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"""
Copyright 2007 Free Software Foundation, Inc.
This file is part of GNU Radio
GNU Radio Companion is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
GNU Radio Companion is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
"""
import Actions
from Constants import STATE_CACHE_SIZE
class StateCache(object):
"""
The state cache is an interface to a list to record data/states and to revert to previous states.
States are recorded into the list in a circular fassion by using an index for the current state,
and counters for the range where states are stored.
"""
def __init__(self, initial_state):
"""
StateCache constructor.
@param initial_state the intial state (nested data)
"""
self.states = [None] * STATE_CACHE_SIZE #fill states
self.current_state_index = 0
self.num_prev_states = 0
self.num_next_states = 0
self.states[0] = initial_state
self.update_actions()
def save_new_state(self, state):
"""
Save a new state.
Place the new state at the next index and add one to the number of previous states.
@param state the new state
"""
self.current_state_index = (self.current_state_index + 1)%STATE_CACHE_SIZE
self.states[self.current_state_index] = state
self.num_prev_states = self.num_prev_states + 1
if self.num_prev_states == STATE_CACHE_SIZE: self.num_prev_states = STATE_CACHE_SIZE - 1
self.num_next_states = 0
self.update_actions()
def get_current_state(self):
"""
Get the state at the current index.
@return the current state (nested data)
"""
self.update_actions()
return self.states[self.current_state_index]
def get_prev_state(self):
"""
Get the previous state and decrement the current index.
@return the previous state or None
"""
if self.num_prev_states > 0:
self.current_state_index = (self.current_state_index + STATE_CACHE_SIZE -1)%STATE_CACHE_SIZE
self.num_next_states = self.num_next_states + 1
self.num_prev_states = self.num_prev_states - 1
return self.get_current_state()
return None
def get_next_state(self):
"""
Get the nest state and increment the current index.
@return the next state or None
"""
if self.num_next_states > 0:
self.current_state_index = (self.current_state_index + 1)%STATE_CACHE_SIZE
self.num_next_states = self.num_next_states - 1
self.num_prev_states = self.num_prev_states + 1
return self.get_current_state()
return None
def update_actions(self):
"""
Update the undo and redo actions based on the number of next and prev states.
"""
Actions.FLOW_GRAPH_REDO.set_sensitive(self.num_next_states != 0)
Actions.FLOW_GRAPH_UNDO.set_sensitive(self.num_prev_states != 0)
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