1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
{-
Copyright © 2012-2018 John MacFarlane <jgm@berkeley.edu>
2017-2018 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 #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE NoImplicitPrelude #-}
{- |
Module : Text.Pandoc.Lua.Util
Copyright : © 2012–2018 John MacFarlane,
© 2017-2018 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
( getTag
, rawField
, addField
, addFunction
, addValue
, pushViaConstructor
, loadScriptFromDataDir
, defineHowTo
, throwTopMessageAsError'
) where
import Prelude
import Control.Monad (unless, when)
import Foreign.Lua ( Lua, NumArgs, Peekable, Pushable, StackIndex
, ToHaskellFunction )
import Text.Pandoc.Class (readDataFile, runIOorExplode, setUserDataDir)
import qualified Foreign.Lua as Lua
import qualified Text.Pandoc.UTF8 as UTF8
-- | Get value behind key from table at given index.
rawField :: Peekable a => StackIndex -> String -> Lua a
rawField idx key = do
absidx <- Lua.absindex idx
Lua.push key
Lua.rawget absidx
Lua.popValue
-- | Add a value to the table at the top of the stack at a string-index.
addField :: Pushable a => String -> a -> Lua ()
addField = addValue
-- | Add a key-value pair to the table at the top of the stack.
addValue :: (Pushable a, Pushable b) => a -> b -> Lua ()
addValue key value = do
Lua.push key
Lua.push value
Lua.rawset (Lua.nthFromTop 3)
-- | Add a function to the table at the top of the stack, using the given name.
addFunction :: ToHaskellFunction a => String -> a -> Lua ()
addFunction name fn = do
Lua.push name
Lua.pushHaskellFunction fn
Lua.rawset (-3)
-- | 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
Lua.push fn
Lua.rawget Lua.registryindex
pushArgs
Lua.call num 1
instance (Pushable a, PushViaCall b) => PushViaCall (a -> b) where
pushViaCall' fn pushArgs num x =
pushViaCall' fn (pushArgs *> Lua.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)
-- | Load a file from pandoc's data directory.
loadScriptFromDataDir :: Maybe FilePath -> FilePath -> Lua ()
loadScriptFromDataDir datadir scriptFile = do
script <- Lua.liftIO . runIOorExplode $
setUserDataDir datadir >> readDataFile scriptFile
status <- Lua.dostring script
when (status /= Lua.OK) $
throwTopMessageAsError' (("Couldn't load '" ++ scriptFile ++ "'.\n") ++)
-- | Get the tag of a value. This is an optimized and specialized version of
-- @Lua.getfield idx "tag"@. It only checks for the field on the table at index
-- @idx@ and on its metatable, also ignoring any @__index@ value on the
-- metatable.
getTag :: StackIndex -> Lua String
getTag idx = do
-- push metatable or just the table
Lua.getmetatable idx >>= \hasMT -> unless hasMT (Lua.pushvalue idx)
Lua.push "tag"
Lua.rawget (Lua.nthFromTop 2)
Lua.tostring Lua.stackTop <* Lua.pop 2 >>= \case
Nothing -> Lua.throwException "untagged value"
Just x -> return (UTF8.toString x)
-- | Modify the message at the top of the stack before throwing it as an
-- Exception.
throwTopMessageAsError' :: (String -> String) -> Lua a
throwTopMessageAsError' modifier = do
msg <- Lua.tostring' Lua.stackTop
Lua.pop 2 -- remove error and error string pushed by tostring'
Lua.throwException (modifier (UTF8.toString msg))
defineHowTo :: String -> Lua a -> Lua a
defineHowTo ctx = Lua.withExceptionMessage (("Could not " <> ctx <> ": ") <>)
|
