#[derive(Debug, Default)]
struct Foo {
    data: String,
}

impl Foo {
    fn open(&mut self, src: &str) {
        let url: Vec<&str> = src.splitn(2, "://").collect();

        let mut open_file = |x: &str| {
            self.data.push_str(&format!("open_file(): {}", x));
            self.data.push_str(" ok!");
        };

        match url[0] {
            _ if url.len() == 1 => open_file(url[0]),
            "file" => open_file(url[1]),
            _ => { panic!("err") },
        };
    }
}

fn main() {
    let mut foo = Foo::default();
    foo.open("/test");
    dbg!(foo);

    let mut foo = Foo::default();
    foo.open("file:///path");
    dbg!(foo);
}