X-Git-Url: http://git.cielonegro.org/gitweb.cgi?a=blobdiff_plain;f=Network%2FHTTP%2FLucu%2FParser.hs;h=34953f58c9dc5de637759c671f672b02815aa59e;hb=8bdd1da1ee1f3e453dbe2bce246618e12e26d30c;hp=3fa4c150e669dd088112efaf4f7f457fb36add83;hpb=3c7a58ab749a55a30466a033b170536bcdf18b98;p=Lucu.git

diff --git a/Network/HTTP/Lucu/Parser.hs b/Network/HTTP/Lucu/Parser.hs
index 3fa4c15..34953f5 100644
--- a/Network/HTTP/Lucu/Parser.hs
+++ b/Network/HTTP/Lucu/Parser.hs
@@ -1,130 +1,324 @@
+-- |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(..)
-    , 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]
-    , option    -- a -> Parser a -> Parser a
-    , sp        -- Parser Char
-    , ht        -- Parser Char
-    , crlf      -- Parser String
+    ( 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
-import           Control.Monad.State
-import qualified Data.ByteString.Lazy.Char8 as B
-import           Data.ByteString.Lazy.Char8 (ByteString)
-
-data Parser a = Parser {
-      runParser :: State ByteString (Maybe a)
+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
-                            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 = 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)
 
 
-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
+    = 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
+    = do c <- anyChar
+         if f c then
+             return c
+           else
+             failP
 
 
 char :: Char -> Parser Char
-char c = satisfy (== c)
+char !c = satisfy (== c)
 
 
 string :: String -> Parser String
-string str = do mapM_ char str
-                return str
+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
-                        Just a  -> return (Just a)
-                        Nothing -> do put saved -- 状態を復歸
-                                      runParser g
+(!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 (<|>) (fail "") . map char
+oneOf = foldl (<|>) failP . map char
 
 
 notFollowedBy :: Parser a -> Parser ()
-notFollowedBy p = p >>= fail "" <|> return ()
+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 = 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 :: 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
 
 
-many :: Parser a -> Parser [a]
-many p = do x  <- p
-            xs <- many p
-            return (x:xs)
-         <|>
-         return []
+many1 :: Parser a -> Parser [a]
+many1 !p = do x  <- p
+              xs <- many p
+              return (x:xs)
 
 
-many1 :: Parser a -> Parser [a]
-many1 p = do ret <- many p
-             case ret of
-               [] -> fail ""
-               xs -> return 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
 
-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 <|> 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 = sepBy1 p sep <|> return []
 
-option :: a -> Parser a -> Parser a
-option def p = p <|> return def
+
+sepBy1 :: Parser a -> Parser sep -> Parser [a]
+sepBy1 !p !sep
+    = do x  <- p
+         xs <- many $! sep >> p
+         return (x:xs)
 
 
 sp :: Parser Char