Lua: allow strings in place of compiled templates.

This allows to use a string as parameter to `pandoc.template.apply` and
in the WriterOptions `template` field.

Closes: #8321

4 files changed, 24 insertions, 13 deletions

diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Marshal/Template.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Marshal/Template.hs
index 56878b109..5425a566c 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Marshal/Template.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Marshal/Template.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE LambdaCase           #-}
 {-# LANGUAGE OverloadedStrings    #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 {- |
@@ -16,15 +17,26 @@ module Text.Pandoc.Lua.Marshal.Template
 
 import Data.Text (Text)
 import HsLua as Lua
-import Text.DocTemplates (Template)
+import HsLua.Core.Utf8 as Lua
+import Text.Pandoc.Error (PandocError)
+import Text.Pandoc.Lua.PandocLua (unPandocLua)
+import Text.Pandoc.Templates (Template, compileTemplate, runWithDefaultPartials)
 
 -- | Pushes a 'Template' as a an opaque userdata value.
 pushTemplate :: LuaError e => Pusher e (Template Text)
 pushTemplate = pushUD typeTemplate
 
 -- | Retrieves a 'Template' 'Text' value from the stack.
-peekTemplate :: LuaError e => Peeker e (Template Text)
-peekTemplate = peekUD typeTemplate
+peekTemplate :: Peeker PandocError (Template Text)
+peekTemplate idx = liftLua (ltype idx) >>= \case
+  TypeString -> do
+    let path = "templates/default.custom"
+    let liftPM = liftLua . unPandocLua
+    tmpl <- peekText idx
+    (liftPM $ runWithDefaultPartials (compileTemplate path tmpl)) >>= \case
+      Left e  -> failPeek (Lua.fromString e)
+      Right t -> pure t
+  _ -> peekUD typeTemplate idx
 
 -- | Template object type.
 typeTemplate :: LuaError e => DocumentedType e (Template Text)
diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Marshal/WriterOptions.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Marshal/WriterOptions.hs
index 48451457b..1b0a9ea1c 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Marshal/WriterOptions.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Marshal/WriterOptions.hs
@@ -21,6 +21,7 @@ module Text.Pandoc.Lua.Marshal.WriterOptions
 import Control.Applicative (optional)
 import Data.Default (def)
 import HsLua as Lua
+import Text.Pandoc.Error (PandocError)
 import Text.Pandoc.Lua.Marshal.Context (peekContext, pushContext)
 import Text.Pandoc.Lua.Marshal.Format (peekExtensions, pushExtensions)
 import Text.Pandoc.Lua.Marshal.List (pushPandocList)
@@ -34,7 +35,7 @@ import Text.Pandoc.Options (WriterOptions (..))
 -- | Retrieve a WriterOptions value, either from a normal WriterOptions
 -- value, from a read-only object, or from a table with the same
 -- keys as a WriterOptions object.
-peekWriterOptions :: LuaError e => Peeker e WriterOptions
+peekWriterOptions :: Peeker PandocError WriterOptions
 peekWriterOptions = retrieving "WriterOptions" . \idx ->
   liftLua (ltype idx) >>= \case
     TypeUserdata -> peekUD typeWriterOptions idx
@@ -43,11 +44,11 @@ peekWriterOptions = retrieving "WriterOptions" . \idx ->
                     typeMismatchMessage "WriterOptions userdata or table" idx
 
 -- | Pushes a WriterOptions value as userdata object.
-pushWriterOptions :: LuaError e => Pusher e WriterOptions
+pushWriterOptions :: Pusher PandocError WriterOptions
 pushWriterOptions = pushUD typeWriterOptions
 
 -- | 'WriterOptions' object type.
-typeWriterOptions :: LuaError e => DocumentedType e WriterOptions
+typeWriterOptions :: DocumentedType PandocError WriterOptions
 typeWriterOptions = deftype "WriterOptions"
   [ operation Tostring $ lambda
     ### liftPure show
@@ -223,7 +224,7 @@ typeWriterOptions = deftype "WriterOptions"
 -- 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.
-peekWriterOptionsTable :: LuaError e => Peeker e WriterOptions
+peekWriterOptionsTable :: Peeker PandocError WriterOptions
 peekWriterOptionsTable idx = retrieving "WriterOptions (table)" $ do
   liftLua $ do
     absidx <- absindex idx
@@ -238,6 +239,3 @@ peekWriterOptionsTable idx = retrieving "WriterOptions (table)" $ do
     pushnil -- first key
     setFields
   peekUD typeWriterOptions top `lastly` pop 1
-
-instance Pushable WriterOptions where
-  push = pushWriterOptions
diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Pandoc.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Pandoc.hs
index b42bdc50f..aaca86b02 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Pandoc.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Pandoc.hs
@@ -131,7 +131,7 @@ pushWithConstructorsSubtable constructors = do
     rawset (nth 3)
   pop 1 -- pop constructor table
 
-otherConstructors :: LuaError e => [DocumentedFunction e]
+otherConstructors :: [DocumentedFunction PandocError]
 otherConstructors =
   [ mkPandoc
   , mkMeta
diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Writer.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Writer.hs
index e310b33c8..c5e3e2469 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Writer.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Writer.hs
@@ -32,6 +32,7 @@ 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.Template (peekTemplate)
+import Text.Pandoc.Lua.Marshal.WriterOptions (pushWriterOptions)
 import Text.Pandoc.Templates (Template)
 import Text.Pandoc.Writers (Writer (..))
 import qualified Text.Pandoc.Lua.Writer.Classic as Classic
@@ -96,7 +97,7 @@ writeCustom luaFile = do
             liftIO $ withGCManagedState luaState $ do
               getfield registryindex writerField
               push doc
-              push opts
+              pushWriterOptions opts
               callTrace 2 1
               forcePeek @PandocError $ peekLazyByteString top
       _ -> do
@@ -106,6 +107,6 @@ writeCustom luaFile = do
           liftIO $ withGCManagedState luaState $ do
             getfield registryindex writerField
             push doc
-            push opts
+            pushWriterOptions opts
             callTrace 2 1
             forcePeek @PandocError $ peekText top