py_regex

A small Rust library providing a convenient wrapper around the Python regex module via PyO3.
It allows you to compile fuzzy (approximate) regular expressions with per-pattern thresholds and use Python’s advanced regex engine directly from Rust.

Features

• Compile Python regex patterns (including fuzzy matching) from Rust
• Set individual error thresholds per pattern (insertion, deletion, substitution)
• Call search, finditer, sub, and extract match groups, start/end positions
• Thread-safe (after calling pyo3::prepare_freethreaded_python())
• Minimal dependencies

Requirements

• Python 3.x with the regex package installed
• pyo3 0.24.0

Installation

Add this to your Cargo.toml:

[dependencies]
pyo3 = "0.24.0"
py-regex = "0.1"

Ensure that you have the Python regex module:

pip install regex

Quick Start

Call pyo3::prepare_freethreaded_python() once at program start:

fn main() -> pyo3::PyResult<()> {
    // Initialize the Python interpreter for multi-threaded use
    pyo3::prepare_freethreaded_python();

    // Your code here...
    Ok(())
}

Compile a Pattern

use py_regex::PyRegex;

let re = PyRegex::new(r"(?i)\bhello\b")?;
assert!(re.is_match("Hello, world!")?);

Fuzzy Matching

// Automatically uses fuzzy thresholds per pattern
let fuzzy = PyRegex::new(r"(rust){e<=2}")?;
let m = fuzzy.find_iter("ruxy").pop();
assert!(m.is_some());

Find All Matches

let re = PyRegex::new(r"\d+")?;
for m in re.find_iter("123 abc 456")? {
    println!("Match: {:?}", m.group(0)?);
}

Replace (Substitution)

let re = PyRegex::new(r"\d+")?;
let result = re.replace("There are 123 apples", "NUM")?;
assert_eq!(result, "There are NUM apples");

Extract Groups

let re = PyRegex::new(r"(\w+)@(\w+\.\w+)")?;
if let Some(m) = re.find_iter("user@example.com").pop() {
let parts = m.groups()?; // Vec<Option<String>>
// parts[0] is the full match, parts[1] username, parts[2] domain
}

API

PyRegex::new(pattern: &str) -> PyResult<PyRegex>

Compile a Python regex pattern.

PyRegex::is_match(text: &str) -> PyResult<bool>

Return true if search(text) finds a match.

PyRegex::find_iter(text: &str) -> PyResult<Vec<PyRegexMatch>>

Return all non-overlapping matches as PyRegexMatch.

PyRegex::replace(text: &str, replacement: &str) -> PyResult<String>

Perform substitution (sub) on the input text.

PyRegexMatch

• group(idx: usize) -> PyResult<Option<String>>
• groups() -> PyResult<Vec<Option<String>>>
• start(idx: usize) -> PyResult<isize>
• end(idx: usize) -> PyResult<isize>

License

This project is licensed under the MIT License. See LICENSE for details.