X-Git-Url: http://git.cielonegro.org/gitweb.cgi?a=blobdiff_plain;f=Network%2FHTTP%2FLucu%2FParser.hs;h=cc12cd73733b636ce3270e8518d137ade2eb3266;hb=7b3c7c2c5be4fc05ee03008aa0af56fab798e1bb;hp=7a51ddcab435aa75cfcfc2904370bd104f8caef9;hpb=9961a721f98b101825ef154a2122c1fc2fa6d1ac;p=Lucu.git

diff --git a/Network/HTTP/Lucu/Parser.hs b/Network/HTTP/Lucu/Parser.hs
index 7a51ddc..cc12cd7 100644
--- a/Network/HTTP/Lucu/Parser.hs
+++ b/Network/HTTP/Lucu/Parser.hs
@@ -1,101 +1,213 @@
+-- |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 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(..)
-    , 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(..)
+
+    , failP
+
+    , parse
+    , parseStr
+
+    , anyChar
+    , eof
+    , allowEOF
+    , satisfy
+    , char
+    , string
+    , (<|>)
+    , oneOf
+    , digit
+    , hexDigit
+    , notFollowedBy
+    , many
+    , many1
+    , count
+    , option
+    , sepBy
+    , sepBy1
+
+    , sp
+    , ht
+    , crlf
     )
     where
 
-import           Control.Monad
-import           Control.Monad.State
+import           Control.Monad.State.Strict
 import qualified Data.ByteString.Lazy.Char8 as B
 import           Data.ByteString.Lazy.Char8 (ByteString)
 
-data Parser a = Parser {
-      runParser :: State ByteString (Maybe a)
+
+-- |@Parser a@ is obviously a parser which parses and returns @a@.
+newtype Parser a = Parser {
+      runParser :: State ParserState (ParserResult a)
     }
 
 
+data ParserState
+    = PST {
+        pstInput      :: 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
-                            Just a  -> runParser (f a)
-                            Nothing -> do put saved -- 状態を復歸
-                                          return Nothing
-    return = Parser . return . Just
-    fail _ = Parser $ return Nothing
+    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 = x `seq` Parser $! return $! Success x
+    fail _   = Parser $! return $! IllegalInput
+
+-- |@'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 -> ByteString -> (ParserResult a, ByteString)
+parse p input -- input は lazy である必要有り。
+    = p `seq`
+      let (result, state') = runState (runParser p) (PST input True)
+      in
+        result `seq` (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, ByteString)
+parseStr p input
+    = p `seq` -- input は lazy である必要有り。
+      parse p $! B.pack input
 
 
-parse :: Parser a -> ByteString -> Maybe (a, ByteString)
-parse p input = case runState (runParser p) input of
-                  (Just a , input') -> Just (a, input')
-                  (Nothing, _     ) -> Nothing
+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)
 
 
-anyChar :: Parser Char
-anyChar = Parser $ do input <- get
-                      if B.null input then
-                          return Nothing
-                        else
-                          do let c = B.head input
-                             put (B.tail input)
-                             return (Just c)
+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 = f `seq`
+             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
-               unless (f c) (fail "")
-               return c
+satisfy f = f `seq`
+            do c <- anyChar
+               if f c then
+                   return c
+                 else
+                   failP
 
 
 char :: Char -> Parser Char
-char c = satisfy (== c)
+char c = c `seq` satisfy (== c)
 
 
 string :: String -> Parser String
-string str = do mapM_ char str
+string str = str `seq`
+             do mapM_ char str
                 return 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
-                      result <- runParser f
-                      case result of
-                        Just a  -> return (Just a)
-                        Nothing -> do put saved -- 状態を復歸
-                                      runParser g
+f <|> g
+    = f `seq` g `seq`
+      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
+                                         return ReachedEOF
+                                     else
+                                         do put saved
+                                            runParser g
 
 
 oneOf :: [Char] -> Parser Char
-oneOf = foldl (<|>) (fail "") . map char
+oneOf = foldl (<|>) failP . map char
 
 
 notFollowedBy :: Parser a -> Parser ()
-notFollowedBy p = p >>= fail "" <|> return ()
+notFollowedBy p = p `seq`
+                  (p >> failP) <|> return ()
 
 
 digit :: Parser Char
-digit = oneOf "0123456789"
+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 :: Parser a -> Parser [a]
-many p = do x  <- p
+many p = p `seq`
+         do x  <- p
             xs <- many p
             return (x:xs)
          <|>
@@ -103,27 +215,44 @@ many p = do x  <- p
 
 
 many1 :: Parser a -> Parser [a]
-many1 p = do ret <- many p
-             case ret of
-               [] -> fail ""
-               xs -> return xs
+many1 p = p `seq`
+          do x  <- p
+             xs <- many p
+             return (x:xs)
+
 
+count :: Int -> Parser a -> Parser [a]
+count 0 _ = return []
+count n p = n `seq` p `seq`
+            do x  <- p
+               xs <- count (n-1) p
+               return (x:xs)
 
-manyTill :: Parser a -> Parser end -> Parser [a]
-manyTill p end = many $ do x <- p
-                           end
-                           return x
+-- def may be a _|_
+option :: a -> Parser a -> Parser a
+option def p = p `seq`
+               p <|> return def
 
 
-many1Till :: Parser a -> Parser end -> Parser [a]
-many1Till p end = many1 $ do x <- p
-                             end
-                             return x
+sepBy :: Parser a -> Parser sep -> Parser [a]
+sepBy p sep = p `seq` sep `seq`
+              sepBy1 p sep <|> return []
+
+
+sepBy1 :: Parser a -> Parser sep -> Parser [a]
+sepBy1 p sep = p `seq` sep `seq`
+               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"