Counter-filter-escaping

import re
import itertools

def inject_substring(string, substring):
    sections = []
    for char in string:
        sections.append(char)
        sections.append(substring)
    sections.pop()
    return "".join(sections)

def permutations_with_repetition(iterable, r=None):
    for unique in set(itertools.permutations(iterable, r)):
        yield unique

def anchored_permutation(string):
    if len(string) < 3:
        yield [string]
    else:
        first = string[0]
        last = string[-1]
        for permutation in permutations_with_repetition(string[1:-1]):
            permutation_str = "".join(permutation)
            yield "".join((first, permutation_str, last))

def regex_permutations(string, delims, max_delims):
    sub_pattern = "[{d}]{{0,{m}}}".format(d=delims,m=max_delims)
    for string_permutation in anchored_permutation(string):
        yield inject_substring(string_permutation, sub_pattern)

def compiled_permutations(string, delims, max_delims):
    permutations = regex_permutations(string, delims, max_delims)
    for permutation in permutations:
        yield re.compile(permutation)

def generate_pattern_list(wordlist, delims, max_delims):
    patternlist = []
    for word in wordlist:
        for pattern in compiled_permutations(word, delims, max_delims):
            patternlist.append(pattern)
    return patternlist

def is_profane(msg, patternlist):
    for pattern in patternlist:
        matches = pattern.search(msg)
        if matches is not None:
            return True
    return False