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   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 ##@package StateCache
  20 #Stores the flow graph states to drive the undo/redo and save interface.
  21 #@author Josh Blum
  22
  23 from Actions import FLOW_GRAPH_UNDO, FLOW_GRAPH_REDO, get_action_from_name
  24
  25 from Constants import STATE_CACHE_SIZE
  26
  27 class StateCache(object):
  28         """
  29         The state cache is an interface to a list to record data/states and to revert to previous states.
  30         States are recorded into the list in a circular fassion by using an index for the current state,
  31         and counters for the range where states are stored.
  32         """
  33
  34         def __init__(self, initial_state):
  35                 """!
  36                 StateCache constructor.
  37                 @param initial_state the intial state (nested data)
  38                 """
  39                 self.states = [None] * STATE_CACHE_SIZE #fill states
  40                 self.current_state_index = 0
  41                 self.num_prev_states = 0
  42                 self.num_next_states = 0
  43                 self.states[0] = initial_state
  44                 self.update_actions()
  45
  46         def save_new_state(self, state):
  47                 """!
  48                 Save a new state.
  49                 Place the new state at the next index and add one to the number of previous states.
  50                 @param state the new state
  51                 """
  52                 self.current_state_index = (self.current_state_index + 1)%STATE_CACHE_SIZE
  53                 self.states[self.current_state_index] = state
  54                 self.num_prev_states = self.num_prev_states + 1
  55                 if self.num_prev_states == STATE_CACHE_SIZE: self.num_prev_states = STATE_CACHE_SIZE - 1
  56                 self.num_next_states = 0
  57                 self.update_actions()
  58
  59         def get_current_state(self):
  60                 """!
  61                 Get the state at the current index.
  62                 @return the current state (nested data)
  63                 """
  64                 self.update_actions()
  65                 return self.states[self.current_state_index]
  66
  67         def get_prev_state(self):
  68                 """!
  69                 Get the previous state and decrement the current index.
  70                 @return the previous state or None
  71                 """
  72                 if self.num_prev_states > 0:
  73                         self.current_state_index = (self.current_state_index + STATE_CACHE_SIZE -1)%STATE_CACHE_SIZE
  74                         self.num_next_states = self.num_next_states + 1
  75                         self.num_prev_states = self.num_prev_states - 1
  76                         return self.get_current_state()
  77                 return None
  78
  79         def get_next_state(self):
  80                 """!
  81                 Get the nest state and increment the current index.
  82                 @return the next state or None
  83                 """
  84                 if self.num_next_states > 0:
  85                         self.current_state_index = (self.current_state_index + 1)%STATE_CACHE_SIZE
  86                         self.num_next_states = self.num_next_states - 1
  87                         self.num_prev_states = self.num_prev_states + 1
  88                         return self.get_current_state()
  89                 return None
  90
  91         def update_actions(self):
  92                 """
  93                 Update the undo and redo actions based on the number of next and prev states.
  94                 """
  95                 get_action_from_name(FLOW_GRAPH_REDO).set_sensitive(self.num_next_states != 0)
  96                 get_action_from_name(FLOW_GRAPH_UNDO).set_sensitive(self.num_prev_states != 0)
  97
  98