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Исправлены ошибки с ε-правилами в алгоритме Эрли #2

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Исправлены ошибки с ε-правилами в алгоритме Эрли #2

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7a721d5
Fix
stewkk May 12, 2025
90bd7cd
Add test
stewkk May 13, 2025
c53c7c0
Fix
stewkk May 19, 2025
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57 changes: 52 additions & 5 deletions parser_edsl.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1155,15 +1155,55 @@ def predict(self, state, pos, coords, states):
next_sym = state.next_symbol()
if isinstance(next_sym, NonTerminal):
for prod, fold, _ in next_sym.enum_rules():
new_state = EarleyState((next_sym, tuple(prod), fold),
if not prod:
attrs = state.attrs
if not attrs:
attrs = []
res_coord = Fragment(coords[0].start, coords[-1].following)
attrs = attrs+[fold.callee([], coords, res_coord)]
new_state = EarleyState(state.rule,
state.dot + 1,
state.start,
pos,
attrs,
coords)

if new_state.is_complete():
_, _, fold1 = new_state.rule
coords = new_state.coords
res_coord = Fragment(coords[0].start, coords[-1].following)
res_attr = fold1.callee(attrs, coords, res_coord)
new_state = dataclasses.replace(new_state, attrs=[res_attr])

if new_state not in self.chart[pos] and new_state not in states:
states.append(new_state)
self.chart[pos].add(new_state)

new_state = EarleyState((next_sym, tuple(prod), fold),
0,
pos,
pos,
attrs=[],
coords=coords)
if new_state not in self.chart[pos] and new_state not in states:
states.append(new_state)
self.predict(new_state, pos, coords, states)
if new_state.is_complete():
_, _, fold = new_state.rule
coords = new_state.coords
res_coord = Fragment(coords[0].start, coords[-1].following)
res_attr = fold.callee([], coords, res_coord)
new_state = dataclasses.replace(new_state, attrs=[res_attr])

if new_state not in self.chart[pos] and new_state not in states:
states.append(new_state)
else:
new_state = EarleyState((next_sym, tuple(prod), fold),
0,
pos,
pos,
attrs=[],
coords=coords)
if new_state not in self.chart[pos] and new_state not in states:
states.append(new_state)
self.predict(new_state, pos, coords, states)

def scan(self, state, token, pos):
next_sym = state.next_symbol()
Expand Down Expand Up @@ -1195,6 +1235,9 @@ def scan(self, state, token, pos):
self.chart[pos + 1].add(new_state)

def complete(self, state: EarleyState, pos, states: list[EarleyState]):
_, rhs, _ = state.rule
if not rhs:
return
for prev_state in self.chart[state.start]:
next_sym = prev_state.next_symbol()
if next_sym == state.rule[0]:
Expand Down Expand Up @@ -1273,7 +1316,10 @@ def parse(self, tokens):
# print(next_sym)
if isinstance(next_sym, NonTerminal):
# print('a', next_sym)
self.predict(state, pos, tokens[pos].pos, states)
coords = Fragment(Position(), Position())
if len(tokens) > 0:
coords = tokens[min(pos, len(tokens)-1)].pos
self.predict(state, pos, coords, states)
elif pos < len(tokens):
self.scan(state, tokens[pos], pos)
else:
Expand All @@ -1286,6 +1332,7 @@ def parse(self, tokens):
if (state.rule[0] == self.grammar.start
and state.is_complete()
and state.start == 0)]

if len(final_states) > 1:
raise ParseError(pos=Position(),
expected="",
Expand Down
35 changes: 34 additions & 1 deletion tests/earley_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,4 +22,37 @@ def test_undefiened_grammar():
parser = pe.Parser(expr)

with pytest.raises(pe.ParseError):
result = parser.parse_earley("42+3-5")
result = parser.parse_earley("42+3-5")


def test_epsilon_rule_empty_grammar():
expr = pe.NonTerminal('expr')
expr |= ()

parser = pe.Parser(expr)

assert parser.parse_earley("") == None


def test_epsilon_rule():
expr = pe.NonTerminal('expr')
expr |= ('a', expr, lambda _: None)
expr |= (lambda: None)

parser = pe.Parser(expr)

assert parser.parse_earley("aaa") == None


def test_epsilon_rule_attrs():
NAr = pe.NonTerminal("NAr")
ARRAY = pe.Terminal("array", "array", lambda _: None, priority=10)

NAr |= ARRAY, NAr, lambda x: x + 1
NAr |= lambda: 0

p = pe.Parser(NAr)
p.add_skipped_domain("\\s")

assert p.parse_earley("array array") == 2
assert p.parse_earley(" ") == 0