X-Git-Url: http://git.cielonegro.org/gitweb.cgi?a=blobdiff_plain;f=Network%2FHTTP%2FLucu%2FParser.hs;h=c36655b4fc81f65c2fab16da81ecaef21a3c25f6;hb=30fcb38426696db8b80d322196cc594431e30407;hp=7a51ddcab435aa75cfcfc2904370bd104f8caef9;hpb=9961a721f98b101825ef154a2122c1fc2fa6d1ac;p=Lucu.git

diff --git a/Network/HTTP/Lucu/Parser.hs b/Network/HTTP/Lucu/Parser.hs
index 7a51ddc..c36655b 100644
--- a/Network/HTTP/Lucu/Parser.hs
+++ b/Network/HTTP/Lucu/Parser.hs
@@ -1,20 +1,51 @@
+-- |Yet another parser combinator. This is mostly a subset of Parsec
+-- but there are some differences:
+--
+-- * This parser works on ByteString instead of 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 treat reaching EOF (trying to eat one more letter at the
+--   end of string) a fatal error or 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(..)
-    , parse     -- Parser a -> ByteString -> Maybe (a, ByteString)
-    , anyChar   -- Parser Char
-    , satisfy   -- (Char -> Bool) -> Parser Char
-    , char      -- Char -> Parser Char
-    , string    -- String -> Parser String
-    , (<|>)     -- Parser a -> Parser a -> Parser a
-    , oneOf     -- [Char] -> Parser Char
-    , digit     -- Parser Char
-    , notFollowedBy -- Parser a -> Parser ()
-    , many      -- Parser a -> Parser [a]
-    , many1     -- Parser a -> Parser [a]
-    , manyTill  -- Parser a -> Parser end -> Parser [a]
-    , many1Till -- Parser a -> Parser end -> Parser [a]
-    , sp        -- Parser Char
-    , crlf      -- Parser String
+    ( Parser
+    , ParserResult(..)
+
+    , parse
+    , parseStr
+
+    , anyChar
+    , eof
+    , allowEOF
+    , satisfy
+    , char
+    , string
+    , (<|>)
+    , oneOf
+    , digit
+    , hexDigit
+    , notFollowedBy
+    , many
+    , many1
+    , manyTill
+    , many1Till
+    , count
+    , option
+    , sepBy
+    , sepBy1
+
+    , sp
+    , ht
+    , crlf
     )
     where
 
@@ -23,37 +54,75 @@ import           Control.Monad.State
 import qualified Data.ByteString.Lazy.Char8 as B
 import           Data.ByteString.Lazy.Char8 (ByteString)
 
+-- |@Parser a@ is obviously a parser which parses and returns @a@.
 data Parser a = Parser {
-      runParser :: State ByteString (Maybe a)
+      runParser :: State ParserState (ParserResult a)
     }
 
+type ParserState = (ByteString, IsEOFFatal)
+
+type IsEOFFatal = Bool
+
+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
+    p >>= f = Parser $ do saved@(_, isEOFFatal) <- get -- 失敗した時の爲に状態を保存
                           result <- runParser p
                           case result of
-                            Just a  -> runParser (f a)
-                            Nothing -> do put saved -- 状態を復歸
-                                          return Nothing
-    return = Parser . return . Just
-    fail _ = Parser $ return Nothing
-
-
-parse :: Parser a -> ByteString -> Maybe (a, ByteString)
-parse p input = case runState (runParser p) input of
-                  (Just a , input') -> Just (a, input')
-                  (Nothing, _     ) -> Nothing
+                            Success a    -> runParser (f a)
+                            IllegalInput -> do put saved -- 状態を復歸
+                                               return IllegalInput
+                            ReachedEOF   -> do unless isEOFFatal
+                                                          $ put saved -- 状態を復歸
+                                               return ReachedEOF
+    return = Parser . return . Success
+    fail _ = Parser $ return IllegalInput
+
+-- |@'parse' p bstr@ parses @bstr@ with @p@ and returns @(result,
+-- remaining)@.
+parse :: Parser a -> ByteString -> (ParserResult a, ByteString)
+parse p input = let (result, (input', _)) = runState (runParser p) (input, True)
+                in
+                  (result, input')
+
+-- |@'parseStr' p str@ packs @str@ and parses it.
+parseStr :: Parser a -> String -> (ParserResult a, ByteString)
+parseStr p input = parse p $ B.pack input
 
 
 anyChar :: Parser Char
-anyChar = Parser $ do input <- get
+anyChar = Parser $ do (input, isEOFFatal) <- get
                       if B.null input then
-                          return Nothing
+                          return ReachedEOF
                         else
                           do let c = B.head input
-                             put (B.tail input)
-                             return (Just c)
+                             put (B.tail input, isEOFFatal)
+                             return (Success c)
+
+
+eof :: Parser ()
+eof = Parser $ do (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 (input, isEOFFatal) <- get
+                         put (input, False)
+
+                         result <- runParser f
+                         
+                         (input', _) <- get
+                         put (input', isEOFFatal)
+
+                         return result
 
 
 satisfy :: (Char -> Bool) -> Parser Char
@@ -73,13 +142,20 @@ string str = do mapM_ char str
 
 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
+f <|> g = Parser $ do saved@(_, isEOFFatal) <- get -- 状態を保存
                       result <- runParser f
                       case result of
-                        Just a  -> return (Just a)
-                        Nothing -> do put saved -- 状態を復歸
-                                      runParser g
+                        Success a    -> return $ Success a
+                        IllegalInput -> do put saved -- 状態を復歸
+                                           runParser g
+                        ReachedEOF   -> if isEOFFatal then
+                                            return ReachedEOF
+                                        else
+                                            do put saved
+                                               runParser g
 
 
 oneOf :: [Char] -> Parser Char
@@ -91,7 +167,21 @@ notFollowedBy p = p >>= fail "" <|> return ()
 
 
 digit :: Parser Char
-digit = oneOf "0123456789"
+digit = do c <- anyChar
+           if c >= '0' && c <= '9' then
+               return c
+             else
+               fail ""
+
+
+hexDigit :: Parser Char
+hexDigit = do c <- anyChar
+              if (c >= '0' && c <= '9') ||
+                 (c >= 'a' && c <= 'f') ||
+                 (c >= 'A' && c <= 'F') then
+                  return c
+                else
+                  fail ""
 
 
 many :: Parser a -> Parser [a]
@@ -121,9 +211,34 @@ many1Till p end = many1 $ do x <- p
                              return x
 
 
+count :: Int -> Parser a -> Parser [a]
+count 0 _ = return []
+count n p = do x  <- p
+               xs <- count (n-1) p
+               return (x:xs)
+
+
+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"