reimplement 'yt<char>' motion to use 'Cursor.toNextChr'

fcore/normal-mode/normal-mode.sml

@@ -529,7 +529,7 @@ struct
         parseYankTerminal (str, count, app, chrCmd, time)
       else
         case String.sub (str, strPos + 1) of
-          #"t" => NormalYank.yankToChr (app, 1, Cursor.tillNextChr, op+, chrCmd)
+          #"t" => NormalYank.yankTillNextChr (app, count, chrCmd)
         | #"T" => NormalYank.yankToChr (app, 1, Cursor.tillPrevChr, op-, chrCmd)
         | #"f" => NormalYank.yankToNextChr (app, count, chrCmd)
         | #"F" =>

fcore/normal-mode/normal-yank.sml

@@ -251,6 +251,27 @@ struct
         end
     end
 
+  fun yankTillNextChr (app: app_type, count, chr) =
+    let
+      val {buffer, cursorIdx, ...} = app
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val newCursorIdx =
+        Cursor.toNextChr (buffer, cursorIdx, {findChr = chr, count = count})
+    in
+      if newCursorIdx = ~1 then
+        NormalFinish.clearMode app
+      else
+        let
+          val length = newCursorIdx - cursorIdx
+          val buffer = LineGap.goToIdx (newCursorIdx, buffer)
+          val str = LineGap.substring (cursorIdx, length, buffer)
+          val msg = YANK str
+          val mode = NORMAL_MODE ""
+        in
+          NormalModeWith.modeAndBuffer (app, buffer, mode, [DRAW msg])
+        end
+    end
+
   fun yankToChr (app: app_type, count, fMove, fInc, chr) =
     helpYankToChr
       ( app