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🔥 State assignment.

This commit is contained in:
Rob Rix 2017-04-25 15:05:04 -04:00
parent d5797eba16
commit 335cb3194f

View File

@ -2,7 +2,6 @@
module Data.Syntax.Assignment
( Assignment
, get
, state
, Location
, location
, symbol
@ -39,7 +38,6 @@ type Assignment node = Freer (AssignmentF node)
data AssignmentF node a where
Get :: AssignmentF node node
State :: AssignmentF (Node grammar) (AssignmentState grammar)
Location :: AssignmentF node Location
Source :: AssignmentF symbol ByteString
Children :: Assignment symbol a -> AssignmentF symbol a
@ -52,12 +50,6 @@ data AssignmentF node a where
get :: Assignment (Record fields) (Record fields)
get = Get `Then` return
-- | Zero-width production of the current state.
--
-- Since this is zero-width, care must be taken not to repeat it without chaining on other rules. I.e. 'many (state *> b)' is fine, but 'many state' is not.
state :: Assignment (Node grammar) (AssignmentState grammar)
state = State `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.
@ -126,7 +118,6 @@ 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.
(State, state) -> yield state state
(assignment, AssignmentState offset _ source (subtree@(Rose node@(_ :. range :. span :. Nil) children) : _)) -> case assignment of
Get -> yield node state
Location -> yield (range :. span :. Nil) state
@ -167,7 +158,6 @@ instance Alternative (Assignment symbol) where
instance Show symbol => Show1 (AssignmentF symbol) where
liftShowsPrec sp sl d a = case a of
Get -> showString "Get"
State -> showString "State" . sp d (AssignmentState 0 (Info.SourcePos 0 0) (Source.Source "") [])
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