def parse_alternation(self):
"""
Parse the string from its current index into an alternation or an expression that can be contained by an alternation.
@return: a visitable regular expression object from the Regex package.
"""
concatenations = [self.parse_concatenation()]
while self.get_next_if(u'|'):
concatenations.append(self.parse_concatenation())
if len(concatenations) > 1:
return Regex.Alternation(concatenations)
else:
return concatenations[0]
def visit_alternation(self, alternation):
new_alternation = Regex.Alternation([])
for child in alternation.children:
child.accept(self)
new_alternation.children.append(self.stack.pop())
self.stack.append(new_alternation)
