166 lines
4.9 KiB
Python
166 lines
4.9 KiB
Python
import sys
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from contextlib import contextmanager
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from typing import TYPE_CHECKING, Any, Generator, Optional
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try:
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from contextvars import ContextVar
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except ImportError:
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from prompt_toolkit.eventloop.dummy_contextvars import ContextVar # type: ignore
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if TYPE_CHECKING:
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from .application import Application
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from prompt_toolkit.input.defaults import Input
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from prompt_toolkit.output.defaults import Output
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__all__ = [
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"get_app_session",
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"get_app",
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"get_app_or_none",
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"set_app",
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"create_app_session",
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]
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class AppSession:
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"""
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An AppSession is an interactive session, usually connected to one terminal.
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Within one such session, interaction with many applications can happen, one
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after the other.
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The input/output device is not supposed to change during one session.
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:param input: Use this as a default input for all applications
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running in this session, unless an input is passed to the `Application`
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explicitely.
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:param output: Use this as a default output.
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"""
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def __init__(
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self, input: Optional["Input"] = None, output: Optional["Output"] = None
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) -> None:
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self._input = input
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self._output = output
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# The application will be set dynamically by the `set_app` context
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# manager. This is called in the application itself.
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self.app: Optional["Application[Any]"] = None
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def __repr__(self) -> str:
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return "AppSession(app=%r)" % (self.app,)
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@property
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def input(self) -> "Input":
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if self._input is None:
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from prompt_toolkit.input.defaults import create_input
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self._input = create_input()
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return self._input
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@property
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def output(self) -> "Output":
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if self._output is None:
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from prompt_toolkit.output.defaults import create_output
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self._output = create_output()
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return self._output
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_current_app_session: ContextVar["AppSession"] = ContextVar(
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"_current_app_session", default=AppSession()
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)
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def get_app_session() -> AppSession:
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return _current_app_session.get()
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def get_app() -> "Application[Any]":
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"""
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Get the current active (running) Application.
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An :class:`.Application` is active during the
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:meth:`.Application.run_async` call.
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We assume that there can only be one :class:`.Application` active at the
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same time. There is only one terminal window, with only one stdin and
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stdout. This makes the code significantly easier than passing around the
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:class:`.Application` everywhere.
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If no :class:`.Application` is running, then return by default a
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:class:`.DummyApplication`. For practical reasons, we prefer to not raise
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an exception. This way, we don't have to check all over the place whether
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an actual `Application` was returned.
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(For applications like pymux where we can have more than one `Application`,
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we'll use a work-around to handle that.)
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"""
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session = _current_app_session.get()
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if session.app is not None:
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return session.app
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from .dummy import DummyApplication
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return DummyApplication()
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def get_app_or_none() -> Optional["Application[Any]"]:
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"""
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Get the current active (running) Application, or return `None` if no
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application is running.
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"""
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session = _current_app_session.get()
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return session.app
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@contextmanager
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def set_app(app: "Application[Any]") -> Generator[None, None, None]:
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"""
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Context manager that sets the given :class:`.Application` active in an
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`AppSession`.
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This should only be called by the `Application` itself.
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The application will automatically be active while its running. If you want
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the application to be active in other threads/coroutines, where that's not
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the case, use `contextvars.copy_context()`, or use `Application.context` to
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run it in the appropriate context.
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"""
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session = _current_app_session.get()
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previous_app = session.app
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session.app = app
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try:
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yield
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finally:
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session.app = previous_app
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@contextmanager
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def create_app_session(
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input: Optional["Input"] = None, output: Optional["Output"] = None
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) -> Generator[AppSession, None, None]:
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"""
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Create a separate AppSession.
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This is useful if there can be multiple individual `AppSession`s going on.
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Like in the case of an Telnet/SSH server. This functionality uses
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contextvars and requires at least Python 3.7.
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"""
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if sys.version_info <= (3, 6):
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raise RuntimeError("Application sessions require Python 3.7.")
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# If no input/output is specified, fall back to the current input/output,
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# whatever that is.
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if input is None:
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input = get_app_session().input
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if output is None:
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output = get_app_session().output
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# Create new `AppSession` and activate.
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session = AppSession(input=input, output=output)
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token = _current_app_session.set(session)
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try:
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yield session
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finally:
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_current_app_session.reset(token)
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