lark-parser/lark

Add support for the `a` and `L` regex flags

Open

#1,527 opened on Apr 21, 2025

View on GitHub
 (5 comments) (0 reactions) (0 assignees)Python (384 forks)batch import
enhancementgood first issue

Repository metrics

Stars
 (4,275 stars)
PR merge metrics
 (Avg merge 41m) (1 merged PR in 30d)

Description

Lark currently only supports the flags imslux, however Python supports two additional ones, which perhaps some people will find useful.

While users can still use inline flags, it might be nice for Lark to support it as part of the syntax, and it should be pretty easy.

https://docs.python.org/3/library/re.html#flags

Contributor guide

Research direction
Investigate how Lark currently handles regex flags (i, m, s, l, u, x) and extend the list to include 'a' (ASCII) and 'L' (locale). Modify the relevant lexer or parser module to recognize these flags and pass them to Python's re module accordingly.
Tech stack
python
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Python
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75