code.delx.au - offlineimap/blob - src/Data/Syncable.hs

   1 {- offlineimap component
   2 Copyright (C) 2002-2008 John Goerzen <jgoerzen@complete.org>
   3
   4 This program is free software; you can redistribute it and/or modify
   5 it under the terms of the GNU General Public License as published by
   6 the Free Software Foundation; either version 2 of the License, or
   7 (at your option) any later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program; if not, write to the Free Software
  16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17 -}
  18
  19 {-
  20 The OfflineIMAP v6 algorithm worked like this:
  21
  22 call remoterepos.syncfoldersto(localrepos, [statusrepos])
  23
  24 for each folder, call
  25  syncfolder(remotename, remoterepos, remotefolder, localrepos, statusrepos, quick)
  26    this:
  27    sets localfolder = local folder
  28    adds localfolder to mbnames
  29    sets statusfolder = status folder
  30    if localfolder.getuidvalidity() == None, removes anything in statusfolder
  31
  32    statusfolder.cachemessagelist()
  33
  34    localfolder.cachemessagelist()
  35
  36    Check UID validity
  37    Save UID validity
  38
  39    remotefolder.cachemessagelist()
  40
  41    if not statusfolder.isnewfolder():
  42         # Delete local copies of remote messages.  This way,
  43         # if a message's flag is modified locally but it has been
  44         # deleted remotely, we'll delete it locally.  Otherwise, we
  45         # try to modify a deleted message's flags!  This step
  46         # need only be taken if a statusfolder is present; otherwise,
  47         # there is no action taken *to* the remote repository.
  48         remotefolder.syncmessagesto_delete(localfolder, [localfolder,
  49                                                          statusfolder])
  50         localfolder.syncmessagesto(statusfolder, [remotefolder, statusfolder])
  51
  52    # Synchroonize remote changes
  53    remotefolder.syncmessagesto(localfolder, [localfolder, statusfolder])
  54
  55    # Make sure the status folder is up-to-date.
  56    ui.syncingmessages(localrepos, localfolder, statusrepos, statusfolder)
  57    localfolder.syncmessagesto(statusfolder)
  58    statusfolder.save()
  59    localrepos.restore_atime()
  60
  61
  62
  63 call forgetfolders on local and remote
  64 -}
  65
  66 module Data.Syncable where
  67 import qualified Data.Map as Map
  68
  69 type SyncCollection k = Map.Map k ()
  70
  71 data (Eq k, Ord k, Show k) =>
  72     SyncCommand k =
  73            DeleteItem k
  74          | CopyItem k
  75     deriving (Eq, Ord, Show)
  76
  77 syncThem :: (Ord k, Show k) =>
  78             SyncCollection k  -- ^ Present state of master
  79          -> SyncCollection k  -- ^ Present state of child
  80          -> SyncCollection k  -- ^ Last state of child
  81          -> ([SyncCommand k], [SyncCommand k]) -- ^ Changes to make to (master, child)
  82 syncThem masterstate childstate lastchildstate =
  83     (masterchanges, childchanges)
  84     where masterchanges = (map DeleteItem .
  85                           findDeleted childstate masterstate $ lastchildstate)
  86                           ++
  87                           (map CopyItem .
  88                            findAdded childstate masterstate $ lastchildstate)
  89           childchanges = (map DeleteItem .
  90                           findDeleted masterstate childstate $ lastchildstate)
  91                          ++
  92                          (map CopyItem .
  93                           findAdded masterstate childstate $ lastchildstate)
  94
  95 {- | Returns a list of keys that exist in state2 and lastchildstate
  96 but not in state1 -}
  97 findDeleted :: Ord k =>
  98                SyncCollection k -> SyncCollection k -> SyncCollection k ->
  99                [k]
 100 findDeleted state1 state2 lastchildstate =
 101     Map.keys . Map.difference (Map.intersection state2 lastchildstate) $ state1
 102
 103 {- | Returns a list of keys that exist in state1 but in neither
 104 state2 nor lastchildstate -}
 105 findAdded :: (Ord k, Eq k) =>
 106                SyncCollection k -> SyncCollection k -> SyncCollection k ->
 107                [k]
 108 findAdded state1 state2 lastchildstate =
 109     Map.keys . Map.difference state1 . Map.union state2 $ lastchildstate
 110
 111 {- | Returns a list of keys that exist in the passed state -}
 112 filterKeys :: (Ord k) =>
 113               SyncCollection k -> [k] -> [k]
 114 filterKeys state keylist =
 115     concatMap keyfunc keylist
 116     where keyfunc k =
 117               case Map.lookup k state of
 118                 Nothing -> []
 119                 Just _ -> [k]