translation links knitr compatible

Author: rikivillalba

vignettes/_translation_links.R

@@ -1,23 +1,36 @@
 # build a link list of alternative languages (may be character(0))
 # idea is to look like 'Other languages: en | fr | de'
-.write.translation.links <- function(fmt) {
-    url = "https://rdatatable.gitlab.io/data.table/articles"
-    path = dirname(litedown::get_context("input"))
-    if (basename(path) == "vignettes") {
-      lang = "en"
-    } else {
-      lang = basename(path)
-      path = dirname(path)
-    }
-    translation = dir(path,
-      recursive = TRUE,
-      pattern = glob2rx(litedown::get_context("input"))
-    )
-    transl_lang = ifelse(dirname(translation) == ".", "en", dirname(translation))
-    block = if (!all(transl_lang == lang)) {
-      linked_transl = sprintf("[%s](%s)", transl_lang, file.path(url, sub("(?i)\\.Rmd$", ".html", translation)))
-      linked_transl[transl_lang == lang] = lang
-      sprintf(fmt, paste(linked_transl, collapse = " | "))
-    } else ""
-    litedown::raw_text(block)
+.write.translation.links <- function() {
+  url = "https://rdatatable.gitlab.io/data.table/articles"
+  # this guard is needed because pkgdown::build_article does not use litedown 
+  # https://github.com/yihui/knitr/issues/926#issuecomment-68503962
+  knitr = isTRUE(getOption('knitr.in.progress'))
+  if (knitr) {
+    path = knitr::current_input(TRUE)
+    i18n_msg = knitr::opts_current$get("i18n_msg")
+  } else {
+    path = litedown::get_context("input")
+    i18n_msg = litedown::reactor("i18n_msg")
+  }
+  path_dir = dirname(path)
+  if (basename(path_dir) == "vignettes") {
+    lang = "en"
+  } else {
+    lang = basename(path_dir)
+    path_dir = dirname(path_dir)   # might be "vignettes"
+  }
+  translation = dir(path_dir, recursive = TRUE, pattern = glob2rx(path))
+  transl_lang = dirname(translation)
+  transl_lang[transl_lang == "."] = "en"
+  if (any(transl_lang != lang)) {
+    link_path = file.path(url, sub("(?i)\\.Rmd$", ".html", translation))
+    linked_transl = sprintf("[%s](%s)", transl_lang, link_path)
+    linked_transl[transl_lang == lang] = lang
+    block = sprintf(i18n_msg, paste(linked_transl, collapse = " | "))
+  } else {
+    block = ""
+  }
+   #if (knitr) block else litedown::raw_text(block)
+  cat(block)
 }
+.write.translation.links()