X-Git-Url: http://git.cielonegro.org/gitweb.cgi?a=blobdiff_plain;f=Network%2FHTTP%2FLucu%2FParser.hs;h=174a28997e04b85641392ea6062662f3705ed67d;hb=8e78bc83bfe67a376293c346ae0b30f1a684c787;hp=f99cdf58b5afdd5c2d2a610e1ee3786e056c221d;hpb=cd1b58b84ff354e3fc2a7d2c8fd548a7b59fe138;p=Lucu.git

diff --git a/Network/HTTP/Lucu/Parser.hs b/Network/HTTP/Lucu/Parser.hs
index f99cdf5..174a289 100644
--- a/Network/HTTP/Lucu/Parser.hs
+++ b/Network/HTTP/Lucu/Parser.hs
@@ -1,39 +1,68 @@
+-- |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(..)
+    ( Parser
     , ParserResult(..)
 
-    , parse     -- Parser a -> ByteString -> ParserResult a
-
-    , 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
-    , hexDigit  -- 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
+    , parse
+    , parseStr
+
+    , anyChar
+    , eof
+    , allowEOF
+    , satisfy
+    , char
+    , string
+    , (<|>)
+    , oneOf
+    , digit
+    , hexDigit
+    , notFollowedBy
+    , many
+    , many1
+    , manyTill
+    , many1Till
+    , 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 (ParserResult a)
+-- |@Parser a@ is obviously a parser which parses and returns @a@.
+newtype Parser a = Parser {
+      runParser :: State ParserState (ParserResult a)
     }
 
-data ParserResult a = Success 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)
@@ -41,56 +70,102 @@ data ParserResult a = Success a
 
 --  (>>=) :: 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
-                            Success a    -> runParser (f a)
-                            IllegalInput -> do put saved -- 状態を復歸
-                                               return IllegalInput
-                            ReachedEOF   -> return ReachedEOF
-    return = Parser . return . Success
-    fail _ = Parser $ return IllegalInput
-
-
+    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
+                             Success a    -> a `seq` 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 x = x `seq` Parser $! return $! Success x
+    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 = runState (runParser p) input
+parse p input -- input は lazy である必要有り。
+    = p `seq`
+      let (result, (input', _)) = runState (runParser p) (input, True)
+      in
+        result `seq` (result, input') -- input' 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
 
 
 anyChar :: Parser Char
-anyChar = Parser $ do input <- get
-                      if B.null input then
-                          return ReachedEOF
-                        else
-                          do let c = B.head input
-                             put (B.tail input)
-                             return (Success c)
+anyChar = Parser $!
+          do (input, isEOFFatal) <- get
+             if B.null input then
+                 return ReachedEOF
+               else
+                 do let c = B.head input
+                    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 = f `seq`
+             Parser $! do (input, isEOFFatal) <- get
+                          put (input, False)
+
+                          result <- runParser f
+                         
+                          (input', _) <- get
+                          put (input', isEOFFatal)
+
+                          return result
 
 
 satisfy :: (Char -> Bool) -> Parser Char
-satisfy f = do c <- anyChar
+satisfy f = f `seq`
+            do c <- anyChar
                unless (f c) (fail "")
                return c
 
 
 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
-                        Success a    -> return $ Success a
-                        IllegalInput -> do put saved -- 状態を復歸
-                                           runParser g
-                        ReachedEOF   -> return ReachedEOF
+f <|> g
+    = f `seq` g `seq`
+      Parser $! do saved@(_, isEOFFatal) <- 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 isEOFFatal then
+                                         return ReachedEOF
+                                     else
+                                         do put saved
+                                            runParser g
 
 
 oneOf :: [Char] -> Parser Char
@@ -98,7 +173,8 @@ oneOf = foldl (<|>) (fail "") . map char
 
 
 notFollowedBy :: Parser a -> Parser ()
-notFollowedBy p = p >>= fail "" <|> return ()
+notFollowedBy p = p `seq`
+                  p >>= fail "" <|> return ()
 
 
 digit :: Parser Char
@@ -120,7 +196,8 @@ hexDigit = do c <- anyChar
 
 
 many :: Parser a -> Parser [a]
-many p = do x  <- p
+many p = p `seq`
+         do x  <- p
             xs <- many p
             return (x:xs)
          <|>
@@ -128,26 +205,52 @@ many p = do x  <- p
 
 
 many1 :: Parser a -> Parser [a]
-many1 p = do ret <- many p
+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 = many $ do x <- p
-                           end
-                           return x
+manyTill p end
+    = p `seq` end `seq`
+      many $! do x <- p
+                 end
+                 return x
 
 
 many1Till :: Parser a -> Parser end -> Parser [a]
-many1Till p end = many1 $ do x <- p
-                             end
-                             return x
+many1Till p end
+    = p `seq` end `seq`
+      many1 $! do x <- p
+                  end
+                  return x
 
 
+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)
+
+-- def may be a _|_
 option :: a -> Parser a -> Parser a
-option def p = p <|> return def
+option def p = p `seq`
+               p <|> return def
+
+
+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