Mini Shell

# -*- coding: utf-8 -*-

# slip.dbus.mainloop -- mainloop wrappers
#
# Copyright © 2009, 2012 Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Authors:
# Nils Philippsen <nils@redhat.com>

"""This module contains mainloop wrappers.

Currently only glib main loops are supported."""

from __future__ import absolute_import

__all__ = ("MainLoop", "set_type")


class MainLoop(object):
    """An abstract main loop wrapper class and factory.

    Use MainLoop() to get a main loop wrapper object for a main loop type
    previously registered with set_type(). Defaults to glib main loops.

    Actual main loop wrapper classes are derived from this class."""

    __mainloop_class = None

    def __new__(cls, *args, **kwargs):
        global _mainloop_class
        if MainLoop._mainloop_class is None:
            MainLoop.set_type("glib")
        return super(MainLoop, cls).__new__(
            MainLoop.__mainloop_class, *args, **kwargs)

    @classmethod
    def set_type(cls, mltype):
        """Set a main loop type for non-blocking interfaces.

        mltype: "glib" (currently only glib main loops are supported)"""

        if MainLoop.__mainloop_class is not None:
            raise RuntimeError("The main loop type can only be set once.")

        ml_type_class = {"glib": GlibMainLoop}

        if mltype in ml_type_class:
            MainLoop.__mainloop_class = ml_type_class[mltype]
        else:
            raise ValueError(
                "'%s' is not one of the valid main loop types:\n%s" %
                (mltype, ", ".join(ml_type_class)))

    def pending(self):
        """Returns if there are pending events."""

        raise NotImplementedError()

    def iterate(self):
        """Iterates over one pending event."""

        raise NotImplementedError()

    def iterate_over_pending_events(self):
        """Iterates over all pending events."""

        while self.pending():
            self.iterate()

    def run(self):
        """Runs the main loop."""

        raise NotImplementedError()

    def quit(self):
        """Quits the main loop."""

        raise NotImplementedError()


class GlibMainLoop(MainLoop):

    def __init__(self):
        from .._wrappers import _glib
        ml = _glib.MainLoop()
        ctx = ml.get_context()

        self._mainloop = ml
        self.pending = ctx.pending
        self.iterate = ctx.iteration
        self.run = ml.run
        self.quit = ml.quit


def set_type(mltype):
    """Set a main loop type for non-blocking interfaces.

    mltype: "glib" (currently only glib main loops are supported)

    Deprecated, use MainLoop.set_type() instead."""

    from warnings import warn

    warn("use MainLoop.set_type() instead", DeprecationWarning)

    MainLoop.set_type(mltype)