| # Copyright 2015 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| """A wrapper around list that keep track of changes to it.""" |
| |
| |
| class ChangeTrackingList(list): |
| def __init__(self, seq=()): |
| list.__init__(self, seq) |
| self.added = set() |
| self.removed = set() |
| |
| def append(self, value): |
| list.append(self, value) |
| |
| if value in self.removed: |
| self.removed.remove(value) |
| else: |
| self.added.add(value) |
| |
| def remove(self, value): |
| list.remove(self, value) |
| |
| if value in self.added: |
| self.added.remove(value) |
| else: |
| self.removed.add(value) |
| |
| def isChanged(self): |
| return len(self.added) + len(self.removed) > 0 |
| |
| def reset(self): |
| self.added.clear() |
| self.removed.clear() |
