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|
--
-- Haddock - A Haskell Documentation Tool
--
-- (c) Simon Marlow 2002
--
module HaddockLex (
Token(..),
tokenise
) where
import Char
special = '`' : '\'' : '\"' : '@' : []
data Token
= TokPara
| TokNumber
| TokBullet
| TokSpecial Char
| TokString String
| TokURL String
| TokBirdTrack
deriving Show
-- simple finite-state machine for tokenising the doc string
tokenise :: String -> [Token]
tokenise "" = []
tokenise str = case str of
'<':cs -> tokenise_url cs
'\n':cs -> tokenise_newline cs
c:cs | c `elem` special -> TokSpecial c : tokenise cs
_other -> tokenise_string "" str
tokenise_url cs =
let (url,rest) = break (=='>') cs in
TokURL url : case rest of
'>':rest -> tokenise rest
_ -> tokenise rest
tokenise_newline cs =
case dropWhile nonNewlineSpace cs of
'\n':cs -> TokPara : tokenise_para cs -- paragraph break
'>':cs -> TokBirdTrack : tokenise cs -- bird track
_other -> tokenise_string "\n" cs
tokenise_para cs =
case dropWhile nonNewlineSpace cs of
-- bullet: '*'
'*':cs -> TokBullet : tokenise cs
-- bullet: '-'
'-':cs -> TokBullet : tokenise cs
-- enumerated item: '1.'
'>':cs -> TokBirdTrack : tokenise cs
-- bird track
str | (ds,'.':cs) <- span isDigit str, not (null ds)
-> TokNumber : tokenise cs
-- enumerated item: '(1)'
'(':cs | (ds,')':cs') <- span isDigit cs, not (null ds)
-> TokNumber : tokenise cs'
other -> tokenise cs
nonNewlineSpace c = isSpace c && c /= '\n'
tokenise_string str cs =
case cs of
[] -> [TokString (reverse str)]
'\\':c:cs -> tokenise_string (c:str) cs
'\n':cs -> tokenise_string_newline str cs
c:cs | c == '<' || c `elem` special
-> TokString (reverse str) : tokenise (c:cs)
| otherwise
-> tokenise_string (c:str) cs
tokenise_string_newline str cs =
case dropWhile nonNewlineSpace cs of
'\n':cs -> TokString (reverse str) : TokPara : tokenise_para cs
'>':cs -> TokString (reverse ('\n':str)) : TokBirdTrack : tokenise cs
-- bird track
_other -> tokenise_string ('\n':str) cs -- don't throw away whitespace
|
