convert the table of arguments to the sections of arguments with Lua filter

NEWS.md

@@ -1,3 +1,13 @@
+# languageserver 0.3.13
+
+**Closed issues:**
+
+- Some of the tables of arguments are too complex to be represented by GFM (#533) 
+
+**Merged pull requests.**
+
+- Convert the table of arguments to the sections of arguments with Lua filter (#534)
+
 # languageserver 0.3.12
 
 **Closed issues:**

R/utils.R

@@ -727,8 +727,10 @@ html_to_markdown <- function(html) {
     logger$info("Converting html to markdown using", html_file, md_file)
     stringi::stri_write_lines(html, html_file)
     result <- tryCatch({
-        format <- if (rmarkdown::pandoc_version() >= "2.0") "gfm" else "markdown_github"
-        rmarkdown::pandoc_convert(html_file, to = format, output = md_file)
+        pandoc2 <- rmarkdown::pandoc_version() >= "2.0"
+        format <- if (pandoc2) "gfm" else "markdown_github"
+        options <- if (pandoc2) c("--lua-filter", system.file(package = "languageserver", "lua/html-to-markdown.lua"))
+        rmarkdown::pandoc_convert(html_file, to = format, output = md_file, options = options)
         paste0(stringi::stri_read_lines(md_file, encoding = "utf-8"), collapse = "\n")
     }, error = function(e) {
         logger$info("html_to_markdown failed: ", conditionMessage(e))

inst/lua/html-to-markdown.lua

@@ -0,0 +1,39 @@
+--[[
+Converts the Arguments from a table to sections
+
+Conversion happens if the table cannot be represented by the GFM-syntax.
+Cells in the 1st column become headers and those in the 2nd column becomes
+content of the corresponding headers.
+--]]
+function Table(el)
+  local tb = pandoc.utils.to_simple_table(el)
+
+  -- Do nothing if the table has headers or is not composed of 2 columns
+  if #tb.headers > 0 or #tb.rows[1] ~= 2 then return end
+
+  -- Do nothing if the 1st column has cells not comprised of single Plain block
+  -- or if the 2nd column can be represented by the GFM-syntax.
+  local function unlike_para(x)
+    return x.t ~= "Plain" and x.t ~= "Para"
+  end
+  local complex_table = false
+  for _, row in pairs(tb.rows) do
+    if (#row[1] ~= 1) or unlike_para(row[1][1]) then return end
+    complex_table = complex_table or #row[2] > 1 or unlike_para(row[2][1])
+  end
+  if not complex_table then return end
+
+  -- Conversion
+  local header
+  local blocks = {}
+  for _, row in pairs(tb.rows) do
+    header = row[1][1].content
+    table.insert(header, pandoc.Str(':'))
+    table.insert(blocks, pandoc.Header(4, header))
+    for _, b in pairs(row[2]) do
+      table.insert(blocks, b.t == "Plain" and pandoc.Para(b.content) or b)
+    end
+  end
+  return blocks
+end
+