parcom-lib 0.6.0.0 → 0.7.0.0

raw patch · 2 files changed

+24/−10 lines, 2 files

Files

• Text/Parcom/Core.hs +23/−9
• parcom-lib.cabal +1/−1

@@ -9,7 +9,7 @@ , ParcomT, parseT , Parcom, parse , peek, next, atEnd-, try, handle+, try, handle, handleB , notFollowedBy , (<?>), (<|>), empty , Stream, Token, Listish, Textish@@ -122,14 +122,20 @@ modifyState :: Monad m => (ParcomState s -> ParcomState s) -> ParcomT s t m () modifyState f = ParcomT $ \s -> return (Right (), f s) --- | Very general error / success handler--- Each of the error / success branches takes both the old and the new state,--- so that the branch handler itself can decide whether to backtrack or--- continue with the new state.+-- | Wrap a raw parser with error and success handler functions, such that:+--+-- * the handlers can choose whether to fail or succeed+--+-- * the handlers can choose to backtrack (by returning the previous state) or+--   consume (by returning the new state).+--+-- In order to facilitate this, both the error and success handler functions+-- accept three arguments: the error or parsed value, respectively; the parser+-- state before parsing; and the parser state after parsing. handle' :: Monad m-    => ParcomT s t m a-    -> (ParcomError -> ParcomState s -> ParcomState s -> m (Either ParcomError b, ParcomState s))-    -> (a -> ParcomState s -> ParcomState s -> m (Either ParcomError b, ParcomState s))+    => ParcomT s t m a -- ^ The parser we're wrapping+    -> (ParcomError -> ParcomState s -> ParcomState s -> m (Either ParcomError b, ParcomState s)) -- ^ error handler+    -> (a -> ParcomState s -> ParcomState s -> m (Either ParcomError b, ParcomState s)) -- ^ success handler     -> ParcomT s t m b handle' p errorH successH = ParcomT $ \s -> do     (r, s') <- runParcomT p s@@ -139,6 +145,10 @@         -- parse succeeded: run success handler         Right x -> successH x s s' +-- | Wrap a raw parser to allow handling success and failure. The error and+-- success handlers take the error or parsed value, respectively, and return+-- a parser that should be applied in the error or success case, respectively.+-- No backtracking is performed. handle :: Monad m     => ParcomT s t m a     -> (ParcomError -> ParcomT s t m b)@@ -147,13 +157,15 @@ handle p f t =     handle' p (\e _ s' -> runParcomT (f e) s') (\x _ s' -> runParcomT (t x) s') +-- | Same as 'handle', but backtrack on error (that is, if the raw parser+-- fails, any input it has consumed is restored. handleB :: Monad m     => ParcomT s t m a     -> (ParcomError -> ParcomT s t m b)     -> (a -> ParcomT s t m b)     -> ParcomT s t m b handleB p f t =-    handle' p (\e s _ -> runParcomT (f e) s) (\x s _ -> runParcomT (t x) s)+    handle' p (\e s _ -> runParcomT (f e) s) (\x _ s' -> runParcomT (t x) s')  -- | Backtracking modifier; restores the parser state to the previous situation -- if the wrapped parser fails.@@ -181,10 +193,12 @@ atEnd :: (Monad m, Stream s t) => ParcomT s t m Bool atEnd = useState (Stream.atEnd . psStream) +-- | Update a source position to proceed to the next line nextLine :: SourcePosition -> SourcePosition nextLine s =     s { posLine = posLine s + 1, posColumn = 1 } +-- | Update a source position to proceed to the next column nextColumn :: SourcePosition -> SourcePosition nextColumn s =     s { posColumn = posColumn s + 1 }

@@ -2,7 +2,7 @@ -- documentation, see http://haskell.org/cabal/users-guide/  name:                parcom-lib-version:             0.6.0.0+version:             0.7.0.0 synopsis:            A simple parser-combinator library, a bit like Parsec but without the frills description:         Parcom provides parser combinator functionality in a string-type-agnostic way;                      it supports strict ByteStrings (with Word8 tokens) and any list type (with