attoparsec-run 0.0.0.0 → 0.0.1.0

raw patch · 3 files changed

+53/−5 lines, 3 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• attoparsec-run.cabal +1/−1
• changelog.md +11/−0
• library/Data/Attoparsec/Run.hs +41/−4

@@ -1,7 +1,7 @@ cabal-version: 3.0  name: attoparsec-run-version: 0.0.0.0+version: 0.0.1.0 synopsis: Conveniently run Attoparsec parsers category: Parsing 

@@ -1,3 +1,14 @@+### 0.0.1.0 (2023-01-09)++New function:++```haskell+newRestorableIO :: IO i -> IO (RestorableInput IO i)+```++This makes it easy to turn any `IO` input source into a `RestorableInput`,+backed by an `IORef` that holds any unparsed remainder.+ ### 0.0.0.0 (2023-01-09)  Initial release

@@ -2,8 +2,10 @@  import Data.Attoparsec.Types +import Data.IORef (newIORef, readIORef, writeIORef) import Data.List (intercalate)-import Prelude (Either (..), Eq, Ord, Show, String, error, otherwise, null, (++))+import Prelude (Either (..), Eq, Ord, Show, String, IO,+          pure, error, otherwise, null, ($), ($!), (++))  data FinalResult i a = FinalResult     i -- ^ Remaining unparsed input@@ -34,8 +36,43 @@  data BufferedInput m i = BufferedInput     i -- ^ Initial input-    (m i) -- ^ Should return an empty string once the end of input is reached+    (m i) -- ^ Get the next chunk of input, or an empty string if the+          --   end of input has been reached +{-| An effectful source of parser input which supports a "restore" operation+    that can be used to push unused portions of input back to the source++For an example, see 'newRestorableIO'. -} data RestorableInput m i = RestorableInput-    (m i) -- ^ Return an empty string once the end of input is reached-    (i -> m ()) -- ^ Return a non-empty chunk of input to the input stream+    (m i) -- ^ Get the next chunk of input, or an empty string if the+          --   end of input has been reached+    (i -> m ()) -- ^ Restore a non-empty chunk of input to the input stream++{-| Turn any 'IO' input source into a 'RestorableInput'++Internally, this is backed by an 'IORef' that holds any unparsed remainder. -}+newRestorableIO :: IO i -> IO (RestorableInput IO i)+newRestorableIO unbufferedGet = do+    buffer <- newIORef [] -- The buffer stores the unparsed inputs+                          -- that have pushed back by "restore".+    pure $ RestorableInput (get buffer) (restore buffer)++  where+    -- Restoring writes an input chunk to the top of the stack.+    restore buffer x = do+        xs <- readIORef buffer+        writeIORef buffer $! (x : xs)++    get buffer = do+        bufferContent <- readIORef buffer+        case bufferContent of++            -- If the buffer is empty, then "get" just runs the action.+            [] -> unbufferedGet++            -- If there is content that has been pushed back onto the+            -- buffer, then "get" pops a chunk off of the stack instead+            -- of running the action.+            (x : xs) -> do+                writeIORef buffer $! xs+                pure x