Write a program that uses the Stack implementation given to you in stack.py to c

Question

Write a program that uses the Stack implementation given to you in stack.py to check for matching parentheses (brackets) in a Python file. There are three types of parentheses your program must check for: (), {}, and []. Your program should also count how many pairs of each type of parentheses occur. Your program should start by asking the user for the name of a file. The program must then read the file, checking if there is a matching closing parenthesis for each opening parenthesis. Finally, it will print out whether or not there was a matching closing and opening parenthesis for each type, and how many pairs of parentheses occurred.

# A Stack implementation

class Stack:

   

    def __init__(self):

        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 is_empty(self):

        return len(self.__items) == 0

   

    def size(self):

        return len(self.__items)

Explanation / Answer

def calculate(string): stack = [] pushChars, popChars = ")}]" for d in string : if d in pushChars : stack.append(d) elif d in popChars : if not len(stack) : return False else : stackTop = stack.pop() balancingBracket = pushChars[popChars.index(d)] if stackTop != balancingBracket : return False else : return False return not len(stack)

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