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, 3 deletions

diff --git a/src/Text/Pandoc/App/CommandLineOptions.hs b/src/Text/Pandoc/App/CommandLineOptions.hs
index a65fe5a04..30b5693fd 100644
--- a/src/Text/Pandoc/App/CommandLineOptions.hs
+++ b/src/Text/Pandoc/App/CommandLineOptions.hs
@@ -51,7 +51,7 @@ import Text.Pandoc.App.Opt (Opt (..), LineEnding (..), IpynbOutput (..),
                             fullDefaultsPath, OptInfo(..))
 import Text.Pandoc.Filter (Filter (..))
 import Text.Pandoc.Highlighting (highlightingStyles, lookupHighlightingStyle)
-import Text.Pandoc.Scripting (ScriptingEngine (..))
+import Text.Pandoc.Scripting (ScriptingEngine (..), customTemplate)
 import Text.Pandoc.Shared (safeStrRead)
 import Text.Printf
 import qualified Control.Exception as E
@@ -161,8 +161,8 @@ handleOptInfo engine info = E.handle (handleError . Left) $ do
                       getDefaultTemplate fmt
                     _ -> do
                       -- format looks like a filepath => custom writer
-                      (_, _, mt) <- engineWriteCustom engine (T.unpack fmt)
-                      case mt of
+                      components <- engineLoadCustom engine (T.unpack fmt)
+                      case customTemplate components of
                         Just t  -> pure t
                         Nothing -> E.throw $ PandocNoTemplateError fmt
       case templ of