pysize/core/history.py

   1 # This program is free software; you can redistribute it and/or modify
   2 # it under the terms of the GNU General Public License as published by
   3 # the Free Software Foundation; either version 2 of the License, or
   4 # (at your option) any later version.
   5 #
   6 # This program is distributed in the hope that it will be useful,
   7 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 # GNU Library General Public License for more details.
  10 #
  11 # You should have received a copy of the GNU General Public License
  12 # along with this program; if not, write to the Free Software
  13 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  14 #
  15 # See the COPYING file for license information.
  16 #
  17 # Copyright (c) 2006, 2007, 2008  Guillaume Chazarain <guichaz@gmail.com>
  18
  19 from pysize.core.observable import observable
  20
  21 # [(fullpaths, name)]
  22 history = []
  23 next_insertion_index = 0
  24 history_observable = observable()
  25
  26 def add_entry(tree):
  27     global next_insertion_index
  28     fp = tree.fullpaths
  29     if not fp:
  30         return
  31     same = next_insertion_index and fp == history[next_insertion_index - 1][0]
  32     if not same:
  33         if next_insertion_index == len(history):
  34             # History is being written
  35             history.append(None)
  36         else:
  37             paths, name = history[next_insertion_index]
  38             if fp != paths:
  39                 # History took another path, clear the remaining forward history
  40                 del history[next_insertion_index + 1:]
  41         history[next_insertion_index] = fp, tree.root.get_name()
  42         next_insertion_index += 1
  43         history_observable.fire_observers(next_insertion_index, history)
  44
  45 def go_to_history(index):
  46     global next_insertion_index
  47     entry = history[index][0]
  48     next_insertion_index = index + 1
  49     history_observable.fire_observers(next_insertion_index, history)
  50     return entry
  51
  52 def forward():
  53     if len(history) > next_insertion_index:
  54         return go_to_history(next_insertion_index)
  55
  56 def back():
  57     if next_insertion_index > 1:
  58         return go_to_history(next_insertion_index - 2)