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#------------------------------------------------------------------------------
# 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>
#------------------------------------------------------------------------------
from __future__ import absolute_import
# Enthought library imports.
from traits.api import Bool, Event, HasTraits, Instance, Int, Property, \
Unicode, provides
# 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('apptools.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(Unicode)
# 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(Unicode)
###########################################################################
# '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.
###########################################################################
def _active_stack_changed(self, new):
""" Handle a different stack becoming active. """
# 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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