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|
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{- |
Module : Text.Pandoc.Lua
Copyright : Copyright © 2017-2021 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
( runLua
) where
import Control.Monad (when)
import Control.Monad.Catch (throwM, try)
import Control.Monad.Trans (MonadIO (..))
import Data.Data (Data, dataTypeConstrs, dataTypeOf, showConstr)
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.PandocLua (PandocLua, liftPandocLua, runPandocLua)
import qualified Data.Text as T
import qualified Lua.LPeg as LPeg
import qualified Text.Pandoc.Definition as Pandoc
import qualified Text.Pandoc.Lua.Module.Pandoc as ModulePandoc
-- | Run the lua interpreter, using pandoc's default way of environment
-- initialization.
runLua :: (PandocMonad m, MonadIO m)
=> LuaE PandocError a -> m (Either PandocError a)
runLua luaOp = do
enc <- liftIO $ getForeignEncoding <* setForeignEncoding utf8
res <- runPandocLua . try $ do
initLuaState
liftPandocLua luaOp
liftIO $ setForeignEncoding enc
return res
-- | Initialize the lua state with all required values
initLuaState :: PandocLua ()
initLuaState = do
liftPandocLua Lua.openlibs
installPandocPackageSearcher
initPandocModule
requireGlobalModules
loadInitScript "init.lua"
where
initPandocModule :: PandocLua ()
initPandocModule = do
-- Push module table
ModulePandoc.pushModule
-- 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
-- copy constructors into registry
putConstructorsInRegistry
-- assign module to global variable
liftPandocLua $ Lua.setglobal "pandoc"
loadInitScript :: FilePath -> PandocLua ()
loadInitScript scriptFile = do
script <- readDataFile scriptFile
status <- liftPandocLua $ Lua.dostring script
when (status /= Lua.OK) . liftPandocLua $ do
err <- popException
let prefix = "Couldn't load '" <> T.pack scriptFile <> "':\n"
throwM . PandocLuaError . (prefix <>) $ case err of
PandocLuaError msg -> msg
_ -> T.pack $ show err
requireGlobalModules :: PandocLua ()
requireGlobalModules = liftPandocLua $ do
Lua.pushcfunction LPeg.luaopen_lpeg_ptr
Lua.pcall 0 1 Nothing >>= \case
Lua.OK -> do
-- Success. Register as a loaded module.
-- Get table "_LOADED" from registry, add entry.
_ <- Lua.getfield Lua.registryindex Lua.loaded
Lua.pushvalue (Lua.nth 2)
Lua.setfield (Lua.nth 2) "lpeg"
Lua.pop 1 -- pop _LOADED
_ -> do
-- Maybe LPeg was not compiled into the program. Try loading via
-- the normal package loading mechanism.
pop 1 -- ignore error message
Lua.getglobal "require"
Lua.pushName "lpeg"
Lua.call 1 1 -- throws an exception if the module is not found
-- Module on top of stack. Register as global
Lua.setglobal "lpeg"
-- | 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 :: PandocLua ()
putConstructorsInRegistry = liftPandocLua $ do
constrsToReg $ Pandoc.Meta mempty
constrsToReg $ Pandoc.MetaList mempty
putInReg "List" -- pandoc.List
putInReg "SimpleTable" -- helper for backward-compatible table handling
where
constrsToReg :: Data a => a -> LuaE PandocError ()
constrsToReg = mapM_ (putInReg . showConstr) . dataTypeConstrs . dataTypeOf
putInReg :: String -> LuaE PandocError ()
putInReg name = do
Lua.push ("pandoc." ++ name) -- name in registry
Lua.push name -- in pandoc module
Lua.rawget (Lua.nth 3)
Lua.rawset Lua.registryindex
|
