[−][src]Crate matchit
Matches URL patterns with support for dynamic and wildcard segments.
use matchit::Node; fn main() { let mut matcher = Node::default(); matcher.insert("/home", "Welcome!"); matcher.insert("/users/:id", "A User"); let matched = matcher.match_path("/users/1").unwrap(); assert_eq!(matched.params().by_name("id"), Some("1")); }
It relies on a tree structure which makes heavy use of common prefixes, it is basically a radix tree. This makes lookups extremely fast. See below for technical details.
The tree is optimized for high performance and a small memory footprint. It scales well even with very long paths and a large number of routes. A compressing dynamic trie (radix tree) structure is used for efficient matching.
Parameters
As you can see, :user is a parameter. The values are accessible via Params, which stores a vector of keys and values. You can get the value of a parameter either by its index in the vector, or by using the Params::by_name(name) method. For example, :user can be retrieved by params.by_name("user").
The registered path can contain two types of parameters:
Syntax Type :name named parameter *name catch-all parameter
Named Parameters
Named parameters are dynamic path segments. They match anything until the next / or the path end:
Pattern: /user/:user /user/gordon match /user/you match /user/gordon/profile no match /user/ no match
Note: Since the tree only supports explicit matches, you can not register static routes and parameters for the same path segment. For example you can not register the patterns /user/new and /user/:user for the same request method at the same time. The routing of different request methods is independent from each other.
Catch-All parameters
The second type are catch-all parameters and have the form *name. Like the name suggests, they match everything. Therefore they must always be at the end of the pattern:
Pattern: /src/*filepath /src/ match /src/somefile.go match /src/subdir/somefile.go match
How does it work?
The matcher relies on a tree structure which makes heavy use of common prefixes, it is basically a compact prefix tree (or just Radix tree). Nodes with a common prefix also share a common parent. Here is a short example what the routing tree for the GET request method could look like:
Priority Path Handle 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>
Every *<num> represents the memory address of a handler function (a pointer). If you follow a path trough the tree from the root to the leaf, you get the complete route path, e.g /blog/:post, where :post is just a placeholder (parameter) for an actual post name. Unlike hash-maps, a tree structure also allows us to use dynamic parts like the :post parameter, since we actually match against the routing patterns instead of just comparing hashes. This works very well and efficiently.
Since URL paths have a hierarchical structure and make use only of a limited set of characters (byte values), it is very likely that there are a lot of common prefixes. This allows us to easily reduce the routing into ever smaller problems. Moreover the matcher manages a separate tree for every request method. For one thing it is more space efficient than holding a method->handle map in every single node, it also allows us to greatly reduce the routing problem before even starting the look-up in the prefix-tree.
For even better scalability, the child nodes on each tree level are ordered by priority, where the priority is just the number of handles registered in sub nodes (children, grandchildren, and so on..). This helps in two ways:
- Nodes which are part of the most routing paths are evaluated first. This helps to make as much routes as possible to be reachable as fast as possible.
- It is some sort of cost compensation. The longest reachable path (highest cost) can always be evaluated first. The following scheme visualizes the tree structure. Nodes are evaluated from top to bottom and from left to right.
├------------ ├--------- ├----- ├---- ├-- ├-- └-
Structs
| Match | The response returned when getting the value for a specific path with
|
| Node | A node in radix tree ordered by priority. |
| Param | Param is a single URL parameter, consisting of a key and a value. |
| Params | A |
Enums
| NodeType | The types of nodes the tree can hold |