{-# LANGUAGE RecordWildCards, PatternGuards, ScopedTypeVariables #-}
module Text.HTML.TagSoup.Implementation where
import Text.HTML.TagSoup.Type
import Text.HTML.TagSoup.Options
import Text.StringLike as Str
import Numeric
import Data.Char
import Data.Ix
import Control.Exception(assert)
import Control.Arrow
data Out
= Char Char
| Tag
| TagShut
| AttName
| AttVal
| TagEnd
| TagEndClose
| Comment
| CommentEnd
| EntityName
| EntityNum
| EntityHex
| EntityEnd Bool
| Warn String
| Pos Position
deriving (Show,Eq)
errSeen x = Warn $ "Unexpected " ++ show x
errWant x = Warn $ "Expected " ++ show x
data S = S
{s :: S
,tl :: S
,hd :: Char
,eof :: Bool
,next :: String -> Maybe S
,pos :: [Out] -> [Out]
}
expand :: Position -> String -> S
expand p text = res
where res = S{s = res
,tl = expand (positionChar p (head text)) (tail text)
,hd = if null text then '\0' else head text
,eof = null text
,next = next p text
,pos = (Pos p:)
}
next p (t:ext) (s:tr) | t == s = next (positionChar p t) ext tr
next p text [] = Just $ expand p text
next _ _ _ = Nothing
infixr &
class Outable a where (&) :: a -> [Out] -> [Out]
instance Outable Char where (&) = ampChar
instance Outable Out where (&) = ampOut
ampChar x y = Char x : y
ampOut x y = x : y
state :: String -> S
state s = expand nullPosition s
output :: forall str . StringLike str => ParseOptions str -> [Out] -> [Tag str]
output ParseOptions{..} x = (if optTagTextMerge then tagTextMerge else id) $ go ((nullPosition,[]),x)
where
go :: ((Position,[Tag str]),[Out]) -> [Tag str]
go ((p,ws),xs) | p `seq` False = []
go ((p,ws),xs) | not $ null ws = (if optTagWarning then (reverse ws++) else id) $ go ((p,[]),xs)
go ((p,ws),Pos p2:xs) = go ((p2,ws),xs)
go x | isChar x = pos x $ TagText a : go y
where (y,a) = charsStr x
go x | isTag x = pos x $ TagOpen a b : (if isTagEndClose z then pos x $ TagClose a : go (next z) else go (skip isTagEnd z))
where (y,a) = charsStr $ next x
(z,b) = atts y
go x | isTagShut x = pos x $ (TagClose a:) $
(if not (null b) then warn x "Unexpected attributes in close tag" else id) $
if isTagEndClose z then warn x "Unexpected self-closing in close tag" $ go (next z) else go (skip isTagEnd z)
where (y,a) = charsStr $ next x
(z,b) = atts y
go x | isComment x = pos x $ TagComment a : go (skip isCommentEnd y)
where (y,a) = charsStr $ next x
go x | isEntityName x = poss x ((if optTagWarning then id else filter (not . isTagWarning)) $ optEntityData (a, getEntityEnd y)) ++ go (skip isEntityEnd y)
where (y,a) = charsStr $ next x
go x | isEntityNumHex x = pos x $ TagText (fromChar $ entityChr x a) : go (skip isEntityEnd y)
where (y,a) = chars $ next x
go x | Just a <- fromWarn x = if optTagWarning then pos x $ TagWarning (fromString a) : go (next x) else go (next x)
go x | isEof x = []
atts :: ((Position,[Tag str]),[Out]) -> ( ((Position,[Tag str]),[Out]) , [(str,str)] )
atts x | isAttName x = second ((a,b):) $ atts z
where (y,a) = charsStr (next x)
(z,b) = if isAttVal y then charsEntsStr (next y) else (y, empty)
atts x | isAttVal x = second ((empty,a):) $ atts y
where (y,a) = charsEntsStr (next x)
atts x = (x, [])
chars x = charss False x
charsStr x = (id *** fromString) $ chars x
charsEntsStr x = (id *** fromString) $ charss True x
charss :: Bool -> ((Position,[Tag str]),[Out]) -> ( ((Position,[Tag str]),[Out]) , String)
charss t x | Just a <- fromChr x = (y, a:b)
where (y,b) = charss t (next x)
charss t x | t, isEntityName x = second (toString n ++) $ charss t $ addWarns m z
where (y,a) = charsStr $ next x
b = getEntityEnd y
z = skip isEntityEnd y
(n,m) = optEntityAttrib (a,b)
charss t x | t, isEntityNumHex x = second (entityChr x a:) $ charss t z
where (y,a) = chars $ next x
z = skip isEntityEnd y
charss t ((_,w),Pos p:xs) = charss t ((p,w),xs)
charss t x | Just a <- fromWarn x = charss t $ (if optTagWarning then addWarns [TagWarning $ fromString a] else id) $ next x
charss t x = (x, [])
next x = second (drop 1) x
skip f x = assert (isEof x || f x) (next x)
addWarns ws x@((p,w),y) = ((p, reverse (poss x ws) ++ w), y)
pos ((p,_),_) rest = if optTagPosition then tagPosition p : rest else rest
warn x s rest = if optTagWarning then pos x $ TagWarning (fromString s) : rest else rest
poss x = concatMap (\w -> pos x [w])
entityChr x s | isEntityNum x = chr_ $ read s
| isEntityHex x = chr_ $ fst $ head $ readHex s
where chr_ x | inRange (toInteger $ ord minBound, toInteger $ ord maxBound) x = chr $ fromInteger x
| otherwise = '?'
isEof (_,[]) = True; isEof _ = False
isChar (_,Char{}:_) = True; isChar _ = False
isTag (_,Tag{}:_) = True; isTag _ = False
isTagShut (_,TagShut{}:_) = True; isTagShut _ = False
isAttName (_,AttName{}:_) = True; isAttName _ = False
isAttVal (_,AttVal{}:_) = True; isAttVal _ = False
isTagEnd (_,TagEnd{}:_) = True; isTagEnd _ = False
isTagEndClose (_,TagEndClose{}:_) = True; isTagEndClose _ = False
isComment (_,Comment{}:_) = True; isComment _ = False
isCommentEnd (_,CommentEnd{}:_) = True; isCommentEnd _ = False
isEntityName (_,EntityName{}:_) = True; isEntityName _ = False
isEntityNumHex (_,EntityNum{}:_) = True; isEntityNumHex (_,EntityHex{}:_) = True; isEntityNumHex _ = False
isEntityNum (_,EntityNum{}:_) = True; isEntityNum _ = False
isEntityHex (_,EntityHex{}:_) = True; isEntityHex _ = False
isEntityEnd (_,EntityEnd{}:_) = True; isEntityEnd _ = False
isWarn (_,Warn{}:_) = True; isWarn _ = False
fromChr (_,Char x:_) = Just x ; fromChr _ = Nothing
fromWarn (_,Warn x:_) = Just x ; fromWarn _ = Nothing
getEntityEnd (_,EntityEnd b:_) = b
tagTextMerge :: StringLike str => [Tag str] -> [Tag str]
tagTextMerge (TagText x:xs) = TagText (strConcat (x:a)) : tagTextMerge b
where
(a,b) = f xs
f (TagText x:xs) = (x:a,b)
where (a,b) = f xs
f (TagPosition{}:(x@TagText{}:xs)) = f $ x : xs
f x = g x id x
g o op (p@TagPosition{}:(w@TagWarning{}:xs)) = g o (op . (p:) . (w:)) xs
g o op (w@TagWarning{}:xs) = g o (op . (w:)) xs
g o op (p@TagPosition{}:(x@TagText{}:xs)) = f $ p : x : op xs
g o op (x@TagText{}:xs) = f $ x : op xs
g o op _ = ([], o)
tagTextMerge (x:xs) = x : tagTextMerge xs
tagTextMerge [] = []