正则表达式搜索和替换：如何在一个文本块中移动字符

Question

I'm having a search and replace problem. Take this example.

I want to go from:

"Word1 word2 =word3 *word4 word5= word6 word7* (*word8)"

To this:

"Word1 word2 word3= word4* word5= word6 word7* word8*"

ie To replace any word starting a * or = with itself with the * or = moved to the end of the word, and to make it worse sometimes those words are in brackets, and/or could be at the start or end of a line.

I've tried to search for the solution but I am relatively new at regex and whilst I can cobble together solutions that find the words I am looking for, eg:

\[\*,\=][a-zA-Z]{1,}[\s,\)]

I can't figure out / understand how to do the replace and maintain end of line / start of line characters, white space and brackets.

I am using Python, but if it makes a material difference I'm happy to try using something else.

Answer 1

You need 2 capture group and replace them together:

>>> import re
>>> 
>>> s = "Word1 word2 =word3 *word4 word5= word6 word7* (*word8)"
>>>
>>> re.sub(r'(\*|=)(\b\w+\b)', r'\2\1', s)
'Word1 word2 word3= word4* word5= word6 word7* (word8*)'

Answer 2

Use a verbose expression like the following:

import re
rx = re.compile('''
    \(?    # opening parenthesis or not
    ([*=]) # capture one of * or = to Group 1
    (\w+)  # at least one word chararacter to Group 2
    \)?    # a closing parenthesis
''', re.VERBOSE)

string = "Word1 word2 =word3 *word4 word5= word6 word7* (*word8)"
new_string = rx.sub(r'\2\1', string)

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See a demo on ideone.com and add other characters to the class in square brackets ( [...] ) as needed.