From f6124213073cf162bd3cfa5e6d455807e8a502a9 Mon Sep 17 00:00:00 2001
From: Albert Krewinkel <albert@zeitkraut.de>
Date: Fri, 26 Oct 2018 23:45:01 +0200
Subject: T.P.Lua: expose more useful internals (API change)

Newly exported from Text.Pandoc.Lua:

- `runFilterFile` to run a Lua filter from file;
- data type `Global` and its constructors; and
- `setGlobals` to add globals to a Lua environment.

This module also contains `Pushable` and `Peekable` instances required
to get pandoc's data types to and from Lua. Low-level Lua operation
remain hidden in Text.Pandoc.Lua.
---
 src/Text/Pandoc/Lua/Filter.hs | 20 ++++++++++++++++++++
 src/Text/Pandoc/Lua/Init.hs   |  3 +--
 2 files changed, 21 insertions(+), 2 deletions(-)

(limited to 'src/Text/Pandoc/Lua')

diff --git a/src/Text/Pandoc/Lua/Filter.hs b/src/Text/Pandoc/Lua/Filter.hs
index d17f9a969..d47d3bd9b 100644
--- a/src/Text/Pandoc/Lua/Filter.hs
+++ b/src/Text/Pandoc/Lua/Filter.hs
@@ -30,6 +30,7 @@ Types and functions for running Lua filters.
 -}
 module Text.Pandoc.Lua.Filter ( LuaFilterFunction
                               , LuaFilter
+                              , runFilterFile
                               , tryFilter
                               , runFilterFunction
                               , walkMWithLuaFilter
@@ -54,6 +55,25 @@ import qualified Data.Map.Strict as Map
 import qualified Foreign.Lua as Lua
 import qualified Text.Pandoc.Lua.Util as LuaUtil
 
+-- | Transform document using the filter defined in the given file.
+runFilterFile :: FilePath -> Pandoc -> Lua Pandoc
+runFilterFile filterPath doc = do
+  top <- Lua.gettop
+  stat <- LuaUtil.dofileWithTraceback filterPath
+  if stat /= Lua.OK
+    then Lua.throwTopMessage
+    else do
+      newtop <- Lua.gettop
+      -- Use the returned filters, or the implicitly defined global
+      -- filter if nothing was returned.
+      luaFilters <- if newtop - top >= 1
+                    then Lua.peek Lua.stackTop
+                    else Lua.pushglobaltable *> fmap (:[]) Lua.popValue
+      runAll luaFilters doc
+
+runAll :: [LuaFilter] -> Pandoc -> Lua Pandoc
+runAll = foldr ((>=>) . walkMWithLuaFilter) return
+
 -- | Filter function stored in the registry
 newtype LuaFilterFunction = LuaFilterFunction Lua.Reference
 
diff --git a/src/Text/Pandoc/Lua/Init.hs b/src/Text/Pandoc/Lua/Init.hs
index e922e3d93..e69447ae5 100644
--- a/src/Text/Pandoc/Lua/Init.hs
+++ b/src/Text/Pandoc/Lua/Init.hs
@@ -30,7 +30,6 @@ module Text.Pandoc.Lua.Init
   ( LuaException (..)
   , LuaPackageParams (..)
   , runLua
-  , initLuaState
   , luaPackageParams
   ) where
 
@@ -94,7 +93,7 @@ luaPackageParams = do
     , luaPkgMediaBag = mbRef
     }
 
--- Initialize the lua state with all required values
+-- | Initialize the lua state with all required values
 initLuaState :: LuaPackageParams -> Lua ()
 initLuaState luaPkgParams = do
   Lua.openlibs
-- 
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