def test_cnf(self):
""" Tests the conversion to CNF form """
# pylint: disable=too-many-locals
var_i = Variable("I")
var_f = Variable("F")
var_e = Variable("E")
var_t = Variable("C#CNF#1")
ter_a = Terminal("a")
ter_b = Terminal("b")
ter_0 = Terminal("0")
ter_1 = Terminal("1")
ter_par_open = Terminal("(")
ter_par_close = Terminal(")")
ter_mult = Terminal("*")
ter_plus = Terminal("+")
productions = {
Production(var_i, [ter_a]),
Production(var_i, [ter_b]),
Production(var_i, [var_i, ter_a]),
Production(var_i, [var_i, ter_b]),
Production(var_i, [var_i, ter_0]),
Production(var_i, [var_i, ter_1]),
Production(var_f, [var_i]),
Production(var_f, [ter_par_open, var_e, ter_par_close]),
Production(var_t, [var_f]),
Production(var_t, [var_t, ter_mult, var_f]),
Production(var_e, [var_t]),
Production(var_e, [var_e, ter_plus, var_t])
}
cfg = CFG({var_i, var_f, var_e, var_t}, {
ter_a, ter_b, ter_0, ter_1, ter_par_open, ter_par_close, ter_mult,
ter_plus
}, var_e, productions)
new_cfg = cfg.to_normal_form()
self.assertEqual(len(new_cfg.variables), 15)
self.assertEqual(len(new_cfg.terminals), 8)
self.assertEqual(len(new_cfg.productions), 41)
self.assertFalse(cfg.is_empty())
new_cfg2 = cfg.to_normal_form()
self.assertEqual(new_cfg, new_cfg2)
cfg2 = CFG(start_symbol=var_e,
productions={Production(var_e, [var_t])})
new_cfg = cfg2.to_normal_form()
self.assertEqual(len(new_cfg.variables), 1)
self.assertEqual(len(new_cfg.terminals), 0)
self.assertEqual(len(new_cfg.productions), 0)
self.assertTrue(cfg2.is_empty())
def test_intersection_with_epsilon(self):
state0 = State(0)
state1 = State(1)
symb_a = Symbol("a")
dfa = DeterministicFiniteAutomaton({state0, state1}, {symb_a},
start_state=state0,
final_states={state1})
dfa.add_transition(state0, symb_a, state1)
self.assertTrue(dfa.accepts([symb_a]))
ter_a = Terminal("a")
var_s = Variable("S")
var_l = Variable("L")
var_t = Variable("T")
productions = {
Production(var_s, [var_l, var_t]),
Production(var_l, [Epsilon()]),
Production(var_t, [ter_a])
}
cfg = CFG(productions=productions, start_symbol=var_s)
self.assertFalse(cfg.is_empty())
self.assertTrue(cfg.contains([ter_a]))
cfg_temp = cfg.to_pda().to_cfg()
self.assertFalse(cfg_temp.is_empty())
self.assertTrue(cfg_temp.contains([ter_a]))
cfg_temp = cfg.to_pda().to_final_state().to_empty_stack().to_cfg()
self.assertFalse(cfg_temp.is_empty())
self.assertTrue(cfg_temp.contains([ter_a]))
cfg_i = cfg.intersection(dfa)
self.assertFalse(cfg_i.is_empty())
def test_creation(self):
""" Tests creatin of CFG """
variable0 = Variable(0)
terminal0 = Terminal("a")
prod0 = Production(variable0, [terminal0, Terminal("A"), Variable(1)])
cfg = CFG({variable0}, {terminal0}, variable0, {prod0})
self.assertIsNotNone(cfg)
self.assertEqual(len(cfg.variables), 2)
self.assertEqual(len(cfg.terminals), 2)
self.assertEqual(len(cfg.productions), 1)
self.assertTrue(cfg.is_empty())
cfg = CFG()
self.assertIsNotNone(cfg)
self.assertEqual(len(cfg.variables), 0)
self.assertEqual(len(cfg.terminals), 0)
self.assertEqual(len(cfg.productions), 0)
self.assertTrue(cfg.is_empty())
def test_emptiness(self):
""" Tests the emptiness of a CFG """
# pylint: disable=too-many-locals
var_s = Variable("S")
ter_a = Terminal("a")
ter_b = Terminal("b")
prod0 = Production(var_s, [ter_a, var_s, ter_b])
prod1 = Production(var_s, [])
cfg = CFG({var_s}, {ter_a, ter_b}, var_s, {prod0, prod1})
self.assertFalse(cfg.is_empty())
def test_useless_removal(self):
""" Test the removal of useless symbols """
var_a = Variable("A")
var_b = Variable("B")
ter_a = Terminal("a")
ter_b = Terminal("b")
start = Variable("S")
prod0 = Production(start, [var_a, var_b])
prod1 = Production(start, [ter_a])
prod2 = Production(var_a, [ter_b])
cfg = CFG({var_a, var_b, start}, {ter_a, ter_b}, start,
{prod0, prod1, prod2})
new_cfg = cfg.remove_useless_symbols()
self.assertEqual(len(new_cfg.variables), 1)
self.assertEqual(len(new_cfg.terminals), 1)
self.assertEqual(len(new_cfg.productions), 1)
self.assertFalse(cfg.is_empty())
def test_remove_epsilon(self):
""" Tests the removal of epsilon """
var_a = Variable("A")
var_b = Variable("B")
ter_a = Terminal("a")
ter_b = Terminal("b")
start = Variable("S")
prod0 = Production(start, [var_a, var_b])
prod1 = Production(var_a, [ter_a, var_a, var_a])
prod2 = Production(var_a, [Epsilon()])
prod3 = Production(var_b, [ter_b, var_b, var_b])
prod4 = Production(var_b, [])
cfg = CFG({var_a, var_b, start}, {ter_a, ter_b}, start,
{prod0, prod1, prod2, prod3, prod4})
new_cfg = cfg.remove_epsilon()
self.assertEqual(len(new_cfg.variables), 3)
self.assertEqual(len(new_cfg.terminals), 2)
self.assertEqual(len(set(new_cfg.productions)), 9)
self.assertEqual(len(new_cfg.get_nullable_symbols()), 0)
self.assertFalse(cfg.is_empty())
