implement additional non-terminal yank commands

fcore/normal-mode/normal-mode.sml

@@ -280,7 +280,18 @@ struct
       parseYankTerminal (str, count, app, chrCmd, time)
     else
       (* todo: handle non-terminal characters *)
-      app
+      case String.sub (str, strPos + 1) of
+        #"t" => NormalYank.yankToChr (app, 1, Cursor.tillNextChr, op+, chrCmd)
+      | #"T" => NormalYank.yankToChr (app, 1, Cursor.tillPrevChr, op-, chrCmd)
+      | #"f" => NormalYank.yankToChr (app, count, Cursor.toNextChr, op+, chrCmd)
+      | #"F" => NormalYank.yankToChr (app, count, Cursor.toPrevChr, op-, chrCmd)
+      (* todo: implement
+        | #"g" => 
+        | #"i" => 
+        | #"a" => 
+        | #"d" => 
+      *)
+      | _ => NormalFinish.clearMode app
 
   (* useful reference as list of non-terminal commands *)
   fun parseAfterCount (strPos, str, count, app, chrCmd, time) =

fcore/normal-mode/normal-yank.sml

@@ -188,4 +188,42 @@ struct
           NormalModeWith.modeAndBuffer (app, buffer, mode, [DRAW msg])
         end
     end
+
+  fun helpYankToChr
+    (app: app_type, buffer, cursorIdx, otherIdx, count, fMove, fInc, chr) =
+    if count = 0 then
+      let
+        val low = Int.min (cursorIdx, otherIdx)
+        val high = Int.max (cursorIdx, otherIdx)
+        val length = high - low
+
+        val buffer = LineGap.goToIdx (high, buffer)
+        val str = LineGap.substring (low, length, buffer)
+        val msg = YANK str
+        val mode = NORMAL_MODE ""
+      in
+        NormalModeWith.modeAndBuffer (app, buffer, mode, [DRAW msg])
+      end
+    else
+      let
+        val buffer = LineGap.goToIdx (otherIdx, buffer)
+        val newOtherIdx = fMove (buffer, otherIdx, chr)
+        val newCount = if newOtherIdx = otherIdx then 0 else count - 1
+        val newOtherIdx = fInc (newOtherIdx, 1)
+      in
+        helpYankToChr
+          (app, buffer, cursorIdx, newOtherIdx, newCount, fMove, fInc, chr)
+      end
+
+  fun yankToChr (app: app_type, count, fMove, fInc, chr) =
+    helpYankToChr
+      ( app
+      , #buffer app
+      , #cursorIdx app
+      , #cursorIdx app
+      , count
+      , fMove
+      , fInc
+      , chr
+      )
 end