fix : TODO the AllowMissing shim doesn't appear to offer much over Permissive.

[chidea]

AllowMissing might be different from Permissive on special match cases "" and "/" but be the same on others.
This PR is making it return AllowMissing(None) on these special cases and AllowMissing(Some(_)) on others.
Some test cases are given to assert that both AllowMissing and Permissive act the same or the different correctly on some match cases.
A probable misinformation in the documentation of AllowMissing is also corrected.

[teymour-aldridge]

I'm not exactly sure what without any refers to.

[chidea]

It's the contents without any.
Sorry, I'm not a native.

[teymour-aldridge]

That's no problem!
I just want to make it clear for people who stumble across this in the future :)
Do you mean that there's nothing after the slash (i.e. / but not /<something here>

[chidea]

Yes it is.

[teymour-aldridge]

Suggested change

	/// if its contents are entirely missing, or ends with a '/' without any.
	/// if it doesn't have any contents, or is a pure path (i.e. doesn't have any query strings such as `?b=1` or fragments such as `#fragment`).

[chidea]

Thanks, it's more readable now.
Probably matches would be better than characters because there's a case like /# which also ends as AllowMissing(None).

[chidea]

Or matched characters would be better?

[teymour-aldridge]

Perhaps mentioning which characters don't count?

[chidea]

Well, cases like #a=1 and ?b=1 would also be ignore. There are just too many cases that could be ignored.
Besides, this chracter matching is what matcher part of code does.
Too much information on another file would make people confused.

[teymour-aldridge]

That makes sense.

[jstarry]

@chidea sorry for the major delay in the review. I'm wondering if you'd be willing to move your changes to Classes into a separate PR so that this one can focus on fixing the router TODO.

EDIT: actually the best thing is to rebase now that #1448 has been merged

[jstarry]

@chidea I personally feel that there shouldn't be a distinction between AllowMissing and Permissive behaviour because it's too confusing. Permissive to me allows having an optional wild card matcher. Here's an example using a regex style matcher that shows what I think the behaviour should be:

    #[to = "/{(.*)?}"]
    NotFound(Option<String>), // could be used to redirect the page but capture the original bad url

And AllowMissing to me should allow skipping certain arguments if you want:

    #[to = "/accounts/{id}/posts/{post_id?}", ignoreTrailingSlash]
    Accounts(String, Option<String>),

I think it requires a big rethinking of the Switch derive macro. We can add syntax like ? to indicate optional arguments and other options like ignoreTrailingSlash or exact to change other matching behaviour

[jstarry]

@siku2 do you have any thoughts here? I'm thinking we could start a new project board for router improvements, it needs some love in my opinion

[jstarry]

This work could be captured by #1107

[siku2]

@jstarry I've spotted a lot of things in yew-router that could be improved. Adding a new project board makes sense!

[jstarry]

Awesome, here it is: https://github.com/yewstack/yew/projects/11