Extract or remove substrings between curly brackets in rust https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=c51dd846d0b0361855cbd6a19c026539

main.rs

fn main() {
    let s = "system/{id}/start/{mode}";
    let substrings = extract_substrings(s);
    assert_eq!(substrings, vec!["id", "mode"]);
    
    let removed = remove_substrings(&s, &substrings);
    assert_eq!(removed, "system/{}/start/{}");
}

fn extract_substrings(s: &str) -> Vec<&str> {
    s.split('{')
        .skip(1)
        .filter_map(|substr| substr.split_once('}'))
        .map(|(outer, _)| outer)
        .collect()
}

fn remove_substrings(s: &str, substrings: &[&str]) -> String {
    let mut result = String::from(s);
    for substring in substrings {
        result = result.replace(&format!("{{{}}}", substring), "{}");
    }
    result
}