wayfind

A speedy, flexible router for Rust.

Currently in a pre-alpha state.

Why another router?

wayfind attempts to bridge the gap between existing Rust router options:

• fast routers, lacking in flexibility
• flexible routers, lacking in speed

Real-world projects often need fancy routing capabilities, such as projects ported from frameworks like Ruby on Rails, or those adhering to specifications like the Open Container Initiative (OCI) Distribution Specification.

The goal of wayfind is to remain competitive with the fastest libraries, while offering advanced routing features when needed. Unused features shouldn't impact performance - you only pay for what you use.

Features

Dynamic Routing

Dynamic parameters allow matching for any byte, excluding the path delimiter /.

We support both:

• Whole segment parameters: /{name}/
• Inline parameters: /{year}-{month}-{day}/

Inline dynamic parameters are greedy in nature, similar to a regex .*, and will attempt to match as many bytes as possible.

Example

use std::error::Error;
use wayfind::{Path, Router};

fn main() -> Result<(), Box<dyn Error>> {
    let mut router = Router::new();
    router.insert("/users/{id}", 1)?;
    router.insert("/users/{id}/files/{filename}.{extension}", 2)?;

    let path = Path::new("/users/123")?;
    let search = router.search(&path).unwrap();
    assert_eq!(search.data.value, 1);
    assert_eq!(search.parameters[0].key, "id");
    assert_eq!(search.parameters[0].value, "123");

    let path = Path::new("/users/123/files/my.document.pdf")?;
    let search = router.search(&path).unwrap();
    assert_eq!(search.data.value, 2);
    assert_eq!(search.parameters[0].key, "id");
    assert_eq!(search.parameters[0].value, "123");
    assert_eq!(search.parameters[1].key, "filename");
    assert_eq!(search.parameters[1].value, "my.document");
    assert_eq!(search.parameters[2].key, "extension");
    assert_eq!(search.parameters[2].value, "pdf");

    Ok(())
}

Wildcard Routing

Wildcard parameters enable matching of one or more segments within a path.

We support both:

• mid-route wildcards: /api/{*path}/help
• end-route catch-all: /{*catch_all}

Example

use std::error::Error;
use wayfind::{Path, Router};

fn main() -> Result<(), Box<dyn Error>> {
    let mut router = Router::new();
    router.insert("/files/{*slug}/delete", 1)?;
    router.insert("/{*catch_all}", 2)?;

    let path = Path::new("/files/documents/reports/annual.pdf/delete")?;
    let search = router.search(&path).unwrap();
    assert_eq!(search.data.value, 1);
    assert_eq!(search.parameters[0].key, "slug");
    assert_eq!(search.parameters[0].value, "documents/reports/annual.pdf");

    let path = Path::new("/any/other/path")?;
    let search = router.search(&path).unwrap();
    assert_eq!(search.data.value, 2);
    assert_eq!(search.parameters[0].key, "catch_all");
    assert_eq!(search.parameters[0].value, "any/other/path");

    Ok(())
}

Constraints

Constraints allow for custom logic to be injected into the routing process.

We support constraints for all types of parameters:

• Dynamic constraint: /{name:constraint}
• Wildcard constraint: /{*name:constraint}

The typical use-case for constraints would be to run a regex, or a simple FromStr implementation, against a path segment.

A common mistake would be to use these for validation of parameters. This should be avoided.

If a constraint fails to match, and no other suitable match exists, it results in a Not Found response, rather than any sort of Bad Request.

They act as an escape-hatch for when you need to disambiguate routes.

The current constraint implementation has a number of limitations:

• constraints cannot take parameters
• checks cannot make use of any prior state
• checks cannot store data after a successful check

Example

use std::error::Error;
use wayfind::{Constraint, Path, Router};

struct NamespaceConstraint;
impl Constraint for NamespaceConstraint {
    const NAME: &'static str = "namespace";

    fn check(segment: &str) -> bool {
        segment
            .split('/')
            .all(|part| {
                !part.is_empty() && part.chars().all(|c| c.is_ascii_alphanumeric() || c == '.' || c == '_' || c == '-')
            })
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let mut router = Router::new();
    router.constraint::<NamespaceConstraint>()?;

    router.insert("/v2", 1)?;
    router.insert("/v2/{*name:namespace}/blobs/{type}:{digest}", 2)?;

    let path = Path::new("/v2")?;
    let search = router.search(&path).unwrap();
    assert_eq!(search.data.value, 1);

    let path = Path::new("/v2/my-org/my-repo/blobs/sha256:1234567890")?;
    let search = router.search(&path).unwrap();
    assert_eq!(search.data.value, 2);
    assert_eq!(search.parameters[0].key, "name");
    assert_eq!(search.parameters[0].value, "my-org/my-repo");
    assert_eq!(search.parameters[1].key, "type");
    assert_eq!(search.parameters[1].value, "sha256");
    assert_eq!(search.parameters[2].key, "digest");
    assert_eq!(search.parameters[2].value, "1234567890");

    let path = Path::new("/v2/invalid repo/blobs/uploads")?;
    assert!(router.search(&path).is_none());

    Ok(())
}

User-Friendly Error Messages

Where possible, we try to provide user-friendly error messages.

Example

use std::error::Error;
use wayfind::{Constraint, Router, errors::ConstraintError};

const ERROR_DISPLAY: &str = "
duplicate constraint name

The constraint name 'my_constraint' is already in use:
    - existing constraint type: 'rust_out::ConstraintA'
    - new constraint type: 'rust_out::ConstraintB'

help: each constraint must have a unique name

try:
    - Check if you have accidentally added the same constraint twice
    - Ensure different constraints have different names
";

struct ConstraintA;
impl Constraint for ConstraintA {
    const NAME: &'static str = "my_constraint";

    fn check(segment: &str) -> bool {
        segment == "a"
    }
}

struct ConstraintB;
impl Constraint for ConstraintB {
    const NAME: &'static str = "my_constraint";

    fn check(segment: &str) -> bool {
        segment == "b"
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let mut router: Router<usize> = Router::new();
    router.constraint::<ConstraintA>()?;

    let error = router.constraint::<ConstraintB>().unwrap_err();
    assert_eq!(error.to_string(), ERROR_DISPLAY.trim());

    Ok(())
}

Router Display

Routers can print their routes as an tree diagram.

[*] here represents nodes within the route tree that can be matched against.

Example

use std::error::Error;
use wayfind::Router;

const ROUTER_DISPLAY: &str = "
$
╰─ /
   ├─ pet [*]
   │    ╰─ /
   │       ├─ findBy
   │       │       ├─ Status [*]
   │       │       ╰─ Tags [*]
   │       ╰─ {petId} [*]
   │                ╰─ /uploadImage [*]
   ├─ store/
   │       ├─ inventory [*]
   │       ╰─ order [*]
   │              ╰─ /
   │                 ╰─ {orderId} [*]
   ╰─ user [*]
         ╰─ /
            ├─ createWithList [*]
            ├─ log
            │    ├─ in [*]
            │    ╰─ out [*]
            ╰─ {username} [*]
";

fn main() -> Result<(), Box<dyn Error>> {
    let mut router = Router::new();

    router.insert("/pet", 1)?;
    router.insert("/pet/findByStatus", 2)?;
    router.insert("/pet/findByTags", 3)?;
    router.insert("/pet/{petId}", 4)?;
    router.insert("/pet/{petId}/uploadImage", 5)?;

    router.insert("/store/inventory", 6)?;
    router.insert("/store/order", 7)?;
    router.insert("/store/order/{orderId}", 8)?;

    router.insert("/user", 9)?;
    router.insert("/user/createWithList", 10)?;
    router.insert("/user/login", 11)?;
    router.insert("/user/logout", 12)?;
    router.insert("/user/{username}", 13)?;

    assert_eq!(router.to_string(), ROUTER_DISPLAY.trim_start());
    Ok(())
}

Performance

wayfind is fast, and appears to be competitive against other top performers in all benchmarks we currently run.

This is due to a number of reasons:

• use of recursion, rather than manual walking of a tree, which seems to perform better.
• use of smallvec, allowing for storage of small parameter lists on the stack.
• enforcement of UTF-8 upfront, which can prevent duplicate UTF-8 checks internally while extracting parameters (via unsafe usage).

However, as is often the case, your mileage may vary (YMMV). Benchmarks, especially micro-benchmarks, should be taken with a grain of salt.

Benchmarks

All benchmarks ran on a M1 Pro laptop.

Check out our codspeed results for a more accurate set of timings.

Context

For all benchmarks, we percent-decode the path before matching. After matching, we convert any extracted parameters to strings.

Some routers perform these operations automatically, while others require them to be done manually.

We do this to try and match behaviour as best as possible. This is as close to an "apples-to-apples" comparison as we can get.

matchit inspired benches

In a router of 130 routes, benchmark matching 4 paths.

path-tree inspired benches

In a router of 320 routes, benchmark matching 80 paths.

Minimum Supported Rust Version (MSRV)

The MSRV is 1.66.

License

wayfind is licensed under the terms of both the MIT License and the Apache License (Version 2.0).

Inspirations

• poem: Initial experimentations started out as a Poem router fork
• matchit: Performance leader among pre-existing routers
• path-tree: Extensive testing and router display feature
• ASP.NET Core: Constraints-based approach to routing