How to add a whitespace before "((VERB)" only if it is not preceded by a space or the beginning of the string?

import re

#input string example:
input_text = "((VERB)ayudar a nosotros) ár((VERB)ayudar a nosotros) Los computadores pueden ((VERB)ayudar a nosotros)"


#this give me a raise error("look-behind requires fixed-width pattern") re.error: look-behind requires fixed-width pattern
#input_text = re.sub(r"(?<!^|\s)\(\(VERB\)", " ((VERB)", input_text)

#and this other option simply places a space in front of all ((VERB) ) 
# without caring if there is a space or the beginning of the string in front 
input_text = re.sub(r"(^|\s)\(\(VERB\)", lambda match: match.group(1) + "((VERB)", input_text)

print(repr(input_text)) # --> output

I have tried using (^|\s) as it is a capturing group that looks for the start of the string ^ or a whitespace just before the pattern "((VERB)". Another pattern option could be with a non-capturing group (?:|) or better still using a context limiter like look-behind (?<!^|\s)

This is the output you should be getting when running this script:

"((VERB)ayudar a nosotros) ár ((VERB)ayudar a nosotros) Los computadores pueden ((VERB)ayudar a nosotros)"

>Solution :

You can assert a non whitespace char to the left:

(?<=\S)\(\(VERB\)

Regex demo | Python demo

In the replacement use a space followed by the full match r" \g<0>"

import re

input_text = "((VERB)ayudar a nosotros) ár((VERB)ayudar a nosotros) Los computadores pueden ((VERB)ayudar a nosotros)"
input_text = re.sub(r"(?<=\S)\(\(VERB\)", r" \g<0>", input_text)
print(input_text)

Output

((VERB)ayudar a nosotros) ár ((VERB)ayudar a nosotros) Los computadores pueden ((VERB)ayudar a nosotros)