fix minor bug regarding 'NormalMove.moveCursorDown': after a <count-j> that moved the cursor to the last line in the buffer, the cursor would be at the last column too, even if that wasn't the previous column. To address this issue, we take out code that calculates the lineIdx from the 'NormalMove.finishMoveCursorUpDown' function, and have both 'NormalMove.moveCursorUp' and 'NormalMove.moveCursorDown' calculate their own lineIdx in different ways and pass it to the 'NormalMove.finishMoveCursorUpAndDown' function.

fcore/normal-mode/normal-move.sml

@@ -108,7 +108,7 @@ struct
     end
 
   fun finishMoveCursorUpDown
-    (app: app_type, newCursorLineNumber, buffer, column) =
+    (app: app_type, newCursorLineNumber, buffer, column, lineIdx) =
     let
       val
         { windowWidth
@@ -121,13 +121,6 @@ struct
         , ...
         } = app
 
-      val buffer = LineGap.goToLine (newCursorLineNumber, buffer)
-      val lineIdx = LineGap.lineNumberToIdx (newCursorLineNumber, buffer)
-      val buffer = LineGap.goToIdx (lineIdx, buffer)
-      val lineIdx =
-        if Cursor.isNextChrEndOfLine (buffer, lineIdx) then lineIdx
-        else lineIdx + 1
-
       val buffer = LineGap.goToIdx (lineIdx, buffer)
       val endOfLineIdx = Cursor.viDlr (buffer, lineIdx, 1)
       val endOfLineIdx =
@@ -200,8 +193,15 @@ struct
           LineGap.idxToLineNumber (cursorIdx, buffer)
       val newCursorLineNumber = Int.max (cursorLineNumber - count, 0)
       val column = if newCursorLineNumber = 0 then column - 1 else column
+
+      val buffer = LineGap.goToLine (newCursorLineNumber, buffer)
+      val lineIdx = LineGap.lineNumberToIdx (newCursorLineNumber, buffer)
+      val buffer = LineGap.goToIdx (lineIdx, buffer)
+      val lineIdx =
+        if Cursor.isNextChrEndOfLine (buffer, lineIdx) then lineIdx
+        else lineIdx + 1
     in
-      finishMoveCursorUpDown (app, newCursorLineNumber, buffer, column)
+      finishMoveCursorUpDown (app, newCursorLineNumber, buffer, column, lineIdx)
     end
 
   fun moveCursorDown (app: app_type, count) =
@@ -236,8 +236,22 @@ struct
           Int.max (0, #lineLength buffer - 1)
         else
           newCursorLineNumber
+
+      val buffer = LineGap.goToLine (newCursorLineNumber, buffer)
+      val lineIdx = LineGap.lineNumberToIdx (newCursorLineNumber, buffer)
+      val buffer = LineGap.goToIdx (lineIdx, buffer)
+      val lineIdx =
+        if lineIdx >= #textLength buffer - 2 then
+          Int.max (0, #textLength buffer - 2)
+        else
+          lineIdx
+      val lineIdx =
+        if Cursor.isNextChrEndOfLine (buffer, lineIdx) then lineIdx
+        else lineIdx + 1
+      val buffer = LineGap.goToIdx (lineIdx, buffer)
+      val lineIdx = Cursor.vi0 (buffer, lineIdx)
     in
-      finishMoveCursorUpDown (app, newCursorLineNumber, buffer, column)
+      finishMoveCursorUpDown (app, newCursorLineNumber, buffer, column, lineIdx)
     end
 
   fun moveToLine (app: app_type, reqLine) =