def test_given_last_unprocessed_reference_then_lookaheads_of_parent(
self) -> None:
grammar = Grammar(Rule('A', ['x', 'B']), Rule('A', ['B', 'x']),
Rule('B', ['x']))
state = RuleState(0, 1, {'a'})
self.assertEqual({RuleState(2, 0, {'a'})},
state.follow_states(grammar))
def test_given_reference_followed_by_reference_then_lookahead_is_first_set(
self) -> None:
grammar = Grammar(Rule('A', ['B', 'X']), Rule('B', ['x']),
Rule('X', ['a']), Rule('X', ['b']))
state = RuleState(0, 0, {'x'})
self.assertEqual({RuleState(1, 0, {'a', 'b'})},
state.follow_states(grammar))
def test_given_states_followed_by_terminals_then_complete_closure(
self) -> None:
grammar = Grammar(Rule('A', ['X', 'a']), Rule('A', ['A', 'X']),
Rule('X', ['x']))
result = closure_for(grammar, RuleState(0, 1, {'$'}),
RuleState(1, 2, {'$'}))
self.assertEqual({RuleState(0, 1, {'$'}),
RuleState(1, 2, {'$'})}, result)
def test_given_states_followed_by_recursion_then_closure_includes_all_lookaheads(
self) -> None:
grammar = Grammar(Rule('A', ['a', 'A']), Rule('A', ['A', 'A']))
result = closure_for(grammar, RuleState(0, 1, {'$'}))
expected = {
RuleState(0, 1, {'$'}),
RuleState(1, 0, {'$', 'a'}),
RuleState(0, 0, {'$', 'a'})
}
self.assertEqual(expected, result)
def test_given_states_followed_by_references_then_closure_includes_references(
self) -> None:
grammar = Grammar(Rule('A', ['x', 'B']), Rule('B', ['C']),
Rule('C', ['x']))
result = closure_for(grammar, RuleState(0, 1, {'$'}))
expected = {
RuleState(0, 1, {'$'}),
RuleState(1, 0, {'$'}),
RuleState(2, 0, {'$'})
}
self.assertEqual(expected, result)
def closure(*states: Tuple[int, int, str]) -> Closure:
from typing import FrozenSet
from cmaj.parser.closure import RuleState
from cmaj.parser.grammar import Grammar
def unpack_lookaheads(terminals: str) -> FrozenSet[str]:
return frozenset(
{Grammar.AUGMENTED_EOF if ch == '$' else ch
for ch in terminals})
return frozenset({
RuleState(rule_index, num_processed, unpack_lookaheads(lookaheads))
for rule_index, num_processed, lookaheads in states
})
def test_given_states_in_cycles_then_closure_includes_all_lookaheads(
self) -> None:
grammar = Grammar(Rule('C', ['A']), Rule('A', ['B', 'B']),
Rule('B', ['C']), Rule('C', ['c']), Rule('A', ['a']),
Rule('B', ['b']))
result = closure_for(grammar, RuleState(1, 1, {'$'}))
expected = {
RuleState(1, 1, {'$'}),
RuleState(2, 0, {'$', 'c', 'a', 'b'}),
RuleState(5, 0, {'$', 'c', 'a', 'b'}),
RuleState(0, 0, {'$', 'c', 'a', 'b'}),
RuleState(3, 0, {'$', 'c', 'a', 'b'}),
RuleState(1, 0, {'$', 'c', 'a', 'b'}),
RuleState(4, 0, {'$', 'c', 'a', 'b'})
}
self.assertEqual(expected, result)
def graph_for(grammar: Grammar) -> ClosureGraph:
from cmaj.parser.closure import closure_for, successors_for
graph = ClosureGraph()
fringe = {closure_for(grammar, RuleState.start(grammar))}
while fringe:
source = fringe.pop()
graph.add_closure(source)
successors = successors_for(grammar, source)
fringe |= {
target
for target in successors.values() if target not in graph
}
for symbol, target in successors.items():
graph.add_edge(source, symbol, target)
return graph
def test_given_lookaheads_then_closure_simplifies_lookaheads(self) -> None:
grammar = Grammar(Rule('A', ['a']), Rule('A', ['B', 'B']),
Rule('B', ['b']), Rule('B', ['A', 'B']))
result = closure_for(grammar, RuleState(1, 1, {'x', 'y'}))
expected = {
RuleState(1, 1, {'x', 'y'}),
RuleState(2, 0, {'x', 'y', 'b', 'a'}),
RuleState(3, 0, {'x', 'y', 'b', 'a'}),
RuleState(0, 0, {'b', 'a'}),
RuleState(1, 0, {'b', 'a'})
}
self.assertEqual(expected, result)
def test_given_reference_followed_by_recursion_then_lookahead_is_first_set(
self) -> None:
grammar = Grammar(Rule('X', ['a']), Rule('X', ['b', 'X', 'X']))
state = RuleState(1, 1, {'x'})
expected = {RuleState(0, 0, {'a', 'b'}), RuleState(1, 0, {'a', 'b'})}
self.assertEqual(expected, state.follow_states(grammar))
def test_given_equal_states_then_equal(self) -> None:
self.assertEqual(RuleState(0, 0, {'x'}), RuleState(0, 0, {'x'}))
self.assertEqual(RuleState(1, 2, {'3', '4'}),
RuleState(1, 2, {'3', '4'}))
def test_given_grammar_with_single_rule_then_complete_closure(
self) -> None:
grammar = Grammar(Rule('X', ['x']))
result = closure_for(grammar, RuleState(0, 0, {'$'}))
self.assertEqual({RuleState(0, 0, {'$'})}, result)
def test_given_unprocessed_terminal_then_no_follow_states(self) -> None:
grammar = Grammar(Rule('A', ['a']))
state = RuleState(0, 0, {'a'})
self.assertEqual(set(), state.follow_states(grammar))
def test_given_unprocessed_reference_then_initial_reference_states(
self) -> None:
grammar = Grammar(Rule('A', ['B']), Rule('B', ['b']))
state = RuleState(0, 0, {'b'})
self.assertEqual({RuleState(1, 0, {'b'})},
state.follow_states(grammar))
def test_given_equal_states_then_same_hash(self) -> None:
self.assertEqual(hash(RuleState(1, 2, {'3', '4'})),
hash(RuleState(1, 2, {'3', '4'})))
def test_given_different_lookaheads_then_not_equal(self) -> None:
self.assertNotEqual(RuleState(1, 2, {'3'}),
RuleState(1, 2, {'3', '4'}))
self.assertNotEqual(RuleState(1, 2, {'0', '4'}),
RuleState(1, 2, {'3', '4'}))
def test_given_different_num_processed_then_not_equal(self) -> None:
self.assertNotEqual(RuleState(1, 0, {'3', '4'}),
RuleState(1, 2, {'3', '4'}))
def test_given_state_followed_by_two_references_then_lookahead_of_reference(
self) -> None:
grammar = Grammar(Rule('A', ['B', 'B']), Rule('B', ['b']))
result = closure_for(grammar, RuleState(0, 0, {'$'}))
self.assertEqual({RuleState(0, 0, {'$'}),
RuleState(1, 0, {'b'})}, result)
def test_given_unprocessed_reference_then_not_reducible_and_next_symbol_is_reference(
self) -> None:
grammar = Grammar(Rule('A', ['a', 'A']))
state = resolve(RuleState(0, 1, {'$'}), grammar)
self.assertFalse(state.reducible)
self.assertEqual('A', state.next_symbol)
def test_given_processed_rule_then_reducible(self) -> None:
grammar = Grammar(Rule('A', ['a', 'A']))
state = resolve(RuleState(0, 2, {'$'}), grammar)
self.assertTrue(state.reducible)
def test_given_different_rule_index_then_not_equal(self) -> None:
self.assertNotEqual(RuleState(0, 2, {'3', '4'}),
RuleState(1, 2, {'3', '4'}))