From 554c3b035428a716e53f5a46aabbbb5b38efce68 Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Sun, 20 Jul 2025 13:28:40 +0100
Subject: [PATCH] done refactoring 'startOfCurrentWORD' function, with tests
 still passing

---
 fcore/cursor-dfa/vi-WORD-dfa.sml | 73 +++++++++++++++++++-------------
 1 file changed, 43 insertions(+), 30 deletions(-)

diff --git a/fcore/cursor-dfa/vi-WORD-dfa.sml b/fcore/cursor-dfa/vi-WORD-dfa.sml
index 3ea28e9..b19b835 100644
--- a/fcore/cursor-dfa/vi-WORD-dfa.sml
+++ b/fcore/cursor-dfa/vi-WORD-dfa.sml
@@ -108,39 +108,52 @@ struct
              end
        end)
 
-  structure StartOfCurrentWORD =
-    MakePrevDfaLoop
-      (struct
-         val startState = startState
-
-         fun fStart (idx, absIdx, str, tl, currentState, counter) =
-           if idx < 0 then
-             case tl of
-               str :: tl =>
-                 fStart
-                   (String.size str - 1, absIdx, str, tl, currentState, counter)
-             | [] => 0
-           else
-             let
-               val chr = String.sub (str, idx)
-               val newState = next (currentState, chr)
-             in
-               if newState = spaceAfterNonBlankState then
-                 if counter - 1 = 0 then
-                   absIdx + 1
-                 else
-                   fStart
-                     (idx - 1, absIdx - 1, str, tl, startState, counter - 1)
-               else
-                 fStart (idx - 1, absIdx - 1, str, tl, newState, counter)
-             end
-       end)
-
   val startOfNextWORD = StartOfNextWORD.next
   val endOfPrevWORD = EndOfPrevWORD.prev
 
+  fun loopStartOfCurrentWORD (idx, absIdx, str, tl, currentState, counter) =
+    if idx < 0 then
+      case tl of
+        str :: tl =>
+          loopStartOfCurrentWORD
+            (String.size str - 1, absIdx, str, tl, currentState, counter)
+      | [] => 0
+    else
+      let
+        val chr = String.sub (str, idx)
+        val newState = next (currentState, chr)
+      in
+        if newState = spaceAfterNonBlankState then
+          if counter - 1 = 0 then
+            absIdx + 1
+          else
+            loopStartOfCurrentWORD
+              (idx - 1, absIdx - 1, str, tl, startState, counter - 1)
+        else
+          loopStartOfCurrentWORD
+            (idx - 1, absIdx - 1, str, tl, newState, counter)
+      end
+
+  (* we do not rely on MakeDfaLoop functor because we want to 
+   * ignore the character the cursor is currently on,
+   * and start tracking state from the character before the current one. *)
   fun startOfCurrentWORD (lineGap: LineGap.t, cursorIdx) =
-    let val lineGap = LineGap.goToIdx (cursorIdx - 1, lineGap)
-    in StartOfCurrentWORD.prev (lineGap, cursorIdx - 1)
+    let
+      val {idx = bufferIdx, leftStrings, ...} = lineGap
+      val strIdx = cursorIdx - bufferIdx - 1
+      val absIdx = cursorIdx - 1
+    in
+      if strIdx < 0 then
+        case leftStrings of
+          lhd :: ltl =>
+            loopStartOfCurrentWORD
+              (String.size lhd - 1, absIdx, lhd, ltl, startState, 1)
+        | [] => 0
+      else
+        case #rightStrings lineGap of
+          rhd :: _ =>
+            loopStartOfCurrentWORD
+              (strIdx, absIdx, rhd, leftStrings, startState, 1)
+        | [] => Int.max (0, cursorIdx - 2)
     end
 end