MatchIt

A blazing fast URL router.

use matchit::Router;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut router = Router::new();
    router.insert("/home", "Welcome!")?;
    router.insert("/users/:id", "A User")?;

    let matched = router.at("/users/978")?;
    assert_eq!(matched.params.get("id"), Some("978"));
    assert_eq!(*matched.value, "A User");

    Ok(())
}

Parameters

Along with static routes, the router also supports dynamic route segments. These can either be named or catch-all parameters:

Named Parameters

Named parameters like /:id match anything until the next / or the end of the path:

let mut m = Router::new();
m.insert("/users/:id", true)?;

assert_eq!(m.at("/users/1")?.params.get("id"), Some("1"));
assert_eq!(m.at("/users/23")?.params.get("id"), Some("23"));
assert!(m.at("/users").is_err());

Catch-all Parameters

Catch-all parameters start with * and match everything, including slashes. They must always be at the end of the route:

let mut m = Router::new();
m.insert("/*p", true)?;

assert_eq!(m.at("/")?.params.get("p"), Some("/"));
assert_eq!(m.at("/foo.js")?.params.get("p"), Some("/foo.js"));
assert_eq!(m.at("/c/bar.css")?.params.get("p"), Some("/c/bar.css"));

Routing Priority

Static and dynamic route segments are allowed to overlap. If they do, static segments will be given higher priority:

let mut m = Router::new();
m.insert("/home", "Welcome!").unwrap();  // priority: 1
m.insert("/about", "About Me").unwrap(); // priority: 1
m.insert("/:other", "...").unwrap();     // priority: 2

Note that catch-all parameters are not allowed to overlap with other path segments. Attempting to insert a conflicting route will result in an error:

let mut m = Router::new();
m.insert("/home", "Welcome!").unwrap();

assert_eq!(
    m.insert("/*filepath", "..."),
    Err(InsertError::Conflict {
        with: "/home".into()
    })
);

How does it work?

The router takes advantage of the fact that URL routes generally follow a hierarchical structure. Routes are stored them in a radix trie that makes heavy use of common prefixes:

Priority   Path             Value
9          \                1
3          ├s               None
2          |├earch\         2
1          |└upport\        3
2          ├blog\           4
1          |    └:post      None
1          |         └\     5
2          ├about-us\       6
1          |        └team\  7
1          └contact\        8

This allows us to reduce the route search to a small number of branches. Child nodes on the same level of the tree are also prioritized by the number of children with registered values, increasing the chance of choosing the correct branch of the first try.

Benchmarks

As it turns out, this method of routing is extremely fast. In a benchmark matching 4 paths against 130 registered routes, matchit find the correct routes in just over 200 nanoseconds, an order of magnitude faster than most other routers. You can view the benchmark code here.

Compare Routers/matchit 
time:   [219.10 ns 219.38 ns 219.70 ns]

Compare Routers/actix   
time:   [31.629 us 31.664 us 31.701 us]

Compare Routers/path-tree
time:   [468.95 ns 470.34 ns 471.65 ns]

Compare Routers/regex   
time:   [21.995 us 22.144 us 22.319 us]

Compare Routers/route-recognizer
time:   [4.2389 us 4.2434 us 4.2482 us]

Credits

A lot of the code in this package was based on Julien Schmidt's httprouter.