Error.hs

module Wireform.Parser.Error (
  ParseError (..),
  CleanEof (..),
) where

import Control.Exception (Exception, SomeException)
import Data.Typeable (Typeable)
import Data.Word (Word64)


-- | The result of a failed parse.
data ParseError e
  = {- | The parser failed (recoverably) at the given absolute position
    and the failure was not caught by an enclosing alternative.
    -}
    ParseFail !Word64
  | -- | The parser failed unrecoverably (via cut\/commit) with user error @e@.
    ParseErr !Word64 !e
  | {- | Transport reported EOF while the parser was mid-message.
    The position is where the parser was; the 'Int' is how many
    additional bytes it needed.
    -}
    ParseUnexpectedEof !Word64 !Int
  | -- | Transport-level failure (broken connection, closed socket, etc.).
    ParseTransportError !SomeException
  | {- | The parser asked for more bytes than the magic ring can ever
    hold (or, more precisely, more than the remaining capacity from
    the parser's current position).  Continuing would deadlock —
    the producer cannot make room because the consumer is suspended
    waiting for bytes the producer cannot deliver.  Fields: parser
    position, requested bytes, ring size.
    -}
    ParseRingOverflow !Word64 !Int !Int
  deriving stock (Show, Functor)


{- | Internal sentinel: clean EOF before any bytes were consumed for
this parse.  Never exposed to users — the driver converts it to
either clean loop termination or 'ParseUnexpectedEof' depending on
context.
-}
data CleanEof = CleanEof
  deriving stock (Show, Typeable)


instance Exception CleanEof