Lexr and parsr are two libraries that can be used together to create a lexer and parser for a language. They can also be used separately, if you only need one of them.

They are both designed to be simple and flexible, and to be used in a variety of situations, together or not.

Currently only the lexr library is available, and the parsr library is in development.

Here is an example of uing the lexr library to create a lexer for a simple language:

use lexr::lex_rule;
#[derive(Debug, PartialEq)]
enum T {
    Integer(i32),
    Plus,
    Minus,
    Eof
}
use T::*;

lex_rule!{lex -> T {
    r"[0-9]+" => |s| Integer(s.parse().unwrap()),
    r"[+]" => |_| Plus,
    "-" => |_| Minus,
    ws => |_| continue,
    eof => |_| Eof,
}}

let tokens = lex("1 + 2 - 3").into_token_vec();
assert_eq!(tokens, vec![Integer(1), Plus, Integer(2), Minus, Integer(3), Eof]);