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{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE FlexibleContexts #-}
import Control.Applicative
import Control.Monad.State
import Data.Attoparsec.Text hiding ( take )
import Data.Char ( isAlpha
, isDigit
)
import qualified Data.Text as T
import qualified Data.Text.IO as T
import Prelude hiding ( print
, takeWhile
)
data Tokens = Wrd {unwrd :: T.Text} | Cmd T.Text | BSq [Tokens] | BCr [Tokens] | NL | Cmt T.Text | Nobs
deriving Show
isCtrl x = not $ isAlpha x || isDigit x
-- tokens to strings
toStr (Wrd w) = do
if T.length w >= 1 && T.head w `elem` (".,;:!?)" :: [Char])
then print' w
else print w
when (T.last w == '.') printnl
toStr (Cmd c) = if T.length c > 0 && isCtrl (T.head c)
then print' $ "\\" `T.append` c
else do
printnl'
when (c == "end") unindent
print $ "\\" `T.append` c
when (c == "begin") indent
toStr (BSq ts) = do
print' "["
suppress
indent
mapM_ toStr ts
unindent
print' "]"
toStr (BCr ts) = do
print' "{"
suppress
indent
mapM_ toStr ts
unindent
print' "}"
toStr NL = printnl' >> printnl
toStr (Cmt c) = do
print "%"
print' c
toStr Nobs = do
print' "~"
suppress
-- Tokeniser
ws = inClass " \t\n"
pad = takeWhile ws
token = nl <|> pad *> (nobs <|> cmd <|> bsq <|> bcr <|> cmt <|> wrd)
nobs = string "~" *> pure Nobs
nl = string "\n" *> takeWhile (inClass " \t") *> string "\n" *> pure NL
cmd :: Parser Tokens
cmd = Cmd <$> (string "\\" *> ((unwrd <$> wrd) <|> pure ""))
bsq = BSq <$> (string "[" *> many' token) <* pad <* string "]"
bcr = BCr <$> (string "{" *> many' token) <* pad <* string "}"
wrd = Wrd <$> takeWhile1 (notInClass " \t\n[]{}\\~")
cmt = Cmt <$> (takeWhile1 (== '%') *> takeWhile (/= '\n'))
-- indented printer
type Beginning = Bool
type Indent = Int
type SuppressSpace = Bool
data Printer = Printer Beginning SuppressSpace Indent T.Text
deriving Show
print :: T.Text -> State Printer ()
print str = do
(Printer beg sup i s) <- get
if sup
then print' str
else do
let indent = T.pack . take (2 * i) $ repeat ' '
str' = T.concat [s, if beg then indent else " ", str]
put $ Printer False False i str'
-- force unindented
print' :: T.Text -> State Printer ()
print' str = do
(Printer beg _ i s) <- get
let indent = T.pack . take (2 * i) $ repeat ' '
str' = T.concat [s, if beg then indent else "", str]
put $ Printer False False i str'
printnl :: State Printer ()
printnl = do
(Printer beg sup i str) <- get
when (not sup) $ put $ Printer True False i $ str `T.append` "\n"
printnl' :: State Printer ()
printnl' = do
(Printer beg sup i str) <- get
when (not beg && not sup) $ put $ Printer True False i $ str `T.append` "\n"
println :: T.Text -> State Printer ()
println str = do
print str
printnl
println' :: T.Text -> State Printer ()
println' str = do
print' str
printnl
indent :: State Printer ()
indent = do
(Printer b sup i s) <- get
put $ Printer b sup (i + 1) s
unindent :: State Printer ()
unindent = do
(Printer b sup i s) <- get
put $ Printer b sup (i - 1) s
suppress :: State Printer ()
suppress = do
(Printer b _ i s) <- get
put $ Printer b True i s
-- entry
main = do
str <- T.getContents
let Right toks = parseOnly (many' token) str
Printer _ _ _ str' =
flip execState (Printer True False 0 "") $ mapM_ toStr toks
T.putStr str'
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