# Minimum Viable Zig Regex

**URL:** <https://ziggit.dev/t/minimum-viable-zig-regex/5160>\
**Category:** Showcase\
**Tags:** regex\
**Created:** [July 16, 2024, 12:16am UTC](https://ziggit.dev/t/minimum-viable-zig-regex/5160 "2024-07-16T00:16:04Z")\
**Posts on this page:** 1\
**Showing post:** 1

<div class="post-metadata">

**Author:** ![mnemnion](https://ziggit.dev/user_avatar/ziggit.dev/mnemnion/32/2478_2.png) [@mnemnion](https://ziggit.dev/u/mnemnion)\
**Post date:** [July 16, 2024, 12:16am UTC](https://ziggit.dev/t/minimum-viable-zig-regex/5160/1 "2024-07-16T00:16:04Z")

</div>

# mvzr: The Minimum Viable Zig Regex Library

Finding myself in need of a regular expressions library for a Zig project, and needing it to build regex at runtime, not just comptime, I ended up speedrunning a little library for just that purpose.

[This is that library](https://github.com/mnemnion/mvzr). It’s a simple bytecode-based Commander Pike-style VM. Less than 1000 lines of load-bearing code, no dependencies other than `std`.

## Features

- Zero Allocation
- Possessive qualifiers: `*`, `+`, `?`
- Lazy qualifiers: `*?`, `+?`, `??`
- Alternation: `foo|bar|baz`
- Grouping `foo|(bar|baz)+|quux`
- Sets: `[abc]`, `[^abc]`, `[a-z]`, `[^a=z]`
- Built-in character groups (ASCII): `\w`, `\W`, `\s`, `\S`, `\d`, `\D`
- Escape sequences: `\t`, `\n`, `\r`, `\xXX` hex format
- Begin and end `^` and `$`

## Limitations and Quirks

- Only 64 operations per regex
- Only 8 character sets per regex (ASCII only)
  - These values could probably be made comptime-configurable, but I didn’t

- No Unicode support to speak of
- No fancy modifiers (you want case-insensitive, great, lowercase your string)
- `.` matches anything (split into lines first if you don’t like this)
- Backtracks (sorry. For this to work without backtracking, we need async back)
- Compiler does some best-effort validation but I haven’t really pounded on it
- No min/max `{X,}`, `{X,Y}`. Might get around to it (escape your curlies just in case)

As long as you color within the lines, it should be fine.

## Bugs

I wrote this thing in two days flat (check the log). There are bugs. Point them out and I might even fix them.

* * *

Feel free to kick the tires and try it out, let me know how it goes!

---

_[View the full topic](https://ziggit.dev/t/minimum-viable-zig-regex/5160)._