Lua filter: use destructured functions for block filters

Filtering functions take element components as arguments instead of the
whole block elements. This resembles the way elements are handled in
custom writers.

3 files changed, 26 insertions, 21 deletions

diff --git a/src/Text/Pandoc/Lua.hs b/src/Text/Pandoc/Lua.hs
index bca6a2589..9903d4df6 100644
--- a/src/Text/Pandoc/Lua.hs
+++ b/src/Text/Pandoc/Lua.hs
@@ -107,24 +107,30 @@ execBlockLuaFilter :: LuaState
                    -> Map String (LuaFilterFunction Block)
                    -> Block -> IO Block
 execBlockLuaFilter lua fnMap x = do
-  let filterOrId constr = case Map.lookup constr fnMap of
-                            Nothing -> return x
-                            Just fn -> runLuaFilterFunction lua fn x
+  let runFn :: PushViaFilterFunction Block a => LuaFilterFunction Block -> a
+      runFn fn = runLuaFilterFunction lua fn
+  let tryFilter :: String -> (LuaFilterFunction Block -> IO Block) -> IO Block
+      tryFilter fnName callFilterFn =
+        case Map.lookup fnName fnMap of
+          Nothing -> return x
+          Just fn -> callFilterFn fn
   case x of
-    Plain _          -> filterOrId "Plain"
-    Para _           -> filterOrId "Para"
-    LineBlock _      -> filterOrId "LineBlock"
-    CodeBlock _ _    -> filterOrId "CodeBlock"
-    RawBlock _ _     -> filterOrId "RawBlock"
-    BlockQuote _     -> filterOrId "BlockQuote"
-    OrderedList _ _  -> filterOrId "OrderedList"
-    BulletList _     -> filterOrId "BulletList"
-    DefinitionList _ -> filterOrId "DefinitionList"
-    Header _ _ _     -> filterOrId "Header"
-    HorizontalRule   -> filterOrId "HorizontalRule"
-    Table _ _ _ _ _  -> filterOrId "Table"
-    Div _ _          -> filterOrId "Div"
-    Null             -> filterOrId "Null"
+    HorizontalRule             -> tryFilter "HorizontalRule" runFn
+    Null                       -> tryFilter "Null" runFn
+    BlockQuote blcks           -> tryFilter "BlockQuote" $ \fn -> runFn fn blcks
+    BulletList items           -> tryFilter "BulletList" $ \fn -> runFn fn items
+    CodeBlock attr code        -> tryFilter "CodeBlock" $ \fn -> runFn fn attr code
+    DefinitionList lst         -> tryFilter "DefinitionList" $ \fn -> runFn fn lst
+    Div attr content           -> tryFilter "Div" $ \fn -> runFn fn content attr
+    Header lvl attr inlns      -> tryFilter "Header" $ \fn -> runFn fn lvl inlns attr
+    LineBlock inlns            -> tryFilter "LineBlock" $ \fn -> runFn fn inlns
+    Para inlns                 -> tryFilter "Para" $ \fn -> runFn fn inlns
+    Plain inlns                -> tryFilter "Plain" $ \fn -> runFn fn inlns
+    RawBlock format str        -> tryFilter "RawBlock" $ \fn -> runFn fn format str
+    OrderedList (num,sty,delim) items ->
+      tryFilter "OrderedList" $ \fn -> runFn fn items (num,sty,delim)
+    Table capt aligns widths headers rows ->
+      tryFilter "Table" $ \fn -> runFn fn capt aligns widths headers rows
 
 execInlineLuaFilter :: LuaState
                     -> Map String (LuaFilterFunction Inline)
diff --git a/test/lua/markdown-reader.lua b/test/lua/markdown-reader.lua
index 6356113ec..a72af5546 100644
--- a/test/lua/markdown-reader.lua
+++ b/test/lua/markdown-reader.lua
@@ -1,7 +1,6 @@
 return {
   {
-    RawBlock = function (blk)
-      local format, content = unpack(blk.c)
+    RawBlock = function (format, content)
       if format == "markdown" then
         return pandoc.reader.markdown.read_block(content)
       else
diff --git a/test/lua/plain-to-para.lua b/test/lua/plain-to-para.lua
index 747257411..a11edbbe2 100644
--- a/test/lua/plain-to-para.lua
+++ b/test/lua/plain-to-para.lua
@@ -1,6 +1,6 @@
 return {
-  { Plain = function (blk)
-      return pandoc.Para(blk.c)
+  { Plain = function (content)
+      return pandoc.Para(content)
   end,
   }
 }