1 files changed, 39 insertions, 8 deletions
diff --git a/src/Text/Pandoc/Filter/Lua.hs b/src/Text/Pandoc/Filter/Lua.hs
index d559fb912..6c78bef06 100644
--- a/src/Text/Pandoc/Filter/Lua.hs
+++ b/src/Text/Pandoc/Filter/Lua.hs
@@ -32,24 +32,55 @@ module Text.Pandoc.Filter.Lua (apply) where
 
 import Prelude
 import Control.Exception (throw)
+import Control.Monad ((>=>))
+import Foreign.Lua (Lua)
 import Text.Pandoc.Class (PandocIO)
 import Text.Pandoc.Definition (Pandoc)
 import Text.Pandoc.Error (PandocError (PandocFilterError))
 import Text.Pandoc.Filter.Path (expandFilterPath)
-import Text.Pandoc.Lua (LuaException (..), runLuaFilter)
+import Text.Pandoc.Lua (LuaException (..), runPandocLua)
+import Text.Pandoc.Lua.Filter (LuaFilter, walkMWithLuaFilter)
+import Text.Pandoc.Lua.Global (Global (..), setGlobals)
+import Text.Pandoc.Lua.Util (dofileWithTraceback)
 import Text.Pandoc.Options (ReaderOptions)
 
+import qualified Foreign.Lua as Lua
+
+-- | Run the Lua filter in @filterPath@ for a transformation to the
+-- target format (first element in args). Pandoc uses Lua init files to
+-- setup the Lua interpreter.
 apply :: ReaderOptions
       -> [String]
       -> FilePath
       -> Pandoc
       -> PandocIO Pandoc
-apply ropts args f d = do
-  f' <- expandFilterPath f
+apply ropts args f doc = do
+  filterPath <- expandFilterPath f
   let format = case args of
                  (x:_) -> x
-                 _     -> error "Format not supplied for lua filter"
-  res <- runLuaFilter ropts f' format d
-  case res of
-    Right x               -> return x
-    Left (LuaException s) -> throw (PandocFilterError f s)
+                 _     -> error "Format not supplied for Lua filter"
+  runPandocLua >=> forceResult filterPath $ do
+    setGlobals [ FORMAT format
+               , PANDOC_READER_OPTIONS ropts
+               , PANDOC_SCRIPT_FILE filterPath
+               ]
+    top <- Lua.gettop
+    stat <- dofileWithTraceback filterPath
+    if stat /= Lua.OK
+      then Lua.throwTopMessage
+      else do
+        newtop <- Lua.gettop
+        -- Use the returned filters, or the implicitly defined global
+        -- filter if nothing was returned.
+        luaFilters <- if newtop - top >= 1
+                      then Lua.peek Lua.stackTop
+                      else Lua.pushglobaltable *> fmap (:[]) Lua.popValue
+        runAll luaFilters doc
+
+forceResult :: FilePath -> Either LuaException Pandoc -> PandocIO Pandoc
+forceResult fp eitherResult = case eitherResult of
+  Right x               -> return x
+  Left (LuaException s) -> throw (PandocFilterError fp s)
+
+runAll :: [LuaFilter] -> Pandoc -> Lua Pandoc
+runAll = foldr ((>=>) . walkMWithLuaFilter) return