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🔥 Get assignment.

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This commit is contained in:
Rob Rix 2017-04-25 15:09:41 -04:00
parent 7be5f34a38
commit 49f5e007da
1 changed files with 1 additions and 12 deletions
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13
src/Data/Syntax/Assignment.hs
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@ -1,7 +1,6 @@
{-# LANGUAGE DataKinds, GADTs, TypeFamilies #-}
module Data.Syntax.Assignment
( Assignment
, get
, Location
, location
, symbol
@ -36,19 +35,12 @@ type Assignment node = Freer (AssignmentF node)
data AssignmentF node a where
Symbol :: symbol -> AssignmentF (Node symbol) ()
Get :: AssignmentF node node
Location :: AssignmentF node Location
Source :: AssignmentF symbol ByteString
Children :: Assignment symbol a -> AssignmentF symbol a
Alt :: a -> a -> AssignmentF symbol a
Empty :: AssignmentF symbol a
-- | Zero-width production of the current node.
--
-- Since this is zero-width, care must be taken not to repeat it without chaining on other rules. I.e. 'many (get *> b)' is fine, but 'many get' is not.
get :: Assignment (Record fields) (Record fields)
get = Get `Then` return
-- | Zero-width production of the current location.
--
-- If assigning at the end of input or at the end of a list of children, the loccation will be returned as an empty Range and SourceSpan at the current offset. Otherwise, it will be the Range and SourceSpan of the current node.
@ -105,16 +97,14 @@ runAssignment :: (Symbol grammar, Eq grammar, Show grammar) => Assignment (Node
runAssignment = iterFreer (\ assignment yield state -> case (assignment, dropAnonymous state) of
-- 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, state) -> yield a state <|> yield b state -- FIXME: Symbol `Alt` Symbol `Alt` Symbol is inefficient, should build and match against an IntMap instead.
(assignment, AssignmentState offset _ source (subtree@(Rose node@(symbol :. range :. span :. Nil) children) : _)) -> case assignment of
(assignment, AssignmentState offset _ source (subtree@(Rose (symbol :. range :. span :. Nil) children) : _)) -> case assignment of
Symbol s -> guard (s == symbol) >> yield () state
Get -> yield node state
Location -> yield (range :. span :. Nil) state
Source -> yield (Source.sourceText (Source.slice (offsetRange range (negate offset)) source)) (advanceState state)
Children childAssignment -> do
c <- assignAllFrom childAssignment state { stateNodes = children }
yield c (advanceState state)
_ -> Error ["No rule to match " <> show subtree]
(Get, AssignmentState{}) -> Error [ "Expected node but got end of input." ]
(Location, AssignmentState{..}) -> yield (Info.Range stateOffset stateOffset :. Info.SourceSpan statePos statePos :. Nil) state
(Source, AssignmentState{}) -> Error [ "Expected leaf node but got end of input." ]
(Children _, AssignmentState{}) -> Error [ "Expected branch node but got end of input." ]
@ -146,7 +136,6 @@ instance Alternative (Assignment symbol) where
instance Show symbol => Show1 (AssignmentF (Node symbol)) where
liftShowsPrec sp sl d a = case a of
Symbol s -> showsUnaryWith showsPrec "Symbol" d s
Get -> showString "Get"
Location -> showString "Location" . sp d (Info.Range 0 0 :. Info.SourceSpan (Info.SourcePos 0 0) (Info.SourcePos 0 0) :. Nil)
Source -> showString "Source" . showChar ' ' . sp d ""
Children a -> showsUnaryWith (liftShowsPrec sp sl) "Children" d a