from __future__ import unicode_literals
import re
import string
import sys


PY3 = sys.version_info[0] == 3


class StringProcessor(object):
    """
    This class defines method to process strings in the most
    efficient way. Ideally all the methods below use unicode strings
    for both input and output.
    """

    regex = re.compile(r"(?ui)\W")

    @classmethod
    def replace_non_letters_non_numbers_with_whitespace(cls, a_string):
        """
        This function replaces any sequence of non letters and non
        numbers with a single white space.
        """
        return cls.regex.sub(u" ", a_string)

    if PY3:
        strip = staticmethod(str.strip)
        to_lower_case = staticmethod(str.lower)
        to_upper_case = staticmethod(str.upper)
    else:
        strip = staticmethod(string.strip)
        to_lower_case = staticmethod(string.lower)
        to_upper_case = staticmethod(string.upper)