Crate matchit

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.

Structs

Match

A successful match consisting of the registered value and URL parameters, returned by Router::at.

Params

A list of parameters returned by a route match.

ParamsIter

An iterator over the keys and values of a route’s parameters.

Router

A URL router.

Enums

InsertError

Represents errors that can occur when inserting a new route.

MatchError

A failed match attempt.