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refactor Cursor.viH to use DFA

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This commit is contained in:
Humza Shahid
2025-09-17 10:45:37 +01:00
parent 9ddb5f68d7
commit dbf05ec8dc
5 changed files with 63 additions and 79 deletions
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72
fcore/cursor.sml
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@@ -57,77 +57,7 @@ struct
val viDlrForDelete = ViDlrDfa.nextForDelete
val viL = ViLDfa.next
structure ViH =
MakeIfCharFolderPrev
(struct
type env = unit
fun helpViH (strIdx, hd, cursorIdx, leftStrings) =
if strIdx > 0 then
(* bounds check: can access prev char in hd *)
if String.sub (hd, strIdx - 1) = #"\n" then
(* prev char is line break *)
if strIdx - 1 > 0 then
(* bounds check: can access two chars back in hd *)
if String.sub (hd, strIdx - 2) = #"\n" then
(* line break followed by line break
* so it is fine to decrement by 1 *)
cursorIdx - 1
else
(* non-line break followed by line break
* so we have to decrement by two,
* skipping over line break *)
cursorIdx - 2
else
(* need to check two chars back in leftStrings *)
(case leftStrings of
lhd :: ltl =>
if String.sub (lhd, String.size lhd - 1) = #"\n" then
(* double line break *)
cursorIdx - 1
else
(* non-line break precedes line break *)
cursorIdx - 2
| [] => cursorIdx - 1)
else
(* prev char is not line break so we can decrement by 1 *)
cursorIdx - 1
else
(* prev char is in leftStrings *)
(case leftStrings of
lhd :: ltl =>
if String.sub (lhd, String.size lhd - 1) = #"\n" then
(* one line break *)
if String.size lhd > 1 then
(* bounds check: prev-prev chr is in lhd *)
if String.sub (lhd, String.size lhd - 2) = #"\n" then
(* double line break *)
cursorIdx - 1
else
(* non-line break precedes line break *)
cursorIdx - 2
else
(* prev-prev chr is in ltl *)
(case ltl of
ltlhd :: _ =>
if String.sub (ltlhd, String.size ltlhd - 1) = #"\n" then
(* double line break *)
cursorIdx - 1
else
(* non-line break precedes line break *)
cursorIdx - 2
| [] => cursorIdx - 1)
else
(* no line break *)
cursorIdx - 1
| [] => 0)
fun fStart (strIdx, hd, _, cursorIdx, leftStrings, _, _) =
helpViH (strIdx, hd, cursorIdx, leftStrings)
end)
fun viH (lineGap, cursorIdx) = ViH.foldPrev (lineGap, cursorIdx, ())
val viH = ViLDfa.prev
fun helpGetCursorColumn (distanceFromLine, strList, lineList) =
case (strList, lineList) of