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{-
Copyright © 2012-2017 John MacFarlane <jgm@berkeley.edu>
2017 Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-}
{-# LANGUAGE FlexibleInstances #-}
{- |
Module : Text.Pandoc.Lua.Util
Copyright : © 2012–2016 John MacFarlane,
© 2017 Albert Krewinkel
License : GNU GPL, version 2 or above
Maintainer : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
Stability : alpha
Lua utility functions.
-}
module Text.Pandoc.Lua.Util
( adjustIndexBy
, getTable
, addValue
, getRawInt
, setRawInt
, addRawInt
, PushViaCall
, pushViaCall
, pushViaConstructor
) where
import Foreign.Lua (Lua, FromLuaStack (..), ToLuaStack (..), NumArgs,
StackIndex, getglobal')
import Foreign.Lua.Api (call, pop, rawget, rawgeti, rawset, rawseti)
-- | Adjust the stack index, assuming that @n@ new elements have been pushed on
-- the stack.
adjustIndexBy :: StackIndex -> StackIndex -> StackIndex
adjustIndexBy idx n =
if idx < 0
then idx - n
else idx
-- | Get value behind key from table at given index.
getTable :: (ToLuaStack a, FromLuaStack b) => StackIndex -> a -> Lua b
getTable idx key = do
push key
rawget (idx `adjustIndexBy` 1)
peek (-1) <* pop 1
-- | Add a key-value pair to the table at the top of the stack
addValue :: (ToLuaStack a, ToLuaStack b) => a -> b -> Lua ()
addValue key value = do
push key
push value
rawset (-3)
-- | Get value behind key from table at given index.
getRawInt :: FromLuaStack a => StackIndex -> Int -> Lua a
getRawInt idx key =
rawgeti idx key
*> peek (-1)
<* pop 1
-- | Set numeric key/value in table at the given index
setRawInt :: ToLuaStack a => StackIndex -> Int -> a -> Lua ()
setRawInt idx key value = do
push value
rawseti (idx `adjustIndexBy` 1) key
-- | Set numeric key/value in table at the top of the stack.
addRawInt :: ToLuaStack a => Int -> a -> Lua ()
addRawInt = setRawInt (-1)
-- | Helper class for pushing a single value to the stack via a lua function.
-- See @pushViaCall@.
class PushViaCall a where
pushViaCall' :: String -> Lua () -> NumArgs -> a
instance PushViaCall (Lua ()) where
pushViaCall' fn pushArgs num = do
getglobal' fn
pushArgs
call num 1
instance (ToLuaStack a, PushViaCall b) => PushViaCall (a -> b) where
pushViaCall' fn pushArgs num x =
pushViaCall' fn (pushArgs *> push x) (num + 1)
-- | Push an value to the stack via a lua function. The lua function is called
-- with all arguments that are passed to this function and is expected to return
-- a single value.
pushViaCall :: PushViaCall a => String -> a
pushViaCall fn = pushViaCall' fn (return ()) 0
-- | Call a pandoc element constructor within lua, passing all given arguments.
pushViaConstructor :: PushViaCall a => String -> a
pushViaConstructor pandocFn = pushViaCall ("pandoc." ++ pandocFn)
|
