fix 'Cursor.getLineStartIdx' function, which should look at the left nodes if there is no relevant line in this node

fcore/cursor.sml

@@ -1125,22 +1125,46 @@ struct
   (* Prerequisite: move lineGap to reqLine *)
   fun getLineStartIdx (lineGap: LineGap.t, reqLine) =
     let
-      val {rightStrings, rightLines, line = bufferLine, idx = bufferIdx, ...} =
-        lineGap
+      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
-            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
+            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
-              bufferIdx + lineIdx + 1
+              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 + 1
+              end
           end
       | (_, _) =>
           (* reqLine does not exist in lineGap, so just go to start of last line *)

fcore/normal-mode/normal-mode.sml

@@ -192,7 +192,7 @@ struct
          * interpret as "go to line" command;
          * else, interpret as a command to move to end *)
         if String.size str = 0 then NormalMove.moveToEnd app
-        else NormalMove.moveToLine (app, count - 1)
+        else NormalMove.moveToLine (app, count)
     | #"%" => NormalMove.moveToMatchingPair app
     | #"x" => NormalDelete.removeChr (app, count, time)
     | #"J" => NormalDelete.removeLineBreaks (app, count, time)

fcore/normal-mode/normal-move.sml

@@ -107,65 +107,69 @@ struct
     end
 
   fun moveToLine (app: app_type, reqLine) =
-    if reqLine = 0 then
-      moveToStart app
-    else
-      let
-        val
-          { windowWidth
-          , windowHeight
-          , buffer
-          , startLine = prevLineNumber
-          , searchList
-          , searchString
-          , bufferModifyTime
-          , visualScrollColumn = prevScrollColumn
-          , ...
-          } = app
-        val buffer = LineGap.goToLine (reqLine, buffer)
+    let
+      val reqLine = reqLine - 1
+    in
+      if reqLine = 0 then
+        moveToStart app
+      else
+        let
+          val
+            { windowWidth
+            , windowHeight
+            , buffer
+            , startLine = prevLineNumber
+            , searchList
+            , searchString
+            , bufferModifyTime
+            , visualScrollColumn = prevScrollColumn
+            , ...
+            } = app
+          val buffer = LineGap.goToLine (reqLine, buffer)
 
-        (* get idx of first chr after linebreak *)
-        val cursorIdx = Cursor.getLineStartIdx (buffer, reqLine)
+          (* get idx of first chr after linebreak *)
+          val cursorIdx = Cursor.getLineStartIdx (buffer, reqLine)
 
-        val buffer = LineGap.goToIdx (cursorIdx, buffer)
-        val visualScrollColumn =
-          TextScroll.getScrollColumn
-            (buffer, cursorIdx, windowWidth, prevScrollColumn)
+          val buffer = LineGap.goToIdx (cursorIdx, buffer)
+          val visualScrollColumn =
+            TextScroll.getScrollColumn
+              (buffer, cursorIdx, windowWidth, prevScrollColumn)
 
-        val cursorLine = LineGap.getLineNumberOfIdx (cursorIdx, buffer)
-        val startLine =
-          TextScroll.getStartLine (prevLineNumber, cursorLine, windowHeight)
+          val cursorLine = LineGap.getLineNumberOfIdx (cursorIdx, buffer)
+          val startLine =
+            TextScroll.getStartLine (prevLineNumber, cursorLine, windowHeight)
 
-        val buffer = LineGap.goToLine (startLine, buffer)
+          val buffer = LineGap.goToLine (startLine, buffer)
 
-        val drawMsg = NormalModeTextBuilder.build
-          ( startLine
-          , cursorIdx
-          , buffer
-          , windowWidth
-          , windowHeight
-          , searchList
-          , searchString
-          , visualScrollColumn
-          )
-        val drawMsg = Vector.concat drawMsg
-        val drawMsg = DrawMsg.DRAW_TEXT drawMsg
-        val drawMsg = [MailboxType.DRAW drawMsg]
+          val drawMsg = NormalModeTextBuilder.build
+            ( startLine
+            , cursorIdx
+            , buffer
+            , windowWidth
+            , windowHeight
+            , searchList
+            , searchString
+            , visualScrollColumn
+            )
+          val drawMsg = Vector.concat drawMsg
+          val drawMsg = DrawMsg.DRAW_TEXT drawMsg
+          val drawMsg = [MailboxType.DRAW drawMsg]
 
-        val mode = NORMAL_MODE ""
-      in
-        NormalModeWith.bufferAndCursorIdx
-          ( app
-          , buffer
-          , cursorIdx
-          , mode
-          , startLine
-          , searchList
-          , drawMsg
-          , bufferModifyTime
-          , visualScrollColumn
-          )
-      end
+          val mode = NORMAL_MODE ""
+        in
+          NormalModeWith.bufferAndCursorIdx
+            ( app
+            , buffer
+            , cursorIdx
+            , mode
+            , startLine
+            , searchList
+            , drawMsg
+            , bufferModifyTime
+            , visualScrollColumn
+            )
+        end
+    end
 
   fun moveToMatchingPair (app: app_type) =
     let