1 # Copyright 2013 The Chromium Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 6 class HostFileSystemIterator(object): 7 '''Provides methods for iterating through host file systems, in both 8 ascending (oldest to newest version) and descending order. 9 ''' 10 11 def __init__(self, file_system_provider, branch_utility): 12 self._file_system_provider = file_system_provider 13 self._branch_utility = branch_utility 14 15 def _ForEach(self, channel_info, callback, get_next): 16 '''Iterates through a sequence of file systems defined by |get_next| until 17 |callback| returns False, or until the end of the sequence of file systems 18 is reached. Returns the BranchUtility.ChannelInfo of the last file system 19 for which |callback| returned True. 20 ''' 21 last_true = None 22 while channel_info is not None: 23 if channel_info.branch == 'master': 24 file_system = self._file_system_provider.GetMaster() 25 else: 26 file_system = self._file_system_provider.GetBranch(channel_info.branch) 27 if not callback(file_system, channel_info): 28 return last_true 29 last_true = channel_info 30 channel_info = get_next(channel_info) 31 return last_true 32 33 def Ascending(self, channel_info, callback): 34 return self._ForEach(channel_info, callback, self._branch_utility.Newer) 35 36 def Descending(self, channel_info, callback): 37 return self._ForEach(channel_info, callback, self._branch_utility.Older) 38
