Coding dojo in Minsk session result for 2019-01-19

open_and_close.py

"""
See https://www.codewars.com/kata/all-that-is-open-must-be-closed-dot-dot-dot

## Background
We all know about "balancing parentheses" (plus brackets, braces and chevrons)
and even balancing characters that are identical.

Read that last sentence again, I balanced different characters and identical
characters twice and you didn't even notice... :)

## Kata
Your challenge in this kata is to write a piece of code to validate that a
supplied string is balanced.

You must determine if all that is open is then closed, and nothing is closed
which is not already open!

You will be given a string to validate, and a second string, where each pair
of characters defines an opening and closing sequence that needs balancing.

You may assume that the second string always has an even number of characters.
"""

def filter_brackets(text, brackets):
    """
    >>> filter_brackets('yes', '')
    ''
    >>> filter_brackets('()', '()')
    '()'
    >>> filter_brackets('((yes', '()')
    '(('
    """
    result = []
    for i in text:
        if i in brackets:
            result.append(i)

    return ''.join(result)


def is_balanced(text, brackets):
    """
    >>> is_balanced('', '()')
    True
    >>> is_balanced('Sensei says yes!', '()')
    True
    >>> is_balanced('))((', '{}()')
    False
    >>> is_balanced('(Sensei says yes!)', '()[]')
    True
    >>> is_balanced('(Sensei says no!', '()')
    False
    >>> is_balanced('(Sensei) (says) (yes!)', '()')
    True
    >>> is_balanced('(Sensei (says) yes!)', '()[]')
    True
    >>> is_balanced('((Sensei) says) no!)', '()[]{}')
    False
    >>> is_balanced('(Sensei (says) (yes!))', '()[]{}')
    True
    >>> is_balanced('(Sensei [says] yes)', '()[]')
    True
    >>> is_balanced('[Sensei (says] no)', '()[]')
    False
    >>> is_balanced('', '')
    True
    >>> is_balanced('([{}])', '()[]{}')
    True
    >>> is_balanced('([{]})', '()[]{}')
    False
    >>> is_balanced('!Senei says yes!', '!!')
    True
    >>> is_balanced('Sensei says no!', '!!')
    False
    >>> is_balanced('!Sensei (says) yes!', '!!()')
    True
    """
    text = filter_brackets(text, brackets)
    opening = brackets[::2]
    closing = brackets[1::2]
    brackets = dict(zip(closing, opening))

    state = []
    for char in text:
        if char in brackets:
            #if len(state) == 0:
            #    return False
            last = state.pop() if state else None
            if brackets[char] != last:
                return False
        if char in opening:
            state.append(char)


    return state == []


if __name__ == '__main__':
    import doctest
    failures, errors = doctest.testmod()