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|
{-|
Module : Lua.LPeg
Copyright : © 2021-2023 Albert Krewinkel
License : MIT
Maintainer : Albert Krewinkel <tarleb@hslua.org>
Haskell bindings to the LPeg Lua package.
-}
module Lua.LPeg
( luaopen_lpeg_ptr
, luaopen_re_ptr
, lpeg_searcher
) where
import Foreign.C
import Foreign.Ptr (nullPtr)
import Foreign.Storable (peek)
import Foreign.Marshal (alloca)
import Lua
-- | Pointer to the placeholder lpeg library loader. Trying to load the
-- library will result in an error.
foreign import ccall unsafe "placeholder.c &luaopen_lpeg"
luaopen_lpeg_ptr :: CFunction
-- | Pointer to the placeholder re library loader. Trying to load the
-- library will result in an error.
foreign import ccall unsafe "placeholder.c &luaopen_re"
luaopen_re_ptr :: CFunction
-- | Placeholder package searcher to be used with @package.searchers@),
-- just for the "lpeg" module. Returns @nil@ on most inputs, but pushes
-- adds a message about the module being unavailable when called on the
-- search key "lpeg".
lpeg_searcher :: PreCFunction
lpeg_searcher l = do
alloca $ \lenPtr -> do
cstr <- lua_tolstring l 1 lenPtr
if cstr == nullPtr
then 1 <$ lua_pushnil l
else do
cstrLen <- peek lenPtr
pkg <- peekCStringLen (cstr, fromIntegral cstrLen)
case pkg of
"lpeg" -> 1 <$ withCString msg (lua_pushstring l)
"re" -> 1 <$ withCString msg (lua_pushstring l)
_ -> 1 <$ lua_pushnil l
where
msg = "\n\tlpeg was configured to be excluded from the binary."
|
