Add function tonumberx and tointegerx

Those functions are part of the 5.2 and 5.3 API and can help to avoid an
additional call to the API.

src/Foreign/Lua/Api.hs

@@ -89,7 +89,9 @@ module Foreign.Lua.Api (
   , toboolean
   , tocfunction
   , tointeger
+  , tointegerx
   , tonumber
+  , tonumberx
   , topointer
   , tostring
   , tothread
@@ -175,7 +177,7 @@ import Foreign.Lua.Api.RawBindings
 import Foreign.Lua.Api.Types
 import Foreign.Lua.Types.Error
 import Foreign.Lua.Types.Lua
-import Foreign.Marshal.Alloc
+import Foreign.Marshal.Alloc (alloca)
 import Foreign.Ptr
 
 import qualified Data.ByteString as B
@@ -1045,23 +1047,57 @@ tocfunction n = liftLua $ \l -> lua_tocfunction l n
 -- <https://www.lua.org/manual/5.3/manual.html#lua_tointeger lua_tointeger>.
 tointeger :: StackIndex -> Lua LuaInteger
 #if LUA_VERSION_NUMBER >= 502
-tointeger n = liftLua $ \l -> lua_tointegerx l n 0
+tointeger n = liftLua $ \l -> lua_tointegerx l n nullPtr
 #else
 tointeger n = liftLua $ \l -> lua_tointeger l n
 #endif
 
+-- | Like @'tointeger'@, but returns @Nothing@ if the conversion failed
+tointegerx :: StackIndex -> Lua (Maybe LuaInteger)
+#if LUA_VERSION_NUMBER >= 502
+tointegerx n = liftLua $ \l -> alloca $ \bptr -> do
+  res <- lua_tointegerx l n bptr
+  isNum <- fromLuaBool <$> F.peek bptr
+  if isNum
+    then return $ Just res
+    else return $ Nothing
+#else
+tointegerx n = do
+  isNum <- isnumber n
+  if isNum
+    then Just <$> tointeger n
+    else return Nothing
+#endif
+
 -- | Converts the Lua value at the given index to the C type lua_Number. The Lua
 -- value must be a number or a string convertible to a number; otherwise,
 -- @tonumber@ returns 0.
 --
 -- See <https://www.lua.org/manual/5.3/manual.html#lua_tonumber lua_tonumber>.
 tonumber :: StackIndex -> Lua LuaNumber
 #if LUA_VERSION_NUMBER >= 502
-tonumber n = liftLua $ \l -> lua_tonumberx l n 0
+tonumber n = liftLua $ \l -> lua_tonumberx l n nullPtr
 #else
 tonumber n = liftLua $ \l -> lua_tonumber l n
 #endif
 
+-- | Like @'tonumber'@, but returns @Nothing@ if the conversion failed
+tonumberx :: StackIndex -> Lua (Maybe LuaNumber)
+#if LUA_VERSION_NUMBER >= 502
+tonumberx n = liftLua $ \l -> alloca $ \bptr -> do
+  res <- lua_tonumberx l n bptr
+  isNum <- fromLuaBool <$> F.peek bptr
+  if isNum
+    then return $ Just res
+    else return $ Nothing
+#else
+tonumberx n = do
+  isNum <- isnumber n
+  if isNum
+    then Just <$> tonumber n
+    else return Nothing
+#endif
+
 -- | Converts the value at the given index to a generic C pointer (void*). The
 -- value can be a userdata, a table, a thread, or a function; otherwise,
 -- lua_topointer returns NULL. Different objects will give different pointers.
@@ -1077,9 +1113,9 @@ topointer n = liftLua $ \l -> lua_topointer l n
 -- | See <https://www.lua.org/manual/5.3/manual.html#lua_tostring lua_tostring>.
 tostring :: StackIndex -> Lua B.ByteString
 tostring n = liftLua $ \l -> alloca $ \lenPtr -> do
-    cstr <- lua_tolstring l n lenPtr
-    cstrLen <- F.peek lenPtr
-    B.packCStringLen (cstr, fromIntegral cstrLen)
+  cstr <- lua_tolstring l n lenPtr
+  cstrLen <- F.peek lenPtr
+  B.packCStringLen (cstr, fromIntegral cstrLen)
 
 -- | Converts the value at the given index to a Lua thread (represented as
 -- lua_State*). This value must be a thread; otherwise, the function returns

src/Foreign/Lua/Api/RawBindings.hsc

@@ -170,11 +170,11 @@ foreign import ccall unsafe "lua.h lua_tocfunction"
 #if LUA_VERSION_NUMBER >= 502
 -- | See <https://www.lua.org/manual/5.3/manual.html#lua_tointegerx lua_tointegerx>
 foreign import ccall unsafe "lua.h lua_tointegerx"
-  lua_tointegerx :: LuaState -> StackIndex -> CInt -> IO LuaInteger
+  lua_tointegerx :: LuaState -> StackIndex -> Ptr LuaBool -> IO LuaInteger
 
 -- | See <https://www.lua.org/manual/5.3/manual.html#lua_tonumberx lua_tonumberx>
 foreign import ccall unsafe "lua.h lua_tonumberx"
-  lua_tonumberx :: LuaState -> StackIndex -> CInt -> IO LuaNumber
+  lua_tonumberx :: LuaState -> StackIndex -> Ptr LuaBool -> IO LuaNumber
 #else
 -- | See <https://www.lua.org/manual/5.1/manual.html#lua_tointeger lua_tointeger>
 foreign import ccall unsafe "lua.h lua_tointeger"

src/Foreign/Lua/Api/Types.hsc

@@ -43,6 +43,7 @@ import Prelude hiding (EQ, LT)
 import Data.Int (#{type LUA_INTEGER})
 import Foreign.C (CInt)
 import Foreign.Ptr (FunPtr, Ptr)
+import Foreign.Storable (Storable)
 
 #include "lua.h"
 
@@ -94,7 +95,8 @@ type LuaNumber = #{type LUA_NUMBER}
 
 -- | Boolean value returned by a Lua C API function. This is a @'CInt'@ and
 -- interpreted as @'False'@ iff the value is @0@, @'True'@ otherwise.
-newtype LuaBool = LuaBool CInt deriving Eq
+newtype LuaBool = LuaBool CInt
+  deriving (Eq, Storable)
 
 -- | Convert a @'LuaBool'@ to a Haskell @'Bool'@.
 fromLuaBool :: LuaBool -> Bool

test/Foreign/Lua/ApiTest.hs

@@ -93,15 +93,54 @@ tests = testGroup "Haskell version of the C API"
       slen <- strlen (-1)
       return $ rlen == olen && rlen == slen && rlen == 6
 
-  , luaTestCase "isfunction" $ do
-      pushLuaExpr "function () print \"hi!\" end"
-      isfunction (-1)
-
-  , luaTestCase "isnil" $ pushLuaExpr "nil" *> isnil (-1)
-  , luaTestCase "isnone" $ isnone 500 -- stack index 500 does not exist
-  , luaTestCase "isnoneornil" $ do
-      pushLuaExpr "nil"
-      (&&) <$> isnoneornil 500 <*> isnoneornil (-1)
+  , testGroup "Type checking"
+    [ luaTestCase "isfunction" $ do
+        pushLuaExpr "function () print \"hi!\" end"
+        isfunction (-1)
+
+    , luaTestCase "isnil" $ pushLuaExpr "nil" *> isnil (-1)
+
+    , luaTestCase "isnone" $ isnone 500 -- stack index 500 does not exist
+
+    , luaTestCase "isnoneornil" $ do
+        pushLuaExpr "nil"
+        (&&) <$> isnoneornil 500 <*> isnoneornil (-1)
+    ]
+
+  , testGroup "getting values"
+    [ testCase "tointegerx returns numbers verbatim" . runLua $ do
+        pushLuaExpr "149"
+        res <- tointegerx (-1)
+        liftIO $ assertEqual "Not the correct number" (Just 149) res
+
+    , testCase "tointegerx accepts strings coercible to integers" . runLua $ do
+        pushLuaExpr "'451'"
+        res <- tointegerx (-1)
+        liftIO $ assertEqual "Not the correct number" (Just 451) res
+
+    , testCase "tointegerx returns Nothing for non-integer numbers" . runLua $ do
+        pushLuaExpr "4.5"
+        res <- tointegerx (-1)
+        liftIO $ assertEqual "Not the correct number" Nothing res
+
+    , testCase "tointegerx returns Nothing when given a boolean" . runLua $ do
+        pushLuaExpr "true"
+        liftIO . assertEqual "Not the correct number" Nothing =<< tointegerx (-1)
+
+    , testCase "tonumberx returns numbers verbatim" . runLua $ do
+        pushLuaExpr "14.9"
+        res <- tonumberx (-1)
+        liftIO $ assertEqual "Not the correct number" (Just 14.9) res
+
+    , testCase "tonumberx accepts strings as numbers" . runLua $ do
+        pushLuaExpr "'42.23'"
+        res <- tonumberx (-1)
+        liftIO $ assertEqual "Not the correct number" (Just 42.23) res
+
+    , testCase "tonumberx returns Nothing when given a boolean" . runLua $ do
+        pushLuaExpr "true"
+        liftIO . assertEqual "Not the correct number" Nothing =<< tonumberx (-1)
+    ]
 
   , luaTestCase "setting and getting a global works" $ do
       pushLuaExpr "{'Moin', Hello = 'World'}"