Lua: add function pandoc.format.extensions.

This simplifies the creation of custom readers and writers that are
based on built-in formats.

1 files changed, 17 insertions, 1 deletions

diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Format.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Format.hs
index 8707acbf9..63753532a 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Format.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Format.hs
@@ -14,7 +14,8 @@ module Text.Pandoc.Lua.Module.Format
 import HsLua
 import Text.Pandoc.Error (PandocError)
 import Text.Pandoc.Extensions (getAllExtensions, getDefaultExtensions)
-import Text.Pandoc.Lua.Marshal.Format (pushExtensions)
+import Text.Pandoc.Format (getExtensionsConfig)
+import Text.Pandoc.Lua.Marshal.Format (pushExtensions, pushExtensionsConfig)
 import Text.Pandoc.Lua.PandocLua ()
 
 import qualified Data.Text as T
@@ -56,4 +57,19 @@ functions =
         , "can have an effect when reading a format but not when"
         , "writing it, or *vice versa*."
         ]
+
+  , defun "extensions"
+     ### liftPure getExtensionsConfig
+     <#> textParam "format" "format identifier"
+     =#> functionResult pushExtensionsConfig "table" "extensions config"
+     #? T.unlines
+        [ "Returns the extension configuration for the given format."
+        , "The configuration is represented as a table with all supported"
+        , "extensions as keys and their default status as value, with"
+        , "`true` indicating that the extension is enabled by default,"
+        , "while `false` marks a supported extension that's disabled."
+        , ""
+        , "This function can be used to assign a value to the `Extensions`"
+        , "global in custom readers and writers."
+        ]
   ]