{-# LANGUAGE BangPatterns, FlexibleInstances, GADTs, OverloadedStrings, Rank2Types, RecordWildCards, TypeFamilies, TypeSynonymInstances #-} {-# OPTIONS_GHC -fno-warn-orphans #-} -- | -- Module : Data.Attoparsec.Text.Internal -- Copyright : Bryan O'Sullivan 2007-2014 -- License : BSD3 -- -- Maintainer : bos@serpentine.com -- Stability : experimental -- Portability : unknown -- -- Simple, efficient parser combinators for 'Text' strings, loosely -- based on the Parsec library. module Data.Attoparsec.Text.Internal ( -- * Parser types Parser , Result -- * Running parsers , parse , parseOnly -- * Combinators , module Data.Attoparsec.Combinator -- * Parsing individual characters , satisfy , satisfyWith , anyChar , skip , char , notChar -- ** Lookahead , peekChar , peekChar' -- ** Character classes , inClass , notInClass -- * Efficient string handling , skipWhile , string , stringCI , asciiCI , take , scan , runScanner , takeWhile , takeWhile1 , takeTill -- ** Consume all remaining input , takeText , takeLazyText -- * Utilities , endOfLine , endOfInput , match , atEnd ) where import Control.Applicative ((<|>), (<$>)) import Control.Monad (when) import Data.Attoparsec.Combinator ((<?>)) import Data.Attoparsec.Internal import Data.Attoparsec.Internal.Types hiding (Parser, Failure, Success) import qualified Data.Attoparsec.Text.Buffer as Buf import Data.Attoparsec.Text.Buffer (Buffer, buffer) import Data.Char (chr, ord) import Data.String (IsString(..)) import Data.Text.Internal (Text(..)) import Prelude hiding (getChar, length, succ, take, takeWhile) import qualified Data.Attoparsec.Internal.Types as T import qualified Data.Attoparsec.Text.FastSet as Set import qualified Data.Text as T import qualified Data.Text.Lazy as L import qualified Data.Text.Unsafe as T type Parser = T.Parser Text type Result = IResult Text type Failure r = T.Failure Text Buffer r type Success a r = T.Success Text Buffer a r instance (a ~ Text) => IsString (Parser a) where fromString = string . T.pack -- | The parser @satisfy p@ succeeds for any character for which the -- predicate @p@ returns 'True'. Returns the character that is -- actually parsed. -- -- >digit = satisfy isDigit -- > where isDigit c = c >= '0' && c <= '9' satisfy :: (Char -> Bool) -> Parser Char satisfy p = do (k,c) <- ensure 1 let !h = T.unsafeHead c if p h then advance k >> return h else fail "satisfy" {-# INLINE satisfy #-} -- | The parser @skip p@ succeeds for any character for which the -- predicate @p@ returns 'True'. -- -- >skipDigit = skip isDigit -- > where isDigit c = c >= '0' && c <= '9' skip :: (Char -> Bool) -> Parser () skip p = do (k,s) <- ensure 1 if p (T.unsafeHead s) then advance k else fail "skip" -- | The parser @satisfyWith f p@ transforms a character, and succeeds -- if the predicate @p@ returns 'True' on the transformed value. The -- parser returns the transformed character that was parsed. satisfyWith :: (Char -> a) -> (a -> Bool) -> Parser a satisfyWith f p = do (k,s) <- ensure 1 let c = f $! T.unsafeHead s if p c then advance k >> return c else fail "satisfyWith" {-# INLINE satisfyWith #-} -- | Consume @n@ characters of input, but succeed only if the -- predicate returns 'True'. takeWith :: Int -> (Text -> Bool) -> Parser Text takeWith n p = do (k,s) <- ensure n if p s then advance k >> return s else fail "takeWith" -- | Consume exactly @n@ characters of input. take :: Int -> Parser Text take n = takeWith (max n 0) (const True) {-# INLINE take #-} -- | @string s@ parses a sequence of characters that identically match -- @s@. Returns the parsed string (i.e. @s@). This parser consumes no -- input if it fails (even if a partial match). -- -- /Note/: The behaviour of this parser is different to that of the -- similarly-named parser in Parsec, as this one is all-or-nothing. -- To illustrate the difference, the following parser will fail under -- Parsec given an input of @\"for\"@: -- -- >string "foo" <|> string "for" -- -- The reason for its failure is that the first branch is a -- partial match, and will consume the letters @\'f\'@ and @\'o\'@ -- before failing. In attoparsec, the above parser will /succeed/ on -- that input, because the failed first branch will consume nothing. string :: Text -> Parser Text string s = takeWith (T.length s) (==s) {-# INLINE string #-} -- | Satisfy a literal string, ignoring case. -- -- Note: this function is currently quite inefficient. Unicode case -- folding can change the length of a string (\"&#223;\" becomes -- "ss"), which makes a simple, efficient implementation tricky. We -- have (for now) chosen simplicity over efficiency. stringCI :: Text -> Parser Text stringCI s = go 0 where go !n | n > T.length fs = fail "stringCI" | otherwise = do (k,t) <- ensure n if T.toCaseFold t == fs then advance k >> return t else go (n+1) fs = T.toCaseFold s {-# INLINE stringCI #-} {-# DEPRECATED stringCI "this is very inefficient, use asciiCI instead" #-} -- | Satisfy a literal string, ignoring case for characters in the ASCII range. asciiCI :: Text -> Parser Text asciiCI input = do (k,t) <- ensure n if asciiToLower t == s then advance k >> return t else fail "asciiCI" where n = T.length input s = asciiToLower input -- convert letters in the ASCII range to lower-case asciiToLower = T.map f where offset = ord 'a' - ord 'A' f c | 'A' <= c && c <= 'Z' = chr (ord c + offset) | otherwise = c {-# INLINE asciiCI #-} -- | Skip past input for as long as the predicate returns 'True'. skipWhile :: (Char -> Bool) -> Parser () skipWhile p = go where go = do t <- T.takeWhile p <$> get continue <- inputSpansChunks (length t) when continue go {-# INLINE skipWhile #-} -- | Consume input as long as the predicate returns 'False' -- (i.e. until it returns 'True'), and return the consumed input. -- -- This parser does not fail. It will return an empty string if the -- predicate returns 'True' on the first character of input. -- -- /Note/: Because this parser does not fail, do not use it with -- combinators such as 'Control.Applicative.many', because such -- parsers loop until a failure occurs. Careless use will thus result -- in an infinite loop. takeTill :: (Char -> Bool) -> Parser Text takeTill p = takeWhile (not . p) {-# INLINE takeTill #-} -- | Consume input as long as the predicate returns 'True', and return -- the consumed input. -- -- This parser does not fail. It will return an empty string if the -- predicate returns 'False' on the first character of input. -- -- /Note/: Because this parser does not fail, do not use it with -- combinators such as 'Control.Applicative.many', because such -- parsers loop until a failure occurs. Careless use will thus result -- in an infinite loop. takeWhile :: (Char -> Bool) -> Parser Text takeWhile p = (T.concat . reverse) `fmap` go [] where go acc = do h <- T.takeWhile p <$> get continue <- inputSpansChunks (length h) if continue then go (h:acc) else return (h:acc) takeRest :: Parser [Text] takeRest = go [] where go acc = do input <- wantInput if input then do s <- get advance (length s) go (s:acc) else return (reverse acc) -- | Consume all remaining input and return it as a single string. takeText :: Parser Text takeText = T.concat `fmap` takeRest -- | Consume all remaining input and return it as a single string. takeLazyText :: Parser L.Text takeLazyText = L.fromChunks `fmap` takeRest data Scan s = Continue s | Finished {-# UNPACK #-} !Int Text scan_ :: (s -> [Text] -> Parser r) -> s -> (s -> Char -> Maybe s) -> Parser r scan_ f s0 p = go [] s0 where scanner s !n t = case T.uncons t of Just (c,t') -> case p s c of Just s' -> scanner s' (n+1) t' Nothing -> Finished n t Nothing -> Continue s go acc s = do input <- get case scanner s 0 input of Continue s' -> do continue <- inputSpansChunks (length input) if continue then go (input : acc) s' else f s' (input : acc) Finished n t -> do advance (length input - length t) f s (T.take n input : acc) {-# INLINE scan_ #-} -- | A stateful scanner. The predicate consumes and transforms a -- state argument, and each transformed state is passed to successive -- invocations of the predicate on each character of the input until one -- returns 'Nothing' or the input ends. -- -- This parser does not fail. It will return an empty string if the -- predicate returns 'Nothing' on the first character of input. -- -- /Note/: Because this parser does not fail, do not use it with -- combinators such as 'Control.Applicative.many', because such -- parsers loop until a failure occurs. Careless use will thus result -- in an infinite loop. scan :: s -> (s -> Char -> Maybe s) -> Parser Text scan = scan_ $ \_ chunks -> case chunks of [x] -> return x xs -> return . T.concat . reverse $ xs {-# INLINE scan #-} -- | Like 'scan', but generalized to return the final state of the -- scanner. runScanner :: s -> (s -> Char -> Maybe s) -> Parser (Text, s) runScanner = scan_ $ \s xs -> return (T.concat (reverse xs), s) {-# INLINE runScanner #-} -- | Consume input as long as the predicate returns 'True', and return -- the consumed input. -- -- This parser requires the predicate to succeed on at least one -- character of input: it will fail if the predicate never returns -- 'True' or if there is no input left. takeWhile1 :: (Char -> Bool) -> Parser Text takeWhile1 p = do (`when` demandInput) =<< endOfChunk h <- T.takeWhile p <$> get let len = length h when (len == 0) $ fail "takeWhile1" advance len eoc <- endOfChunk if eoc then (h<>) `fmap` takeWhile p else return h -- | Match any character in a set. -- -- >vowel = inClass "aeiou" -- -- Range notation is supported. -- -- >halfAlphabet = inClass "a-nA-N" -- -- To add a literal @\'-\'@ to a set, place it at the beginning or end -- of the string. inClass :: String -> Char -> Bool inClass s = (`Set.member` mySet) where mySet = Set.charClass s {-# NOINLINE mySet #-} {-# INLINE inClass #-} -- | Match any character not in a set. notInClass :: String -> Char -> Bool notInClass s = not . inClass s {-# INLINE notInClass #-} -- | Match any character. anyChar :: Parser Char anyChar = satisfy $ const True {-# INLINE anyChar #-} -- | Match a specific character. char :: Char -> Parser Char char c = satisfy (== c) <?> show c {-# INLINE char #-} -- | Match any character except the given one. notChar :: Char -> Parser Char notChar c = satisfy (/= c) <?> "not " ++ show c {-# INLINE notChar #-} -- | Match any character, to perform lookahead. Returns 'Nothing' if -- end of input has been reached. Does not consume any input. -- -- /Note/: Because this parser does not fail, do not use it with -- combinators such as 'Control.Applicative.many', because such -- parsers loop until a failure occurs. Careless use will thus result -- in an infinite loop. peekChar :: Parser (Maybe Char) peekChar = T.Parser $ \t pos more _lose succ -> case () of _| pos < lengthOf t -> let T.Iter !c _ = Buf.iter t (fromPos pos) in succ t pos more (Just c) | more == Complete -> succ t pos more Nothing | otherwise -> let succ' t' pos' more' = let T.Iter !c _ = Buf.iter t' (fromPos pos') in succ t' pos' more' (Just c) lose' t' pos' more' = succ t' pos' more' Nothing in prompt t pos more lose' succ' {-# INLINE peekChar #-} -- | Match any character, to perform lookahead. Does not consume any -- input, but will fail if end of input has been reached. peekChar' :: Parser Char peekChar' = do (_,s) <- ensure 1 return $! T.unsafeHead s {-# INLINE peekChar' #-} -- | Match either a single newline character @\'\\n\'@, or a carriage -- return followed by a newline character @\"\\r\\n\"@. endOfLine :: Parser () endOfLine = (char '\n' >> return ()) <|> (string "\r\n" >> return ()) -- | Terminal failure continuation. failK :: Failure a failK t (Pos pos) _more stack msg = Fail (Buf.dropWord16 pos t) stack msg {-# INLINE failK #-} -- | Terminal success continuation. successK :: Success a a successK t (Pos pos) _more a = Done (Buf.dropWord16 pos t) a {-# INLINE successK #-} -- | Run a parser. parse :: Parser a -> Text -> Result a parse m s = runParser m (buffer s) 0 Incomplete failK successK {-# INLINE parse #-} -- | Run a parser that cannot be resupplied via a 'Partial' result. -- -- This function does not force a parser to consume all of its input. -- Instead, any residual input will be discarded. To force a parser -- to consume all of its input, use something like this: -- -- @ --'parseOnly' (myParser 'Control.Applicative.<*' 'endOfInput') -- @ parseOnly :: Parser a -> Text -> Either String a parseOnly m s = case runParser m (buffer s) 0 Complete failK successK of Fail _ _ err -> Left err Done _ a -> Right a _ -> error "parseOnly: impossible error!" {-# INLINE parseOnly #-} get :: Parser Text get = T.Parser $ \t pos more _lose succ -> succ t pos more (Buf.dropWord16 (fromPos pos) t) {-# INLINE get #-} endOfChunk :: Parser Bool endOfChunk = T.Parser $ \t pos more _lose succ -> succ t pos more (pos == lengthOf t) {-# INLINE endOfChunk #-} inputSpansChunks :: Pos -> Parser Bool inputSpansChunks i = T.Parser $ \t pos_ more _lose succ -> let pos = pos_ + i in if pos < lengthOf t || more == Complete then succ t pos more False else let lose' t' pos' more' = succ t' pos' more' False succ' t' pos' more' = succ t' pos' more' True in prompt t pos more lose' succ' {-# INLINE inputSpansChunks #-} advance :: Pos -> Parser () advance n = T.Parser $ \t pos more _lose succ -> succ t (pos+n) more () {-# INLINE advance #-} ensureSuspended :: Int -> Buffer -> Pos -> More -> Failure r -> Success (Pos, Text) r -> Result r ensureSuspended n t pos more lose succ = runParser (demandInput >> go) t pos more lose succ where go = T.Parser $ \t' pos' more' lose' succ' -> case lengthAtLeast pos' n t' of Just n' -> succ' t' pos' more' (n', substring pos n' t') Nothing -> runParser (demandInput >> go) t' pos' more' lose' succ' -- | If at least @n@ elements of input are available, return the -- current input, otherwise fail. ensure :: Int -> Parser (Pos, Text) ensure n = T.Parser $ \t pos more lose succ -> case lengthAtLeast pos n t of Just n' -> succ t pos more (n', substring pos n' t) -- The uncommon case is kept out-of-line to reduce code size: Nothing -> ensureSuspended n t pos more lose succ -- Non-recursive so the bounds check can be inlined: {-# INLINE ensure #-} -- | Return both the result of a parse and the portion of the input -- that was consumed while it was being parsed. match :: Parser a -> Parser (Text, a) match p = T.Parser $ \t pos more lose succ -> let succ' t' pos' more' a = succ t' pos' more' (substring pos (pos'-pos) t', a) in runParser p t pos more lose succ' lengthAtLeast :: Pos -> Int -> Buffer -> Maybe Pos lengthAtLeast pos n t = go 0 (fromPos pos) where go i !p | i == n = Just (Pos p - pos) | p == len = Nothing | otherwise = go (i+1) (p + Buf.iter_ t p) Pos len = lengthOf t {-# INLINE lengthAtLeast #-} substring :: Pos -> Pos -> Buffer -> Text substring (Pos pos) (Pos n) = Buf.substring pos n {-# INLINE substring #-} lengthOf :: Buffer -> Pos lengthOf = Pos . Buf.length length :: Text -> Pos length = Pos . T.length