/usr/lib/hugs/programs/cpphs/Language/Preprocessor/Unlit.hs is in hugs 98.200609.21-5.3ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 | -- | Part of this code is from "Report on the Programming Language Haskell",
-- version 1.2, appendix C.
module Language.Preprocessor.Unlit (unlit) where
import Char
data Classified = Program String | Blank | Comment
| Include Int String | Pre String
classify :: [String] -> [Classified]
classify [] = []
classify (('\\':x):xs) | x == "begin{code}" = Blank : allProg xs
where allProg [] = [] -- Should give an error message,
-- but I have no good position information.
allProg (('\\':x):xs) | x == "end{code}" = Blank : classify xs
allProg (x:xs) = Program x:allProg xs
classify (('>':x):xs) = Program (' ':x) : classify xs
classify (('#':x):xs) = (case words x of
(line:file:_) | all isDigit line
-> Include (read line) file
_ -> Pre x
) : classify xs
classify (x:xs) | all isSpace x = Blank:classify xs
classify (x:xs) = Comment:classify xs
unclassify :: Classified -> String
unclassify (Program s) = s
unclassify (Pre s) = '#':s
unclassify (Include i f) = '#':' ':show i ++ ' ':f
unclassify Blank = ""
unclassify Comment = ""
-- | 'unlit' takes a filename (for error reports), and transforms the
-- given string, to eliminate the literate comments from the program text.
unlit :: FilePath -> String -> String
unlit file lhs = (unlines
. map unclassify
. adjacent file (0::Int) Blank
. classify) (inlines lhs)
adjacent :: FilePath -> Int -> Classified -> [Classified] -> [Classified]
adjacent file 0 _ (x :xs) = x : adjacent file 1 x xs -- force evaluation of line number
adjacent file n y@(Program _) (x@Comment :xs) = error (message file n "program" "comment")
adjacent file n y@(Program _) (x@(Include i f):xs) = x: adjacent f i y xs
adjacent file n y@(Program _) (x@(Pre _) :xs) = x: adjacent file (n+1) y xs
adjacent file n y@Comment (x@(Program _) :xs) = error (message file n "comment" "program")
adjacent file n y@Comment (x@(Include i f):xs) = x: adjacent f i y xs
adjacent file n y@Comment (x@(Pre _) :xs) = x: adjacent file (n+1) y xs
adjacent file n y@Blank (x@(Include i f):xs) = x: adjacent f i y xs
adjacent file n y@Blank (x@(Pre _) :xs) = x: adjacent file (n+1) y xs
adjacent file n _ (x@next :xs) = x: adjacent file (n+1) x xs
adjacent file n _ [] = []
message "\"\"" n p c = "Line "++show n++": "++p++ " line before "++c++" line.\n"
message [] n p c = "Line "++show n++": "++p++ " line before "++c++" line.\n"
message file n p c = "In file " ++ file ++ " at line "++show n++": "++p++ " line before "++c++" line.\n"
-- Re-implementation of 'lines', for better efficiency (but decreased laziness).
-- Also, importantly, accepts non-standard DOS and Mac line ending characters.
inlines s = lines' s id
where
lines' [] acc = [acc []]
lines' ('\^M':'\n':s) acc = acc [] : lines' s id -- DOS
lines' ('\^M':s) acc = acc [] : lines' s id -- MacOS
lines' ('\n':s) acc = acc [] : lines' s id -- Unix
lines' (c:s) acc = lines' s (acc . (c:))
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