python - How to make sure that regex is not in [] or {}?

Question

I am trying to replace all the word in a give sentence with a random word list. Here is my code:

import re
import random

WORDS = ["Brawk" , "Buh-gok", "Bok bok", "Bawk"] # My random word list
PATTERN = r"([a-zA-Z0-9']+)"
DELIMITER = " "

def callback(matchobj):
    return random.choice(WORDS)

def parse_sentence(sentence):
    return re.sub(PATTERN, callback, sentence)

When I run the code, this is what happens:

>>> print(parse_sentence("some text's[color=#ff8a00]smoe more text[/color]{n}"))
Bok bok Bok bok[Buh-gok=#Buh-gok]Bok bok Buh-gok Buh-gok[/Bawk]{Brawk}

I need it to be Buh-gok Bok bok[color=#ff8a00]Bok bok Bok bok Bawk[/color]{n}, so is there anyway to ignore it if it is inside [] or {}?

Answer 1

You need to modify two things in the code:

PATTERN = r"([[^][]*]|{[^{}]*})|[a-zA-Z0-9']+"

def callback(matchobj):
    return matchobj.group(1) or random.choice(WORDS)

See the Python demo.

The regex - ([[^][]*]|{[^{}]*})|[a-zA-Z0-9']+ - matches and captures into Group 1 all substrings between square brackets and between curly braces and just matches alphanumeric character chunks, and return matchobj.group(1) or random.choice(WORDS) returns either Group 1 values (if Group 1 matched), or the random words if Group 1 did not match.

Pattern details:

• ( - start of a capturing group #1
  • [[^][]*] - [, then any zero or more chars other than ] and [, and then a ] char
  • | - or
  • {[^{}]*} - {, then any zero or more chars other than { and }, and then a } char
• ) - end of the group
• | - or
• [a-zA-Z0-9']+ - one or more ASCII letters or digits or '.