adjust functor to move by dfa so that we cannot go to the last char of the file if (last char is a newline and is preceded by a non-newline), but otherwise we can go to the last char of the file.

fcore/cursor.sml

@@ -737,4 +737,9 @@ struct
           end
       | [] => true
     end
+
+  (* Prerequisite: lineGap is moved to cursorIdx *)
+  fun isOnNewlineAfterChr (buffer, cursorIdx) =
+    cursorIdx > 0 andalso not (isPrevChrStartOfLine (buffer, cursorIdx))
+    andalso isCursorAtStartOfLine (buffer, cursorIdx)
 end

fcore/move.sml

@@ -63,12 +63,26 @@ struct
       val cursorIdx = Fn.fMove (buffer, cursorIdx, count)
 
       val textLength = #textLength buffer
-      val cursorIdx =
-        if cursorIdx >= textLength - 1 then Int.max (textLength - 1, 0)
-        else cursorIdx
     in
-      NormalFinish.buildTextAndClear
-        (app, buffer, cursorIdx, searchList, [], bufferModifyTime)
+      if cursorIdx >= textLength - 1 then
+        let
+          val cursorIdx = Int.max (textLength - 1, 0)
+          val buffer = LineGap.goToIdx (cursorIdx, buffer)
+        in
+          if Cursor.isOnNewlineAfterChr (buffer, cursorIdx) then
+            let
+              val cursorIdx = cursorIdx - 1
+            in
+              NormalFinish.buildTextAndClear
+                (app, buffer, cursorIdx, searchList, [], bufferModifyTime)
+            end
+          else
+            NormalFinish.buildTextAndClear
+              (app, buffer, cursorIdx, searchList, [], bufferModifyTime)
+        end
+      else
+        NormalFinish.buildTextAndClear
+          (app, buffer, cursorIdx, searchList, [], bufferModifyTime)
     end
 end