git.gag.com Git - debian/gnuradio/blob - grc/gui/StateCache.py

   1 """
   2 Copyright 2007 Free Software Foundation, Inc.
   3 This file is part of GNU Radio
   4
   5 GNU Radio Companion is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU General Public License
   7 as published by the Free Software Foundation; either version 2
   8 of the License, or (at your option) any later version.
   9
  10 GNU Radio Companion is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  18 """
  19
  20 from Actions import FLOW_GRAPH_UNDO, FLOW_GRAPH_REDO, get_action_from_name
  21 from Constants import STATE_CACHE_SIZE
  22
  23 class StateCache(object):
  24         """
  25         The state cache is an interface to a list to record data/states and to revert to previous states.
  26         States are recorded into the list in a circular fassion by using an index for the current state,
  27         and counters for the range where states are stored.
  28         """
  29
  30         def __init__(self, initial_state):
  31                 """
  32                 StateCache constructor.
  33                 @param initial_state the intial state (nested data)
  34                 """
  35                 self.states = [None] * STATE_CACHE_SIZE #fill states
  36                 self.current_state_index = 0
  37                 self.num_prev_states = 0
  38                 self.num_next_states = 0
  39                 self.states[0] = initial_state
  40                 self.update_actions()
  41
  42         def save_new_state(self, state):
  43                 """
  44                 Save a new state.
  45                 Place the new state at the next index and add one to the number of previous states.
  46                 @param state the new state
  47                 """
  48                 self.current_state_index = (self.current_state_index + 1)%STATE_CACHE_SIZE
  49                 self.states[self.current_state_index] = state
  50                 self.num_prev_states = self.num_prev_states + 1
  51                 if self.num_prev_states == STATE_CACHE_SIZE: self.num_prev_states = STATE_CACHE_SIZE - 1
  52                 self.num_next_states = 0
  53                 self.update_actions()
  54
  55         def get_current_state(self):
  56                 """
  57                 Get the state at the current index.
  58                 @return the current state (nested data)
  59                 """
  60                 self.update_actions()
  61                 return self.states[self.current_state_index]
  62
  63         def get_prev_state(self):
  64                 """
  65                 Get the previous state and decrement the current index.
  66                 @return the previous state or None
  67                 """
  68                 if self.num_prev_states > 0:
  69                         self.current_state_index = (self.current_state_index + STATE_CACHE_SIZE -1)%STATE_CACHE_SIZE
  70                         self.num_next_states = self.num_next_states + 1
  71                         self.num_prev_states = self.num_prev_states - 1
  72                         return self.get_current_state()
  73                 return None
  74
  75         def get_next_state(self):
  76                 """
  77                 Get the nest state and increment the current index.
  78                 @return the next state or None
  79                 """
  80                 if self.num_next_states > 0:
  81                         self.current_state_index = (self.current_state_index + 1)%STATE_CACHE_SIZE
  82                         self.num_next_states = self.num_next_states - 1
  83                         self.num_prev_states = self.num_prev_states + 1
  84                         return self.get_current_state()
  85                 return None
  86
  87         def update_actions(self):
  88                 """
  89                 Update the undo and redo actions based on the number of next and prev states.
  90                 """
  91                 get_action_from_name(FLOW_GRAPH_REDO).set_sensitive(self.num_next_states != 0)
  92                 get_action_from_name(FLOW_GRAPH_UNDO).set_sensitive(self.num_prev_states != 0)