Refactor routing to a pattern-based implementation

[thekid]

This pull request refactors the web.Routing class to use regular expressions for routing. This reduces complexity (by removing more than 200 lines of code) and increases performance (by not delegating to a variety of method calls) while sacrificing a completely flexible way of routing requests by using matcher functions, while adding the possibility to route patterns.

Route patterns

...are essentially regular expressions, with the small difference that . matches its literal form and that the ^ and $ metacharacters cannot be used due to how the patterns are constructed. If you want to match a single character use \C instead. Here are a couple of examples:

• /(favicon.ico|robots.txt) matches the files favicon.ico and robots.txt (but not favicon_ico, which a regular expression would match)
• /(?i)test.html using the internal-optional syntax matches the file test.html in any case
• /users/[a-z]+ matches /users/test but not /users/0815.
• HEAD / and HEAD both match HEAD requests to the root path.

Route patterns are matched against /[PATH] or [METHOD] /[PATH] if they do not start with forward slash.

Compacting

With route patterns, the following typical routing definition can be rewritten in a more compact way:

// Each static resource needed to be listed individually
$static= new AssetsFrom($this->environment->path('src/main/webapp'));
return [
  '/static'      => $static,
  '/favicon.ico' => $static,
  '/robots.txt'  => $static,
  /* ... */
];

// Group static resources in one pattern
return [
  '/(static|favicon.ico|robots.txt)' => new AssetsFrom($this->environment->path('src/main/webapp')),
  /* ... */
];

BC breaks

• Changes Routing::routes() to return [:web.Handler] instead of web.Route[]
• The class CannotRoute now lives directly in the web package instead of web.routing.
• Removes Routing::with()
• Removes Routing::mapping()

See also

https://pkg.go.dev/net/http#ServeMux

[thekid]

An alternative could be to add a web.Routes class with the new functionality and deprecate web.Routing in favor of it.

[thekid]

Closed in favor of #111