How to match against nested String in Rust

Question

How do I match against a nested String in Rust? Suppose I have an enum like

pub enum TypeExpr {
    Ident((String, Span)),
    // other variants...
}

and a value lhs of type &Box<TypeExpr> . How do I check whether it is an Ident with the value "float"?

I tried

if let TypeExpr::Ident(("float", lhs_span)) = **lhs {}

but this doesn't work since TypeExpr contains a String , not a &str . I tried every variation of the pattern I could think of, but nothing seems to work.

Answer 1

If you really want to do this with an if let , you might have to do it like this

if let TypeExpr::Ident((lhs_name, lhs_span)) = lhs {
    if lhs_name == "float" {
        // Do the things
    }
}

Of course, it can also be done with a match :

match lhs {
    TypeExpr::Ident((lhs_name, lhs_span)) if lhs_name == "float" => {
        // Do the things
    }
    _ => {}
}