-{-# LANGUAGE
- BangPatterns
- , ScopedTypeVariables
- , UnboxedTuples
- , UnicodeSyntax
- #-}
--- |Yet another parser combinator. This is mostly a subset of
--- "Text.ParserCombinators.Parsec" but there are some differences:
---
--- * This parser works on 'Data.ByteString.Base.LazyByteString'
--- instead of 'Prelude.String'.
---
--- * Backtracking is the only possible behavior so there is no \"try\"
--- action.
---
--- * On success, the remaining string is returned as well as the
--- parser result.
---
--- * You can choose whether to treat reaching EOF (trying to eat one
--- more letter at the end of string) a fatal error or to treat it a
--- normal failure. If a fatal error occurs, the entire parsing
--- process immediately fails without trying any backtracks. The
--- default behavior is to treat EOF fatal.
---
--- In general, you don't have to use this module directly.
-module Network.HTTP.Lucu.Parser
- ( Parser
- , ParserResult(..)
-
- , failP
-
- , parse
- , parseStr
-
- , anyChar
- , eof
- , allowEOF
- , satisfy
- , char
- , string
- , (<|>)
- , choice
- , oneOf
- , digit
- , hexDigit
- , notFollowedBy
- , many
- , manyChar
- , many1
- , count
- , option
- , sepBy
- , sepBy1
-
- , sp
- , ht
- , crlf
- )
- where
-
-import Control.Monad.State.Strict hiding (state)
-import qualified Data.ByteString.Lazy as Lazy (ByteString)
-import qualified Data.ByteString.Lazy.Char8 as B hiding (ByteString)
-import qualified Data.Foldable as Fold
-import Data.Int
-import qualified Data.Sequence as Seq
-import Data.Sequence (Seq, (|>))
-
--- |@'Parser' a@ is obviously a parser which parses and returns @a@.
-newtype Parser a = Parser {
- runParser :: State ParserState (ParserResult a)
- }
-
-
-data ParserState
- = PST {
- pstInput :: Lazy.ByteString
- , pstIsEOFFatal :: !Bool
- }
- deriving (Eq, Show)
-
-
-data ParserResult a = Success !a
- | IllegalInput -- 受理出來ない入力があった
- | ReachedEOF -- 限界を越えて讀まうとした
- deriving (Eq, Show)
-
-
--- (>>=) :: Parser a -> (a -> Parser b) -> Parser b
-instance Monad Parser where
- p >>= f = Parser $! do saved <- get -- 失敗した時の爲に状態を保存
- result <- runParser p
- case result of
- Success a -> runParser (f a)
- IllegalInput -> do put saved -- 状態を復歸
- return IllegalInput
- ReachedEOF -> do put saved -- 状態を復歸
- return ReachedEOF
- return !x = Parser $! return $! Success x
- fail _ = Parser $! return $! IllegalInput
-
-instance Functor Parser where
- fmap f p = p >>= return . f
-
--- |@'failP'@ is just a synonym for @'Prelude.fail'
--- 'Prelude.undefined'@.
-failP :: Parser a
-failP = fail undefined
-
--- |@'parse' p bstr@ parses @bstr@ with @p@ and returns @(# result,
--- remaining #)@.
-parse :: Parser a -> Lazy.ByteString -> (# ParserResult a, Lazy.ByteString #)
-parse !p input -- input は lazy である必要有り。
- = let (!result, state') = runState (runParser p) (PST input True)
- in
- (# result, pstInput state' #) -- pstInput state' も lazy である必要有り。
-
--- |@'parseStr' p str@ packs @str@ and parses it.
-parseStr :: Parser a -> String -> (# ParserResult a, Lazy.ByteString #)
-parseStr !p input -- input は lazy である必要有り。
- = parse p (B.pack input)
-
-
-anyChar :: Parser Char
-anyChar = Parser $!
- do state@(PST input _) <- get
- if B.null input then
- return ReachedEOF
- else
- do put $! state { pstInput = B.tail input }
- return (Success $! B.head input)
-
-
-eof :: Parser ()
-eof = Parser $!
- do PST input _ <- get
- if B.null input then
- return $! Success ()
- else
- return IllegalInput
-
--- |@'allowEOF' p@ makes @p@ treat reaching EOF a normal failure.
-allowEOF :: Parser a -> Parser a
-allowEOF !f
- = Parser $! do saved@(PST _ isEOFFatal) <- get
- put $! saved { pstIsEOFFatal = False }
-
- result <- runParser f
-
- state <- get
- put $! state { pstIsEOFFatal = isEOFFatal }
-
- return result
-
-
-satisfy :: (Char -> Bool) -> Parser Char
-satisfy !f
- = do c <- anyChar
- if f c then
- return c
- else
- failP
-
-
-char :: Char -> Parser Char
-char !c = satisfy (== c)
-
-
-string :: String -> Parser String
-string !str
- = let bs = B.pack str
- len = B.length bs
- in
- Parser $!
- do st <- get
- let (bs', rest) = B.splitAt len $ pstInput st
- st' = st { pstInput = rest }
- if B.length bs' < len then
- return ReachedEOF
- else
- if bs == bs' then
- do put st'
- return $ Success str
- else
- return IllegalInput
-
-
-infixr 0 <|>
-
--- |This is the backtracking alternation. There is no non-backtracking
--- equivalent.
-(<|>) :: Parser a -> Parser a -> Parser a
-(!f) <|> (!g)
- = Parser $! do saved <- get -- 状態を保存
- result <- runParser f
- case result of
- Success a -> return $! Success a
- IllegalInput -> do put saved -- 状態を復歸
- runParser g
- ReachedEOF -> if pstIsEOFFatal saved then
- do put saved
- return ReachedEOF
- else
- do put saved
- runParser g
-
-
-choice :: [Parser a] -> Parser a
-choice = foldl (<|>) failP
-
-
-oneOf :: [Char] -> Parser Char
-oneOf = foldl (<|>) failP . map char
-
-
-notFollowedBy :: Parser a -> Parser ()
-notFollowedBy !p
- = Parser $! do saved <- get -- 状態を保存
- result <- runParser p
- case result of
- Success _ -> do put saved -- 状態を復歸
- return IllegalInput
- IllegalInput -> do put saved -- 状態を復歸
- return $! Success ()
- ReachedEOF -> do put saved -- 状態を復歸
- return $! Success ()
-
-
-digit :: Parser Char
-digit = do c <- anyChar
- if c >= '0' && c <= '9' then
- return c
- else
- failP
-
-
-hexDigit :: Parser Char
-hexDigit = do c <- anyChar
- if (c >= '0' && c <= '9') ||
- (c >= 'a' && c <= 'f') ||
- (c >= 'A' && c <= 'F') then
- return c
- else
- failP
-
-
-many :: forall a. Parser a -> Parser [a]
-many !p = Parser $!
- do state <- get
- let (# result, state' #) = many' state Seq.empty
- put state'
- return result
- where
- many' :: ParserState -> Seq a -> (# ParserResult [a], ParserState #)
- many' !st !soFar
- = case runState (runParser p) st of
- (Success a, st') -> many' st' (soFar |> a)
- (IllegalInput, _) -> (# Success (Fold.toList soFar), st #)
- (ReachedEOF , _) -> if pstIsEOFFatal st then
- (# ReachedEOF, st #)
- else
- (# Success (Fold.toList soFar), st #)
-
-manyChar :: Parser Char -> Parser Lazy.ByteString
-manyChar !p = Parser $!
- do state <- get
- case scan' state 0 of
- Success len
- -> do let (bs, rest) = B.splitAt len (pstInput state)
- state' = state { pstInput = rest }
- put state'
- return $ Success bs
- ReachedEOF
- -> if pstIsEOFFatal state then
- return ReachedEOF
- else
- error "internal error"
- _ -> error "internal error"
- where
- scan' :: ParserState -> Int64 -> ParserResult Int64
- scan' !st !soFar
- = case runState (runParser p) st of
- (Success _ , st') -> scan' st' (soFar + 1)
- (IllegalInput, _ ) -> Success soFar
- (ReachedEOF , _ ) -> if pstIsEOFFatal st then
- ReachedEOF
- else
- Success soFar
-
-
-many1 :: Parser a -> Parser [a]
-many1 !p = do x <- p
- xs <- many p
- return (x:xs)
-
-
-count :: Int -> Parser a -> Parser [a]
-count !n !p = Parser $! count' n p Seq.empty
-
--- This implementation is rather ugly but we need to make it
--- tail-recursive to avoid stack overflow.
-count' :: Int -> Parser a -> Seq a -> State ParserState (ParserResult [a])
-count' 0 _ !soFar = return $! Success $! Fold.toList soFar
-count' !n !p !soFar = do saved <- get
- result <- runParser p
- case result of
- Success a -> count' (n-1) p (soFar |> a)
- IllegalInput -> do put saved
- return IllegalInput
- ReachedEOF -> do put saved
- return ReachedEOF
-
-
--- def may be a _|_
-option :: a -> Parser a -> Parser a
-option def !p = p <|> return def
-
-
-sepBy :: Parser a -> Parser sep -> Parser [a]
-sepBy !p !sep = sepBy1 p sep <|> return []
-
-
-sepBy1 :: Parser a -> Parser sep -> Parser [a]
-sepBy1 !p !sep
- = do x <- p
- xs <- many $! sep >> p
- return (x:xs)
-
-
-sp :: Parser Char
-sp = char ' '
-
-
-ht :: Parser Char
-ht = char '\t'
-
-
-crlf :: Parser String
-crlf = string "\x0d\x0a"
projects / Lucu.git / commitdiff