def rm_common_prefix(grammar: Grammar):
"""
:type grammar: Grammar
"""
grammar.Productions = []
q = Queue()
for non_terminal in grammar.nonTerminals:
q.put(non_terminal)
while not q.empty():
non_terminal = q.get()
visited = set()
productions = non_terminal.productions.copy()
non_terminal.productions = []
for i in range(len(productions)):
if productions[i] not in visited:
length = len(productions[i].Right)
common_prefixes = []
for prodct in productions[i:]:
counter = 0
for index in range(min(len(productions[i].Right), len(prodct.Right))):
if productions[i].Right[index] == prodct.Right[index]:
counter += 1
else:
break
if counter > 0:
common_prefixes.append(prodct)
length = min(length, counter)
if len(common_prefixes) > 1:
visited.update(common_prefixes)
tmp = grammar.NonTerminal(f'{non_terminal.Name}{i + 1}')
non_terminal %= (Sentence(*productions[i].Right[:length]) + tmp)
for nt in grammar.nonTerminals:
if nt.Name == non_terminal.Name:
nt = non_terminal
for prodct in common_prefixes:
if length == len(prodct.Right):
tmp %= grammar.Epsilon
else:
tmp %= Sentence(*prodct.Right[length:])
else:
visited.add(productions[i])
grammar.Productions.append(productions[i])
for nt in grammar.nonTerminals:
if nt.Name == non_terminal.Name:
nt.productions.append(productions[i])
