[+] improve vim, beta

1. add filter callback;
  1.1. partially
    added recording of pressed keys;
  1.2. TODO,
    handle esape to close the window;
    handle to select the entry;
    handle hjkl, arrows
    to change the selection;
    handle pressed keys otherwise, ideally
    after i has been pressed,
    or handle hjkl after escape has been presed;
    to restrict entries to the matching pattern
    visualize current filter, and ins/normal mode
    in the popup title;

dotfiles/.vim/online_fxreader_pr34_vim/beta.py

@@ -44,6 +44,8 @@ class FastSelect:
 		self._buffer_frequency : dict[int, int] = dict()
 		self._buffer_last_used : dict[int, int] = dict()
 
+		self._filter_pattern : Optional[str] = None
+
 		self._queue : collections.deque[Callable[[], None]] = collections.deque()
 		self._lock = threading.Lock()
 
@@ -160,6 +162,8 @@ augroup END
 	) -> Optional[int]:
 		logger.info(dict(msg='started'))
 
+		self._filter_pattern = ''
+
 		self._options = options
 
 		self._option_id = asyncio.Future[int]()
@@ -209,6 +213,22 @@ augroup END
 
 		result.add_done_callback(future_dump_exception)
 
+	def on_filter_key(self, key: str) -> None:
+		logger.info(dict(msg='got key', key=key))
+
+		try:
+			key_str = key.decode('utf-8')
+		except:
+			return 0
+
+		if not key_str.isprintable():
+			return 0
+
+		with self._lock:
+			self._filter_pattern += key_str
+
+		return 1
+
 	async def _on_buf_enter(
 		self,
 		buf_number: int,
@@ -242,6 +262,12 @@ augroup END
 			'popup_callback',
 		).capitalize()
 
+		filter_name = '{}_{}_{}'.format(
+			MODULE_NAME,
+			type(self).__name__.lower(),
+			'popup_filter',
+		).capitalize()
+
 		if int(vim.eval('exists("{}")'.format(callback_name))) == 1:
 			logger.warning(dict(msg='callback already defined, %s' % callback_name))
 
@@ -257,6 +283,14 @@ augroup END
 			callback_name=callback_name,
 		))
 
+		vim.command(r"""
+			function! {filter_name}(win_id, key)
+				return py3eval('online_fxreader_pr34_vim.beta.FastSelect.singleton().on_filter_key(key)', #{key: a:key})
+			endfunction
+		""".replace(
+			'{filter_name}', filter_name,
+		))
+
 		logger.info(dict(msg='before popup'))
 
 		popup_menu = vim.Function('popup_menu')
@@ -268,6 +302,7 @@ augroup END
 					{
 						'title': 'Select a file',
 						'callback': callback_name,
+						'filter': filter_name,
 						'wrap': 1,
 						'maxwidth': 80,
 						'close': 'button',