diff options
Diffstat (limited to 'src/prompt_toolkit/application/current.py')
| -rw-r--r-- | src/prompt_toolkit/application/current.py | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/src/prompt_toolkit/application/current.py b/src/prompt_toolkit/application/current.py new file mode 100644 index 0000000..908141a --- /dev/null +++ b/src/prompt_toolkit/application/current.py @@ -0,0 +1,189 @@ +from __future__ import annotations + +from contextlib import contextmanager +from contextvars import ContextVar +from typing import TYPE_CHECKING, Any, Generator + +if TYPE_CHECKING: + from prompt_toolkit.input.base import Input + from prompt_toolkit.output.base import Output + + from .application import Application + +__all__ = [ + "AppSession", + "get_app_session", + "get_app", + "get_app_or_none", + "set_app", + "create_app_session", + "create_app_session_from_tty", +] + + +class AppSession: + """ + An AppSession is an interactive session, usually connected to one terminal. + Within one such session, interaction with many applications can happen, one + after the other. + + The input/output device is not supposed to change during one session. + + Warning: Always use the `create_app_session` function to create an + instance, so that it gets activated correctly. + + :param input: Use this as a default input for all applications + running in this session, unless an input is passed to the `Application` + explicitly. + :param output: Use this as a default output. + """ + + def __init__( + self, input: Input | None = None, output: Output | None = None + ) -> None: + self._input = input + self._output = output + + # The application will be set dynamically by the `set_app` context + # manager. This is called in the application itself. + self.app: Application[Any] | None = None + + def __repr__(self) -> str: + return f"AppSession(app={self.app!r})" + + @property + def input(self) -> Input: + if self._input is None: + from prompt_toolkit.input.defaults import create_input + + self._input = create_input() + return self._input + + @property + def output(self) -> Output: + if self._output is None: + from prompt_toolkit.output.defaults import create_output + + self._output = create_output() + return self._output + + +_current_app_session: ContextVar[AppSession] = ContextVar( + "_current_app_session", default=AppSession() +) + + +def get_app_session() -> AppSession: + return _current_app_session.get() + + +def get_app() -> Application[Any]: + """ + Get the current active (running) Application. + An :class:`.Application` is active during the + :meth:`.Application.run_async` call. + + We assume that there can only be one :class:`.Application` active at the + same time. There is only one terminal window, with only one stdin and + stdout. This makes the code significantly easier than passing around the + :class:`.Application` everywhere. + + If no :class:`.Application` is running, then return by default a + :class:`.DummyApplication`. For practical reasons, we prefer to not raise + an exception. This way, we don't have to check all over the place whether + an actual `Application` was returned. + + (For applications like pymux where we can have more than one `Application`, + we'll use a work-around to handle that.) + """ + session = _current_app_session.get() + if session.app is not None: + return session.app + + from .dummy import DummyApplication + + return DummyApplication() + + +def get_app_or_none() -> Application[Any] | None: + """ + Get the current active (running) Application, or return `None` if no + application is running. + """ + session = _current_app_session.get() + return session.app + + +@contextmanager +def set_app(app: Application[Any]) -> Generator[None, None, None]: + """ + Context manager that sets the given :class:`.Application` active in an + `AppSession`. + + This should only be called by the `Application` itself. + The application will automatically be active while its running. If you want + the application to be active in other threads/coroutines, where that's not + the case, use `contextvars.copy_context()`, or use `Application.context` to + run it in the appropriate context. + """ + session = _current_app_session.get() + + previous_app = session.app + session.app = app + try: + yield + finally: + session.app = previous_app + + +@contextmanager +def create_app_session( + input: Input | None = None, output: Output | None = None +) -> Generator[AppSession, None, None]: + """ + Create a separate AppSession. + + This is useful if there can be multiple individual `AppSession`s going on. + Like in the case of an Telnet/SSH server. + """ + # If no input/output is specified, fall back to the current input/output, + # whatever that is. + if input is None: + input = get_app_session().input + if output is None: + output = get_app_session().output + + # Create new `AppSession` and activate. + session = AppSession(input=input, output=output) + + token = _current_app_session.set(session) + try: + yield session + finally: + _current_app_session.reset(token) + + +@contextmanager +def create_app_session_from_tty() -> Generator[AppSession, None, None]: + """ + Create `AppSession` that always prefers the TTY input/output. + + Even if `sys.stdin` and `sys.stdout` are connected to input/output pipes, + this will still use the terminal for interaction (because `sys.stderr` is + still connected to the terminal). + + Usage:: + + from prompt_toolkit.shortcuts import prompt + + with create_app_session_from_tty(): + prompt('>') + """ + from prompt_toolkit.input.defaults import create_input + from prompt_toolkit.output.defaults import create_output + + input = create_input(always_prefer_tty=True) + output = create_output(always_prefer_tty=True) + + with create_app_session(input=input, output=output) as app_session: + yield app_session |