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 <[email protected]>

2 files changed, 19 insertions, 9 deletions

diff --git a/pandoc-lua-engine/test/Tests/Lua/Reader.hs b/pandoc-lua-engine/test/Tests/Lua/Reader.hs
index 15ad685b4..dbf125432 100644
--- a/pandoc-lua-engine/test/Tests/Lua/Reader.hs
+++ b/pandoc-lua-engine/test/Tests/Lua/Reader.hs
@@ -9,11 +9,13 @@ Tests for custom Lua readers.
 -}
 module Tests.Lua.Reader (tests) where
 
+import Control.Arrow ((>>>))
 import Data.Char (chr)
 import Data.Default (Default (def))
 import Text.Pandoc.Class (runIOorExplode)
-import Text.Pandoc.Lua (readCustom)
-import Text.Pandoc.Readers (Reader (ByteStringReader, TextReader))
+import Text.Pandoc.Lua (loadCustom)
+import Text.Pandoc.Readers (Reader (ByteStringReader))
+import Text.Pandoc.Scripting (customReader)
 import Test.Tasty (TestTree)
 import Test.Tasty.HUnit ((@?=), testCase)
 
@@ -26,9 +28,9 @@ tests =
   [ testCase "read binary to code block" $ do
     input <- BL.readFile "bytestring.bin"
     doc <- runIOorExplode $
-      readCustom "bytestring-reader.lua" >>= \case
-        (ByteStringReader f, _) -> f def input
-        (TextReader {}, _)      -> error "Expected a bytestring reader"
+      loadCustom "bytestring-reader.lua" >>= (customReader >>> \case
+        Just (ByteStringReader f) -> f def input
+        _                         -> error "Expected a bytestring reader")
     let bytes = mconcat $ map (B.str . T.singleton . chr) [0..255]
     doc @?= B.doc (B.plain bytes)
   ]
diff --git a/pandoc-lua-engine/test/Tests/Lua/Writer.hs b/pandoc-lua-engine/test/Tests/Lua/Writer.hs
index 19db66da0..692c6b83d 100644
--- a/pandoc-lua-engine/test/Tests/Lua/Writer.hs
+++ b/pandoc-lua-engine/test/Tests/Lua/Writer.hs
@@ -16,9 +16,10 @@ import Text.Pandoc.Class (runIOorExplode, readFileStrict)
 import Text.Pandoc.Extensions (Extension (..), extensionsFromList)
 import Text.Pandoc.Format (ExtensionsDiff (..), FlavoredFormat (..),
                            applyExtensionsDiff)
-import Text.Pandoc.Lua (writeCustom)
+import Text.Pandoc.Lua (loadCustom)
 import Text.Pandoc.Options (WriterOptions (..))
 import Text.Pandoc.Readers (readNative)
+import Text.Pandoc.Scripting (CustomComponents (..))
 import Text.Pandoc.Writers (Writer (ByteStringWriter, TextWriter))
 import Test.Tasty (TestTree)
 import Test.Tasty.Golden (goldenVsString)
@@ -35,9 +36,9 @@ tests =
     (runIOorExplode $ do
         source <- UTF8.toText <$> readFileStrict "testsuite.native"
         doc <- readNative def source
-        txt <- writeCustom "sample.lua" >>= \case
-          (TextWriter f, _, _) -> f def doc
-          _            -> error "Expected a text writer"
+        txt <- customWriter <$> loadCustom "sample.lua" >>= \case
+          Just (TextWriter f) -> f def doc
+          _                   -> error "Expected a text writer"
         pure $ BL.fromStrict (UTF8.fromText txt))
 
   , goldenVsString "tables testsuite"
@@ -84,3 +85,10 @@ tests =
           _                        -> error "Expected a text writer"
       result @?= "smart extension is enabled;\ncitations extension is enabled\n"
   ]
+ where
+  writeCustom fp = do
+    components <- loadCustom fp
+    let exts = fromMaybe mempty (customExtensions components)
+    case customWriter components of
+      Nothing -> error "Expected a writer to be defined"
+      Just w  -> return (w, exts, customTemplate components)