// 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"(?mi)\{\{(?:(?!\}\}).)*?default=(.*?)\}\}").unwrap();
let string = "It was a {{color, default=black}} and scary {{phase}}. As the {{animals, default=dogs}} {{make_sound, default=barked}} and the trees swayed {{setting, default=to the breeze}}, a {{size, default=}} {{monster, default=troll}} that emerged from the shadows.";
let substitution = "\\1";
// 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/