Release 0.3.3

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

diff --git a/Network/HTTP/Lucu/Parser.hs b/Network/HTTP/Lucu/Parser.hs
index 4bb8fa013e79f84d65aec51ec4c658d9ea461d6d..6c66e7f42e3c02c7fc12b63ceab537dfda0774d1 100644 (file)
--- a/Network/HTTP/Lucu/Parser.hs
+++ b/Network/HTTP/Lucu/Parser.hs
@@ -33,6 +33,7 @@ module Network.HTTP.Lucu.Parser
     , char
     , string
     , (<|>)
+    , choice
     , oneOf
     , digit
     , hexDigit
@@ -53,6 +54,9 @@ module Network.HTTP.Lucu.Parser
 import           Control.Monad.State.Strict
 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 qualified Data.Sequence as Seq
+import           Data.Sequence (Seq, (|>))
 
 -- |@'Parser' a@ is obviously a parser which parses and returns @a@.
 newtype Parser a = Parser {
@@ -141,22 +145,22 @@ allowEOF f = f `seq`
 
 
 satisfy :: (Char -> Bool) -> Parser Char
-satisfy f = f `seq`
-            do c <- anyChar
-               if f $! c then
-                   return c
-                 else
-                   failP
+satisfy !f
+    = do c <- anyChar
+         if f c then
+             return c
+           else
+             failP
 
 
 char :: Char -> Parser Char
-char c = c `seq` satisfy (== c)
+char !c = satisfy (== c)
 
 
 string :: String -> Parser String
-string str = str `seq`
-             do mapM_ char str
-                return str
+string !str = str `seq`
+              do mapM_ char str
+                 return str
 
 
 infixr 0 <|>
@@ -173,20 +177,24 @@ f <|> g
                      IllegalInput -> do put saved -- 状態を復歸
                                         runParser g
                      ReachedEOF   -> if pstIsEOFFatal saved then
-                                         return ReachedEOF
+                                         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 (<|>) failP . map char
 
 
 notFollowedBy :: Parser a -> Parser ()
-notFollowedBy p
-    = p `seq`
-      Parser $! do saved  <- get -- 状態を保存
+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
@@ -215,28 +223,46 @@ hexDigit = do c <- anyChar
                   failP
 
 
-many :: Parser a -> Parser [a]
-many p = p `seq`
-         do x  <- p
-            xs <- many p
-            return (x:xs)
-         <|>
-         return []
+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 #)
 
 
 many1 :: Parser a -> Parser [a]
-many1 p = p `seq`
-          do x  <- p
-             xs <- many p
-             return (x:xs)
+many1 !p = 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)
+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
+
 
 -- def may be a _|_
 option :: a -> Parser a -> Parser a