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# Copyright 2007 Owen Taylor
#
# This file is part of Reinteract and distributed under the terms
# of the BSD license. See the file COPYING in the Reinteract
# distribution for full details.
#
########################################################################
import re
# Two consecutive inserts are merged together if the sum of the
# two matches this. The (?!\n) is to defeat the normal regular
# expression behavior where 'a$' matches 'a\n' because $ matches
# before the last newline in the string
COALESCE_RE = re.compile(r'^\S+ *(?!\n)$')
class _InsertDeleteOp(object):
def __init__(self, start, end, text):
self.start = start
self.end = end
self.text = text
def _insert(self, worksheet):
worksheet.begin_user_action()
worksheet.insert(self.start[0], self.start[1], self.text)
worksheet.end_user_action()
worksheet.place_cursor(self.end[0], self.end[1])
def _delete(self, worksheet):
worksheet.begin_user_action()
worksheet.delete_range(self.start[0], self.start[1], self.end[0], self.end[1])
worksheet.end_user_action()
worksheet.place_cursor(self.start[0], self.start[1])
class InsertOp(_InsertDeleteOp):
def redo(self, worksheet):
self._insert(worksheet)
def undo(self, worksheet):
self._delete(worksheet)
def __repr__(self):
return "InsertOp(%s, %s, %s)" % (self.start, self.end, repr(self.text))
class DeleteOp(_InsertDeleteOp):
def redo(self, worksheet):
self._delete(worksheet)
def undo(self, worksheet):
self._insert(worksheet)
def __repr__(self):
return "DeleteOp(%s, %s, %s)" % (self.start, self.end, repr(self.text))
class BeginActionOp(object):
def __repr__(self):
return "BeginActionOp()"
class EndActionOp(object):
def __repr__(self):
return "EndActionOp()"
class UndoStack(object):
def __init__(self, worksheet):
self.__worksheet = worksheet
self.__position = 0
# The position at which we last pruned the stack; everything after
# this has been inserted consecutively without any intervening
# undos and redos
self.__prune_position = 0
self.__stack = []
self.__applying_undo = False
self.__user_action_count = 0
self.__action_ops = 0
def undo(self):
if self.__position == 0:
return
self.__position -= 1
self.__applying_undo = True
try:
if isinstance(self.__stack[self.__position], EndActionOp):
self.__position -= 1
while not isinstance(self.__stack[self.__position], BeginActionOp):
self.__stack[self.__position].undo(self.__worksheet)
self.__position -= 1
else:
self.__stack[self.__position].undo(self.__worksheet)
finally:
self.__applying_undo = False
def redo(self):
if self.__position == len(self.__stack):
return
self.__position += 1
self.__applying_undo = True
try:
if isinstance(self.__stack[self.__position - 1], BeginActionOp):
self.__position += 1
while not isinstance(self.__stack[self.__position - 1], EndActionOp):
self.__stack[self.__position - 1].redo(self.__worksheet)
self.__position += 1
else:
self.__stack[self.__position - 1].redo(self.__worksheet)
finally:
self.__applying_undo = False
def __check_coalesce(self):
assert self.__position == len(self.__stack)
# Don't coalesce two ops unless they are actually adjacent in time
if self.__position < self.__prune_position + 2:
return
cur = self.__stack[-1]
prev = self.__stack[-2]
if isinstance(cur, InsertOp) and isinstance(prev, InsertOp) and \
cur.start == prev.end and COALESCE_RE.match(prev.text + cur.text):
prev.end = cur.end
prev.text += cur.text
self.__stack.pop()
self.__position -= 1
def append_op(self, op):
if self.__applying_undo:
return
if self.__position < len(self.__stack):
assert self.__action_ops == 0
self.__stack[self.__position:] = []
self.__prune_position = self.__position
self.__stack.append(op)
self.__position += 1
if self.__user_action_count > 0:
self.__action_ops += 1
else:
self.__check_coalesce()
def begin_user_action(self):
self.__user_action_count += 1
def end_user_action(self):
self.__user_action_count -= 1
if self.__user_action_count == 0:
if self.__action_ops > 1:
self.__stack.insert(len(self.__stack) - self.__action_ops, BeginActionOp())
self.__stack.append(EndActionOp())
self.__position += 2
elif self.__action_ops == 1:
self.__check_coalesce()
self.__action_ops = 0
def clear(self):
self.__stack = []
self.__position = 0
def __repr__(self):
return "UndoStack(stack=%s, position=%d)" % (self.__stack, self.__position)
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