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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 (..), pushPandocModule, runLuaFilter) where
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 Foreign.Lua (Lua, FromLuaStack (peek), LuaException (..), StackIndex,
Status(OK), ToLuaStack (push), call, isnil, dofile,
getglobal', gettop, isfunction, newtable, openlibs, pcall,
peekEither, pop, pushvalue, rawgeti, rawseti, ref,
registryindex, runLua, setglobal, throwLuaError)
import Text.Pandoc.Definition
import Text.Pandoc.Lua.PandocModule (pushPandocModule)
import Text.Pandoc.Walk (Walkable (walkM))
import qualified Data.Map as Map
runLuaFilter :: (MonadIO m)
=> Maybe FilePath -> FilePath -> [String] -> Pandoc -> m Pandoc
runLuaFilter datadir filterPath args pd = liftIO . runLua $ do
openlibs
-- store module in global "pandoc"
pushPandocModule datadir
setglobal "pandoc"
top <- gettop
stat<- dofile filterPath
if stat /= OK
then do
luaErrMsg <- peek (-1) <* pop 1
throwLuaError luaErrMsg
else do
newtop <- gettop
-- Use the implicitly defined global filter if nothing was returned
when (newtop - top < 1) $ pushGlobalFilter
luaFilters <- peek (-1)
push args
setglobal "PandocParameters"
runAll luaFilters pd
pushGlobalFilter :: Lua ()
pushGlobalFilter = do
newtable
getglobal' "pandoc.global_filter"
call 0 1
rawseti (-2) 1
runAll :: [LuaFilter] -> Pandoc -> Lua Pandoc
runAll = foldr ((>=>) . walkMWithLuaFilter) return
walkMWithLuaFilter :: LuaFilter -> Pandoc -> Lua Pandoc
walkMWithLuaFilter (LuaFilter fnMap) = walkLua
where
walkLua :: Pandoc -> Lua Pandoc
walkLua =
(if hasOneOf (constructorsFor (dataTypeOf (Str [])))
then walkM (tryFilter fnMap :: Inline -> Lua Inline)
else return)
>=>
(if hasOneOf (constructorsFor (dataTypeOf (Para [])))
then walkM (tryFilter fnMap :: Block -> Lua Block)
else return)
>=>
(case Map.lookup "Meta" fnMap of
Just fn -> walkM (\(Pandoc meta blocks) -> do
meta' <- runFilterFunction fn meta
return $ Pandoc meta' blocks)
Nothing -> return)
>=>
(case Map.lookup "Pandoc" fnMap `mplus` Map.lookup "Doc" fnMap of
Just fn -> runFilterFunction fn :: Pandoc -> Lua Pandoc
Nothing -> return)
hasOneOf = any (\k -> isJust (Map.lookup k fnMap))
constructorsFor x = map show (dataTypeConstrs x)
type FunctionMap = Map String LuaFilterFunction
data LuaFilter = LuaFilter FunctionMap
newtype LuaFilterFunction = LuaFilterFunction { functionIndex :: Int }
-- | Try running a filter for the given element
tryFilter :: (Data a, FromLuaStack a, ToLuaStack a) => FunctionMap -> a -> Lua a
tryFilter fnMap x =
let filterFnName = showConstr (toConstr x) in
case Map.lookup filterFnName fnMap of
Nothing -> return x
Just fn -> runFilterFunction fn x
instance FromLuaStack LuaFilter where
peek idx = LuaFilter <$> peek 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 :: (FromLuaStack a, ToLuaStack a)
=> LuaFilterFunction -> a -> Lua a
runFilterFunction lf x = do
pushFilterFunction lf
push x
z <- pcall 1 1 Nothing
if z /= OK
then do
msg <- peek (-1)
let prefix = "Error while running filter function: "
throwLuaError $ prefix ++ msg
else do
noExplicitFilter <- isnil (-1)
if noExplicitFilter
then pop 1 *> return x
else do
mbres <- peekEither (-1)
case mbres of
Left err -> throwLuaError
("Error while trying to get a filter's return "
++ "value from lua stack.\n" ++ err)
Right res -> res <$ pop 1
-- | Push the filter function to the top of the stack.
pushFilterFunction :: LuaFilterFunction -> Lua ()
pushFilterFunction lf =
-- The function is stored in a lua registry table, retrieve it from there.
rawgeti registryindex (functionIndex lf)
registerFilterFunction :: StackIndex -> Lua LuaFilterFunction
registerFilterFunction idx = do
isFn <- isfunction idx
unless isFn . throwLuaError $ "Not a function at index " ++ show idx
pushvalue idx
refIdx <- ref registryindex
return $ LuaFilterFunction refIdx
instance ToLuaStack LuaFilterFunction where
push = pushFilterFunction
instance FromLuaStack LuaFilterFunction where
peek = registerFilterFunction
|
