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