def eval_rpn(rpn, variables):
stack = Stack()
for el in rpn:
if el in operators:
if stack.Length() < 2:
raise Exception("Missing an operand")
res = Evaluator.process_op(stack.pop(), stack.pop(), el)
stack.push(res)
else:
if el in variables:
stack.push(int(variables[el]))
else:
stack.push(el)
if stack.Length() > 1:
raise Exception("Missing an operation")
return stack.pop()
def infix_to_postfix(infix):
rpn = []
stack = Stack()
for idx, token in enumerate(infix):
if token in operators:
while stack.Length() > 0 and Converter.opcmp(stack.peek(), token) >= 0:
rpn.append(stack.pop())
stack.push(token)
elif token == '(':
stack.push(token)
elif token == ')':
while stack.peek() != '(':
rpn.append(stack.pop())
stack.pop()
else:
rpn.append(token)
while not stack.isEmpty():
rpn.append(stack.pop())
return rpn
