/usr/lib/python2.7/dist-packages/traitsui/undo.py is in python-traitsui 4.5.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
# Copyright (c) 2005, Enthought, Inc.
# 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: David C. Morrill
# Date: 10/07/2004
#
#------------------------------------------------------------------------------
""" Defines the manager for Undo and Redo history for Traits user interface
support.
"""
#-------------------------------------------------------------------------------
# Imports:
#-------------------------------------------------------------------------------
from __future__ import absolute_import
from operator import isSequenceType
from traits.api import (Event, HasPrivateTraits, HasStrictTraits, HasTraits,
Instance, Int, List, Property, Str, Trait)
from traits.trait_base import enumerate
#-------------------------------------------------------------------------------
# Constants:
#-------------------------------------------------------------------------------
NumericTypes = ( int, long, float, complex )
SimpleTypes = ( str, unicode, int, long, float, complex )
#-------------------------------------------------------------------------------
# 'AbstractUndoItem' class:
#-------------------------------------------------------------------------------
class AbstractUndoItem ( HasPrivateTraits ):
""" Abstract base class for undo items.
"""
#---------------------------------------------------------------------------
# Undoes the change:
#---------------------------------------------------------------------------
def undo ( self ):
""" Undoes the change.
"""
raise NotImplementedError
#---------------------------------------------------------------------------
# Re-does the change:
#---------------------------------------------------------------------------
def redo ( self ):
""" Re-does the change.
"""
raise NotImplementedError
#---------------------------------------------------------------------------
# Merges two undo items if possible:
#---------------------------------------------------------------------------
def merge_undo ( self, undo_item ):
""" Merges two undo items if possible.
"""
return False
#-------------------------------------------------------------------------------
# 'UndoItem' class:
#-------------------------------------------------------------------------------
class UndoItem ( AbstractUndoItem ):
""" A change to an object trait, which can be undone.
"""
#---------------------------------------------------------------------------
# Trait definitions:
#---------------------------------------------------------------------------
# Object the change occurred on
object = Trait( HasTraits )
# Name of the trait that changed
name = Str
# Old value of the changed trait
old_value = Property
# New value of the changed trait
new_value = Property
#---------------------------------------------------------------------------
# Implementation of the 'old_value' and 'new_value' properties:
#---------------------------------------------------------------------------
def _get_old_value ( self ):
return self._old_value
def _set_old_value ( self, value ):
if isinstance( value, list ):
value = value[:]
self._old_value = value
def _get_new_value ( self ):
return self._new_value
def _set_new_value ( self, value ):
if isinstance( value, list ):
value = value[:]
self._new_value = value
#---------------------------------------------------------------------------
# Undoes the change:
#---------------------------------------------------------------------------
def undo ( self ):
""" Undoes the change.
"""
try:
setattr( self.object, self.name, self.old_value )
except:
pass
#---------------------------------------------------------------------------
# Re-does the change:
#---------------------------------------------------------------------------
def redo ( self ):
""" Re-does the change.
"""
try:
setattr( self.object, self.name, self.new_value )
except:
pass
#---------------------------------------------------------------------------
# Merges two undo items if possible:
#---------------------------------------------------------------------------
def merge_undo ( self, undo_item ):
""" Merges two undo items if possible.
"""
# Undo items are potentially mergeable only if they are of the same
# class and refer to the same object trait, so check that first:
if (isinstance( undo_item, self.__class__ ) and
(self.object is undo_item.object) and
(self.name == undo_item.name)):
v1 = self.new_value
v2 = undo_item.new_value
t1 = type( v1 )
if t1 is type( v2 ):
if isinstance(t1, basestring):
# Merge two undo items if they have new values which are
# strings which only differ by one character (corresponding
# to a single character insertion, deletion or replacement
# operation in a text editor):
n1 = len( v1 )
n2 = len( v2 )
n = min( n1, n2 )
i = 0
while (i < n) and (v1[i] == v2[i]):
i += 1
if v1[i + (n2 <= n1):] == v2[i + (n2 >= n1):]:
self.new_value = v2
return True
elif isSequenceType( v1 ):
# Merge sequence types only if a single element has changed
# from the 'original' value, and the element type is a
# simple Python type:
v1 = self.old_value
if isSequenceType( v1 ):
# Note: wxColour says it's a sequence type, but it
# doesn't support 'len', so we handle the exception
# just in case other classes have similar behavior:
try:
if len( v1 ) == len( v2 ):
diffs = 0
for i, item in enumerate( v1 ):
titem = type( item )
item2 = v2[i]
if ((titem not in SimpleTypes) or
(titem is not type( item2 )) or
(item != item2)):
diffs += 1
if diffs >= 2:
return False
if diffs == 0:
return False
self.new_value = v2
return True
except:
pass
elif t1 in NumericTypes:
# Always merge simple numeric trait changes:
self.new_value = v2
return True
return False
#---------------------------------------------------------------------------
# Returns a 'pretty print' form of the object:
#---------------------------------------------------------------------------
def __repr__ ( self ):
""" Returns a "pretty print" form of the object.
"""
n = self.name
cn = self.object.__class__.__name__
return 'undo( %s.%s = %s )\nredo( %s.%s = %s )' % (
cn, n, self.old_value, cn, n, self.new_value )
#-------------------------------------------------------------------------------
# 'ListUndoItem' class:
#-------------------------------------------------------------------------------
class ListUndoItem ( AbstractUndoItem ):
""" A change to a list, which can be undone.
"""
#---------------------------------------------------------------------------
# Trait definitions:
#---------------------------------------------------------------------------
# Object that the change occurred on
object = Trait( HasTraits )
# Name of the trait that changed
name = Str
# Starting index
index = Int
# Items added to the list
added = List
# Items removed from the list
removed = List
#---------------------------------------------------------------------------
# Undoes the change:
#---------------------------------------------------------------------------
def undo ( self ):
""" Undoes the change.
"""
try:
list = getattr( self.object, self.name )
list[ self.index: (self.index + len( self.added )) ] = self.removed
except:
pass
#---------------------------------------------------------------------------
# Re-does the change:
#---------------------------------------------------------------------------
def redo ( self ):
""" Re-does the change.
"""
try:
list = getattr( self.object, self.name )
list[ self.index: (self.index + len( self.removed )) ] = self.added
except:
pass
#---------------------------------------------------------------------------
# Merges two undo items if possible:
#---------------------------------------------------------------------------
def merge_undo ( self, undo_item ):
""" Merges two undo items if possible.
"""
# Discard undo items that are identical to us. This is to eliminate
# the same undo item being created by multiple listeners monitoring the
# same list for changes:
if (isinstance( undo_item, self.__class__ ) and
(self.object is undo_item.object) and
(self.name == undo_item.name) and
(self.index == undo_item.index)):
added = undo_item.added
removed = undo_item.removed
if ((len( self.added ) == len( added )) and
(len( self.removed ) == len( removed ))):
for i, item in enumerate( self.added ):
if item is not added[i]:
break
else:
for i, item in enumerate( self.removed ):
if item is not removed[i]:
break
else:
return True
return False
#---------------------------------------------------------------------------
# Returns a 'pretty print' form of the object:
#---------------------------------------------------------------------------
def __repr__ ( self ):
""" Returns a 'pretty print' form of the object.
"""
return 'undo( %s.%s[%d:%d] = %s )' % (
self.object.__class__.__name__, self.name, self.index,
self.index + len( self.removed ), self.added )
#-------------------------------------------------------------------------------
# 'UndoHistory' class:
#-------------------------------------------------------------------------------
class UndoHistory ( HasStrictTraits ):
""" Manages a list of undoable changes.
"""
#---------------------------------------------------------------------------
# Trait definitions:
#---------------------------------------------------------------------------
# List of accumulated undo changes
history = List
# The current position in the list
now = Int
# Fired when state changes to undoable
undoable = Event( False )
# Fired when state changes to redoable
redoable = Event( False )
# Can an action be undone?
can_undo = Property
# Can an action be redone?
can_redo = Property
#---------------------------------------------------------------------------
# Adds an UndoItem to the history:
#---------------------------------------------------------------------------
def add ( self, undo_item, extend = False ):
""" Adds an UndoItem to the history.
"""
if extend:
self.extend( undo_item )
return
# Try to merge the new undo item with the previous item if allowed:
now = self.now
if now > 0:
previous = self.history[ now - 1 ]
if (len( previous ) == 1) and previous[0].merge_undo( undo_item ):
self.history[ now: ] = []
return
old_len = len( self.history )
self.history[ now: ] = [ [ undo_item ] ]
self.now += 1
if self.now == 1:
self.undoable = True
if self.now <= old_len:
self.redoable = False
#---------------------------------------------------------------------------
# Extends the most recent 'undo' item:
#---------------------------------------------------------------------------
def extend ( self, undo_item ):
""" Extends the undo history.
If possible the method merges the new UndoItem with the last item in
the history; otherwise, it appends the new item.
"""
if self.now > 0:
undo_list = self.history[ self.now - 1 ]
if not undo_list[-1].merge_undo( undo_item ):
undo_list.append( undo_item )
#---------------------------------------------------------------------------
# Undo an operation:
#---------------------------------------------------------------------------
def undo ( self ):
""" Undoes an operation.
"""
if self.can_undo:
self.now -= 1
items = self.history[ self.now ]
for i in range( len( items ) - 1, -1, -1 ):
items[i].undo()
if self.now == 0:
self.undoable = False
if self.now == (len( self.history ) - 1):
self.redoable = True
#---------------------------------------------------------------------------
# Redo an operation:
#---------------------------------------------------------------------------
def redo ( self ):
""" Redoes an operation.
"""
if self.can_redo:
self.now += 1
for item in self.history[ self.now - 1 ]:
item.redo()
if self.now == 1:
self.undoable = True
if self.now == len( self.history ):
self.redoable = False
#---------------------------------------------------------------------------
# Reverts all changes made so far and clears the history:
#---------------------------------------------------------------------------
def revert ( self ):
""" Reverts all changes made so far and clears the history.
"""
history = self.history[ : self.now ]
self.clear()
for i in range( len( history ) - 1, -1, -1 ):
items = history[i]
for j in range( len( items ) - 1, -1, -1 ):
items[j].undo()
#---------------------------------------------------------------------------
# Clears the undo history
#---------------------------------------------------------------------------
def clear ( self ):
""" Clears the undo history.
"""
old_len = len( self.history )
old_now = self.now
self.now = 0
del self.history[:]
if old_now > 0:
self.undoable = False
if old_now < old_len:
self.redoable = False
#---------------------------------------------------------------------------
# Are there any undoable operations?
#---------------------------------------------------------------------------
def _get_can_undo ( self ):
""" Are there any undoable operations?
"""
return self.now > 0
#---------------------------------------------------------------------------
# Are there any redoable operations?
#---------------------------------------------------------------------------
def _get_can_redo ( self ):
""" Are there any redoable operations?
"""
return self.now < len( self.history )
#-------------------------------------------------------------------------------
# 'UndoHistoryUndoItem' class:
#-------------------------------------------------------------------------------
class UndoHistoryUndoItem ( AbstractUndoItem ):
""" An undo item for the undo history.
"""
#---------------------------------------------------------------------------
# Trait definitions:
#---------------------------------------------------------------------------
# The undo history to undo or redo
history = Instance( UndoHistory )
#---------------------------------------------------------------------------
# Undoes the change:
#---------------------------------------------------------------------------
def undo ( self ):
""" Undoes the change.
"""
history = self.history
for i in range( history.now - 1, -1, -1 ):
items = history.history[i]
for j in range( len( items ) - 1, -1, -1 ):
items[j].undo()
#---------------------------------------------------------------------------
# Re-does the change:
#---------------------------------------------------------------------------
def redo ( self ):
""" Re-does the change.
"""
history = self.history
for i in range( 0, history.now ):
for item in history.history[i]:
item.redo()
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