Lua: allow to pass Sources to pandoc.read (#8002)

Sources, the data type passed to the `Reader` function in custom
readers, are now accepted as input to `pandoc.read`.

doc/lua-filters.md

@@ -3414,7 +3414,7 @@ retrieved from the other parsed input files.
 Parameters:
 
 `markup`
-:   the markup to be parsed (string)
+:   the markup to be parsed (string|Sources)
 
 `format`
 :   format specification, defaults to `"markdown"` (string)

src/Text/Pandoc/Lua/Marshal/Sources.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE LambdaCase           #-}
 {-# LANGUAGE OverloadedStrings    #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 {- |
@@ -9,13 +10,15 @@ Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
 Marshal 'Sources'.
 -}
 module Text.Pandoc.Lua.Marshal.Sources
-  ( pushSources
+  ( peekSources
+  , pushSources
   ) where
 
+import Control.Monad ((<$!>))
 import Data.Text (Text)
 import HsLua as Lua
 import Text.Pandoc.Lua.Marshal.List (newListMetatable)
-import Text.Pandoc.Sources (Sources (..))
+import Text.Pandoc.Sources (Sources (..), toSources)
 import Text.Parsec (SourcePos, sourceName)
 
 -- | Pushes the 'Sources' as a list of lazy Lua objects.
@@ -31,6 +34,13 @@ pushSources (Sources srcs) = do
     rawset (nth 3)
   setmetatable (nth 2)
 
+-- | Retrieves sources from the stack.
+peekSources :: LuaError e => Peeker e Sources
+peekSources idx = liftLua (ltype idx) >>= \case
+  TypeString -> toSources <$!> peekText idx
+  TypeTable  -> Sources <$!> peekList (peekUD typeSource) idx
+  _          -> Sources . (:[]) <$!> peekUD typeSource idx
+
 -- | Source object type.
 typeSource :: LuaError e => DocumentedType e (SourcePos, Text)
 typeSource = deftype "pandoc input source"

src/Text/Pandoc/Lua/Module/Pandoc.hs

@@ -19,6 +19,7 @@ module Text.Pandoc.Lua.Module.Pandoc
   ) where
 
 import Prelude hiding (read)
+import Control.Applicative ((<|>))
 import Control.Monad (forM_, when)
 import Control.Monad.Catch (catch, throwM)
 import Data.Data (Data, dataTypeConstrs, dataTypeOf, showConstr)
@@ -34,6 +35,7 @@ import Text.Pandoc.Lua.Marshal.AST
 import Text.Pandoc.Lua.Marshal.Filter (peekFilter)
 import Text.Pandoc.Lua.Marshal.ReaderOptions ( peekReaderOptions
                                              , pushReaderOptions)
+import Text.Pandoc.Lua.Marshal.Sources (peekSources)
 import Text.Pandoc.Lua.Marshal.WriterOptions ( peekWriterOptions
                                              , pushWriterOptions)
 import Text.Pandoc.Lua.Module.Utils (sha1)
@@ -42,6 +44,7 @@ import Text.Pandoc.Options ( ReaderOptions (readerExtensions)
                            , WriterOptions (writerExtensions) )
 import Text.Pandoc.Process (pipeProcess)
 import Text.Pandoc.Readers (Reader (..), getReader)
+import Text.Pandoc.Sources (toSources)
 import Text.Pandoc.Writers (Writer (..), getWriter)
 
 import qualified HsLua as Lua
@@ -181,9 +184,16 @@ functions =
                 readerOpts = fromMaybe def mreaderOptions
                 readAction = getReader formatSpec >>= \case
                   (TextReader r, es)       ->
-                    r readerOpts{readerExtensions = es} (UTF8.toText content)
+                    r readerOpts{readerExtensions = es}
+                      (case content of
+                         Left bs       -> toSources $ UTF8.toText bs
+                         Right sources -> sources)
                   (ByteStringReader r, es) ->
-                    r readerOpts{readerExtensions = es} (BSL.fromStrict content)
+                    case content of
+                      Left bs -> r readerOpts{readerExtensions = es}
+                                   (BSL.fromStrict bs)
+                      Right _ -> liftPandocLua $ Lua.failLua
+                                 "Cannot use bytestring reader with Sources"
             try (unPandocLua readAction) >>= \case
               Right pd ->
                 -- success, got a Pandoc document
@@ -195,7 +205,9 @@ functions =
                 "Extension " <> e <> " not supported for " <> f
               Left e ->
                 throwM e)
-    <#> parameter peekByteString "string" "content" "text to parse"
+    <#> parameter (\idx -> (Left  <$> peekByteString idx)
+                       <|> (Right <$> peekSources idx))
+          "string|Sources" "content" "text to parse"
     <#> opt (textParam "formatspec" "format and extensions")
     <#> opt (parameter peekReaderOptions "ReaderOptions" "reader_options"
              "reader options")