Ensure compatibility with hslua 0.5.*

The 0.5.0 release of hslua fixes problems with lua C modules on linux.
The signature of the `loadstring` function changed, so a compatibility
wrapper is introduced to allow both 0.4.* and 0.5.* versions to be used.

3 files changed, 45 insertions, 3 deletions

diff --git a/src/Text/Pandoc/Lua/Compat.hs b/src/Text/Pandoc/Lua/Compat.hs
new file mode 100644
index 000000000..998d8d032
--- /dev/null
+++ b/src/Text/Pandoc/Lua/Compat.hs
@@ -0,0 +1,40 @@
+{-
+Copyright © 2017 Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+-}
+{-# LANGUAGE CPP #-}
+{- |
+   Module      : Text.Pandoc.Lua.Compat
+   Copyright   : Copyright © 2017 Albert Krewinkel
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+   Stability   : alpha
+
+Compatibility helpers for hslua
+-}
+module Text.Pandoc.Lua.Compat ( loadstring ) where
+
+import Scripting.Lua ( LuaState )
+import qualified Scripting.Lua as Lua
+
+-- | Interpret string as lua code and load into the lua environment.
+loadstring :: LuaState -> String -> String -> IO Int
+#if MIN_VERSION_hslua(0,5,0)
+loadstring lua script _ = Lua.loadstring lua script
+#else
+loadstring lua script cn = Lua.loadstring lua script cn
+#endif
diff --git a/src/Text/Pandoc/Lua/PandocModule.hs b/src/Text/Pandoc/Lua/PandocModule.hs
index 5b2e82103..87d1fa6b9 100644
--- a/src/Text/Pandoc/Lua/PandocModule.hs
+++ b/src/Text/Pandoc/Lua/PandocModule.hs
@@ -28,7 +28,8 @@ Pandoc module for lua.
 module Text.Pandoc.Lua.PandocModule ( pushPandocModule ) where
 
 import Data.ByteString.Char8 ( unpack )
-import Scripting.Lua ( LuaState, loadstring, call)
+import Scripting.Lua ( LuaState, call)
+import Text.Pandoc.Lua.Compat ( loadstring )
 import Text.Pandoc.Shared ( readDataFile )
 
 
@@ -36,7 +37,7 @@ import Text.Pandoc.Shared ( readDataFile )
 pushPandocModule :: LuaState -> IO ()
 pushPandocModule lua = do
   script <- pandocModuleScript
-  status <- loadstring lua script "cn"
+  status <- loadstring lua script "pandoc.lua"
   if (status /= 0)
     then return ()
     else do
diff --git a/src/Text/Pandoc/Writers/Custom.hs b/src/Text/Pandoc/Writers/Custom.hs
index d7374b68b..9bed1dcd3 100644
--- a/src/Text/Pandoc/Writers/Custom.hs
+++ b/src/Text/Pandoc/Writers/Custom.hs
@@ -47,6 +47,7 @@ import Data.Typeable
 import GHC.IO.Encoding (getForeignEncoding, setForeignEncoding, utf8)
 import Scripting.Lua (LuaState, StackValue, callfunc)
 import qualified Scripting.Lua as Lua
+import Text.Pandoc.Lua.Compat ( loadstring )
 import Text.Pandoc.Definition
 import Text.Pandoc.Options
 import Text.Pandoc.Templates
@@ -186,7 +187,7 @@ writeCustom luaFile opts doc@(Pandoc meta _) = do
   setForeignEncoding utf8
   lua <- Lua.newstate
   Lua.openlibs lua
-  status <- Lua.loadstring lua luaScript luaFile
+  status <- loadstring lua luaScript luaFile
   -- check for error in lua script (later we'll change the return type
   -- to handle this more gracefully):
   when (status /= 0) $