guard against renderMarkdown(text = character(0) or '') (yihui/knitr#918

)
rstudio · Dec 18, 2014 · 24a71d0 · 24a71d0
1 parent d2ca2ff
commit 24a71d0
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Showing 2 changed files with 11 additions and 0 deletions.
diff --git a/R/renderMarkdown.R b/R/renderMarkdown.R
@@ -94,6 +94,9 @@ rendererOutputType <- function(name) {
 #' @export renderMarkdown
 #' @examples
 #' (renderMarkdown(text = "Hello World!"))
+#' # a few corner cases
+#' (renderMarkdown(text = character(0)))
+#' (renderMarkdown(text = ''))
 renderMarkdown <- function(
   file, output = NULL, text = NULL, renderer = 'HTML', renderer.options = NULL,
   extensions = getOption('markdown.extensions'), encoding = getOption('encoding')
@@ -125,6 +128,11 @@ renderMarkdown <- function(
       stop('HTML options must be a character vector')
   }
 
+  if (length(text) == 0 || text == '') {
+     if (is.null(output)) return(invisible(character(length(text))))
+     file.create(output)
+     return()
+  }
   ret <- .Call(rmd_render_markdown,
                file, output, text, renderer, renderer.options, extensions)
 

diff --git a/man/renderMarkdown.Rd b/man/renderMarkdown.Rd
@@ -46,6 +46,9 @@ GitHub. C stubs are available to implement new renderers.
 }
 \examples{
 (renderMarkdown(text = "Hello World!"))
+# a few corner cases
+(renderMarkdown(text = character(0)))
+(renderMarkdown(text = ""))
 }
 \seealso{
 \code{\link{markdownExtensions}}, \code{\link{markdownHTMLOptions}},