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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
-- ----------------------------------------------------------------------------
-- At the beginning of a paragraph, we throw away initial whitespace
tokenise :: String -> [Token]
tokenise "" = []
tokenise str = case str of
'<':cs -> tokenise_url cs
'\n':cs -> tokenise_newline tokenise cs
c:cs | c `elem` special -> TokSpecial c : tokenise cs
_other -> tokenise_string "" str
tokenise_newline next cs =
case dropWhile nonNewlineSpace cs of
'\n':cs -> TokPara : tokenise_para cs -- paragraph break
'>':cs -> TokBirdTrack : next cs -- bird track
_other -> tokenise_string "" 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'
-- ----------------------------------------------------------------------------
-- Within a paragraph, we don't throw away any whitespace (except before a
-- birdtrack, and before a paragraph break).
tokenise1 :: String -> [Token]
tokenise1 "" = []
tokenise1 str = case str of
'<':cs -> tokenise_url cs
'\n':cs -> tokenise_newline1 cs
c:cs | c `elem` special -> TokSpecial c : tokenise1 cs
_other -> tokenise_string "" str
tokenise_newline1 cs =
case dropWhile nonNewlineSpace cs of
'\n':cs -> TokPara : tokenise_para cs -- paragraph break
'>':cs -> TokString "\n" : TokBirdTrack : tokenise1 cs -- bird track
_other -> tokenise_string "\n" cs
tokenise_url cs =
let (url,rest) = break (=='>') cs in
TokURL url : case rest of
'>':rest -> tokenise1 rest
_ -> tokenise1 rest
-- ----------------------------------------------------------------------------
-- Within a string, we don't throw away any whitespace
tokenise_string str cs =
case cs of
[] -> [TokString (reverse str)]
'\\':c:cs -> tokenise_string (c:str) cs
'\n':cs -> tokenise_string_newline str cs
'<':cs -> TokString (reverse str) : tokenise_url cs
c:cs | c `elem` special -> TokString (reverse str) : tokenise1 (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 : tokenise1 cs
-- bird track
_other -> tokenise_string ('\n':str) cs -- don't throw away whitespace
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