rename yaml_front_matter to front_matter because the former is al…

…so a function in this package (this is to amend rstudio#1710)

R/render.R

@@ -415,17 +415,17 @@ render <- function(input,
   input_lines <- read_utf8(knit_input)
 
   # read the yaml front matter
-  yaml_front_matter <- parse_yaml_front_matter(input_lines)
+  front_matter <- parse_yaml_front_matter(input_lines)
 
   # metadata to be attached to the returned value of render() as an attribute
   old_output_metadata <- output_metadata$get()
   on.exit(output_metadata$restore(old_output_metadata), add = TRUE)
-  output_metadata$restore(as.list(yaml_front_matter[['rmd_output_metadata']]))
+  output_metadata$restore(as.list(front_matter[['rmd_output_metadata']]))
 
   # if this is shiny_prerendered then modify the output format to
   # be single-page and to output dependencies to the shiny.dep file
   shiny_prerendered_dependencies <- list()
-  if (requires_knit && is_shiny_prerendered(yaml_front_matter$runtime)) {
+  if (requires_knit && is_shiny_prerendered(front_matter$runtime)) {
 
     # first validate that the user hasn't passed an already created output_format
     if (is_output_format(output_format)) {
@@ -511,12 +511,7 @@ render <- function(input,
   # presume that we're rendering as a static document unless specified
   # otherwise in the parameters
   runtime <- match.arg(runtime)
-  if (identical(runtime, "auto")) {
-    if (!is.null(yaml_front_matter$runtime))
-      runtime <- yaml_front_matter$runtime
-    else
-      runtime <- "static"
-  }
+  if (identical(runtime, "auto")) runtime <- front_matter$runtime %||% "static"
 
   # set df_print
   context <- render_context()
@@ -530,7 +525,7 @@ render <- function(input,
   # function used to call post_knit handler
   call_post_knit_handler <- function() {
     if (!is.null(output_format$post_knit)) {
-      post_knit_extra_args <- output_format$post_knit(yaml_front_matter,
+      post_knit_extra_args <- output_format$post_knit(front_matter,
                                                       knit_input,
                                                       runtime)
     } else {
@@ -587,7 +582,7 @@ render <- function(input,
     # read root directory from argument (has precedence) or front matter
     root_dir <- knit_root_dir
     if (is.null(root_dir))
-      root_dir <- yaml_front_matter$knit_root_dir
+      root_dir <- front_matter$knit_root_dir
     if (!is.null(root_dir))
       knitr::opts_knit$set(root.dir = root_dir)
 
@@ -667,7 +662,7 @@ render <- function(input,
     # make the params available within the knit environment
     # (only do this if there are parameters in the front matter
     # so we don't require recent knitr for all users)
-    if (!is.null(yaml_front_matter$params)) {
+    if (!is.null(front_matter$params)) {
 
       params <- knit_params_get(input_lines, params)
 
@@ -703,9 +698,8 @@ render <- function(input,
       }, add = TRUE)
     }
 
-    # make the yaml_front_matter available as 'metadata' within the
-    # knit environment (unless it is already defined there in which case
-    # we emit a warning)
+    # make the front_matter available as 'metadata' within the knit environment
+    # (unless it is already defined there, in which case we emit a warning)
     env <- environment(render)
     metadata_this <- env$metadata
     do.call("unlockBinding", list("metadata", env))
@@ -716,7 +710,7 @@ render <- function(input,
       env$metadata <- metadata_this
       lockBinding("metadata", env)
     }, add = TRUE)
-    env$metadata <- yaml_front_matter
+    env$metadata <- front_matter
 
     # call onKnit hooks (normalize to list)
     sapply(as.list(getHook("rmarkdown.onKnit")), function(hook) {
@@ -738,7 +732,7 @@ render <- function(input,
 
     perf_timer_stop("knitr")
 
-    yaml_front_matter <- yaml_front_matter(input)
+    front_matter <- yaml_front_matter(input)
 
     # call post_knit handler
     output_format$pandoc$args <- call_post_knit_handler()
@@ -763,7 +757,7 @@ render <- function(input,
   if (!(is_pandoc_to_html(output_format$pandoc) ||
         identical(tolower(tools::file_ext(output_file)), "html")))  {
     if (has_html_dependencies(knit_meta)) {
-      if (!isTRUE(yaml_front_matter$always_allow_html)) {
+      if (!isTRUE(front_matter$always_allow_html)) {
         stop("Functions that produce HTML output found in document targeting ",
              pandoc_to, " output.\nPlease change the output type ",
              "of this document to HTML. Alternatively, you can allow\n",
@@ -811,7 +805,7 @@ render <- function(input,
 
     # call any pre_processor
     if (!is.null(output_format$pre_processor)) {
-      extra_args <- output_format$pre_processor(yaml_front_matter,
+      extra_args <- output_format$pre_processor(front_matter,
                                                 utf8_input,
                                                 runtime,
                                                 knit_meta,
@@ -843,7 +837,7 @@ render <- function(input,
         figures_dir <- gsub('/$', '', knitr::opts_chunk$get("fig.path"))
         files <- list.files(figures_dir, full.names = TRUE, recursive = TRUE)
         # https://github.com/rstudio/rmarkdown/issues/1358
-        if (citeproc) files <- c(files, yaml_front_matter[['bibliography']])
+        if (citeproc) files <- c(files, front_matter[['bibliography']])
         for (f in files) {
           intermediates <<- c(intermediates, copy_file_with_dir(f, intermediates_dir))
         }
@@ -908,7 +902,7 @@ render <- function(input,
     texfile <- file_with_ext(output_file, "tex")
     # determine whether we need to run citeproc (based on whether we have
     # references in the input)
-    run_citeproc <- citeproc_required(yaml_front_matter, input_lines)
+    run_citeproc <- citeproc_required(front_matter, input_lines)
     # if the output format is LaTeX, first convert .md to .tex, and then convert
     # .tex to .pdf via latexmk() if PDF output is requested (in rmarkdown <=
     # v1.8, we used to call Pandoc to convert .md to .tex and .pdf separately)
@@ -941,7 +935,7 @@ render <- function(input,
 
     # if there is a post-processor then call it
     if (!is.null(output_format$post_processor))
-      output_file <- output_format$post_processor(yaml_front_matter,
+      output_file <- output_format$post_processor(front_matter,
                                                   utf8_input,
                                                   output_file,
                                                   clean,