// include the latest version of the regex crate in your Cargo.toml
extern crate regex;
use regex::Regex;
fn main() {
let regex = Regex::new(r"(?m)^[\s\S]*(?:^|\r?\n)\s*(\d+)(?![\s\S]*(\r?\n){2})").unwrap();
let string = "this is test
1. this is test
2. this is test
3. this is test
this is test
1. this test
2. this is test
this is test";
let substitution = "$1";
// result will be a String with the substituted value
let result = regex.replace(string, substitution);
println!("{}", result);
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Rust, please visit: https://docs.rs/regex/latest/regex/