Support new pre_knit feature

From rstudio/rmarkdown#2485

closes #544

DESCRIPTION

@@ -1,7 +1,7 @@
 Type: Package
 Package: rticles
 Title: Article Formats for R Markdown
-Version: 0.27.7
+Version: 0.27.8
 Authors@R: c(
     person("JJ", "Allaire", , "[email protected]", role = "aut"),
     person("Yihui", "Xie", , "[email protected]", role = "aut",
@@ -89,7 +89,7 @@ BugReports: https://github.com/rstudio/rticles/issues
 Imports: 
     knitr (>= 1.30),
     lifecycle,
-    rmarkdown (>= 2.14),
+    rmarkdown (>= 2.25),
     tinytex (>= 0.30),
     utils,
     xfun,

R/article.R

@@ -507,30 +507,30 @@ springer_article <- function(..., keep_tex = TRUE,  citation_package = "natbib",
   )
 
   pre_knit_fun <- format$pre_knit
-  format$pre_knit <-  function(input, ...) {
+  format$pre_knit <-  function(input, metadata, ...) {
     if (is.function(pre_knit_fun)) pre_knit_fun(input, ...)
     # for backward compatibility as we changed the template in
     # https://github.com/rstudio/rticles/pull/494
-    options <- rmarkdown::yaml_front_matter(input)
     new_template_msg <- function(ver) return (c(sprintf("If you are rendering an old Rmd, be advise that the template has changed in version '%s'\n", ver),
     " and you should check new template or start from a fresh template to get latest resources and new YAML header format."))
-    if (is.null(options[["classoptions"]])) {
+    if (is.null(metadata[["classoptions"]])) {
       stop("`springer_article()` now requires the 'classoptions' field in YAML front matter. ",
            new_template_msg("0.25"), call. = FALSE)
-    } else if ("sn-mathphys" %in% options[["classoptions"]]) {
+    } else if ("sn-mathphys" %in% metadata[["classoptions"]]) {
       stop("classoptions `sn-mathphys` detected. `springer_article()` now uses 'sn-mathphys-num' or `sn-mathphys-ay`. ",
               new_template_msg("0.28"), call. = FALSE)
     }
-    if (!is.null(options[["biblio-style"]])) {
+    if (!is.null(metadata[["biblio-style"]])) {
       warning("`springer_article()` now ignores the 'biblio-style' field in YAML front matter. ",
       "Reference style for 'natbib' is now set using the 'classoptions' field.\n",
-      new_template_msg("0.25"))
+      new_template_msg("0.25"),
+      immediate. = TRUE, call. = FALSE)
     }
-    if (!is.null(options[["PACS"]])) {
+    if (!is.null(metadata[["PACS"]])) {
       warning("`springer_article()` now ignores the 'PACS' field in YAML front matter to use `pacs.jel` and `pacs.msc`. ",
-              new_template_msg("0.25"))
+              new_template_msg("0.25"), immediate. = TRUE, call. = FALSE)
     }
-    if (!is.null(options[["authors"]][["name"]])) {
+    if (!is.null(metadata[["authors"]][["name"]])) {
       stop("`springer_article()` now uses different authors and affiliations fields.\n",
               new_template_msg("0.25"), call. = FALSE)
     }