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|
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TupleSections #-}
{- |
Module : Text.Pandoc.Lua.Reader
Copyright : Copyright (C) 2021-2022 John MacFarlane
License : GNU GPL, version 2 or above
Maintainer : John MacFarlane <[email protected]>
Stability : alpha
Portability : portable
Supports custom parsers written in Lua which produce a Pandoc AST.
-}
module Text.Pandoc.Lua.Reader ( readCustom ) where
import Control.Exception
import Control.Monad ((<=<), (<$!>), when)
import Control.Monad.IO.Class (MonadIO)
import Data.Maybe (fromMaybe)
import HsLua as Lua hiding (Operation (Div))
import HsLua.Core.Run (GCManagedState, newGCManagedState, withGCManagedState)
import Text.Pandoc.Class (PandocMonad, findFileWithDataFallback, report)
import Text.Pandoc.Error (PandocError)
import Text.Pandoc.Format (ExtensionsConfig (..))
import Text.Pandoc.Logging
import Text.Pandoc.Lua.Global (Global (..), setGlobals)
import Text.Pandoc.Lua.Init (runLuaWith)
import Text.Pandoc.Lua.PandocLua
import Text.Pandoc.Lua.Marshal.Format (peekExtensionsConfig)
import Text.Pandoc.Lua.Marshal.Pandoc (peekPandoc)
import Text.Pandoc.Readers (Reader (..))
import Text.Pandoc.Sources (ToSources(..), sourcesToText)
import qualified Data.Text as T
-- | Convert custom markup to Pandoc.
readCustom :: (PandocMonad m, MonadIO m)
=> FilePath -> m (Reader m, ExtensionsConfig)
readCustom luaFile = do
luaState <- liftIO newGCManagedState
luaFile' <- fromMaybe luaFile <$> findFileWithDataFallback "readers" luaFile
either throw pure <=< runLuaWith luaState $ do
let globals = [ PANDOC_SCRIPT_FILE luaFile ]
setGlobals globals
stat <- dofileTrace luaFile'
-- check for error in lua script (later we'll change the return type
-- to handle this more gracefully):
when (stat /= Lua.OK)
Lua.throwErrorAsException
extsConf <- getglobal "reader_extensions" >>= \case
TypeNil -> pure $ ExtensionsConfig mempty mempty
_ -> forcePeek $ peekExtensionsConfig top `lastly` pop 1
(,extsConf) <$!> getCustomReader luaState
where
readerField = "PANDOC Reader function"
inLua st = liftIO . withGCManagedState @PandocError st
byteStringReader :: MonadIO m => GCManagedState -> Reader m
byteStringReader st = ByteStringReader $ \ropts input -> inLua st $ do
getfield registryindex readerField
push input
push ropts
callTrace 2 1
forcePeek $ peekPandoc top
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
ErrRun -> do
-- Caught a runtime error. Check if parsing might work if we
-- pass a string instead of a Sources list, then retry.
runPeek (peekText top) >>= \case
Failure {} ->
-- not a string error object. Bail!
throwErrorAsException
Success errmsg ->
if "string expected, got pandoc Sources" `T.isInfixOf` errmsg
then do
pop 1
_ <- unPandocLua $ do
report $ Deprecated "old Reader function signature" $
T.unlines
[ "Reader functions should accept a sources list; "
, "functions expecting `string` input are deprecated. "
, "Use `tostring` to convert the first argument to a "
, "string."
]
getglobal "Reader"
push $ sourcesToText input -- push sources as string
push ropts
callTrace 2 1
forcePeek $ peekPandoc top
else
-- nothing we can do here
throwErrorAsException
_ -> -- not a runtime error, we won't be able to recover from that
throwErrorAsException
getCustomReader st = do
getglobal "Reader" >>= \case
TypeNil -> do
pop 1
getglobal "ByteStringReader" >>= \case
TypeNil -> failLua $ "No reader function found: either 'Reader' or "
<> "'ByteStringReader' must be defined."
_ -> do
setfield registryindex readerField
pure (byteStringReader st)
_ -> do
setfield registryindex readerField
pure (textReader st)
|
