parse_resistances.py

def parse_resistances(damage, resistances, immunities, vulnerabilities):
    COMMENT_REGEX = r'\[(?P<comment>.*?)\]'
    ROLL_STRING_REGEX = r'\[.*?]'

    comments = re.findall(COMMENT_REGEX, damage)
    roll_strings = re.split(ROLL_STRING_REGEX, damage)

    formatted_comments = []
    formatted_roll_strings = []

    for t, _ in enumerate(comments):
        if not roll_strings[t].replace(' ', '') == '':
            formatted_roll_strings.append(roll_strings[t])
            formatted_comments.append(comments[t])
        else:
            if len(formatted_comments) > 0:
                formatted_comments[-1] += ' ' + comments[t]
            else:
                pass  # eh, it'll error anyway

    if not roll_strings[-1].replace(' ', '') == '':
        formatted_roll_strings.append(roll_strings[-1])
        if formatted_comments:
            formatted_comments.append(formatted_comments[-1])  # carry over thingies
        else:
            formatted_comments.append('')

    for index, comment in enumerate(formatted_comments):
        roll_string = formatted_roll_strings[index].replace(' ', '')

        preop = ''
        if roll_string[0] in '-+*/().<>=':  # case: +6[blud]
            preop = roll_string[0]
            roll_string = roll_string[1:]
        if not comment.endswith('^'):
            for resistance in resistances:
                if resistance.lower() in comment.lower() and len(resistance) > 0:
                    roll_string = '({0}) / 2'.format(roll_string)
                    break
            for immunity in immunities:
                if immunity.lower() in comment.lower() and len(immunity) > 0:
                    roll_string = '({0}) * 0'.format(roll_string)
                    break
            for vulnerability in vulnerabilities:
                if vulnerability.lower() in comment.lower() and len(vulnerability) > 0:
                    roll_string = '({0}) * 2'.format(roll_string)
                    break
        formatted_roll_strings[index] = '{0}{1}{2}'.format(preop, roll_string,
                                                           "[{}]".format(comment) if comment is not '' else "")
    if formatted_roll_strings:
        damage = ''.join(formatted_roll_strings)

    return damage