1 module Network.HTTP.Lucu.Parser
3 , parse -- Parser a -> ByteString -> Maybe (a, ByteString)
4 , anyChar -- Parser Char
5 , satisfy -- (Char -> Bool) -> Parser Char
6 , char -- Char -> Parser Char
7 , string -- String -> Parser String
8 , (<|>) -- Parser a -> Parser a -> Parser a
9 , oneOf -- [Char] -> Parser Char
10 , digit -- Parser Char
11 , notFollowedBy -- Parser a -> Parser ()
12 , many -- Parser a -> Parser [a]
13 , many1 -- Parser a -> Parser [a]
14 , manyTill -- Parser a -> Parser end -> Parser [a]
15 , many1Till -- Parser a -> Parser end -> Parser [a]
17 , crlf -- Parser String
22 import Control.Monad.State
23 import qualified Data.ByteString.Lazy.Char8 as B
24 import Data.ByteString.Lazy.Char8 (ByteString)
26 data Parser a = Parser {
27 runParser :: State ByteString (Maybe a)
31 -- (>>=) :: Parser a -> (a -> Parser b) -> Parser b
32 instance Monad Parser where
33 p >>= f = Parser $ do saved <- get -- 失敗した時の爲に状態を保存
36 Just a -> runParser (f a)
37 Nothing -> do put saved -- 状態を復歸
39 return = Parser . return . Just
40 fail _ = Parser $ return Nothing
43 parse :: Parser a -> ByteString -> Maybe (a, ByteString)
44 parse p input = case runState (runParser p) input of
45 (Just a , input') -> Just (a, input')
46 (Nothing, _ ) -> Nothing
49 anyChar :: Parser Char
50 anyChar = Parser $ do input <- get
54 do let c = B.head input
59 satisfy :: (Char -> Bool) -> Parser Char
60 satisfy f = do c <- anyChar
61 unless (f c) (fail "")
65 char :: Char -> Parser Char
66 char c = satisfy (== c)
69 string :: String -> Parser String
70 string str = do mapM_ char str
76 (<|>) :: Parser a -> Parser a -> Parser a
77 f <|> g = Parser $ do saved <- get -- 状態を保存
80 Just a -> return (Just a)
81 Nothing -> do put saved -- 状態を復歸
85 oneOf :: [Char] -> Parser Char
86 oneOf = foldl (<|>) (fail "") . map char
89 notFollowedBy :: Parser a -> Parser ()
90 notFollowedBy p = p >>= fail "" <|> return ()
94 digit = oneOf "0123456789"
97 many :: Parser a -> Parser [a]
105 many1 :: Parser a -> Parser [a]
106 many1 p = do ret <- many p
112 manyTill :: Parser a -> Parser end -> Parser [a]
113 manyTill p end = many $ do x <- p
118 many1Till :: Parser a -> Parser end -> Parser [a]
119 many1Till p end = many1 $ do x <- p
128 crlf :: Parser String
129 crlf = string "\x0d\x0a"