pysize/core/history.py

   1 from pysize.core.pysize_fs_tree import pysize_tree
   2 from pysize.core.observable import observable
   3
   4 # [(fullpaths, name)]
   5 history = []
   6 next_insertion_index = 0
   7 history_observable = observable()
   8
   9 def add_entry(tree):
  10     global next_insertion_index
  11     fp = tree.fullpaths
  12     same = next_insertion_index and fp == history[next_insertion_index - 1][0]
  13     if not same:
  14         if next_insertion_index == len(history):
  15             # History is being written
  16             history.append(None)
  17         else:
  18             (paths, name) = history[next_insertion_index]
  19             if fp != paths:
  20                 # History took another path, clear the remaining forward history
  21                 del history[next_insertion_index + 1:]
  22         history[next_insertion_index] = (fp, tree.root.get_name())
  23         next_insertion_index += 1
  24         history_observable.fire_observers(next_insertion_index, history)
  25
  26 def get_entry(index):
  27     if 0 <= index and index < len(history):
  28         return history[index][0]
  29
  30 def move_history(delta):
  31     global next_insertion_index
  32     entry = get_entry(next_insertion_index - 1 + delta)
  33     next_insertion_index += delta
  34     history_observable.fire_observers(next_insertion_index, history)
  35     return entry
  36
  37 def forward():
  38     if len(history) > next_insertion_index:
  39         return move_history(1)
  40
  41 def back():
  42     if next_insertion_index > 1:
  43         return move_history(-1)