Better support for overlapping parameters

[ibraheemdev]

Currently routes like /:a/:b and /:a are supported, but only if they have a common prefix (/:a). This means a route like /:a/:b conflicts with /:c. We can support this by normalizing route parameters positionally when they are first inserted. /:user/:id would become /:a/:b, and /:id becomes /:a. Param nodes get an additional field representing the user-defined parameter name, which is used to construct the parameter list.

[BratSinot]

Also, another variant:

use axum::{
    routing::{get, post},
    Router,
};

fn main() {
    /* these are configurable */
    let base_path = "/";
    let get_base_path = "/";
    let post_base_path = "/";

    let get_route = Router::new().nest(
        get_base_path,
        Router::new().route("/get", get(|| std::future::ready("Ho".to_owned()))),
    );
    let post_route = Router::new().nest(
        post_base_path,
        Router::new().route("/post", post(|| std::future::ready("Ho".to_owned()))),
    );
    let app: Router<String> =
        Router::new().nest(base_path, Router::new().merge(get_route).merge(post_route));
}

cause this error:

thread 'main' panicked at 'Invalid route "/": insertion failed due to conflict with previously registered route: /*__private__axum_nest_tail_param', src/main.rs:21:70
stack backtrace:

[ibraheemdev]

@BratSinot I'm not 100% familiar with how axum uses matchit internally, but that looks more like an axum issue than a matchit one. Maybe open an axum issue?

[BratSinot]

@BratSinot I'm not 100% familiar with how axum uses matchit internally, but that looks more like an axum issue than a matchit one. Maybe open an axum issue?

Ow, sorry! I came here from axum issues list =)

[ibraheemdev]

I realized this is more complicated because the name of the parameter would change depending on the rest of the path, which hasn't been parsed yet. There's another approach that could work by storing a remapping at the end of each route, but I'm starting to think it's not worth handling this edge case.

[ibraheemdev]

Storing the remapping at leaf nodes turned out to be simpler than expected. I've implemented it in #37, this should be released as part of 0.8.0.

[davidpdrsn]

Great news! Thanks for looking into it.

Any change you would back port that to 0.7 as well? I think axum users would really appreciate that :)

[ibraheemdev]

Released in 0.7.3 🎉

[davidpdrsn]

Great news! Thanks for fixing it 😃