Lua modules: move to dedicated submodule

The Haskell module defining the Lua `pandoc` module is moved to
Text.Pandoc.Lua.Module.Pandoc.

Change: minor

pandoc.cabal

@@ -523,8 +523,8 @@ library
                    Text.Pandoc.Readers.Org.Shared,
                    Text.Pandoc.Lua.Filter,
                    Text.Pandoc.Lua.Init,
+                   Text.Pandoc.Lua.Module.Pandoc,
                    Text.Pandoc.Lua.Packages,
-                   Text.Pandoc.Lua.PandocModule,
                    Text.Pandoc.Lua.StackInstances,
                    Text.Pandoc.Lua.Util,
                    Text.Pandoc.CSS,

src/Text/Pandoc/Lua.hs

@@ -39,7 +39,7 @@ import Text.Pandoc.Class (PandocIO)
 import Text.Pandoc.Definition (Pandoc)
 import Text.Pandoc.Lua.Filter (LuaFilter, walkMWithLuaFilter)
 import Text.Pandoc.Lua.Init (runPandocLua)
-import Text.Pandoc.Lua.PandocModule (pushPandocModule) -- TODO: remove
+import Text.Pandoc.Lua.Module.Pandoc (pushModule) -- TODO: remove
 import qualified Foreign.Lua as Lua
 
 -- | Run the Lua filter in @filterPath@ for a transformation to target
@@ -81,3 +81,7 @@ pushGlobalFilter = do
 
 runAll :: [LuaFilter] -> Pandoc -> Lua Pandoc
 runAll = foldr ((>=>) . walkMWithLuaFilter) return
+
+-- | DEPRECATED: Push the pandoc module to the Lua Stack.
+pushPandocModule :: Maybe FilePath -> Lua Lua.NumResults
+pushPandocModule = pushModule

src/Text/Pandoc/Lua/Module/Pandoc.hs

@@ -17,7 +17,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 -}
 {-# LANGUAGE FlexibleContexts #-}
 {- |
-   Module      : Text.Pandoc.Lua.PandocModule
+   Module      : Text.Pandoc.Lua.Module.Pandoc
    Copyright   : Copyright © 2017 Albert Krewinkel
    License     : GNU GPL, version 2 or above
 
@@ -26,8 +26,8 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 Pandoc module for lua.
 -}
-module Text.Pandoc.Lua.PandocModule
-  ( pushPandocModule
+module Text.Pandoc.Lua.Module.Pandoc
+  ( pushModule
   , pushMediaBagModule
   ) where
 
@@ -44,7 +44,8 @@ import Text.Pandoc.Class (CommonState (..), fetchItem, putCommonState,
 import Text.Pandoc.Definition (Block, Inline)
 import Text.Pandoc.Lua.Filter (walkInlines, walkBlocks, LuaFilter)
 import Text.Pandoc.Lua.StackInstances ()
-import Text.Pandoc.Lua.Util (addFunction, addValue, loadScriptFromDataDir)
+import Text.Pandoc.Lua.Util (OrNil (toMaybe), addFunction, addValue,
+                             loadScriptFromDataDir, raiseError)
 import Text.Pandoc.Walk (Walkable)
 import Text.Pandoc.MIME (MimeType)
 import Text.Pandoc.Options (ReaderOptions (readerExtensions))
@@ -58,8 +59,8 @@ import qualified Text.Pandoc.MediaBag as MB
 
 -- | Push the "pandoc" on the lua stack. Requires the `list` module to be
 -- loaded.
-pushPandocModule :: Maybe FilePath -> Lua NumResults
-pushPandocModule datadir = do
+pushModule :: Maybe FilePath -> Lua NumResults
+pushModule datadir = do
   loadScriptFromDataDir datadir "pandoc.lua"
   addFunction "read" readDoc
   addFunction "pipe" pipeFn
@@ -91,10 +92,6 @@ readDoc content formatSpecOrNil = do
             Right pd -> (1 :: NumResults) <$ Lua.push pd -- success, push Pandoc
             Left s   -> raiseError (show s)              -- error while reading
         _  -> raiseError "Only string formats are supported at the moment."
- where
-  raiseError s = do
-    Lua.push s
-    fromIntegral <$> Lua.lerror
 
 --
 -- MediaBag submodule
@@ -122,12 +119,8 @@ pipeFn :: String
 pipeFn command args input = do
   (ec, output) <- liftIO $ pipeProcess Nothing command args input
   case ec of
-    ExitSuccess -> do
-      Lua.push output
-      return 1
-    ExitFailure n -> do
-      Lua.push (PipeError command n output)
-      fromIntegral <$> Lua.lerror
+    ExitSuccess -> 1 <$ Lua.push output
+    ExitFailure n -> raiseError (PipeError command n output)
 
 data PipeError = PipeError
   { pipeErrorCommand :: String
@@ -218,16 +211,3 @@ fetch commonState mbRef src = do
   Lua.push $ fromMaybe "" mimeType
   Lua.push bs
   return 2 -- returns 2 values: contents, mimetype
-
---
--- Helper types
---
-
-newtype OrNil a = OrNil { toMaybe :: Maybe a }
-
-instance FromLuaStack a => FromLuaStack (OrNil a) where
-  peek idx = do
-    noValue <- Lua.isnoneornil idx
-    if noValue
-      then return (OrNil Nothing)
-      else OrNil . Just <$> Lua.peek idx

src/Text/Pandoc/Lua/Packages.hs

@@ -38,10 +38,11 @@ import Data.IORef (IORef)
 import Foreign.Lua (Lua, NumResults, liftIO)
 import Text.Pandoc.Class (CommonState, readDataFile, runIO, setUserDataDir)
 import Text.Pandoc.MediaBag (MediaBag)
-import Text.Pandoc.Lua.PandocModule (pushPandocModule, pushMediaBagModule)
+import Text.Pandoc.Lua.Module.Pandoc (pushMediaBagModule)
 import Text.Pandoc.Lua.Util (dostring')
 
 import qualified Foreign.Lua as Lua
+import Text.Pandoc.Lua.Module.Pandoc as Pandoc
 
 -- | Parameters used to create lua packages/modules.
 data LuaPackageParams = LuaPackageParams
@@ -72,7 +73,7 @@ pandocPackageSearcher :: LuaPackageParams -> String -> Lua NumResults
 pandocPackageSearcher luaPkgParams pkgName =
   case pkgName of
     "pandoc"          -> let datadir = luaPkgDataDir luaPkgParams
-                         in pushWrappedHsFun (pushPandocModule datadir)
+                         in pushWrappedHsFun (Pandoc.pushModule datadir)
     "pandoc.mediabag" -> let st    = luaPkgCommonState luaPkgParams
                              mbRef = luaPkgMediaBag luaPkgParams
                          in pushWrappedHsFun (pushMediaBagModule st mbRef)

src/Text/Pandoc/Lua/Util.hs

@@ -36,6 +36,8 @@ module Text.Pandoc.Lua.Util
   , getRawInt
   , setRawInt
   , addRawInt
+  , raiseError
+  , OrNil (..)
   , PushViaCall
   , pushViaCall
   , pushViaConstructor
@@ -45,8 +47,8 @@ module Text.Pandoc.Lua.Util
 
 import Control.Monad (when)
 import Data.ByteString.Char8 (unpack)
-import Foreign.Lua (FromLuaStack (..), ToHaskellFunction, Lua, NumArgs,
-                    StackIndex, ToLuaStack (..), getglobal')
+import Foreign.Lua (FromLuaStack (..), NumResults, Lua, NumArgs, StackIndex,
+                    ToLuaStack (..), ToHaskellFunction, getglobal')
 import Foreign.Lua.Api (Status, call, pop, rawget, rawgeti, rawset, rawseti)
 import Text.Pandoc.Class (readDataFile, runIOorExplode, setUserDataDir)
 
@@ -99,6 +101,22 @@ setRawInt idx key value = do
 addRawInt :: ToLuaStack a => Int -> a -> Lua ()
 addRawInt = setRawInt (-1)
 
+raiseError :: ToLuaStack a => a -> Lua NumResults
+raiseError e = do
+  Lua.push e
+  fromIntegral <$> Lua.lerror
+
+-- | Newtype wrapper intended to be used for optional Lua values. Nesting this
+-- type is strongly discouraged and will likely lead to a wrong result.
+newtype OrNil a = OrNil { toMaybe :: Maybe a }
+
+instance FromLuaStack a => FromLuaStack (OrNil a) where
+  peek idx = do
+    noValue <- Lua.isnoneornil idx
+    if noValue
+      then return (OrNil Nothing)
+      else OrNil . Just <$> Lua.peek idx
+
 -- | Helper class for pushing a single value to the stack via a lua function.
 -- See @pushViaCall@.
 class PushViaCall a where