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|
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TupleSections #-}
{- |
Module : Text.Pandoc.Lua.Custom
Copyright : © 2021-2023 Albert Krewinkel, John MacFarlane
License : GPL-2.0-or-later
Maintainer : Albert Krewinkel <[email protected]>
Supports custom parsers written in Lua which produce a Pandoc AST.
-}
module Text.Pandoc.Lua.Custom ( loadCustom ) where
import Control.Exception
import Control.Monad ((<=<), (<$!>))
import Control.Monad.IO.Class (MonadIO)
import Data.Maybe (fromMaybe)
import HsLua as Lua hiding (Operation (Div))
import HsLua.Core.Run (GCManagedState, newGCManagedState, withGCManagedState)
import Text.Pandoc.Class (PandocMonad, findFileWithDataFallback)
import Text.Pandoc.Error (PandocError)
import Text.Pandoc.Lua.Global (Global (..), setGlobals)
import Text.Pandoc.Lua.Init (runLuaWith)
import Text.Pandoc.Lua.Marshal.Format (peekExtensionsConfig)
import Text.Pandoc.Lua.Marshal.Pandoc (peekPandoc)
import Text.Pandoc.Lua.Marshal.WriterOptions (pushWriterOptions)
import Text.Pandoc.Readers (Reader (..))
import Text.Pandoc.Sources (ToSources(..))
import Text.Pandoc.Scripting (CustomComponents (..))
import Text.Pandoc.Writers (Writer (..))
import qualified Text.Pandoc.Lua.Writer.Classic as Classic
-- | Convert custom markup to Pandoc.
loadCustom :: (PandocMonad m, MonadIO m)
=> FilePath -> m (CustomComponents m)
loadCustom luaFile = do
luaState <- liftIO newGCManagedState
luaFile' <- fromMaybe luaFile <$>
findFileWithDataFallback "custom" luaFile
either throw pure <=< runLuaWith luaState $ do
let globals = [ PANDOC_SCRIPT_FILE luaFile ]
setGlobals globals
dofileTrace luaFile' >>= \case
OK -> pure ()
_ -> throwErrorAsException
mextsConf <- rawgetglobal "Extensions" >>= \case
TypeNil -> pure Nothing
TypeFunction -> Just <$!> do
callTrace 0 1
forcePeek $ peekExtensionsConfig top `lastly` pop 1
_ -> Just <$!> do
forcePeek $ peekExtensionsConfig top `lastly` pop 1
mtemplate <- rawgetglobal "Template" >>= \case
TypeNil -> pure Nothing
TypeFunction -> Just <$!> do
callTrace 0 1
forcePeek $ peekText top `lastly` pop 1
_ -> Just <$!> do
forcePeek $ peekText top `lastly` pop 1
mreader <- rawgetglobal "Reader" >>= \case
TypeNil -> do
pop 1
rawgetglobal "ByteStringReader" >>= \case
TypeNil -> pure Nothing
_ -> do
setfield registryindex readerField
pure . Just $ byteStringReader luaState
_ -> do
setfield registryindex readerField
pure . Just $ textReader luaState
mwriter <- rawgetglobal "Writer" >>= \case
TypeNil -> rawgetglobal "ByteStringWriter" >>= \case
TypeNil -> do
-- Neither `Writer` nor `BinaryWriter` are defined. Check for
-- "Doc"; if present, use the file as a classic writer.
docType <- rawgetglobal "Doc"
pop 3 -- remove nils/value of "Writer", "ByteStringWriter", "Doc"
pure $
if docType /= TypeFunction
then Nothing
else Just . TextWriter $ \opts doc ->
liftIO $ withGCManagedState luaState $
Classic.runCustom @PandocError opts doc
_ -> Just <$!> do
-- Binary writer. Writer function is on top of the stack.
setfield registryindex writerField
pure $ ByteStringWriter $ \opts doc ->
-- Call writer with document and writer options as arguments.
liftIO $ withGCManagedState luaState $ do
getfield registryindex writerField
push doc
pushWriterOptions opts
callTrace 2 1
forcePeek @PandocError $ peekLazyByteString top
_ -> Just <$!> do
-- New-type text writer. Writer function is on top of the stack.
setfield registryindex writerField
pure $ TextWriter $ \opts doc ->
liftIO $ withGCManagedState luaState $ do
getfield registryindex writerField
push doc
pushWriterOptions opts
callTrace 2 1
forcePeek @PandocError $ peekText top
pure $ CustomComponents
{ customReader = mreader
, customWriter = mwriter
, customTemplate = mtemplate
, customExtensions = mextsConf
}
-- | "Raw", non-metatable lookup of a key in the global table.
--
-- Most classic writers contain code that throws an error if a global
-- is not present. This would break our check for the existence of a
-- "Writer" function. We resort to raw access for that reason, but
-- could also catch the error instead.
--
-- TODO: This function ensures the proper behavior of legacy custom
-- writers. It should be replaced with 'getglobal' in the future.
rawgetglobal :: LuaError e => Name -> LuaE e Lua.Type
rawgetglobal x = do
pushglobaltable
pushName x
rawget (nth 2) <* remove (nth 2) -- remove global table
-- | Name under which the reader function is stored in the registry.
readerField :: Name
readerField = "Pandoc Reader function"
-- | Name under which the writer function is stored in the registry.
writerField :: Name
writerField = "Pandoc Writer function"
-- | Runs a Lua action in a continueable environment.
inLua :: MonadIO m => GCManagedState -> LuaE PandocError a -> m a
inLua st = liftIO . withGCManagedState @PandocError st
-- | Returns the ByteStringReader function
byteStringReader :: MonadIO m => GCManagedState -> Reader m
byteStringReader st = ByteStringReader $ \ropts input -> inLua st $ do
getfield registryindex readerField
push input
push ropts
pcallTrace 2 1 >>= \case
OK -> forcePeek $ peekPandoc top
_ -> throwErrorAsException
-- | Returns the TextReader function
textReader :: MonadIO m => GCManagedState -> Reader m
textReader st = TextReader $ \ropts srcs -> inLua st $ do
let input = toSources srcs
getfield registryindex readerField
push input
push ropts
pcallTrace 2 1 >>= \case
OK -> forcePeek $ peekPandoc top
_ -> throwErrorAsException
|
