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# (C) Copyright 2008-2023 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
# ------------------------------------------------------------------------------
# Copyright (c) 2008, Riverbank Computing Limited
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in enthought/LICENSE.txt and may be redistributed only
# under the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
# Thanks for using Enthought open source!
#
# Author: Riverbank Computing Limited
# Description: <Enthought undo package component>
# ------------------------------------------------------------------------------
# Enthought library imports.
from traits.api import (
Bool,
Event,
HasTraits,
Instance,
Int,
Property,
Str,
provides,
observe,
)
# Local imports.
from .i_undo_manager import IUndoManager
@provides(IUndoManager)
class UndoManager(HasTraits):
"""The UndoManager class is the default implementation of the
IUndoManager interface.
"""
#### 'IUndoManager' interface #############################################
#: This is the currently active command stack and may be None. Typically it
#: is set when some sort of editor becomes active.
active_stack = Instance("pyface.undo.api.ICommandStack")
#: This reflects the clean state of the currently active command stack. It
#: is intended to support a "document modified" indicator in the GUI. It is
#: maintained by the undo manager.
active_stack_clean = Property(Bool)
#: This is the name of the command that can be redone. It will be empty if
#: there is no command that can be redone. It is maintained by the undo
#: manager.
redo_name = Property(Str)
#: This is the sequence number of the next command to be performed. It is
#: incremented immediately before a command is invoked (by its 'do()'
#: method).
sequence_nr = Int()
#: This event is fired when the index of a command stack changes. The value
#: of the event is the stack that has changed. Note that it may not be the
#: active stack.
stack_updated = Event()
#: This is the name of the command that can be undone. It will be empty if
#: there is no command that can be undone. It is maintained by the undo
#: manager.
undo_name = Property(Str)
###########################################################################
# 'IUndoManager' interface.
###########################################################################
def redo(self):
""" Redo the last undone command of the active command stack. """
if self.active_stack is not None:
self.active_stack.redo()
def undo(self):
""" Undo the last command of the active command stack. """
if self.active_stack is not None:
self.active_stack.undo()
###########################################################################
# Private interface.
###########################################################################
@observe("active_stack")
def _update_stack_updated(self, event):
""" Handle a different stack becoming active. """
new = event.new
# Pretend that the stack contents have changed.
self.stack_updated = new
def _get_active_stack_clean(self):
""" Get the current clean state. """
if self.active_stack is None:
active_stack_clean = True
else:
active_stack_clean = self.active_stack.clean
return active_stack_clean
def _get_redo_name(self):
""" Get the current redo name. """
if self.active_stack is None:
redo_name = ""
else:
redo_name = self.active_stack.redo_name
return redo_name
def _get_undo_name(self):
""" Get the current undo name. """
if self.active_stack is None:
undo_name = ""
else:
undo_name = self.active_stack.undo_name
return undo_name
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