Lua: use package pandoc-lua-marshal (#7719)

The marshaling functions for pandoc's AST are extracted into a separate
package. The package comes with a number of changes:

  - Pandoc's List module was rewritten in C, thereby improving error
    messages.

  - Lists of `Block` and `Inline` elements are marshaled using the new
    list types `Blocks` and `Inlines`, respectively. These types
    currently behave identical to the generic List type, but give better
    error messages. This also opens up the possibility of adding
    element-specific methods to these lists in the future.

  - Elements of type `MetaValue` are no longer pushed as values which
    have `.t` and `.tag` properties. This was already true for
    `MetaString` and `MetaBool` values, which are still marshaled as Lua
    strings and booleans, respectively. Affected values:

      + `MetaBlocks` values are marshaled as a `Blocks` list;

      + `MetaInlines` values are marshaled as a `Inlines` list;

      + `MetaList` values are marshaled as a generic pandoc `List`s.

      + `MetaMap` values are marshaled as plain tables and no longer
        given any metatable.

  - The test suite for marshaled objects and their constructors has
    been extended and improved.

  - A bug in Citation objects, where setting a citation's suffix
    modified it's prefix, has been fixed.

4 files changed, 282 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Lua/Marshal/CommonState.hs b/src/Text/Pandoc/Lua/Marshal/CommonState.hs
new file mode 100644
index 000000000..a8c0e28d2
--- /dev/null
+++ b/src/Text/Pandoc/Lua/Marshal/CommonState.hs
@@ -0,0 +1,70 @@
+{-# LANGUAGE OverloadedStrings    #-}
+{- |
+   Module      : Text.Pandoc.Lua.Marshal.CommonState
+   Copyright   : © 2012-2021 John MacFarlane
+                 © 2017-2021 Albert Krewinkel
+   License     : GNU GPL, version 2 or above
+   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+   Stability   : alpha
+
+Instances to marshal (push) and unmarshal (peek) the common state.
+-}
+module Text.Pandoc.Lua.Marshal.CommonState
+  ( typeCommonState
+  , peekCommonState
+  , pushCommonState
+  ) where
+
+import HsLua.Core
+import HsLua.Marshalling
+import HsLua.Packaging
+import Text.Pandoc.Class (CommonState (..))
+import Text.Pandoc.Logging (LogMessage, showLogMessage)
+import Text.Pandoc.Lua.Marshal.List (pushPandocList)
+
+-- | Lua type used for the @CommonState@ object.
+typeCommonState :: LuaError e => DocumentedType e CommonState
+typeCommonState = deftype "pandoc CommonState" []
+  [ readonly "input_files" "input files passed to pandoc"
+      (pushPandocList pushString, stInputFiles)
+
+  , readonly "output_file" "the file to which pandoc will write"
+      (maybe pushnil pushString, stOutputFile)
+
+  , readonly "log" "list of log messages"
+      (pushPandocList (pushUD typeLogMessage), stLog)
+
+  , readonly "request_headers" "headers to add for HTTP requests"
+      (pushPandocList (pushPair pushText pushText), stRequestHeaders)
+
+  , readonly "resource_path"
+      "path to search for resources like included images"
+      (pushPandocList pushString, stResourcePath)
+
+  , readonly "source_url" "absolute URL + dir of 1st source file"
+      (maybe pushnil pushText, stSourceURL)
+
+  , readonly "user_data_dir" "directory to search for data files"
+      (maybe pushnil pushString, stUserDataDir)
+
+  , readonly "trace" "controls whether tracing messages are issued"
+      (pushBool, stTrace)
+
+  , readonly "verbosity" "verbosity level"
+      (pushString . show, stVerbosity)
+  ]
+
+peekCommonState :: LuaError e => Peeker e CommonState
+peekCommonState = peekUD typeCommonState
+
+pushCommonState :: LuaError e => Pusher e CommonState
+pushCommonState = pushUD typeCommonState
+
+typeLogMessage :: LuaError e => DocumentedType e LogMessage
+typeLogMessage = deftype "pandoc LogMessage"
+  [ operation Index $ defun "__tostring"
+      ### liftPure showLogMessage
+      <#> udparam typeLogMessage "msg" "object"
+      =#> functionResult pushText "string" "stringified log message"
+  ]
+  mempty -- no members
diff --git a/src/Text/Pandoc/Lua/Marshal/Context.hs b/src/Text/Pandoc/Lua/Marshal/Context.hs
new file mode 100644
index 000000000..17af936e1
--- /dev/null
+++ b/src/Text/Pandoc/Lua/Marshal/Context.hs
@@ -0,0 +1,28 @@
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+{- |
+   Module      : Text.Pandoc.Lua.Marshaling.Context
+   Copyright   : © 2012-2021 John MacFarlane
+                 © 2017-2021 Albert Krewinkel
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+   Stability   : alpha
+
+Marshaling instance for doctemplates Context and its components.
+-}
+module Text.Pandoc.Lua.Marshal.Context () where
+
+import qualified HsLua as Lua
+import HsLua (Pushable)
+import Text.DocTemplates (Context(..), Val(..), TemplateTarget)
+import Text.DocLayout (render)
+
+instance (TemplateTarget a, Pushable a) => Pushable (Context a) where
+  push (Context m) = Lua.push m
+
+instance (TemplateTarget a, Pushable a) => Pushable (Val a) where
+  push NullVal = Lua.push ()
+  push (BoolVal b) = Lua.push b
+  push (MapVal ctx) = Lua.push ctx
+  push (ListVal xs) = Lua.push xs
+  push (SimpleVal d) = Lua.push $ render Nothing d
diff --git a/src/Text/Pandoc/Lua/Marshal/PandocError.hs b/src/Text/Pandoc/Lua/Marshal/PandocError.hs
new file mode 100644
index 000000000..d1c0ad4f4
--- /dev/null
+++ b/src/Text/Pandoc/Lua/Marshal/PandocError.hs
@@ -0,0 +1,51 @@
+{-# LANGUAGE LambdaCase           #-}
+{-# LANGUAGE OverloadedStrings    #-}
+{-# LANGUAGE ScopedTypeVariables  #-}
+{-# LANGUAGE TypeApplications     #-}
+{- |
+   Module      : Text.Pandoc.Lua.Marshal.PandocError
+   Copyright   : © 2020-2021 Albert Krewinkel
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+   Stability   : alpha
+
+Marshal of @'PandocError'@ values.
+-}
+module Text.Pandoc.Lua.Marshal.PandocError
+  ( peekPandocError
+  , pushPandocError
+  , typePandocError
+  )
+  where
+
+import HsLua.Core (LuaError)
+import HsLua.Marshalling (Peeker, Pusher, pushString, liftLua)
+import HsLua.Packaging
+import Text.Pandoc.Error (PandocError (PandocLuaError))
+
+import qualified HsLua as Lua
+import qualified Text.Pandoc.UTF8 as UTF8
+
+-- | Lua userdata type definition for PandocError.
+typePandocError :: LuaError e => DocumentedType e PandocError
+typePandocError = deftype "PandocError"
+  [ operation Tostring $ defun "__tostring"
+    ### liftPure (show @PandocError)
+    <#> udparam typePandocError "obj" "PandocError object"
+    =#> functionResult pushString "string" "string representation of error."
+  ]
+  mempty -- no members
+
+-- | Peek a @'PandocError'@ element to the Lua stack.
+pushPandocError :: LuaError e => Pusher e PandocError
+pushPandocError = pushUD typePandocError
+
+-- | Retrieve a @'PandocError'@ from the Lua stack.
+peekPandocError :: LuaError e => Peeker e PandocError
+peekPandocError idx = Lua.retrieving "PandocError" $
+  liftLua (Lua.ltype idx) >>= \case
+    Lua.TypeUserdata -> peekUD typePandocError idx
+    _ -> do
+      msg <- liftLua $ Lua.state >>= \l -> Lua.liftIO (Lua.popErrorMessage l)
+      return $ PandocLuaError (UTF8.toText msg)
diff --git a/src/Text/Pandoc/Lua/Marshal/ReaderOptions.hs b/src/Text/Pandoc/Lua/Marshal/ReaderOptions.hs
new file mode 100644
index 000000000..c20770dba
--- /dev/null
+++ b/src/Text/Pandoc/Lua/Marshal/ReaderOptions.hs
@@ -0,0 +1,133 @@
+{-# LANGUAGE LambdaCase           #-}
+{-# LANGUAGE OverloadedStrings    #-}
+{-# LANGUAGE ScopedTypeVariables  #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+{- |
+   Module      : Text.Pandoc.Lua.Marshaling.ReaderOptions
+   Copyright   : © 2012-2021 John MacFarlane
+                 © 2017-2021 Albert Krewinkel
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+   Stability   : alpha
+
+Marshaling instance for ReaderOptions and its components.
+-}
+module Text.Pandoc.Lua.Marshal.ReaderOptions
+  ( peekReaderOptions
+  , pushReaderOptions
+  , pushReaderOptionsReadonly
+  ) where
+
+import Data.Default (def)
+import HsLua as Lua
+import Text.Pandoc.Lua.Marshal.List (pushPandocList)
+import Text.Pandoc.Options (ReaderOptions (..))
+
+--
+-- Reader Options
+--
+
+-- | Retrieve a ReaderOptions value, either from a normal ReaderOptions
+-- value, from a read-only object, or from a table with the same
+-- keys as a ReaderOptions object.
+peekReaderOptions :: LuaError e => Peeker e ReaderOptions
+peekReaderOptions = retrieving "ReaderOptions" . \idx ->
+  liftLua (ltype idx) >>= \case
+    TypeUserdata -> choice [ peekUD typeReaderOptions
+                           , peekUD typeReaderOptionsReadonly
+                           ]
+                           idx
+    TypeTable    -> peekReaderOptionsTable idx
+    _            -> failPeek =<<
+                    typeMismatchMessage "ReaderOptions userdata or table" idx
+
+-- | Pushes a ReaderOptions value as userdata object.
+pushReaderOptions :: LuaError e => Pusher e ReaderOptions
+pushReaderOptions = pushUD typeReaderOptions
+
+-- | Pushes a ReaderOptions object, but makes it read-only.
+pushReaderOptionsReadonly :: LuaError e => Pusher e ReaderOptions
+pushReaderOptionsReadonly = pushUD typeReaderOptionsReadonly
+
+-- | ReaderOptions object type for read-only values.
+typeReaderOptionsReadonly :: LuaError e => DocumentedType e ReaderOptions
+typeReaderOptionsReadonly = deftype "ReaderOptions (read-only)"
+  [ operation Tostring $ lambda
+    ### liftPure show
+    <#> udparam typeReaderOptions "opts" "options to print in native format"
+    =#> functionResult pushString "string" "Haskell representation"
+  , operation Newindex $ lambda
+    ### (failLua "This ReaderOptions value is read-only.")
+    =?> "Throws an error when called, i.e., an assignment is made."
+  ]
+  readerOptionsMembers
+
+-- | 'ReaderOptions' object type.
+typeReaderOptions :: LuaError e => DocumentedType e ReaderOptions
+typeReaderOptions = deftype "ReaderOptions"
+  [ operation Tostring $ lambda
+    ### liftPure show
+    <#> udparam typeReaderOptions "opts" "options to print in native format"
+    =#> functionResult pushString "string" "Haskell representation"
+  ]
+  readerOptionsMembers
+
+-- | Member properties of 'ReaderOptions' Lua values.
+readerOptionsMembers :: LuaError e
+                     => [Member e (DocumentedFunction e) ReaderOptions]
+readerOptionsMembers =
+  [ property "abbreviations" ""
+      (pushSet pushText, readerAbbreviations)
+      (peekSet peekText, \opts x -> opts{ readerAbbreviations = x })
+  , property "columns" ""
+      (pushIntegral, readerColumns)
+      (peekIntegral, \opts x -> opts{ readerColumns = x })
+  , property "default_image_extension" ""
+      (pushText, readerDefaultImageExtension)
+      (peekText, \opts x -> opts{ readerDefaultImageExtension = x })
+  , property "extensions" ""
+      (pushString . show, readerExtensions)
+      (peekRead, \opts x -> opts{ readerExtensions = x })
+  , property "indented_code_classes" ""
+      (pushPandocList pushText, readerIndentedCodeClasses)
+      (peekList peekText, \opts x -> opts{ readerIndentedCodeClasses = x })
+  , property "strip_comments" ""
+      (pushBool, readerStripComments)
+      (peekBool, \opts x -> opts{ readerStripComments = x })
+  , property "standalone" ""
+      (pushBool, readerStandalone)
+      (peekBool, \opts x -> opts{ readerStandalone = x })
+  , property "tab_stop" ""
+      (pushIntegral, readerTabStop)
+      (peekIntegral, \opts x -> opts{ readerTabStop = x })
+  , property "track_changes" ""
+      (pushString . show, readerTrackChanges)
+      (peekRead, \opts x -> opts{ readerTrackChanges = x })
+  ]
+
+-- | Retrieves a 'ReaderOptions' object from a table on the stack, using
+-- the default values for all missing fields.
+--
+-- Internally, this pushes the default reader options, sets each
+-- key/value pair of the table in the userdata value, then retrieves the
+-- object again. This will update all fields and complain about unknown
+-- keys.
+peekReaderOptionsTable :: LuaError e => Peeker e ReaderOptions
+peekReaderOptionsTable idx = retrieving "ReaderOptions (table)" $ do
+  liftLua $ do
+    absidx <- absindex idx
+    pushUD typeReaderOptions def
+    let setFields = do
+          next absidx >>= \case
+            False -> return () -- all fields were copied
+            True -> do
+              pushvalue (nth 2) *> insert (nth 2)
+              settable (nth 4) -- set in userdata object
+              setFields
+    pushnil -- first key
+    setFields
+  peekUD typeReaderOptions top
+
+instance Pushable ReaderOptions where
+  push = pushReaderOptions