def test_empty_symbol(self):
nt = SymbolSet('nt', [
'T',
'S',
])
rules = [
CFGRule(nt.S, (nt.T, nt.T)),
CFGRule(nt.T, (fundamental.empty,)),
]
cfg = CFG(nt, fundamental, rules, nt.S)
self.assertSetEqual(cfg.first_terminals(nt.S), set([fundamental.empty]))
self.assertSetEqual(cfg.first_terminals(nt.T), set([fundamental.empty]))
def test_exp(self):
t = SymbolSet('t', [
('bra_open', '('),
('bra_close', ')'),
('add', '+'),
('mul', '*'),
'id',
'num',
])
nt = SymbolSet('nt', [
('value', 'V'),
('exp', 'E'),
('product', 'P'),
('start', 'S'),
])
rules = [
CFGRule(nt.value, (t.id,)),
CFGRule(nt.value, (t.num,)),
CFGRule(nt.value, (t.bra_open, nt.exp, t.bra_close)),
CFGRule(nt.product, (nt.value,)),
CFGRule(nt.product, (nt.product, t.mul, nt.value)),
CFGRule(nt.exp, (nt.product,)),
CFGRule(nt.exp, (nt.exp, t.add, nt.product)),
CFGRule(nt.start, (nt.exp,)),
]
cfg = CFG(nt, t, rules, nt.start)
first_terminals = set([t.bra_open, t.id, t.num])
for s in nt:
self.assertSetEqual(cfg.first_terminals(s), first_terminals)
for s in [nt.value, nt.product]:
self.assertSetEqual(cfg.follow_terminals(s), set([
t.bra_close, t.add, t.mul, fundamental.end
]))
self.assertSetEqual(cfg.follow_terminals(nt.exp), set([
t.bra_close, t.add, fundamental.end
]))
self.assertSetEqual(cfg.follow_terminals(nt.start), set([
fundamental.end
]))
self.assertSetEqual(cfg.follow_terminals(t.bra_open), set([
t.id, t.num, t.bra_open
]))
self.assertSetEqual(cfg.follow_terminals(t.bra_close), set([
t.mul, t.add, fundamental.end, t.bra_close
]))
self.assertSetEqual(cfg.follow_terminals(t.add), set([
t.id, t.num, t.bra_open
]))
self.assertSetEqual(cfg.follow_terminals(t.mul), set([
t.id, t.num, t.bra_open
]))
self.assertSetEqual(cfg.follow_terminals(t.id), set([
t.mul, t.add, fundamental.end, t.bra_close
]))
self.assertSetEqual(cfg.follow_terminals(t.num), set([
t.mul, t.add, fundamental.end, t.bra_close
]))
def test_simple(self):
terminal_symbols = SymbolSet('terminal', [
('rb_o', '('),
('rb_c', ')'),
('cb_o', '{'),
('cb_c', '}'),
('sb_o', '['),
('sb_c', ']'),
])
nonterminal_symbols = SymbolSet('nonterminal', ['S'])
rb_o = terminal_symbols.rb_o
rb_c = terminal_symbols.rb_c
cb_o = terminal_symbols.cb_o
cb_c = terminal_symbols.cb_c
sb_o = terminal_symbols.sb_o
sb_c = terminal_symbols.sb_c
S = nonterminal_symbols.S
rules = [
CFGRule(S, (rb_o, rb_c)),
CFGRule(S, (sb_o, sb_c)),
CFGRule(S, (cb_o, cb_c)),
CFGRule(S, (rb_o, S, rb_c)),
CFGRule(S, (sb_o, S, sb_c)),
CFGRule(S, (cb_o, S, cb_c)),
CFGRule(S, (S, S)),
]
self.assertEqual(unicode(rules[3]), 'S -> ( S )')
self.assertEqual(len(set(rules + rules)), 7)
reductions = [
Reduction(rules[0], lambda x1, x2: '()'),
Reduction(rules[1], lambda x1, x2: '[]'),
Reduction(rules[2], lambda x1, x2: '{}'),
Reduction(rules[3], lambda x1, x2, x3: '(%s)' % x2),
Reduction(rules[4], lambda x1, x2, x3: '[%s]' % x2),
Reduction(rules[5], lambda x1, x2, x3: '{%s}' % x2),
Reduction(rules[6], lambda x1, x2: '%s%s}' % (x1, x2)),
]
cfg = CFG(nonterminal_symbols, terminal_symbols, rules, S)
cfgex = CFGExtended(nonterminal_symbols, terminal_symbols,
reductions, S)
self.assertSetEqual(set(terminal_symbols), cfg.terminal_symbols)
self.assertSetEqual(set(nonterminal_symbols), cfg.nonterminal_symbols)
symbol_instances1 = [
Token(rb_o),
Token(S, '[]'),
Token(rb_c)
]
si1 = reductions[3].reduce_instances(symbol_instances1)
self.assertEqual(si1.symbol, S)
self.assertEqual(si1.value, '([])')
symbol_instances2 = [
Token(sb_o),
si1,
Token(sb_c)
]
si2 = reductions[4].reduce_instances(symbol_instances2)
self.assertEqual(si2.symbol, S)
self.assertEqual(si2.value, '[([])]')
self.assertSetEqual(cfg.first_terminals(rb_o), set([rb_o]))
self.assertSetEqual(cfg.first_terminals(rb_c), set([rb_c]))
self.assertSetEqual(cfg.first_terminals(S), set([rb_o, cb_o, sb_o]))
self.assertSetEqual(cfgex.first_terminals(rb_o), set([rb_o]))
tuple_reduction = Reduction(rules[3])
si3 = tuple_reduction.reduce_instances(symbol_instances1)
self.assertEqual(si3.symbol, S)
self.assertTupleEqual(si3.value, (None, '[]', None))