App exitable argument for Application object

prompt_toolkit/application/__init__.py

@@ -1,4 +1,4 @@
-from .application import Application
+from .application import Application, handle_exit_on_key
 from .current import (
     AppSession,
     create_app_session,
@@ -13,6 +13,7 @@
 __all__ = [
     # Application.
     "Application",
+    "handle_exit_on_key",
     # Current.
     "AppSession",
     "get_app_session",

prompt_toolkit/application/application.py

@@ -118,6 +118,7 @@ class Application(Generic[_AppResult]):
     :param key_bindings:
         :class:`~prompt_toolkit.key_binding.KeyBindingsBase` instance for
         the key bindings.
+    :param exit_on_key: (str|tuple) auto-bind key to exit the application
     :param clipboard: :class:`~prompt_toolkit.clipboard.Clipboard` to use.
     :param on_abort: What to do when Control-C is pressed.
     :param on_exit: What to do when Control-D is pressed.
@@ -195,6 +196,7 @@ def __init__(
         include_default_pygments_style: FilterOrBool = True,
         style_transformation: Optional[StyleTransformation] = None,
         key_bindings: Optional[KeyBindingsBase] = None,
+        exit_on_key: Optional[Union[str, tuple]] = None,
         clipboard: Optional[Clipboard] = None,
         full_screen: bool = False,
         color_depth: Union[
@@ -242,6 +244,8 @@ def __init__(
 
         # Key bindings.
         self.key_bindings = key_bindings
+        self.exit_on_key = (exit_on_key,) if type(exit_on_key) is str else exit_on_key
+        self._merge_exit_key_binding()
         self._default_bindings = load_key_bindings()
         self._page_navigation_bindings = load_page_navigation_bindings()
 
@@ -339,6 +343,20 @@ def __init__(
         # Trigger initialize callback.
         self.reset()
 
+    def _merge_exit_key_binding(self) -> None:
+        if self.exit_on_key is None:
+            return
+
+        kb = KeyBindings()
+        kb.add(*self.exit_on_key)(handle_exit_on_key)
+
+        if self.key_bindings is None:
+            self.key_bindings = kb
+        else:
+            self.key_bindings = merge_key_bindings([kb, self.key_bindings])
+
+        return
+
     def _create_merged_style(self, include_default_pygments_style: Filter) -> BaseStyle:
         """
         Create a `Style` object that merges the default UI style, the default
@@ -1222,3 +1240,11 @@ def attach_winch_signal_handler(
                 previous_winch_handler._callback,
                 *previous_winch_handler._args,
             )
+
+
+def handle_exit_on_key(event: KeyPressEvent) -> None:
+    """
+    Exit application function, to be used with a key binding
+    """
+    event.app.exit()
+    return

tests/test_application.py

@@ -0,0 +1,96 @@
+import pytest
+
+from prompt_toolkit.application import Application, get_app, handle_exit_on_key
+from prompt_toolkit.application.current import set_app
+from prompt_toolkit.key_binding.key_bindings import KeyBindings, _parse_key
+from prompt_toolkit.keys import Keys
+from test_key_binding import handlers, set_dummy_app
+
+
+def test_exit_on_key_simple():
+    """
+    Setting 'exit_on_key' should create a Binding in 'key_binding'
+    """
+    with set_dummy_app(exit_on_key="c-c"):
+        exit_kb = KeyBindings()
+        exit_kb.add("c-c")(handle_exit_on_key)
+
+        app = get_app()
+
+        assert len(app.key_bindings.bindings) == 1
+
+        app_binding = app.key_bindings.bindings[0]
+        exit_binding = exit_kb.bindings[0]
+
+        assert app_binding.keys == exit_binding.keys
+        assert app_binding.handler == exit_binding.handler
+
+
+def test_without_exit_on_key():
+    """
+    Ommiting 'exit_on_key' should leave 'key_binding' unmodified
+    """
+    kb = KeyBindings()
+
+    @kb.add("c-d")
+    def bind(e):
+        pass
+
+    with set_dummy_app(key_bindings=kb):
+        app = get_app()
+
+        assert app.exit_on_key is None
+        assert len(app.key_bindings.bindings) == 1
+
+        app_binding = app.key_bindings.bindings[0]
+
+        assert app_binding.keys == (_parse_key("c-d"),)
+        assert app_binding.handler == bind
+
+
+def test_exit_on_key_not_override(handlers):
+    """
+    'exit_on_key' should NOT override a 'key_bindings' Binding with same keys
+    """
+    kb = KeyBindings()
+    kb.add("c-c")(handlers.control_c)
+
+    with set_dummy_app(exit_on_key="c-c", key_bindings=kb):
+        app = get_app()
+
+        assert len(app.key_bindings.bindings) == 2
+
+        app_last_binding = app.key_bindings.bindings[-1]
+        key_bindings_arg = kb.bindings[0]
+
+        # The last binding should be the one we passed in the key_bindings arg,
+        # not the one in exit_on_bind
+        assert app_last_binding.keys == key_bindings_arg.keys
+        assert app_last_binding.handler == key_bindings_arg.handler
+
+
+def test_exit_on_key_mixed_bindings():
+    """
+    'exit_on_key' should not interfere with other 'key_bindings' Bindings
+    """
+    kb = KeyBindings()
+
+    @kb.add("c-d")
+    def bind_c_d(event):
+        pass
+
+    @kb.add("s-tab")
+    def bind_s_tab(event):
+        pass
+
+    with set_dummy_app(exit_on_key="c-c", key_bindings=kb):
+        app = get_app()
+
+        binding_tuples = [
+            (binding.keys, binding.handler) for binding in app.key_bindings.bindings
+        ]
+
+        assert len(binding_tuples) == 3
+        assert ((_parse_key("c-c"),), handle_exit_on_key) in binding_tuples
+        assert ((_parse_key("c-d"),), bind_c_d) in binding_tuples
+        assert ((_parse_key("s-tab"),), bind_s_tab) in binding_tuples

tests/test_key_binding.py

@@ -21,14 +21,17 @@ def func(event):
         return func
 
 
-def set_dummy_app():
+def set_dummy_app(**kwargs):
     """
     Return a context manager that makes sure that this dummy application is
     active. This is important, because we need an `Application` with
     `is_done=False` flag, otherwise no keys will be processed.
     """
     app = Application(
-        layout=Layout(Window()), output=DummyOutput(), input=create_pipe_input()
+        layout=Layout(Window()),
+        output=DummyOutput(),
+        input=create_pipe_input(),
+        **kwargs,
     )
     return set_app(app)