Lua: Simplify module loading code.

Modules are now loaded directly; the special pandoc Lua package searcher
is no longer necessary and has been removed.

pandoc.cabal

@@ -753,7 +753,6 @@ library
                    Text.Pandoc.Lua.Module.Types,
                    Text.Pandoc.Lua.Module.Utils,
                    Text.Pandoc.Lua.Orphans,
-                   Text.Pandoc.Lua.Packages,
                    Text.Pandoc.Lua.PandocLua,
                    Text.Pandoc.Lua.Writer.Classic,
                    Text.Pandoc.XML.Light,

src/Text/Pandoc/Lua/Init.hs

@@ -22,11 +22,20 @@ import HsLua as Lua hiding (status, try)
 import GHC.IO.Encoding (getForeignEncoding, setForeignEncoding, utf8)
 import Text.Pandoc.Class.PandocMonad (PandocMonad, readDataFile)
 import Text.Pandoc.Error (PandocError (PandocLuaError))
-import Text.Pandoc.Lua.Packages (installPandocPackageSearcher)
+import Text.Pandoc.Lua.Marshal.List (pushListModule)
 import Text.Pandoc.Lua.PandocLua (PandocLua, liftPandocLua, runPandocLua)
+import qualified Data.ByteString as B
 import qualified Data.Text as T
 import qualified Lua.LPeg as LPeg
-import qualified Text.Pandoc.Lua.Module.Pandoc as ModulePandoc
+import qualified HsLua.Module.DocLayout as Module.Layout
+import qualified HsLua.Module.Path as Module.Path
+import qualified HsLua.Module.Text as Module.Text
+import qualified Text.Pandoc.Lua.Module.Pandoc as Module.Pandoc
+import qualified Text.Pandoc.Lua.Module.MediaBag as Pandoc.MediaBag
+import qualified Text.Pandoc.Lua.Module.System as Pandoc.System
+import qualified Text.Pandoc.Lua.Module.Template as Pandoc.Template
+import qualified Text.Pandoc.Lua.Module.Types as Pandoc.Types
+import qualified Text.Pandoc.Lua.Module.Utils as Pandoc.Utils
 
 -- | Run the lua interpreter, using pandoc's default way of environment
 -- initialization.
@@ -42,47 +51,45 @@ runLua luaOp = do
 
 -- | Modules that are loaded at startup and assigned to fields in the
 -- pandoc module.
-loadedModules :: [(Name, Name)]
+--
+-- Note that @pandoc.List@ is not included here for technical reasons;
+-- it must be handled separately.
+loadedModules :: [Module PandocError]
 loadedModules =
-  [ ("pandoc.List", "List")
+  [ Pandoc.MediaBag.documentedModule
-  , ("pandoc.layout", "layout")
+  , Pandoc.System.documentedModule
-  , ("pandoc.mediabag", "mediabag")
+  , Pandoc.Template.documentedModule
-  , ("pandoc.path", "path")
+  , Pandoc.Types.documentedModule
-  , ("pandoc.system", "system")
+  , Pandoc.Utils.documentedModule
-  , ("pandoc.template", "template")
+  , Module.Layout.documentedModule { moduleName = "pandoc.layout" }
-  , ("pandoc.types", "types")
+  , Module.Path.documentedModule { moduleName = "pandoc.path" }
-  , ("pandoc.utils", "utils")
+  , Module.Text.documentedModule
-  , ("text", "text")
   ]
 
 -- | Initialize the lua state with all required values
 initLuaState :: PandocLua ()
 initLuaState = do
   liftPandocLua Lua.openlibs
-  installPandocPackageSearcher
   initPandocModule
   installLpegSearcher
   setGlobalModules
   loadInitScript "init.lua"
  where
   initPandocModule :: PandocLua ()
-  initPandocModule = do
+  initPandocModule = liftPandocLua $ do
     -- Push module table
-    ModulePandoc.pushModule
+    registerModule Module.Pandoc.documentedModule
-    -- register as loaded module
-    liftPandocLua $ do
-      Lua.getfield Lua.registryindex Lua.loaded
-      Lua.pushvalue (Lua.nth 2)
-      Lua.setfield (Lua.nth 2) "pandoc"
-      Lua.pop 1  -- remove LOADED table
     -- load modules and add them to the `pandoc` module table.
-    liftPandocLua $ forM_ loadedModules $ \(pkgname, fieldname) -> do
+    forM_ loadedModules $ \mdl -> do
-      Lua.getglobal "require"
+      registerModule mdl
-      Lua.pushName pkgname
+      let isNotAsciiDot = (/= 46)
-      Lua.call 1 1
+      let fieldname = B.takeWhileEnd isNotAsciiDot (fromName $ moduleName mdl)
-      Lua.setfield (nth 2) fieldname
+      Lua.setfield (nth 2) (Name fieldname)
+    -- pandoc.List is low-level and must be opened differently.
+    requirehs "pandoc.List" (const pushListModule)
+    setfield (nth 2) "List"
     -- assign module to global variable
-    liftPandocLua $ Lua.setglobal "pandoc"
+    Lua.setglobal "pandoc"
 
   loadInitScript :: FilePath -> PandocLua ()
   loadInitScript scriptFile = do

src/Text/Pandoc/Lua/Packages.hs

@@ -1,75 +0,0 @@
-{-# LANGUAGE FlexibleContexts  #-}
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE TypeApplications  #-}
-{- |
-   Module      : Text.Pandoc.Lua.Packages
-   Copyright   : Copyright © 2017-2022 Albert Krewinkel
-   License     : GNU GPL, version 2 or above
-
-   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
-   Stability   : alpha
-
-Pandoc module for Lua.
--}
-module Text.Pandoc.Lua.Packages
-  ( installPandocPackageSearcher
-  ) where
-
-import Control.Monad (forM_)
-import Data.String (fromString)
-import Text.Pandoc.Error (PandocError)
-import Text.Pandoc.Lua.Marshal.List (pushListModule)
-import Text.Pandoc.Lua.PandocLua (PandocLua, liftPandocLua)
-
-import qualified HsLua as Lua
-import qualified HsLua.Module.DocLayout as DocLayout
-import qualified HsLua.Module.Path as Path
-import qualified HsLua.Module.Text as Text
-import qualified Text.Pandoc.Lua.Module.Pandoc as Pandoc
-import qualified Text.Pandoc.Lua.Module.MediaBag as MediaBag
-import qualified Text.Pandoc.Lua.Module.System as System
-import qualified Text.Pandoc.Lua.Module.Template as Template
-import qualified Text.Pandoc.Lua.Module.Types as Types
-import qualified Text.Pandoc.Lua.Module.Utils as Utils
-
--- | Insert pandoc's package loader as the first loader, making it the default.
-installPandocPackageSearcher :: PandocLua ()
-installPandocPackageSearcher = liftPandocLua $ do
-  Lua.getglobal' "package.searchers"
-  shiftArray
-  Lua.pushHaskellFunction $ Lua.toHaskellFunction pandocPackageSearcher
-  Lua.rawseti (Lua.nth 2) 1
-  Lua.pop 1           -- remove 'package.searchers' from stack
- where
-  shiftArray = forM_ [4, 3, 2, 1] $ \i -> do
-    Lua.rawgeti (-1) i
-    Lua.rawseti (-2) (i + 1)
-
--- | Load a pandoc module.
-pandocPackageSearcher :: String -> PandocLua Lua.NumResults
-pandocPackageSearcher pkgName =
-  case pkgName of
-    "pandoc"          -> pushModuleLoader Pandoc.documentedModule
-    "pandoc.layout"   -> pushModuleLoader DocLayout.documentedModule
-    "pandoc.mediabag" -> pushModuleLoader MediaBag.documentedModule
-    "pandoc.path"     -> pushModuleLoader Path.documentedModule
-    "pandoc.system"   -> pushModuleLoader System.documentedModule
-    "pandoc.template" -> pushModuleLoader Template.documentedModule
-    "pandoc.types"    -> pushModuleLoader Types.documentedModule
-    "pandoc.utils"    -> pushModuleLoader Utils.documentedModule
-    "text"            -> pushModuleLoader Text.documentedModule
-    "pandoc.List"     -> pushWrappedHsFun . Lua.toHaskellFunction @PandocError $
-                         (Lua.NumResults 1 <$ pushListModule @PandocError)
-    _                 -> reportPandocSearcherFailure
- where
-  pushModuleLoader mdl = liftPandocLua $ do
-    let mdl' = mdl { Lua.moduleName = fromString pkgName }
-    Lua.pushHaskellFunction $
-      Lua.NumResults 1 <$ Lua.pushModule mdl'
-    return (Lua.NumResults 1)
-  pushWrappedHsFun f = liftPandocLua $ do
-    Lua.pushHaskellFunction f
-    return 1
-  reportPandocSearcherFailure = liftPandocLua $ do
-    Lua.push ("\n\t" <> pkgName <> " is not one of pandoc's default packages")
-    return (Lua.NumResults 1)