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Define a Many rule.

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This commit is contained in:
Rob Rix 2017-06-24 17:10:04 -04:00
parent 7df59da281
commit eaa4423dec
1 changed files with 10 additions and 0 deletions
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10
src/Data/Syntax/Assignment.hs
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@ -115,6 +115,7 @@ data AssignmentF ast grammar a where
Source :: HasCallStack => AssignmentF ast grammar ByteString
Children :: HasCallStack => Assignment ast grammar a -> AssignmentF ast grammar a
Choose :: HasCallStack => IntMap.IntMap a -> AssignmentF ast grammar a
Many :: HasCallStack => Assignment ast grammar a -> AssignmentF ast grammar [a]
Alt :: HasCallStack => a -> a -> AssignmentF ast grammar a
Empty :: HasCallStack => AssignmentF ast grammar a
Throw :: HasCallStack => Error grammar -> AssignmentF ast grammar a
@ -246,6 +247,8 @@ runAssignment toRecord = iterFreer run . fmap ((pure .) . (,))
Result _ (Just (a, state')) -> yield a (advanceState (rtail . toRecord) state' { stateNodes = stateNodes })
Result err Nothing -> Result err Nothing
(Choose choices, node : _) | Just symbol :. _ <- toRecord (F.project node), Just a <- IntMap.lookup (fromEnum symbol) choices -> yield a state
(Many _, []) -> yield [] state
(Many rule, _) -> uncurry yield (runMany rule state)
-- Nullability: some rules, e.g. @pure a@ and @many a@, should match at the end of input. Either side of an alternation may be nullable, ergo Alt can match at the end of input.
(Alt a b, _) -> yield a state <|> yield b state
(Throw e, _) -> Result (Just e) Nothing
@ -261,6 +264,10 @@ runAssignment toRecord = iterFreer run . fmap ((pure .) . (,))
Choose choices -> choiceSymbols choices
_ -> []
choiceSymbols choices = (toEnum :: Int -> grammar) <$> IntMap.keys choices
runMany :: Assignment ast grammar v -> AssignmentState ast -> ([v], AssignmentState ast)
runMany rule state = case runAssignment toRecord rule state of
Result _ (Just (a, state')) -> first (a :) (runMany rule state')
_ -> ([], state)
dropAnonymous :: (Symbol grammar, Recursive ast) => (forall x. Base ast x -> Maybe grammar) -> AssignmentState ast -> AssignmentState ast
dropAnonymous toSymbol state = state { stateNodes = dropWhile ((`notElem` [Just Regular, Nothing]) . fmap symbolType . toSymbol . F.project) (stateNodes state) }
@ -297,6 +304,8 @@ instance Enum grammar => Alternative (Assignment ast grammar) where
where choices (Choose choices `Then` continue) = Just (continue <$> choices)
choices (Empty `Then` _) = Just mempty
choices _ = Nothing
many :: HasCallStack => Assignment ast grammar a -> Assignment ast grammar [a]
many a = Many a `Then` return
instance Show grammar => Show1 (AssignmentF ast grammar) where
liftShowsPrec sp sl d a = case a of
@ -305,6 +314,7 @@ instance Show grammar => Show1 (AssignmentF ast grammar) where
Source -> showString "Source" . showChar ' ' . sp d ""
Children a -> showsUnaryWith (liftShowsPrec sp sl) "Children" d a
Choose choices -> showsUnaryWith (liftShowsPrec (liftShowsPrec sp sl) (liftShowList sp sl)) "Choose" d (IntMap.toList choices)
Many a -> showsUnaryWith (liftShowsPrec (\ d a -> sp d [a]) (sl . pure)) "Many" d a
Alt a b -> showsBinaryWith sp sp "Alt" d a b
Empty -> showString "Empty"
Throw e -> showsUnaryWith showsPrec "Throw" d e