👀 Views: 26 💬 Answers: 1 📅 Created: 2025-06-03

regex python parsing Python

I'm trying to configure I need some guidance on I'm working on a personal project and I'm working on a project in Python 3.10 where I need to extract nested parentheses from a string that contains complex mathematical expressions. I've been trying to utilize regular expressions to capture the innermost content of these parentheses, but I’m running into issues with capturing groups and matching deeper levels correctly. For instance, given the input string `"(3 + (4 * (2 - 1)) + 5)"`, I want to match the innermost parentheses first. I tried using the following regex pattern: ```python import re pattern = r'\(([^()]*|(?R))*\)' ``` However, this throws a `re.behavior: redefinition of group name 'R' as group 1; was group 1` behavior. I understand that Python’s `re` module doesn’t support recursive patterns directly, which is what I think I'm trying to achieve here. I also experimented with a pattern that attempts to capture non-nested content, but it fails in cases where there are multiple nested levels: ```python pattern = r'\(([^()]*)\)' ``` This only captures the immediate contents without addressing nested structures, leading to incomplete results. I’ve looked at alternative methods like using a stack for parsing, but I wonder if there’s a regex-based solution that can handle this complexity in a more elegant way. I would appreciate any advice on how to properly construct a regex for this task or if you think a different approach would be more suitable. Thanks in advance! For context: I'm using Python on Ubuntu. Am I missing something obvious? I appreciate any insights!