def test_pda_conversion(self):
""" Tests conversions from a PDA """
state_p = State("p")
state_q = State("q")
state_a = Symbol("a")
state_b = Symbol("b")
state_c = Symbol("c")
terminal_a = Terminal("a")
terminal_b = Terminal("b")
terminal_c = Terminal("c")
stack_symbol_a = StackSymbol("a")
stack_symbol_b = StackSymbol("b")
stack_symbol_c = StackSymbol("c")
stack_symbol_x0 = StackSymbol("X0")
pda = PDA(states={state_p, state_q},
input_symbols={state_a, state_b, state_c},
stack_alphabet={
stack_symbol_a, stack_symbol_b, stack_symbol_c,
stack_symbol_x0
},
start_state=state_p,
start_stack_symbol=stack_symbol_x0,
final_states={state_q})
pda.add_transition(state_p, Epsilon(), stack_symbol_x0, state_q, [])
pda.add_transition(
state_p, Epsilon(), stack_symbol_x0, state_p,
[stack_symbol_a, stack_symbol_b, stack_symbol_c, stack_symbol_x0])
pda.add_transition(state_p, state_a, stack_symbol_a, state_p, [])
pda.add_transition(state_p, state_b, stack_symbol_b, state_p, [])
pda.add_transition(state_p, state_c, stack_symbol_c, state_p, [])
cfg = pda.to_empty_stack().to_cfg()
self.assertTrue(cfg.contains([]))
self.assertTrue(cfg.contains([terminal_a, terminal_b, terminal_c]))
self.assertFalse(cfg.contains([terminal_c, terminal_b, terminal_a]))
def test_to_empty_stack(self):
""" Test transformation to empty stack """
state_q = State("#STARTTOFINAL#")
state_q0 = State("q0")
symbol_e = Symbol("e")
symbol_i = Symbol("i")
symbol_z = StackSymbol("Z")
symbol_z0 = StackSymbol("Z0")
pda = PDA(states={state_q, state_q0},
input_symbols={symbol_i, symbol_e},
stack_alphabet={symbol_z, symbol_z0},
start_state=state_q,
start_stack_symbol=symbol_z0,
final_states={state_q0})
pda.add_transition(state_q, symbol_i, symbol_z, state_q,
[symbol_z, symbol_z])
pda.add_transition(state_q, symbol_i, symbol_z0, state_q,
[symbol_z, symbol_z0])
pda.add_transition(state_q, symbol_e, symbol_z, state_q, [])
pda.add_transition(state_q, Epsilon(), symbol_z0, state_q0, [])
new_pda = pda.to_empty_stack()
self.assertEqual(len(new_pda.states), 4)
self.assertEqual(len(new_pda.input_symbols), 2)
self.assertEqual(len(new_pda.stack_symbols), 3)
self.assertEqual(new_pda.get_number_transitions(), 11)
self.assertEqual(len(new_pda.final_states), 0)
def test_example62(self):
""" Example from the book """
state0 = State("q0")
state1 = State("q1")
state2 = State("q2")
s_zero = Symbol("0")
s_one = Symbol("1")
ss_zero = StackSymbol("0")
ss_one = StackSymbol("1")
ss_z0 = StackSymbol("Z0")
pda = PDA(states={state0, state1, state2},
input_symbols={s_zero, s_one},
stack_alphabet={ss_zero, ss_one, ss_z0},
start_state=state0,
start_stack_symbol=ss_z0,
final_states={state2})
self.assertEqual(len(pda.states), 3)
self.assertEqual(len(pda.input_symbols), 2)
self.assertEqual(len(pda.stack_symbols), 3)
self.assertEqual(pda.get_number_transitions(), 0)
pda.add_transition(state0, s_zero, ss_z0, state0, [ss_zero, ss_z0])
pda.add_transition(state0, s_one, ss_z0, state0, [ss_one, ss_z0])
pda.add_transition(state0, s_zero, ss_zero, state0, [ss_zero, ss_zero])
pda.add_transition(state0, s_one, ss_one, state0, [ss_zero, ss_one])
pda.add_transition(state0, s_one, ss_zero, state0, [ss_one, ss_zero])
pda.add_transition(state0, s_one, ss_one, state0, [ss_one, ss_one])
pda.add_transition(state0, Epsilon(), ss_z0, state1, [ss_z0])
pda.add_transition(state0, Epsilon(), ss_zero, state1, [ss_zero])
pda.add_transition(state0, Epsilon(), ss_one, state1, [ss_one])
pda.add_transition(state1, s_zero, ss_zero, state1, [])
pda.add_transition(state1, s_one, ss_one, state1, [])
pda.add_transition(state1, Epsilon(), ss_z0, state2, [ss_z0])
self.assertEqual(pda.get_number_transitions(), 12)
t_zero = Terminal("0")
t_one = Terminal("1")
cfg = pda.to_empty_stack().to_cfg()
self.assertTrue(cfg.contains([]))
self.assertTrue(cfg.contains([t_zero, t_zero]))
self.assertTrue(cfg.contains([t_zero, t_one, t_one, t_zero]))
self.assertFalse(cfg.contains([t_zero]))
self.assertFalse(cfg.contains([t_zero, t_one, t_zero]))
def test_pda_paper(self):
""" Code in the paper """
pda = PDA()
pda.add_transitions([("q0", "0", "Z0", "q1", ("Z1", "Z0")),
("q1", "1", "Z1", "q2", []),
("q0", "epsilon", "Z1", "q2", [])])
pda.set_start_state("q0")
pda.set_start_stack_symbol("Z0")
pda.add_final_state("q2")
pda_final_state = pda.to_final_state()
cfg = pda.to_empty_stack().to_cfg()
self.assertTrue(cfg.contains(["0", "1"]))
pda_networkx = PDA.from_networkx(pda.to_networkx())
self.assertEqual(pda.states, pda_networkx.states)
self.assertEqual(pda.start_state, pda_networkx.start_state)
self.assertEqual(pda.final_states, pda_networkx.final_states)
self.assertEqual(pda.input_symbols, pda_networkx.input_symbols)
self.assertEqual(pda.stack_symbols, pda_networkx.stack_symbols)
cfg = pda_networkx.to_empty_stack().to_cfg()
pda_networkx.write_as_dot("pda.dot")
self.assertTrue(cfg.contains(["0", "1"]))
self.assertTrue(path.exists("pda.dot"))
