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"""Base Command class"""
import time
from qtpy import QtCore
from qtpy.QtCore import Qt, Signal
class Command:
"""Mixin interface for commands"""
UNDOABLE = False
def __init__(self):
"""Initialize the base command"""
self.can_undo = False
@staticmethod
def name():
"""Return the command's name"""
return '(undefined)'
@classmethod
def is_undoable(cls):
"""Can this be undone?"""
return cls.UNDOABLE
def do(self):
"""Execute the command"""
self.can_undo = True
return True
def undo(self):
"""Undo the command"""
return self.can_undo
class ContextCommand(Command):
"""Base class for commands that operate on a context"""
def __init__(self, context):
super().__init__()
self.timestamp = time.time()
self.context = context
self.model = context.model
self.cfg = context.cfg
self.git = context.git
self.selection = context.selection
self.fsmonitor = context.fsmonitor
self.old_timestamp = context.timestamp
def do(self):
"""Update the context"""
# Commands can get executed in the background, and completion of one command may
# happen *after* another Diff and similar commands have been fired. We prevent
# the delayed background lookup from overwriting a newer command by checking the
# context's timestamp.
if self.context.timestamp > self.timestamp:
return False
super().do()
self.context.timestamp = self.timestamp
return True
def undo(self):
super().undo()
self.context.timestamp = self.old_timestamp
class CommandBus(QtCore.QObject):
do_command = Signal(object)
undo_command = Signal(object)
def __init__(self, parent=None):
super().__init__(parent)
self.do_command.connect(lambda cmd: cmd.do(), type=Qt.QueuedConnection)
self.undo_command.connect(lambda cmd: cmd.undo(), type=Qt.QueuedConnection)
def do(self, cmd):
"""Run a command on the main thread"""
self.do_command.emit(cmd)
def undo(self, cmd):
"""Undo a command on the main thread"""
self.undo_command.emit(cmd)
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