42-expert-system-2.py

stack = []

for x in npi_rule:
  if x not in OPERATORS:
    stack.append(self.atoms[x])
  else:
    pop0 = stack.pop()
    pop1 = stack.pop()
    # If one of the popped element is the same connector that we will create (AND, OR, XOR)
    if isinstance(pop0, ConnectorNode) and pop0.type is LST_OP[x]:
      pop0.add_operand(pop1)
      new_connector = pop0
      self.connectors.pop()
    elif isinstance(pop1, ConnectorNode) and pop1.type is LST_OP[x]:
      pop1.add_operand(pop0)
      new_connector = pop1
      self.connectors.pop()
    else:
      connector_x = self.create_connector(LST_OP[x])
      connector_x.add_operands([pop0, pop1])
      new_connector = connector_x
    self.connectors.append(new_connector)
    stack.append(new_connector)

return stack.pop()