in NormalMove.moveToLine function, use new LineGap function, 'LineGap.lineNumberToIdx', to get the index a line is at, and delete the Cursor.getLineStartIdx' function which we no longer need, as that functionality is in brolib-sml itself.

fcore/cursor.sml

@@ -1003,73 +1003,6 @@ struct
       | [] => cursorIdx
     end
 
-  (* Prerequisite: move lineGap to reqLine *)
-  fun getLineStartIdx (lineGap: LineGap.t, reqLine) =
-    let
-      val
-        { rightStrings
-        , rightLines
-        , line = bufferLine
-        , idx = bufferIdx
-        , leftStrings
-        , leftLines
-        , ...
-        } = lineGap
-    in
-      case (rightStrings, rightLines) of
-        (shd :: stl, lhd :: ltl) =>
-          (* reqLine exists in lineGap, so retrieve it *)
-          let
-            val relativeLine = reqLine - bufferLine - 1
-          in
-            if relativeLine < 0 then
-              (* line is in left node, if it exists *)
-              (case (leftStrings, leftLines) of
-                 (leftShd :: leftStl, leftLhd :: leftLtl) =>
-                   startVi0
-                     ( String.size leftShd - 1
-                     , leftShd
-                     , leftLhd
-                     , bufferIdx - 1
-                     , leftStl
-                     , leftLtl
-                     ) + 1
-               | (_, _) => 0)
-            else
-              let
-                val lineIdx = Vector.sub (lhd, relativeLine)
-              in
-                if lineIdx = String.size shd - 1 andalso List.null stl then
-                  (* if is end of buffer, return last idx in buffer; else, 
-                   * increment by 1 as we want to go to first char after line break *)
-                  bufferIdx + lineIdx
-                else
-                  bufferIdx + lineIdx
-              end
-          end
-      | (_, _) =>
-          (* reqLine does not exist in lineGap, so just go to start of last line *)
-          let
-            val {leftStrings, leftLines, ...} = lineGap
-          in
-            (case (leftStrings, leftLines) of
-               (lshd :: lstl, llhd :: lltl) =>
-                 let
-                   val result = startVi0
-                     ( String.size lshd - 1
-                     , lshd
-                     , llhd
-                     , bufferIdx - 1
-                     , lstl
-                     , lltl
-                     )
-                 in
-                   if result = bufferIdx then bufferIdx - 1 else result
-                 end
-             | (_, _) => 0)
-          end
-    end
-
   (* Prerequisite: lineGap is moved to cursorIdx *)
   fun isCursorAtStartOfLine (lineGap: LineGap.t, cursorIdx) =
     let

fcore/normal-mode/normal-move.sml

@@ -128,7 +128,7 @@ struct
           val buffer = LineGap.goToLine (reqLine, buffer)
 
           (* get idx of first chr after linebreak *)
-          val cursorIdx = Cursor.getLineStartIdx (buffer, reqLine)
+          val cursorIdx = LineGap.lineNumberToIdx (reqLine, buffer)
           val buffer = LineGap.goToIdx (cursorIdx, buffer)
 
           (* we got the line start idx, but we want to move to the index