ assert('class.source and attr.source works also with collapse = TRUE', {
 
 hook_out = knit_hooks$get("output")
 
-assert('Attributes for souce can be specified class.source and attr.source', {
+assert('Attributes for source can be specified class.source and attr.source', {
   (hook_out("1\n", c(options_, class.output = "a b")) %==%
     "\n\n```{.a .b}\n1\n```\n\n")
   (hook_out("1\n", c(options_, attr.output = ".a .b")) %==%