/usr/lib/hugs/packages/Cabal/Distribution/PreProcess/Unlit.hs is in libhugs-cabal-bundled 98.200609.21-5.3ubuntu1.
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-- |
-- Module : Distribution.PreProcess.Unlit
-- Copyright : ...
--
-- Maintainer : Malcolm Wallace <Malcolm.Wallace@cs.york.ac.uk>
-- Stability : Stable
-- Portability : portable
--
-- Remove the \"literal\" markups from a Haskell source file, including
-- \"@>@\", \"@\\begin{code}@\", \"@\\end{code}@\", and \"@#@\"
--
-- Part of the following code is from
-- /Report on the Programming Language Haskell/,
-- version 1.2, appendix C.
module Distribution.PreProcess.Unlit(unlit,plain) where
import Data.Char
-- exports:
unlit :: String -> String -> String
unlit file lhs = (unlines . map unclassify . adjacent file (0::Int) Blank
. classify 0) (tolines lhs)
plain :: String -> String -> String -- no unliteration
plain _ hs = hs
----
data Classified = Program String | Blank | Comment
| Include Int String | Pre String
classify :: Int -> [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 0 xs'
allProg (x':xs') = Program x':allProg xs'
classify 0 (('>':x):xs) = let (sp,code) = span isSpace x in
Program code : classify (length sp + 1) xs
classify n (('>':x):xs) = Program (drop (n-1) x) : classify n xs
classify _ (('#':x):xs) =
(case words x of
(line:file:_) | all isDigit line -> Include (read line) file
_ -> Pre x
) : classify 0 xs
classify _ (x:xs) | all isSpace x = Blank:classify 0 xs
classify _ (_:xs) = Comment:classify 0 xs
unclassify :: Classified -> String
unclassify (Program s) = s
unclassify (Pre s) = '#':s
unclassify (Include i f) = '#':' ':show i ++ ' ':f
unclassify Blank = ""
unclassify Comment = ""
adjacent :: String -> Int -> Classified -> [Classified] -> [Classified]
adjacent file 0 _ (x :xs) = x: adjacent file 1 x xs
-- force evaluation of line number
adjacent file n (Program _) (Comment :_) =
error (message file n "program" "comment")
adjacent _ _ 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 Comment ((Program _) :_) =
error (message file n "comment" "program")
adjacent _ _ 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 _ _ 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 :xs) = x: adjacent file (n+1) x xs
adjacent _ _ _ [] = []
message :: (Show a) => String -> a -> String -> String -> String
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.
tolines :: String -> [String]
tolines 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:))
{-
-- A very naive version of unliteration....
module Unlit(unlit) where
-- This version does not handle \begin{code} & \end{code}, and it is
-- careless with indentation.
unlit = map unlitline
unlitline ('>' : s) = s
unlitline _ = ""
-}
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