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|
{- |
Module : Text.Pandoc.Lua
Copyright : Copyright © 2017-2020 Albert Krewinkel
License : GNU GPL, version 2 or above
Maintainer : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
Stability : alpha
Functions to initialize the Lua interpreter.
-}
module Text.Pandoc.Lua.Init
( LuaException (..)
, LuaPackageParams (..)
, runLua
, luaPackageParams
) where
import Control.Monad.Trans (MonadIO (..))
import Data.Data (Data, dataTypeConstrs, dataTypeOf, showConstr)
import Foreign.Lua (Lua)
import GHC.IO.Encoding (getForeignEncoding, setForeignEncoding, utf8)
import Text.Pandoc.Class.PandocIO (PandocIO)
import Text.Pandoc.Class.PandocMonad (getCommonState, getUserDataDir,
putCommonState)
import Text.Pandoc.Lua.Global (Global (..), setGlobals)
import Text.Pandoc.Lua.Packages (LuaPackageParams (..),
installPandocPackageSearcher)
import Text.Pandoc.Lua.Util (loadScriptFromDataDir)
import qualified Data.Text as Text
import qualified Foreign.Lua as Lua
import qualified Foreign.Lua.Module.Text as Lua
import qualified Text.Pandoc.Definition as Pandoc
import qualified Text.Pandoc.Lua.Module.Pandoc as ModulePandoc
-- | Lua error message
newtype LuaException = LuaException Text.Text deriving (Show)
-- | Run the lua interpreter, using pandoc's default way of environment
-- initialization.
runLua :: Lua a -> PandocIO (Either LuaException a)
runLua luaOp = do
luaPkgParams <- luaPackageParams
globals <- defaultGlobals
enc <- liftIO $ getForeignEncoding <* setForeignEncoding utf8
res <- liftIO . Lua.runEither $ do
setGlobals globals
initLuaState luaPkgParams
-- run the given Lua operation
opResult <- luaOp
-- get the (possibly modified) state back
Lua.getglobal "PANDOC_STATE"
st <- Lua.peek Lua.stackTop
Lua.pop 1
-- done
return (opResult, st)
liftIO $ setForeignEncoding enc
case res of
Left (Lua.Exception msg) -> return $ Left (LuaException $ Text.pack msg)
Right (x, newState) -> do
putCommonState newState
return $ Right x
-- | Global variables which should always be set.
defaultGlobals :: PandocIO [Global]
defaultGlobals = do
commonState <- getCommonState
return
[ PANDOC_API_VERSION
, PANDOC_STATE commonState
, PANDOC_VERSION
]
-- | Generate parameters required to setup pandoc's lua environment.
luaPackageParams :: PandocIO LuaPackageParams
luaPackageParams = do
datadir <- getUserDataDir
return LuaPackageParams { luaPkgDataDir = datadir }
-- | Initialize the lua state with all required values
initLuaState :: LuaPackageParams -> Lua ()
initLuaState pkgParams = do
Lua.openlibs
Lua.preloadTextModule "text"
installPandocPackageSearcher pkgParams
initPandocModule
loadScriptFromDataDir (luaPkgDataDir pkgParams) "init.lua"
where
initPandocModule :: Lua ()
initPandocModule = do
-- Push module table
ModulePandoc.pushModule (luaPkgDataDir pkgParams)
-- register as loaded module
Lua.pushvalue Lua.stackTop
Lua.getfield Lua.registryindex Lua.loadedTableRegistryField
Lua.setfield (Lua.nthFromTop 2) "pandoc"
Lua.pop 1
-- copy constructors into registry
putConstructorsInRegistry
-- assign module to global variable
Lua.setglobal "pandoc"
-- | AST elements are marshaled via normal constructor functions in the
-- @pandoc@ module. However, accessing Lua globals from Haskell is
-- expensive (due to error handling). Accessing the Lua registry is much
-- cheaper, which is why the constructor functions are copied into the
-- Lua registry and called from there.
--
-- This function expects the @pandoc@ module to be at the top of the
-- stack.
putConstructorsInRegistry :: Lua ()
putConstructorsInRegistry = do
constrsToReg $ Pandoc.Pandoc mempty mempty
constrsToReg $ Pandoc.Str mempty
constrsToReg $ Pandoc.Para mempty
constrsToReg $ Pandoc.Meta mempty
constrsToReg $ Pandoc.MetaList mempty
constrsToReg $ Pandoc.Citation mempty mempty mempty Pandoc.AuthorInText 0 0
putInReg "Attr" -- used for Attr type alias
putInReg "ListAttributes" -- used for ListAttributes type alias
putInReg "List" -- pandoc.List
where
constrsToReg :: Data a => a -> Lua ()
constrsToReg = mapM_ (putInReg . showConstr) . dataTypeConstrs . dataTypeOf
putInReg :: String -> Lua ()
putInReg name = do
Lua.push ("pandoc." ++ name) -- name in registry
Lua.push name -- in pandoc module
Lua.rawget (Lua.nthFromTop 3)
Lua.rawset Lua.registryindex
|
