bugfix in flush key

1. only invalidate ui when some keys are processed 2. do not start_timeout if the last key is _Flush, otherwise it causes a dead loop 3. only send flush key when the queue is not empty

Author: randy3k

prompt_toolkit/key_binding/key_processor.py

@@ -283,11 +283,19 @@ def get_next():
  else:
  return self.input_queue.popleft()
 
+ keys_processed = False
+ is_flush = False
+
  while not_empty():
+ keys_processed = True
+
  # Process next key.
  key_press = get_next()
 
- if key_press.key != Keys.CPRResponse:
+ is_flush = key_press is _Flush
+ is_cpr = key_press.key == Keys.CPRResponse
+
+ if not is_flush and not is_cpr:
  self.before_key_press.fire()
 
  try:
@@ -300,13 +308,16 @@ def get_next():
  app.invalidate()
  raise
 
- if key_press.key != Keys.CPRResponse:
+ if not is_flush and not is_cpr:
  self.after_key_press.fire()
 
- # Invalidate user interface.
- app.invalidate()
+ if keys_processed:
+ # Invalidate user interface.
+ app.invalidate()
 
- self._start_timeout()
+ # skip timeout if the last key was flush
+ if not is_flush:
+ self._start_timeout()
 
  def empty_queue(self):
  """
@@ -387,7 +398,7 @@ def wait():
  " Wait for timeout. "
  time.sleep(self.timeout)
 
- if counter == self._keys_pressed:
+ if len(self.input_queue) > 0 and counter == self._keys_pressed:
  # (No keys pressed in the meantime.)
  call_from_executor(flush_keys)