reru 0.1.2

A high-performance, drop-in replacement for Python's re module, powered by Rust.

reru

reru is a high-performance, drop-in replacement for Python's re module, powered by Rust.

It combines the raw speed of Rust's linear-time regex engine with the flexibility of backtracking engines when necessary. reru intelligently analyzes your regex pattern and automatically selects the most efficient engine for the job.

🚀 Features

• Hybrid Engine Architecture:

• Fast Path: Uses the regex crate (linear time O(n)) for standard patterns, ensuring protection against ReDoS (Regular Expression Denial of Service).

• Feature Path: Automatically switches to fancy-regex for patterns requiring look-arounds ((?=...), (?<=...)) or backreferences (\1), maintaining compatibility with Python's standard regex features.

• High Performance: Implemented purely in Rust using pyo3 and maturin.

• Built-in Caching: Compilations are cached efficiently using a concurrent DashMap implementation, making repeated calls lightning fast.

• Type Safe: Includes full type hints (.pyi) for better IDE integration and static analysis.

• Cross-Platform: Pre-built wheels available for Linux (x86_64, aarch64, armv7, musl), macOS (Intel & Apple Silicon), and Windows (x64, x86, arm64).

📦 Installation

Install reru easily via pip:

pip install reru

🛠 Usage

reru exposes a simple API similar to Python's standard re module but encapsulates methods within the ReRu class for optimized dispatch.

Basic Matching and Searching

from reru import ReRu

# Check if a pattern matches (returns bool)
if ReRu.is_match(r"\d+", "The answer is 42"):
    print("It's a match!")

# Search for a pattern (returns a Match object or None)
match = ReRu.search(r"(\w+) world", "hello world")
if match:
    print(f"Full match: {match.group()}") # "hello world"
    print(f"Start index: {match.start()}") # 0
    print(f"End index: {match.end()}")     # 11

# Optimized usage
RE1 = ReRu.compile(r"\d+")
RE1.is_match(r"\d+", "The answer is 42")
RE2 = ReRu.compile(r"(\w+) world")
RE2.search("hello world")

Advanced Configuration

You can fine-tune the regex engine using ReConfig. This allows you to control case sensitivity, multiline modes, whitespace ignoring, and execution limits.

from reru import ReRu, ReConfig

# Configure the regex engine
config = ReConfig(
    case_insensitive=True,
    ignore_whitespace=False,
    multiline=True,
    unicode_mode=True,
    size_limit=10 * (1 << 20),  # 10 MB size limit
    dfa_size_limit=2 * (1 << 20), # 2 MB DFA limit
    backtrack_limit=1_000_000     # Limit for backtracking engine
)

# Perform search with config
match = ReRu.search(r"ERROR", "Critical error occurred", config=config)
if match:
    print("Found error!")

# Or
RE1 = ReRu.compile(r"ERROR", config=config)
if RE1.match("Critical error occurred"):
    print("Found error!")

⚙️ How It Works

Under the hood, reru inspects the byte-code of your pattern before compilation:

1. Inspection: It checks for "expensive" features like look-aheads, look-behinds, and backreferences.
2. Selection:

• If expensive features are absent, it uses Rust's regex crate. This guarantees linear time execution and is generally faster.
• If expensive features are present, it falls back to fancy-regex. This supports the complex features Python developers expect while still benefiting from Rust's optimizations where possible.

💻 Development

To build reru from source, you will need Rust and uv (or maturin) installed.

1. Clone the repository:

git clone https://github.com/berrytern/reru.git
cd reru

2. Setup environment:

uv venv
source .venv/bin/activate
uv sync

3. Build and install:

maturin develop --release

📄 License

This project is licensed under the Apache License 2.0. See the LICENSE file for details.

👥 Authors

• João Pedro Miranda C. Hluchan - Initial work - berrytern