Regex

Regular Expressions Library for Mojo

mojo-regex is a regex library featuring a hybrid DFA/NFA/PikeVM/LazyDFA engine architecture that automatically optimizes pattern matching based on complexity.

It aims to provide a similar interface as the re stdlib package while leveraging Mojo's performance capabilities.

Beats Python's C-based re module on 96% of benchmarks. Beats Rust's regex crate on 61%.

Installation

1. Install pixi

2. Add the Package (at the top level of your project):

   pixi add mojo-regex

Example Usage

from regex import match_first, findall, search, sub

# Basic matching
var result = match_first("hello", "hello world")
if result:
    print("Match found:", result.value().get_match_text())

# Character classes and quantifiers
result = match_first("[a-z]+\\d+", "item42")

# Find all matches
var numbers = findall("\\d+", "Price: $123, Quantity: 456")
for i in range(len(numbers)):
    print("Number:", numbers[i].get_match_text())

# Pattern substitution (re.sub equivalent)
var cleaned = sub("\\s+", " ", "hello   world")
print(cleaned)  # "hello world"

# Capture group interpolation
var formatted = sub("(\\d{3})(\\d{3})(\\d{4})", "\\1-\\2-\\3", "6502530000")
print(formatted)  # "650-253-0000"

Performance

See benchmarks/results/comparison.md for detailed results across 80 benchmarks comparing Mojo, Python, and Rust.

Building and Testing

# Run tests
pixi run test

# Run benchmarks
pixi run mojo run -I src benchmarks/bench_engine.mojo

Missing Features

• Named groups ((?<name>...))
• Case insensitive matching
• String splitting (split())
• Non-greedy quantifiers (*?, +?, ??)
• Word boundaries (\b, \B)
• Unicode character classes (\p{L}, \p{N})
• Multiline mode, dot-all mode
• Lookahead / lookbehind
• Negated predefined classes (\S, \D, \W)

Contributing

See CONTRIBUTING.md for architecture overview, development setup, and guidelines.

License

MIT. See LICENSE.

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