use Ricardos translation_links version

Author: ben-schwen

vignettes/_translation_links.R

@@ -1,30 +1,30 @@
 # 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) {
-    # Check if we're in a litedown context
-    input_file = litedown::get_context("input")
-    if (is.null(input_file) || !is.character(input_file) || length(input_file) == 0) {
-      # Not in litedown context (e.g., being rendered by rmarkdown/pkgdown)
-      return("")
-    }
-
-    url = "https://rdatatable.gitlab.io/data.table/articles"
-    path = dirname(input_file)
-    if (basename(path) == "vignettes") {
-      lang = "en"
-    } else {
-      lang = basename(path)
-      path = dirname(path)
-    }
-    translation = dir(path,
-      recursive = TRUE,
-      pattern = glob2rx(input_file)
-    )
-    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$", ".html", translation)))
-      linked_transl[transl_lang == lang] = lang
-      sprintf(fmt, paste(linked_transl, collapse = " | "))
-    } else ""
-    litedown::raw_text(block)
+  url = "https://rdatatable.gitlab.io/data.table/articles"
+  # this guard is needed because pkgdown::build_article does not use litedown
+  # https://github.com/yihui/knitr/issues/926#issuecomment-68503962
+  knitr = isTRUE(getOption('knitr.in.progress'))
+  path = if (knitr) knitr::current_input(TRUE) else normalizePath(litedown::get_context("input"))
+  rmdfile = basename(path)
+  rmddir = dirname(path)
+  if (basename(rmddir) == "vignettes") {
+    lang = "en"
+    main_dir = rmddir
+  } else {
+    lang = basename(rmddir)
+    main_dir = dirname(rmddir)
+  }
+  translation = dir(main_dir, recursive = TRUE, pattern = glob2rx(rmdfile))
+  transl_lang = dirname(translation)
+  transl_lang[transl_lang == "."] = "en"
+  if (any(transl_lang != lang)) {
+    link_path = file.path(url, sub("(?i)\\.Rmd$", ".html", translation))
+    linked_transl = sprintf("[%s](%s)", transl_lang, link_path)
+    linked_transl[transl_lang == lang] = lang
+    block = sprintf(fmt, paste(linked_transl, collapse = " | "))
+  } else {
+    block = ""
+  }
+  litedown::raw_text(block)
 }