T.P.Scripting: Refactor the scripting engine.

The new type CustomComponents is exported from T.P.Scripting, and the
ScriptEngine fields are changed. Instead of separate fields for custom
readers and writers, we now have a single function that loads any number
of "components" from a script: these may be custom readers, custom
writers, templates for writers, or extension configs. (Note: it's
possible to have a custom reader and a custom writer for a format
together in the same file.)

Pandoc now checks the folder `custom` in the user's data directory for a
matching script if it can't find one in the local directory. Previously,
the `readers` and `writers` data directories were search for custom
readers and writers, respectively. Scripts in those directories must be
moved to the `custom` folder.

Custom readers used to implement a fallback behavior that allowed to
consume just a string value as input to the `Reader` function. This has
been removed, the first argument is now always a list of sources. Use
`tostring` on that argument to get a string.

Closes #8417.

Signed-off-by: Albert Krewinkel <albert@zeitkraut.de>

1 files changed, 3 insertions, 6 deletions

diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua.hs
index 8ff9a7c64..a42107082 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua.hs
@@ -13,8 +13,7 @@ Running pandoc Lua filters.
 module Text.Pandoc.Lua
   ( -- * High-level functions
     applyFilter
-  , readCustom
-  , writeCustom
+  , loadCustom
   -- * Low-level functions
   , Global(..)
   , setGlobals
@@ -30,8 +29,7 @@ import Text.Pandoc.Error (PandocError)
 import Text.Pandoc.Lua.Filter (applyFilter)
 import Text.Pandoc.Lua.Global (Global (..), setGlobals)
 import Text.Pandoc.Lua.Init (runLua, runLuaNoEnv)
-import Text.Pandoc.Lua.Reader (readCustom)
-import Text.Pandoc.Lua.Writer (writeCustom)
+import Text.Pandoc.Lua.Custom (loadCustom)
 import Text.Pandoc.Lua.Orphans ()
 import Text.Pandoc.Scripting (ScriptingEngine (..))
 import qualified Text.Pandoc.UTF8 as UTF8
@@ -46,6 +44,5 @@ getEngine = do
   pure $ ScriptingEngine
     { engineName = maybe "Lua (unknown version)" UTF8.toText versionName
     , engineApplyFilter = applyFilter
-    , engineReadCustom = readCustom
-    , engineWriteCustom = writeCustom
+    , engineLoadCustom = loadCustom
     }