def expand(item, firsts):
next_symbol = item.NextSymbol
if next_symbol is None or not next_symbol.IsNonTerminal:
return []
lookaheads = ContainerSet()
for preview in item.Preview():
lookaheads.hard_update(compute_local_first(firsts, preview))
assert not lookaheads.contains_epsilon
return [Item(prod, 0, lookaheads) for prod in next_symbol.productions]
def Expand(item, firsts):
next_symbol = item.NextSymbol
if next_symbol is None or not next_symbol.IsNonTerminal:
return []
lookaheads = ContainerSet()
# (Compute lookahead for child items)
for preview in item.Preview():
lookaheads.hard_update(
UtilsParsers.ComputeLocalFirst(firsts, preview))
assert not lookaheads.contains_epsilon
# (Build and return child items)
return [Item(prod, 0, lookaheads) for prod in next_symbol.productions]
def expand(item, firsts):
next_symbol = item.NextSymbol
if next_symbol is None or not next_symbol.IsNonTerminal:
return []
lookaheads = ContainerSet()
# Your code here!!! (Compute lookahead for child items)
for preview in item.Preview():
lookaheads.hard_update(compute_local_first(firsts, preview))
assert not lookaheads.contains_epsilon
# Your code here!!! (Build and return child items)
items = []
for production in next_symbol.productions:
items.append(Item(production, 0, lookaheads))
return items