Support optional fields in struct reflect in typescript #1988
Description
Motivation
Support optional fields in struct reflect in typescript, for example:
#[wasn_bindgen]
pub struct Ping {
pong: Option<bool>,
}in .d.ts
export class Ping {
pong?: bool;
}Proposed Solution
Struct generation in wasm_bindgen separate fields into getters and setters, and the ret_ty for getter or args for setter which decide the final field type out are embedded in JsBuilder, we can't checkout if some fields' types are optional, but...optional fields generate some special docs like @returns{{{}}} and @params{{{}}} we can trace.
If it is appropriate to render fields' types with checking if its doc contains .. | undefined ?
For example, we can change this line
if docs.contains("undefined") {
*ty = "?".to_string() + ret_ty
} else {
*ty = ret_ty.to_string()
}and this line
if &ty[0..1] == "?" {
ts_dst.push_str("?: ");
ts_dst.push_str(&ty[1..]);
} else {
ts_dst.push_str(": ");
ts_dst.push_str(&ty);
}Alternatives
I think the solution above is quite a mess, but I can't figure out a better one.