| # Copyright 2019 Google LLC |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # https://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """Tests for lr1.""" |
| |
| import collections |
| import unittest |
| |
| from compiler.front_end import lr1 |
| from compiler.util import parser_types |
| |
| |
| def _make_items(text): |
| """Makes a list of lr1.Items from the lines in text.""" |
| return frozenset([lr1.Item.parse(line.strip()) for line in text.splitlines()]) |
| |
| |
| Token = collections.namedtuple("Token", ["symbol", "source_location"]) |
| |
| |
| def _tokenize(text): |
| """"Tokenizes" text by making each character into a token.""" |
| result = [] |
| for i in range(len(text)): |
| result.append(Token(text[i], parser_types.make_location( |
| (1, i + 1), (1, i + 2)))) |
| return result |
| |
| |
| def _parse_productions(text): |
| """Parses text into a grammar by calling Production.parse on each line.""" |
| return [parser_types.Production.parse(line) for line in text.splitlines()] |
| |
| # Example grammar 4.54 from Aho, Sethi, Lam, Ullman (ASLU) p263. |
| _alsu_grammar = lr1.Grammar("S", _parse_productions("""S -> C C |
| C -> c C |
| C -> d""")) |
| |
| # Item sets corresponding to the above grammar, ASLU pp263-264. |
| _alsu_items = [ |
| _make_items("""S' -> . S, $ |
| S -> . C C, $ |
| C -> . c C, c |
| C -> . c C, d |
| C -> . d, c |
| C -> . d, d"""), |
| _make_items("""S' -> S ., $"""), |
| _make_items("""S -> C . C, $ |
| C -> . c C, $ |
| C -> . d, $"""), |
| _make_items("""C -> c . C, c |
| C -> c . C, d |
| C -> . c C, c |
| C -> . c C, d |
| C -> . d, c |
| C -> . d, d"""), |
| _make_items("""C -> d ., c |
| C -> d ., d"""), |
| _make_items("""S -> C C ., $"""), |
| _make_items("""C -> c . C, $ |
| C -> . c C, $ |
| C -> . d, $"""), |
| _make_items("""C -> d ., $"""), |
| _make_items("""C -> c C ., c |
| C -> c C ., d"""), |
| _make_items("""C -> c C ., $"""), |
| ] |
| |
| # ACTION table corresponding to the above grammar, ASLU p266. |
| _alsu_action = { |
| (0, "c"): lr1.Shift(3, _alsu_items[3]), |
| (0, "d"): lr1.Shift(4, _alsu_items[4]), |
| (1, lr1.END_OF_INPUT): lr1.Accept(), |
| (2, "c"): lr1.Shift(6, _alsu_items[6]), |
| (2, "d"): lr1.Shift(7, _alsu_items[7]), |
| (3, "c"): lr1.Shift(3, _alsu_items[3]), |
| (3, "d"): lr1.Shift(4, _alsu_items[4]), |
| (4, "c"): lr1.Reduce(parser_types.Production("C", ("d",))), |
| (4, "d"): lr1.Reduce(parser_types.Production("C", ("d",))), |
| (5, lr1.END_OF_INPUT): lr1.Reduce(parser_types.Production("S", ("C", "C"))), |
| (6, "c"): lr1.Shift(6, _alsu_items[6]), |
| (6, "d"): lr1.Shift(7, _alsu_items[7]), |
| (7, lr1.END_OF_INPUT): lr1.Reduce(parser_types.Production("C", ("d",))), |
| (8, "c"): lr1.Reduce(parser_types.Production("C", ("c", "C"))), |
| (8, "d"): lr1.Reduce(parser_types.Production("C", ("c", "C"))), |
| (9, lr1.END_OF_INPUT): lr1.Reduce(parser_types.Production("C", ("c", "C"))), |
| } |
| |
| # GOTO table corresponding to the above grammar, ASLU p266. |
| _alsu_goto = {(0, "S"): 1, (0, "C"): 2, (2, "C"): 5, (3, "C"): 8, (6, "C"): 9,} |
| |
| |
| def _normalize_table(items, table): |
| """Returns a canonical-form version of items and table, for comparisons.""" |
| item_to_original_index = {} |
| for i in range(len(items)): |
| item_to_original_index[items[i]] = i |
| sorted_items = items[0:1] + sorted(items[1:], key=sorted) |
| original_index_to_index = {} |
| for i in range(len(sorted_items)): |
| original_index_to_index[item_to_original_index[sorted_items[i]]] = i |
| updated_table = {} |
| for k in table: |
| new_k = original_index_to_index[k[0]], k[1] |
| new_value = table[k] |
| if isinstance(new_value, int): |
| new_value = original_index_to_index[new_value] |
| elif isinstance(new_value, lr1.Shift): |
| new_value = lr1.Shift(original_index_to_index[new_value.state], |
| new_value.items) |
| updated_table[new_k] = new_value |
| return sorted_items, updated_table |
| |
| |
| class Lr1Test(unittest.TestCase): |
| """Tests for lr1.""" |
| |
| def test_parse_lr1item(self): |
| self.assertEqual(lr1.Item.parse("S' -> . S, $"), |
| lr1.Item(parser_types.Production(lr1.START_PRIME, ("S",)), |
| 0, lr1.END_OF_INPUT, "S")) |
| |
| def test_symbol_extraction(self): |
| self.assertEqual(_alsu_grammar.terminals, set(["c", "d", lr1.END_OF_INPUT])) |
| self.assertEqual(_alsu_grammar.nonterminals, set(["S", "C", |
| lr1.START_PRIME])) |
| self.assertEqual(_alsu_grammar.symbols, |
| set(["c", "d", "S", "C", lr1.END_OF_INPUT, |
| lr1.START_PRIME])) |
| |
| def test_items(self): |
| self.assertEqual(set(_alsu_grammar._items()[0]), frozenset(_alsu_items)) |
| |
| def test_terminal_nonterminal_production_tables(self): |
| parser = _alsu_grammar.parser() |
| self.assertEqual(parser.terminals, _alsu_grammar.terminals) |
| self.assertEqual(parser.nonterminals, _alsu_grammar.nonterminals) |
| self.assertEqual(parser.productions, _alsu_grammar.productions) |
| |
| def test_action_table(self): |
| parser = _alsu_grammar.parser() |
| norm_items, norm_action = _normalize_table(parser.item_sets, parser.action) |
| test_items, test_action = _normalize_table(_alsu_items, _alsu_action) |
| self.assertEqual(norm_items, test_items) |
| self.assertEqual(norm_action, test_action) |
| |
| def test_goto_table(self): |
| parser = _alsu_grammar.parser() |
| norm_items, norm_goto = _normalize_table(parser.item_sets, parser.goto) |
| test_items, test_goto = _normalize_table(_alsu_items, _alsu_goto) |
| self.assertEqual(norm_items, test_items) |
| self.assertEqual(norm_goto, test_goto) |
| |
| def test_successful_parse(self): |
| parser = _alsu_grammar.parser() |
| loc = parser_types.parse_location |
| s_to_c_c = parser_types.Production.parse("S -> C C") |
| c_to_c_c = parser_types.Production.parse("C -> c C") |
| c_to_d = parser_types.Production.parse("C -> d") |
| self.assertEqual( |
| lr1.Reduction("S", [lr1.Reduction("C", [ |
| Token("c", loc("1:1-1:2")), lr1.Reduction( |
| "C", [Token("c", loc("1:2-1:3")), |
| lr1.Reduction("C", |
| [Token("c", loc("1:3-1:4")), lr1.Reduction( |
| "C", [Token("d", loc("1:4-1:5"))], |
| c_to_d, loc("1:4-1:5"))], c_to_c_c, |
| loc("1:3-1:5"))], c_to_c_c, loc("1:2-1:5")) |
| ], c_to_c_c, loc("1:1-1:5")), lr1.Reduction( |
| "C", [Token("c", loc("1:5-1:6")), |
| lr1.Reduction("C", [Token("d", loc("1:6-1:7"))], c_to_d, |
| loc("1:6-1:7"))], c_to_c_c, loc("1:5-1:7"))], |
| s_to_c_c, loc("1:1-1:7")), |
| parser.parse(_tokenize("cccdcd")).parse_tree) |
| self.assertEqual( |
| lr1.Reduction("S", [ |
| lr1.Reduction("C", [Token("d", loc("1:1-1:2"))], c_to_d, loc( |
| "1:1-1:2")), lr1.Reduction("C", [Token("d", loc("1:2-1:3"))], |
| c_to_d, loc("1:2-1:3")) |
| ], s_to_c_c, loc("1:1-1:3")), parser.parse(_tokenize("dd")).parse_tree) |
| |
| def test_parse_with_no_source_information(self): |
| parser = _alsu_grammar.parser() |
| s_to_c_c = parser_types.Production.parse("S -> C C") |
| c_to_d = parser_types.Production.parse("C -> d") |
| self.assertEqual( |
| lr1.Reduction("S", [ |
| lr1.Reduction("C", [Token("d", None)], c_to_d, None), |
| lr1.Reduction("C", [Token("d", None)], c_to_d, None) |
| ], s_to_c_c, None), |
| parser.parse([Token("d", None), Token("d", None)]).parse_tree) |
| |
| def test_failed_parses(self): |
| parser = _alsu_grammar.parser() |
| self.assertEqual(None, parser.parse(_tokenize("d")).parse_tree) |
| self.assertEqual(None, parser.parse(_tokenize("cccd")).parse_tree) |
| self.assertEqual(None, parser.parse(_tokenize("")).parse_tree) |
| self.assertEqual(None, parser.parse(_tokenize("cccdc")).parse_tree) |
| |
| def test_mark_error(self): |
| parser = _alsu_grammar.parser() |
| self.assertIsNone(parser.mark_error(_tokenize("cccdc"), None, |
| "missing last d")) |
| self.assertIsNone(parser.mark_error(_tokenize("d"), None, "missing last C")) |
| # Marking an already-marked error with the same error code should succeed. |
| self.assertIsNone(parser.mark_error(_tokenize("d"), None, "missing last C")) |
| # Marking an already-marked error with a different error code should fail. |
| self.assertRegexpMatches( |
| parser.mark_error(_tokenize("d"), None, "different message"), |
| r"^Attempted to overwrite existing error code 'missing last C' with " |
| r"new error code 'different message' for state \d+, terminal \$$") |
| self.assertEqual( |
| "Input successfully parsed.", |
| parser.mark_error(_tokenize("dd"), None, "good parse")) |
| self.assertEqual( |
| parser.mark_error(_tokenize("x"), None, "wrong location"), |
| "error occurred on x token, not end of input.") |
| self.assertEqual( |
| parser.mark_error([], _tokenize("x")[0], "wrong location"), |
| "error occurred on $ token, not x token.") |
| self.assertIsNone( |
| parser.mark_error([lr1.ANY_TOKEN], lr1.ANY_TOKEN, "default error")) |
| # Marking an already-marked error with the same error code should succeed. |
| self.assertIsNone( |
| parser.mark_error([lr1.ANY_TOKEN], lr1.ANY_TOKEN, "default error")) |
| # Marking an already-marked error with a different error code should fail. |
| self.assertRegexpMatches( |
| parser.mark_error([lr1.ANY_TOKEN], lr1.ANY_TOKEN, "default error 2"), |
| r"^Attempted to overwrite existing default error code 'default error' " |
| r"with new error code 'default error 2' for state \d+$") |
| |
| self.assertEqual( |
| "missing last d", parser.parse(_tokenize("cccdc")).error.code) |
| self.assertEqual("missing last d", parser.parse(_tokenize("dc")).error.code) |
| self.assertEqual("missing last C", parser.parse(_tokenize("d")).error.code) |
| self.assertEqual("default error", parser.parse(_tokenize("z")).error.code) |
| self.assertEqual( |
| "missing last C", parser.parse(_tokenize("ccccd")).error.code) |
| self.assertEqual(None, parser.parse(_tokenize("ccc")).error.code) |
| |
| def test_grammar_with_empty_rhs(self): |
| grammar = lr1.Grammar("S", _parse_productions("""S -> A B |
| A -> a A |
| A -> |
| B -> b""")) |
| parser = grammar.parser() |
| self.assertFalse(parser.conflicts) |
| self.assertTrue(parser.parse(_tokenize("ab")).parse_tree) |
| self.assertTrue(parser.parse(_tokenize("b")).parse_tree) |
| self.assertTrue(parser.parse(_tokenize("aab")).parse_tree) |
| |
| def test_grammar_with_reduce_reduce_conflicts(self): |
| grammar = lr1.Grammar("S", _parse_productions("""S -> A c |
| S -> B c |
| A -> a |
| B -> a""")) |
| parser = grammar.parser() |
| self.assertEqual(len(parser.conflicts), 1) |
| # parser.conflicts is a set |
| for conflict in parser.conflicts: |
| for action in conflict.actions: |
| self.assertTrue(isinstance(action, lr1.Reduce)) |
| |
| def test_grammar_with_shift_reduce_conflicts(self): |
| grammar = lr1.Grammar("S", _parse_productions("""S -> A B |
| A -> a |
| A -> |
| B -> a |
| B ->""")) |
| parser = grammar.parser() |
| self.assertEqual(len(parser.conflicts), 1) |
| # parser.conflicts is a set |
| for conflict in parser.conflicts: |
| reduces = 0 |
| shifts = 0 |
| for action in conflict.actions: |
| if isinstance(action, lr1.Reduce): |
| reduces += 1 |
| elif isinstance(action, lr1.Shift): |
| shifts += 1 |
| self.assertEqual(1, reduces) |
| self.assertEqual(1, shifts) |
| |
| def test_item_str(self): |
| self.assertEqual( |
| "a -> b c ., d", |
| str(lr1.make_item(parser_types.Production.parse("a -> b c"), 2, "d"))) |
| self.assertEqual( |
| "a -> b . c, d", |
| str(lr1.make_item(parser_types.Production.parse("a -> b c"), 1, "d"))) |
| self.assertEqual( |
| "a -> . b c, d", |
| str(lr1.make_item(parser_types.Production.parse("a -> b c"), 0, "d"))) |
| self.assertEqual( |
| "a -> ., d", |
| str(lr1.make_item(parser_types.Production.parse("a ->"), 0, "d"))) |
| |
| def test_conflict_str(self): |
| self.assertEqual("Conflict for 'A' in state 12: R vs S", |
| str(lr1.Conflict(12, "'A'", ["R", "S"]))) |
| self.assertEqual("Conflict for 'A' in state 12: R vs S vs T", |
| str(lr1.Conflict(12, "'A'", ["R", "S", "T"]))) |
| |
| |
| if __name__ == "__main__": |
| unittest.main() |
