From 9ddf84072b27553e9ffd578ae40003108f51015a Mon Sep 17 00:00:00 2001
From: Albert Krewinkel <albert@zeitkraut.de>
Date: Fri, 22 Dec 2017 20:08:45 +0100
Subject: Lua.Util: avoid altering the stack if peeking fails
The stack now remains unaltered if `getRawInt` or `getTable` fail. This
is important when those functions are used in an operation that is part
of an Alternative.
Change: minor
---
src/Text/Pandoc/Lua/Util.hs | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
(limited to 'src/Text/Pandoc/Lua')
diff --git a/src/Text/Pandoc/Lua/Util.hs b/src/Text/Pandoc/Lua/Util.hs
index e688ad255..28d09d339 100644
--- a/src/Text/Pandoc/Lua/Util.hs
+++ b/src/Text/Pandoc/Lua/Util.hs
@@ -67,7 +67,7 @@ getTable :: (ToLuaStack a, FromLuaStack b) => StackIndex -> a -> Lua b
getTable idx key = do
push key
rawget (idx `adjustIndexBy` 1)
- peek (-1) <* pop 1
+ popValue
-- | Add a key-value pair to the table at the top of the stack.
addValue :: (ToLuaStack a, ToLuaStack b) => a -> b -> Lua ()
@@ -86,10 +86,9 @@ addFunction name fn = do
-- | Get value behind key from table at given index.
getRawInt :: FromLuaStack a => StackIndex -> Int -> Lua a
-getRawInt idx key =
+getRawInt idx key = do
rawgeti idx key
- *> peek (-1)
- <* pop 1
+ popValue
-- | Set numeric key/value in table at the given index
setRawInt :: ToLuaStack a => StackIndex -> Int -> a -> Lua ()
@@ -106,6 +105,15 @@ raiseError e = do
Lua.push e
fromIntegral <$> Lua.lerror
+-- | Get, then pop the value at the top of the stack.
+popValue :: FromLuaStack a => Lua a
+popValue = do
+ resOrError <- Lua.peekEither (-1)
+ pop 1
+ case resOrError of
+ Left err -> Lua.throwLuaError err
+ Right x -> return x
+
-- | Newtype wrapper intended to be used for optional Lua values. Nesting this
-- type is strongly discouraged and will likely lead to a wrong result.
newtype OrNil a = OrNil { toMaybe :: Maybe a }
--
cgit v1.2.3