From 5d20b81bcccdccc2526015c8733daf9224884c67 Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Tue, 23 Sep 2025 11:47:25 +0100
Subject: [PATCH] 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 |  5 +++++
 fcore/move.sml   | 24 +++++++++++++++++++-----
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/fcore/cursor.sml b/fcore/cursor.sml
index 48f4358..9e0dc1f 100644
--- a/fcore/cursor.sml
+++ b/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
diff --git a/fcore/move.sml b/fcore/move.sml
index 98407b7..6c1c427 100644
--- a/fcore/move.sml
+++ b/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