>
A bytestring implementation of reg exp pattern matching using partial derivative
This algorithm exploits the extension of partial derivative of regular expression patterns.
This algorithm proceeds by scanning the input word from left to right until we reach
an emptiable pattern and the input word is fully consumed.
>
> module Text.Regex.PDeriv.ByteString.LeftToRight
> ( Regex
> , CompOption(..)
> , ExecOption(..)
> , defaultCompOpt
> , defaultExecOpt
> , compile
> , execute
> , regexec
> ) where
> import Data.List
> import Data.Char (ord)
>
> import qualified Data.IntMap as IM
> import qualified Data.ByteString.Char8 as S
> import Control.DeepSeq
> import System.IO.Unsafe (unsafePerformIO)
> import Text.Regex.Base(RegexOptions(..))
> import Text.Regex.PDeriv.RE
> import Text.Regex.PDeriv.Pretty (Pretty(..))
> import Text.Regex.PDeriv.Common (Range, Letter, IsEmpty(..), my_hash, my_lookup, GFlag(..), IsEmpty(..), nub2, minBinder, maxBinder)
> import Text.Regex.PDeriv.IntPattern (Pat(..), pdPat, pdPat0, toBinder, Binder(..), strip, listifyBinder)
> import Text.Regex.PDeriv.Parse
> import qualified Text.Regex.PDeriv.Dictionary as D (Dictionary(..), Key(..), insertNotOverwrite, lookupAll, empty, isIn, nub)
A word is a byte string.
> type Word = S.ByteString
----------------------------
-- (greedy) pattern matching
> type Env = [(Int,Word)]
> rg_collect :: S.ByteString -> (Int,Int) -> S.ByteString
> rg_collect w (i,j) = S.take (j' i' + 1) (S.drop i' w)
> where i' = fromIntegral i
> j' = fromIntegral j
we compile all the possible partial derivative operation into a table
The table maps key to a set of target integer states and their corresponding
binder update functions.
> type PdPat0Table = IM.IntMap [(Int, Int -> Binder -> Binder)]
A function that builds the above table from the pattern
> buildPdPat0Table :: Pat -> (PdPat0Table, [Int])
> buildPdPat0Table init =
> let sig = map (\x -> (x,0)) (sigmaRE (strip init))
> init_dict = D.insertNotOverwrite (D.hash init) (init,0) D.empty
> (all, delta, dictionary) = sig `seq` builder sig [] [] [init] init_dict 1
> final = all `seq` [ s | s <- all, isEmpty (strip s)]
> sfinal = final `seq` dictionary `seq` map (mapping dictionary) final
> lists = [ (i,l,jfs) |
> (p,l, qfs) <- delta,
> let i = mapping dictionary p
> jfs = map (\(q,f) -> (mapping dictionary q, f)) qfs
> ]
> hash_table = foldl' (\ dict (p,x,q) ->
> let k = my_hash p (fst x)
> in case IM.lookup k dict of
> Just ps -> error "Found a duplicate key in the PdPat0Table, this should not happen."
> Nothing -> IM.insert k q dict) IM.empty lists
> in (hash_table, sfinal)
Some helper functions used in buildPdPat0Table
> myLookup = lookup
> mapping :: D.Dictionary (Pat,Int) -> Pat -> Int
> mapping dictionary x = let candidates = D.lookupAll (D.hash x) dictionary
> in candidates `seq`
> case candidates of
> [(_,i)] -> i
> _ ->
> case myLookup x candidates of
> (Just i) -> i
> Nothing -> error ("this should not happen. looking up " ++ (pretty x) ++ " from " ++ (show candidates) )
> builder :: [Letter]
> -> [Pat]
> -> [(Pat,Letter, [(Pat, Int -> Binder -> Binder)] )]
> -> [Pat]
> -> D.Dictionary (Pat,Int)
> -> Int
> -> ([Pat], [(Pat, Letter, [(Pat, Int -> Binder -> Binder)])], D.Dictionary (Pat,Int))
> builder sig acc_states acc_delta curr_states dict max_id
> | null curr_states = (acc_states, acc_delta, dict)
> | otherwise =
> let
> all_sofar_states = acc_states ++ curr_states
> new_delta = [ (s, l, sfs) | s <- curr_states, l <- sig, let sfs = pdPat0 s l]
> new_states = all_sofar_states `seq` D.nub [ s' | (_,_,sfs) <- new_delta, (s',f) <- sfs
> , not (s' `D.isIn` dict) ]
> acc_delta_next = (acc_delta ++ new_delta)
> (dict',max_id') = new_states `seq` foldl' (\(d,id) p -> (D.insertNotOverwrite (D.hash p) (p,id) d, id + 1) ) (dict,max_id) new_states
> in builder sig all_sofar_states acc_delta_next new_states dict' max_id'
the "partial derivative" operations among integer states + binders
> lookupPdPat0 :: PdPat0Table -> (Int,Binder) -> Letter -> [(Int,Binder)]
> lookupPdPat0 hash_table (i,binder) (l,x) =
>
>
>
> let k = (my_hash i l)
> in k `seq`
> hash_table `seq`
> case IM.lookup k hash_table of
> { Just pairs ->
> binder `seq`
>
> map (\ (j,op) -> let binder' = op x binder
> in binder' `seq`
> (j, binder' ) ) pairs
> ; Nothing -> []
> }
> lookupPdPat0' :: PdPat0Table -> (Int, [Binder -> Binder]) -> Letter -> [(Int,[Binder -> Binder])]
> lookupPdPat0' hash_table (i,fs) (l,x) =
>
>
>
> let k = (my_hash i l)
> in k `seq`
> hash_table `seq`
> case IM.lookup k hash_table of
> { Just pairs ->
> let io = unsafePerformIO (print (length pairs))
> in
> x `seq`
> map (\ (j,op) -> let f = op x
> fs' = f:fs
> in (j, fs')) pairs
> ; Nothing -> []
> }
collection function for binder
> collectPatMatchFromBinder :: Word -> Binder -> Env
> collectPatMatchFromBinder w b =
> collectPatMatchFromBinder_ w (listifyBinder b)
> collectPatMatchFromBinder_ w [] = []
> collectPatMatchFromBinder_ w ((x,[]):xs) = (x,S.empty):(collectPatMatchFromBinder_ w xs)
> collectPatMatchFromBinder_ w ((x,rs):xs) = (x,foldl' S.append S.empty $ map (rg_collect w) (reverse rs)):(collectPatMatchFromBinder_ w xs)
>
> patMatchesIntStatePdPat0 :: Int -> PdPat0Table -> Word -> [(Int,Binder)] -> [(Int,Binder)]
> patMatchesIntStatePdPat0 cnt pdStateTable w' eps =
> case S.uncons w' of
> Nothing -> eps
> Just (l,w) ->
> let
> eps_ =
> concatMap (\ep -> lookupPdPat0 pdStateTable ep (l,cnt)) eps
> eps' =
> nub2 eps_
> cnt' = cnt + 1
> in cnt' `seq` w `seq`
> eps' `seq`
> patMatchesIntStatePdPat0 cnt' pdStateTable w eps'
> patMatchesIntStatePdPat0' :: Int -> PdPat0Table -> Word -> [(Int,[Binder -> Binder])] -> [(Int,[Binder -> Binder])]
> patMatchesIntStatePdPat0' cnt pdStateTable w' eps =
> case S.uncons w' of
> Nothing -> eps
> Just (l,w) ->
> let
> eps_ = l `seq` cnt `seq`
> concatMap (\ep -> lookupPdPat0' pdStateTable ep (l,cnt)) eps
> eps' =
> nub2 eps_
> cnt' = cnt + 1
> in cnt' `seq` w `seq`
> eps' `seq`
> patMatchesIntStatePdPat0' cnt' pdStateTable w eps'
> concatMap' :: (a -> [b]) -> [a] -> [b]
> concatMap' f x = foldr' ( \ b a -> (++) a (f b) ) [] x
> foldr' :: (a -> b -> b) -> b -> [a] -> b
> foldr' f b [] = b
> foldr' f b (a:as) = let b' = f a b
> in b' `seq`
> foldr' f b' as
>
> patMatchIntStatePdPat0 :: Pat -> Word -> [Env]
> patMatchIntStatePdPat0 p w =
> let
> (pdStateTable,sfinal) = buildPdPat0Table p
> s = 0
> b = toBinder p
> allbinders' = b `seq` s `seq` pdStateTable `seq` (patMatchesIntStatePdPat0 0 pdStateTable w [(s,b)])
> allbinders = allbinders' `seq` map snd (filter (\(i,_) -> i `elem` sfinal) allbinders' )
>
>
> in map (collectPatMatchFromBinder w) $! allbinders
>
> greedyPatMatch :: Pat -> Word -> Maybe Env
> greedyPatMatch p w =
> first (patMatchIntStatePdPat0 p w)
> where
> first (env:_) = return env
> first _ = Nothing
Compilation
> compilePat :: Pat -> (PdPat0Table, [Int], Binder)
> compilePat p = (pdStateTable, sfinal, b)
> where
> (pdStateTable,sfinal) = buildPdPat0Table p
> b = toBinder p
> patMatchIntStateCompiled :: (PdPat0Table, [Int], Binder) -> Word -> [Env]
> patMatchIntStateCompiled (pdStateTable,sfinal,b) w =
> let
> s = 0
>
>
> all_func' = s `seq` pdStateTable `seq` (patMatchesIntStatePdPat0' 0 pdStateTable w [(s,[])])
> all_func = all_func' `seq` map snd (filter (\(i,_) -> i `elem` sfinal) all_func' )
> in
> all_func `seq`
> map (\fs -> let fs' = reverse fs
> in fs' `seq` collectPatMatchFromBinder w (applyAll fs' b)) all_func
> applyAll :: [ Binder -> Binder ] -> Binder -> Binder
>
> applyAll [] b = b
> applyAll (f:fs) b = let b' = f b
> in b' `seq` applyAll fs b'
> greedyPatMatchCompiled :: (PdPat0Table, [Int], Binder) -> Word -> Maybe Env
> greedyPatMatchCompiled compiled w =
> first (patMatchIntStateCompiled compiled w)
> where
> first (env:_) = return env
> first _ = Nothing
>
> newtype Regex = Regex (PdPat0Table, [Int], Binder)
-- todo: use the CompOption and ExecOption
> compile :: CompOption
> -> ExecOption
> -> S.ByteString
> -> Either String Regex
> compile compOpt execOpt bs =
> case parsePat (S.unpack bs) of
> Left err -> Left ("parseRegex for Text.Regex.PDeriv.ByteString failed:"++show err)
> Right pat -> Right (patToRegex pat compOpt execOpt)
> where
> patToRegex p _ _ = Regex (compilePat p)
> execute :: Regex
> -> S.ByteString
> -> Either String (Maybe Env)
> execute (Regex r) bs = Right (greedyPatMatchCompiled r bs)
> regexec :: Regex
> -> S.ByteString
> -> Either String (Maybe (S.ByteString, S.ByteString, S.ByteString, [S.ByteString]))
> regexec (Regex r) bs =
> case greedyPatMatchCompiled r bs of
> Nothing -> Right (Nothing)
> Just env ->
> let pre = case lookup minBinder env of { Just w -> w ; Nothing -> S.empty }
> post = case lookup maxBinder env of { Just w -> w ; Nothing -> S.empty }
> full_len = S.length bs
> pre_len = S.length pre
> post_len = S.length post
> main_len = full_len pre_len post_len
> main_and_post = S.drop pre_len bs
> main = main_and_post `seq` main_len `seq` S.take main_len main_and_post
> matched = map snd (filter (\(v,w) -> v > 0) env)
> in Right (Just (pre,main,post,matched))
>
>
> data CompOption = CompOption {
> caseSensitive :: Bool
> , multiline :: Bool
>
> , rightAssoc :: Bool
> , newSyntax :: Bool
> , lastStarGreedy :: Bool
>
>
> } deriving (Read,Show)
> data ExecOption = ExecOption {
> captureGroups :: Bool
> } deriving (Read,Show)
> instance RegexOptions Regex CompOption ExecOption where
> blankCompOpt = CompOption { caseSensitive = True
> , multiline = False
> , rightAssoc = True
> , newSyntax = False
> , lastStarGreedy = False
> }
> blankExecOpt = ExecOption { captureGroups = True }
> defaultCompOpt = CompOption { caseSensitive = True
> , multiline = True
> , rightAssoc = True
> , newSyntax = True
> , lastStarGreedy = False
> }
> defaultExecOpt = ExecOption { captureGroups = True }
> setExecOpts e r = undefined
> getExecOpts r = undefined
-- Kenny's example
> long_pat = PPair (PVar 1 [] (PE (Star (L 'A') Greedy))) (PVar 2 [] (PE (Star (L 'A') Greedy)))
> long_string n = S.pack $ (take 0 (repeat 'A')) ++ (take n (repeat 'B'))
-- p4 = << x : (A|), y : (>|A) >, z : (|C) >
> p4 = PPair (PPair p_x p_y) p_z
> where p_x = PVar 1 [] (PE (Choice (L 'A') (Seq (L 'A') (L 'B')) Greedy))
> p_y = PVar 2 [] (PE (Choice (Seq (L 'B') (Seq (L 'A') (L 'A'))) (L 'A') Greedy))
> p_z = PVar 3 [] (PE (Choice (Seq (L 'A') (L 'C')) (L 'C') Greedy))
> input = S.pack "ABAAC"
> p5 = PStar (PVar 1 [] (PE (Choice (L 'A') (Choice (L 'B') (L 'C') Greedy) Greedy))) Greedy
pattern = ( x :: (A|C), y :: (B|()) )*
> p6 = PStar (PPair (PVar 1 [] (PE (Choice (L 'A') (L 'C') Greedy))) (PVar 2 [] (PE (Choice (L 'B') Empty Greedy)))) Greedy
pattern = ( x :: ( y :: A, z :: B )* )
> p7 = PVar 1 [] (PStar (PPair (PVar 2 [] (PE (L 'A'))) (PVar 3 [] (PE (L 'B')))) Greedy)
> input7 = S.pack "ABABAB"
pattern = ( x :: A*?, y :: A*)
> p8 = PPair (PVar 1 [] (PE (Star (L 'A') NotGreedy))) (PVar 2 [] (PE (Star (L 'A') Greedy)))
> input8 = S.pack "AAAAAA"
pattern = ( x :: A*?, y :: A*)
> p9 = PPair (PStar (PVar 1 [] (PE (L 'A'))) NotGreedy) (PVar 2 [] (PE (Star (L 'A') Greedy)))
pattern = ( x :: (A|B)*?, (y :: (B*,A*)))
> p10 = PPair (PVar 1 [] (PE (Star (Choice (L 'A') (L 'B') Greedy) NotGreedy))) (PVar 2 [] (PE (Seq (Star (L 'B') Greedy) (Star (L 'A') Greedy))))
> input10 = S.pack "ABA"
pattern = <(x :: (0|...|9)+?)*, (y :: (0|...|9)+?)*, (z :: (0|...|9)+?)*>
> digits_re = foldl' (\x y -> Choice x y Greedy) (L '0') (map L "12345789")
> p11 = PPair (PStar (PVar 1 [] (PE (Seq digits_re (Star digits_re Greedy)))) Greedy) (PPair (PStar (PVar 2 [] (PE (Seq digits_re (Star digits_re Greedy)))) Greedy) (PPair (PStar (PVar 3 [] (PE (Seq digits_re (Star digits_re Greedy)))) Greedy) (PStar (PVar 4 [] (PE (Seq digits_re (Star digits_re Greedy)))) Greedy)))
> input11 = S.pack "1234567890123456789-"