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functorise some boilerplate code to start a DFA loop

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This commit is contained in:
Humza Shahid
2025-07-20 09:39:17 +01:00
parent 25fb8bfc5e
commit 10b76d98c5
5 changed files with 122 additions and 89 deletions
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61
fcore/cursor-dfa/make-dfa-loop.sml Normal file
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signature MAKE_DFA_LOOP =
sig
val fNext: int * int * string * string list * Word8.word * int -> int
val fPrev: int * int * string * string list * Word8.word * int -> int
val startState: Word8.word
end
functor MakeDfaLoop(M: MAKE_DFA_LOOP) =
struct
fun next (lineGap: LineGap.t, cursorIdx) =
let
val {rightStrings, idx = bufferIdx, ...} = lineGap
in
case rightStrings of
shd :: stl =>
let
(* convert absolute cursorIdx to idx relative to hd string *)
val strIdx = cursorIdx - bufferIdx
in
if strIdx < String.size shd then
(* strIdx is in this string *)
M.fNext (strIdx, cursorIdx, shd, stl, M.startState, 1)
else
(* strIdx is in tl *)
case stl of
stlhd :: stltl =>
M.fNext (strIdx, cursorIdx, stlhd, stltl, M.startState, 1)
| _ => cursorIdx
end
| [] => cursorIdx
end
fun prev (lineGap: LineGap.t, cursorIdx) =
let
val {rightStrings, leftStrings, idx = bufferIdx, ...} = lineGap
in
case rightStrings of
shd :: stl =>
let
(* convert absolute cursorIdx to idx relative to hd string *)
val strIdx = cursorIdx - bufferIdx
in
if strIdx < String.size shd then
(* strIdx is in this string *)
M.fPrev (strIdx, cursorIdx, shd, leftStrings, M.startState, 1)
else
(* strIdx is in tl *)
(case stl of
stlhd :: stltl =>
let
val strIdx = strIdx - String.size shd
val leftStrings = shd :: leftStrings
in
M.fPrev
(strIdx, cursorIdx, stlhd, leftStrings, M.startState, 1)
end
| [] => cursorIdx)
end
| [] => cursorIdx
end
end