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{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-
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
-}
{- |
Module : Text.Pandoc.Lua
Copyright : Copyright © 2017 Albert Krewinkel
License : GNU GPL, version 2 or above
Maintainer : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
Stability : alpha
Pandoc lua utils.
-}
module Text.Pandoc.Lua ( LuaException(..),
runLuaFilter,
pushPandocModule ) where
import Control.Exception
import Control.Monad (unless, when, (>=>), mplus)
import Control.Monad.Trans (MonadIO (..))
import Data.Data (toConstr, showConstr, dataTypeOf, dataTypeConstrs, Data)
import Data.Map (Map)
import Data.Maybe (isJust)
import Data.Typeable (Typeable)
import Scripting.Lua (LuaState, StackValue (..))
import Text.Pandoc.Definition
import Text.Pandoc.Lua.PandocModule (pushPandocModule)
import Text.Pandoc.Lua.StackInstances ()
import Text.Pandoc.Walk
import qualified Data.Map as Map
import qualified Scripting.Lua as Lua
newtype LuaException = LuaException String
deriving (Show, Typeable)
instance Exception LuaException
runLuaFilter :: (MonadIO m)
=> FilePath -> [String] -> Pandoc -> m Pandoc
runLuaFilter filterPath args pd = liftIO $ do
lua <- Lua.newstate
Lua.openlibs lua
-- store module in global "pandoc"
pushPandocModule lua
Lua.setglobal lua "pandoc"
top <- Lua.gettop lua
status <- Lua.loadfile lua filterPath
if status /= 0
then do
Just luaErrMsg <- Lua.peek lua 1
throwIO (LuaException luaErrMsg)
else do
Lua.call lua 0 Lua.multret
newtop <- Lua.gettop lua
-- Use the implicitly defined global filter if nothing was returned
when (newtop - top < 1) $ pushGlobalFilter lua
Just luaFilters <- Lua.peek lua (-1)
Lua.push lua args
Lua.setglobal lua "PandocParameters"
doc <- runAll luaFilters pd
Lua.close lua
return doc
pushGlobalFilter :: LuaState -> IO ()
pushGlobalFilter lua =
Lua.newtable lua
*> Lua.getglobal2 lua "pandoc.global_filter"
*> Lua.call lua 0 1
*> Lua.rawseti lua (-2) 1
runAll :: [LuaFilter] -> Pandoc -> IO Pandoc
runAll = foldr ((>=>) . walkMWithLuaFilter) return
walkMWithLuaFilter :: LuaFilter -> Pandoc -> IO Pandoc
walkMWithLuaFilter (LuaFilter lua fnMap) =
(if hasOneOf (constructorsFor (dataTypeOf (Str [])))
then walkM (tryFilter lua fnMap :: Inline -> IO Inline)
else return)
>=>
(if hasOneOf (constructorsFor (dataTypeOf (Para [])))
then walkM (tryFilter lua fnMap :: Block -> IO Block)
else return)
>=>
(case Map.lookup "Meta" fnMap of
Just fn -> walkM (\(Pandoc meta blocks) -> do
meta' <- runFilterFunction lua fn meta
return $ Pandoc meta' blocks)
Nothing -> return)
>=>
(case Map.lookup "Pandoc" fnMap `mplus` Map.lookup "Doc" fnMap of
Just fn -> (runFilterFunction lua fn) :: Pandoc -> IO Pandoc
Nothing -> return)
where hasOneOf = any (\k -> isJust (Map.lookup k fnMap))
constructorsFor x = map show (dataTypeConstrs x)
type FunctionMap = Map String LuaFilterFunction
data LuaFilter = LuaFilter LuaState FunctionMap
newtype LuaFilterFunction = LuaFilterFunction { functionIndex :: Int }
tryFilter :: (Data a, StackValue a) => LuaState -> FunctionMap -> a -> IO a
tryFilter lua fnMap x =
let filterFnName = showConstr (toConstr x) in
case Map.lookup filterFnName fnMap of
Nothing -> return x
Just fn -> runFilterFunction lua fn x
instance StackValue LuaFilter where
valuetype _ = Lua.TTABLE
push = undefined
peek lua idx = fmap (LuaFilter lua) <$> Lua.peek lua idx
-- | Push a value to the stack via a lua filter function. The filter function is
-- called with given element as argument and is expected to return an element.
-- Alternatively, the function can return nothing or nil, in which case the
-- element is left unchanged.
runFilterFunction :: StackValue a => LuaState -> LuaFilterFunction -> a -> IO a
runFilterFunction lua lf x = do
pushFilterFunction lua lf
Lua.push lua x
z <- Lua.pcall lua 1 1 0
if (z /= 0)
then do
msg <- Lua.peek lua (-1)
let prefix = "Error while running filter function: "
throwIO . LuaException $
case msg of
Nothing -> prefix ++ "could not read error message"
Just msg' -> prefix ++ msg'
else do
resType <- Lua.ltype lua (-1)
case resType of
Lua.TNIL -> Lua.pop lua 1 *> return x
_ -> do
mbres <- Lua.peek lua (-1)
case mbres of
Nothing -> throwIO $ LuaException
("Error while trying to get a filter's return "
++ "value from lua stack.")
Just res -> res <$ Lua.pop lua 1
-- | Push the filter function to the top of the stack.
pushFilterFunction :: Lua.LuaState -> LuaFilterFunction -> IO ()
pushFilterFunction lua lf =
-- The function is stored in a lua registry table, retrieve it from there.
Lua.rawgeti lua Lua.registryindex (functionIndex lf)
registerFilterFunction :: LuaState -> Int -> IO LuaFilterFunction
registerFilterFunction lua idx = do
isFn <- Lua.isfunction lua idx
unless isFn . throwIO . LuaException $ "Not a function at index " ++ show idx
Lua.pushvalue lua idx
refIdx <- Lua.ref lua Lua.registryindex
return $ LuaFilterFunction refIdx
instance StackValue LuaFilterFunction where
valuetype _ = Lua.TFUNCTION
push = pushFilterFunction
peek = fmap (fmap Just) . registerFilterFunction
|
