rec 0.4.0

Regular Expression Constructor


Regular Expression Constructor - making regular expressions fun

rec is a Rust library that simplifies the process of writing, reading, and using regular expressions. This library is intended for all users working with regular expressions, no matter their familiarity with regular expression syntax. Below is a summary of the functionality provided by rec:

  • WYSIWYG: &str is interpreted exactly as written (i.e. no metacharacters); all metacharacters (as well as other useful patterns) are provided by the ChCls enum.
  • Simple to understand quantifier syntax and capture name syntax.
  • Uses operators to provide easy to understand expressions.
  • Pattern returns exactly what is requested to reduce boilerplate.

This library utilizes the [regex] crate.

Getting Started

Add the following to your Cargo.toml:

rec = "0.3"


Create a Regex

If you prefer API of [regex], you can use a Rec to construct a [Regex].

use rec::{some};
use rec::ChCls::{Digit, Whitespace};

let a_rec = "hello" + some(Whitespace) + (Digit | "world");
let regex =;

assert!(regex.is_match("hello    world"));

Use Pattern to tokenize

Instead of using [Regex], you can use Pattern to handle basic matching needs.

use rec::{some, tkn, var, Element, Pattern};
use rec::ChCls::Digit;

let decimal_number = Pattern::new(tkn!(some(Digit) => "whole") + "." + var(Digit));

assert_eq!(decimal_number.tokenize("23.2").get("whole"), Some("23"));


I know regular expression syntax; why should I use rec?

In order for code to be easily maintainable, it should be as simple as possible. Even if the original developer understands their regular expression, it is beneficial for the project as a whole if all contributors are able to easily understand the function of a regular expression.

License: MIT