Slight speed improvement and bugfix

[Lucu.git] / Network / HTTP / Lucu / Parser.hs

diff --git a/Network/HTTP/Lucu/Parser.hs b/Network/HTTP/Lucu/Parser.hs
index 0033eb482e88b80d111b2aededf9705c5cbb8ac5..cc12cd73733b636ce3270e8518d137ade2eb3266 100644 (file)
--- a/Network/HTTP/Lucu/Parser.hs
+++ b/Network/HTTP/Lucu/Parser.hs
@@ -20,6 +20,8 @@ module Network.HTTP.Lucu.Parser
     ( Parser
     , ParserResult(..)
 
+    , failP
+
     , parse
     , parseStr
 
@@ -36,8 +38,6 @@ module Network.HTTP.Lucu.Parser
     , notFollowedBy
     , many
     , many1
-    , manyTill
-    , many1Till
     , count
     , option
     , sepBy
@@ -49,19 +49,24 @@ module Network.HTTP.Lucu.Parser
     )
     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)
 
+
 -- |@Parser a@ is obviously a parser which parses and returns @a@.
 newtype Parser a = Parser {
       runParser :: State ParserState (ParserResult a)
     }
 
-type ParserState = (ByteString, IsEOFFatal)
 
-type IsEOFFatal = Bool
+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
@@ -71,26 +76,29 @@ data ParserResult a = Success !a
 
 --  (>>=) :: Parser a -> (a -> Parser b) -> Parser b
 instance Monad Parser where
-    p >>= f = Parser $! do saved@(_, isEOFFatal) <- get -- 失敗した時の爲に状態を保存
+    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    -> a `seq` runParser (f a)
+                             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
+                             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, (input', _)) = runState (runParser p) (input, True)
+      let (result, state') = runState (runParser p) (PST input True)
       in
-        result `seq` (result, input') -- input' も lazy である必要有り。
+        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)
@@ -101,33 +109,32 @@ parseStr p input
 
 anyChar :: Parser Char
 anyChar = Parser $!
-          do (input, isEOFFatal) <- get
+          do state@(PST input _) <- get
              if B.null input then
                  return ReachedEOF
                else
-                 do let c = B.head input
-                    put (B.tail input, isEOFFatal)
-                    return (Success c)
+                 do put $! state { pstInput = B.tail input }
+                    return (Success $! B.head input)
 
 
 eof :: Parser ()
 eof = Parser $!
-      do (input, _) <- get
+      do PST input _ <- get
          if B.null input then
-             return $ Success ()
+             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 (input, isEOFFatal) <- get
-                          put (input, False)
+             Parser $! do saved@(PST _ isEOFFatal) <- get
+                          put $! saved { pstIsEOFFatal = False }
 
                           result <- runParser f
                          
-                          (input', _) <- get
-                          put (input', isEOFFatal)
+                          state <- get
+                          put $! state { pstIsEOFFatal = isEOFFatal }
 
                           return result
 
@@ -135,8 +142,10 @@ allowEOF f = f `seq`
 satisfy :: (Char -> Bool) -> Parser Char
 satisfy f = f `seq`
             do c <- anyChar
-               unless (f c) (fail "")
-               return c
+               if f c then
+                   return c
+                 else
+                   failP
 
 
 char :: Char -> Parser Char
@@ -156,13 +165,13 @@ infixr 0 <|>
 (<|>) :: Parser a -> Parser a -> Parser a
 f <|> g
     = f `seq` g `seq`
-      Parser $! do saved@(_, isEOFFatal) <- get -- 状態を保存
+      Parser $! do saved <- get -- 状態を保存
                    result <- runParser f
                    case result of
-                     Success a    -> return $ Success a
+                     Success a    -> return $! Success a
                      IllegalInput -> do put saved -- 状態を復歸
                                         runParser g
-                     ReachedEOF   -> if isEOFFatal then
+                     ReachedEOF   -> if pstIsEOFFatal saved then
                                          return ReachedEOF
                                      else
                                          do put saved
@@ -170,12 +179,12 @@ f <|> g
 
 
 oneOf :: [Char] -> Parser Char
-oneOf = foldl (<|>) (fail "") . map char
+oneOf = foldl (<|>) failP . map char
 
 
 notFollowedBy :: Parser a -> Parser ()
 notFollowedBy p = p `seq`
-                  p >>= fail "" <|> return ()
+                  (p >> failP) <|> return ()
 
 
 digit :: Parser Char
@@ -183,7 +192,7 @@ digit = do c <- anyChar
            if c >= '0' && c <= '9' then
                return c
              else
-               fail ""
+               failP
 
 
 hexDigit :: Parser Char
@@ -193,7 +202,7 @@ hexDigit = do c <- anyChar
                  (c >= 'A' && c <= 'F') then
                   return c
                 else
-                  fail ""
+                  failP
 
 
 many :: Parser a -> Parser [a]
@@ -207,26 +216,9 @@ many p = p `seq`
 
 many1 :: Parser a -> Parser [a]
 many1 p = p `seq`
-          do ret <- many p
-             case ret of
-               [] -> fail ""
-               xs -> return xs
-
-
-manyTill :: Parser a -> Parser end -> Parser [a]
-manyTill p end
-    = p `seq` end `seq`
-      many $! do x <- p
-                 end
-                 return x
-
-
-many1Till :: Parser a -> Parser end -> Parser [a]
-many1Till p end
-    = p `seq` end `seq`
-      many1 $! do x <- p
-                  end
-                  return x
+          do x  <- p
+             xs <- many p
+             return (x:xs)
 
 
 count :: Int -> Parser a -> Parser [a]