// 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"(\d*\.\d*|\d*|x_{\d*}|\(.*?\)+)[\/]+(\(.*?\)|x_{\d*}|\d*\.\d*|\d*)").unwrap();
let string = "311/3-31.2/3+x_{3}/4+(3+4)/2+(x_{12}/2+234)/1+9/(3+8)+(5+9/8)/5.6+x_{8}/x_{7}+(3)/m";
let substitution = "\\\\frac{$1}{$2}";
// result will be a String with the substituted value
let result = regex.replace_all(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/