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
|
module Parser where
import Control.Monad.Except
import qualified Data.Bifunctor as B
import qualified Data.Hashable as DH
import Data.List (intercalate, isInfixOf, isPrefixOf)
import Data.Map (Map, (!))
import qualified Data.Map as M
import qualified Data.Text as T
import LTypes
import Utils
-- | Convert a string into an 'LWord'.
parseWord :: String -> LWord
parseWord rawStr
| isIntStr rawStr = LInteger (read rawStr)
| isFloatStr rawStr = LFloat $ read rawStr
| isCharStr rawStr = LChar $ rawStr !! 1
| "##" `isPrefixOf` rawStr = LStringLitRef $ drop 2 rawStr
| "$" `isPrefixOf` rawStr = LLabel $ tail rawStr
| otherwise = LSymbol rawStr
-- | Remove line suffixes starting with the comment marker '--'.
removeComments :: String -> String
removeComments =
lines .> map (T.pack .> T.splitOn (T.pack "--") .> head .> T.unpack) .> unlines
-- | Preprocess the source by inserting "string literal references" in place of
-- string literals (e.g. "hello world") in order to remove significant whitespace from the source.
processStringLiterals :: Maybe String -> Map String [LWord] -> String -> ExceptT LException IO (String, Map String [LWord])
processStringLiterals currentM refMap [] = case currentM of
Just _ -> throwError $ LException "nonterminated string literal"
Nothing -> pure ([], refMap)
processStringLiterals currentM refMap (c : source) = case c of
'"' -> case currentM of
Just str -> do
-- string literal ends
let hash = DH.hash str $> show
let strP = str $> map LChar .> LPhrase
interpolated <- processSLInterpolations strP
let newRefMap = M.insert hash interpolated refMap
(resSource, resRefMap) <- processStringLiterals Nothing newRefMap source
pure ("##" ++ hash ++ resSource, resRefMap)
Nothing ->
-- string literal starts
processStringLiterals (Just "") refMap source
other -> case currentM of
Just str ->
-- add char to current string literal
processStringLiterals (Just $ str ++ [c]) refMap source
Nothing ->
-- proceed normally
processStringLiterals Nothing refMap source $> fmap (B.first (c :))
-- | Format a new internal variable 'LLabel' for use in string literal desugaring.
produceInternalNVar :: Int -> LWord
produceInternalNVar n = LLabel $ fmt "$__%%" [show n]
-- | Desugar a "string phrase" (i.e. phrase containing only chars).
-- If the string contains the substring '%%', construct a sequence of words that consumes another string
-- phrase from the stack when evaluated, inserting that string where the '%%' substring was located. Can be used
-- with N instances of the '%%' substring (consumes N strings from stack).
processSLInterpolations :: LWord -> ExceptT LException IO [LWord]
processSLInterpolations strP@(LPhrase lChars)
| "%%" `isInfixOf` chars = pure [LPhrase interpolated, LSymbol "unphrase"]
| otherwise = pure [strP]
where
chars = lChars $> map (\(LChar c) -> c)
-- split string on the %% marker into n substrings
separatedByMarker = T.pack chars $> T.splitOn (T.pack "%%") .> map (T.unpack .> map LChar)
labelIndices = [0 .. length separatedByMarker - 1 - 1]
-- store n - 1 variables from stack
varStores = labelIndices $> map (\n -> [produceInternalNVar n, LSymbol "!"]) .> reverse
part1 = concat varStores
-- interleave the n substrings and n - 1 variable reads
symbolLookups = labelIndices $> map (\n -> [produceInternalNVar n, LSymbol "@", LSymbol "unphrase"])
part2 = LSymbol "'[" : concat (mix separatedByMarker symbolLookups) ++ [LSymbol "']", LSymbol "phrase"]
-- forget the temp variables used
varForgets = labelIndices $> map (\n -> [produceInternalNVar n, LSymbol "forget"])
part3 = concat varForgets
-- combine everything into one phrase
interpolated = part1 ++ part2 ++ part3
processSLInterpolations p = throwError $ LException $ fmt "non-phrase in processSLInterpolations: %%" [show p]
-- | Parse source code string to a list of 'LWord's and a string literal refmap (see 'LTypes.LState' for explanation).
-- Throws exception on parsing error.
parseSource :: String -> ExceptT LException IO ([LWord], Map String [LWord])
parseSource source = do
let woComments = source $> removeComments
(woStringLiterals, stringLiteralRefMap) <- processStringLiterals Nothing M.empty woComments
pure (woStringLiterals $> words .> map parseWord, stringLiteralRefMap)
|
