From 9abdbb2783d246c736f05119390e81084f9ab07c Mon Sep 17 00:00:00 2001
From: Albert Krewinkel <albert@zeitkraut.de>
Date: Mon, 1 Oct 2018 16:10:46 +0200
Subject: Lua filters: report traceback when an error occurs
A proper Lua traceback is added if either loading of a file or execution
of a filter function fails. This should be of help to authors of Lua
filters who need to debug their code.
---
src/Text/Pandoc/Lua/Filter.hs | 9 ++++-----
src/Text/Pandoc/Lua/Util.hs | 38 ++++++++++++++++++++++++++++++++++++--
2 files changed, 40 insertions(+), 7 deletions(-)
(limited to 'src/Text/Pandoc/Lua')
diff --git a/src/Text/Pandoc/Lua/Filter.hs b/src/Text/Pandoc/Lua/Filter.hs
index 9b5f5f40a..d17f9a969 100644
--- a/src/Text/Pandoc/Lua/Filter.hs
+++ b/src/Text/Pandoc/Lua/Filter.hs
@@ -52,6 +52,7 @@ import Text.Pandoc.Walk (walkM, Walkable)
import qualified Data.Map.Strict as Map
import qualified Foreign.Lua as Lua
+import qualified Text.Pandoc.Lua.Util as LuaUtil
-- | Filter function stored in the registry
newtype LuaFilterFunction = LuaFilterFunction Lua.Reference
@@ -118,11 +119,9 @@ tryFilter (LuaFilter fnMap) x =
-- element is left unchanged.
runFilterFunction :: Pushable a => LuaFilterFunction -> a -> Lua ()
runFilterFunction lf x = do
- let errorPrefix = "Error while running filter function:\n"
- Lua.withExceptionMessage (errorPrefix <>) $ do
- pushFilterFunction lf
- Lua.push x
- Lua.call 1 1
+ pushFilterFunction lf
+ Lua.push x
+ LuaUtil.callWithTraceback 1 1
walkMWithLuaFilter :: LuaFilter -> Pandoc -> Lua Pandoc
walkMWithLuaFilter f =
diff --git a/src/Text/Pandoc/Lua/Util.hs b/src/Text/Pandoc/Lua/Util.hs
index 89db9520d..77b27b88e 100644
--- a/src/Text/Pandoc/Lua/Util.hs
+++ b/src/Text/Pandoc/Lua/Util.hs
@@ -40,12 +40,14 @@ module Text.Pandoc.Lua.Util
, loadScriptFromDataDir
, defineHowTo
, throwTopMessageAsError'
+ , callWithTraceback
+ , dofileWithTraceback
) where
import Prelude
import Control.Monad (unless, when)
-import Foreign.Lua ( Lua, NumArgs, Peekable, Pushable, StackIndex
- , ToHaskellFunction )
+import Foreign.Lua ( Lua, NumArgs, NumResults, Peekable, Pushable, StackIndex
+ , Status, ToHaskellFunction )
import Text.Pandoc.Class (readDataFile, runIOorExplode, setUserDataDir)
import qualified Foreign.Lua as Lua
@@ -137,3 +139,35 @@ throwTopMessageAsError' modifier = do
-- | Mark the context of a Lua computation for better error reporting.
defineHowTo :: String -> Lua a -> Lua a
defineHowTo ctx = Lua.withExceptionMessage (("Could not " <> ctx <> ": ") <>)
+
+-- | Like @'Lua.pcall'@, but uses a predefined error handler which adds a
+-- traceback on error.
+pcallWithTraceback :: NumArgs -> NumResults -> Lua Status
+pcallWithTraceback nargs nresults = do
+ let traceback' :: Lua NumResults
+ traceback' = do
+ l <- Lua.state
+ msg <- Lua.tostring' (Lua.nthFromBottom 1)
+ Lua.traceback l (Just (UTF8.toString msg)) 2
+ return 1
+ tracebackIdx <- Lua.absindex (Lua.nthFromTop (Lua.fromNumArgs nargs + 1))
+ Lua.pushHaskellFunction traceback'
+ Lua.insert tracebackIdx
+ result <- Lua.pcall nargs nresults (Just tracebackIdx)
+ Lua.remove tracebackIdx
+ return result
+
+-- | Like @'Lua.call'@, but adds a traceback to the error message (if any).
+callWithTraceback :: NumArgs -> NumResults -> Lua ()
+callWithTraceback nargs nresults = do
+ result <- pcallWithTraceback nargs nresults
+ when (result /= Lua.OK) Lua.throwTopMessage
+
+-- | Run the given string as a Lua program, while also adding a traceback to the
+-- error message if an error occurs.
+dofileWithTraceback :: FilePath -> Lua Status
+dofileWithTraceback fp = do
+ loadRes <- Lua.loadfile fp
+ case loadRes of
+ Lua.OK -> pcallWithTraceback 0 Lua.multret
+ _ -> return loadRes
--
cgit v1.2.3