par_checker.py

class Stack:
  def __init__(self):
    self.items = []
  def isEmpty(self):
    return self.items == []
  def push(self, item):
    self.items.append(item)
  def pop(self):
    return self.items.pop()
  def peek(self):
    return self.items[len(self.items)-1]
  def size(self):
    return len(self.items)
  
  
def parChecker(symbolString):
  s = Stack()
  balanced = True
  index = 0
  while index < len(symbolString) and balanced:
    symbol = symbolString[index]
    if symbol in "([{":
      s.push(symbol)
    else:
      if s.isEmpty():
        balanced = False
      else:
        top = s.pop()
        if not matches(top,symbol):
          balanced = False
    index = index + 1
  if balanced and s.isEmpty():
    return True
  else:
    return False

def matches(open,close):
  opens = "([{"
  closers = ")]}"
  return opens.index(open) == closers.index(close)