New implementation of Content-Type and Accept header route matchers

[msrd0]

I have reimplemented the Content-Type and Accept header matchers to suit more advanced needs. This includes a fix for #381. Both now use a HashMap for efficient lookup and also

The Accept matcher

• now supports more than one type from the header
• supports the quality-weighted syntax, although qualities are ignored
• will not only match */* as a wildcard, but also types with subtype-wildcards like image/*
• will now ignore parameters like charset=utf-8 as they are not supposed to be part of the Accept header, and conflict with the list syntax as both use commas as separators

The Content-Type matcher

• now matches content types in respect of their parameters, so that text/plain; charset=utf-8 is considered a match when text/plain was expected, however, text/plain; charset=utf-8 is not a match if text/plain; charset=us-ascii was expected
• allows the user to optionally specify that requests without a Content-Type header are acceptable, which is at least useful during development when your curl commands get shorter

Also, I have added public re-exports in their respective super mod for ContentTypeHeaderRouteMatcher and RouteNonMatch to simplify user code.

[codecov]

Codecov Report

Merging #424 into master will increase coverage by 0.36%.
The diff coverage is 92.30%.

@@            Coverage Diff             @@
##           master     #424      +/-   ##
==========================================
+ Coverage   83.05%   83.41%   +0.36%     
==========================================
  Files         106      106              
  Lines        5027     5156     +129     
==========================================
+ Hits         4175     4301     +126     
- Misses        852      855       +3     

Impacted Files	Coverage Δ
gotham/src/extractor/internal.rs	89.64% <ø> (ø)
gotham/src/router/mod.rs	89.94% <ø> (ø)
gotham/src/router/route/matcher/mod.rs	64.70% <ø> (ø)
gotham/src/router/route/matcher/content_type.rs	91.78% <91.54%> (+91.78%)	⬆️
gotham/src/router/route/matcher/accept.rs	92.30% <92.00%> (+92.30%)	⬆️
gotham/src/router/route/matcher/lookup_table.rs	100.00% <100.00%> (ø)
misc/borrow_bag/src/lookup.rs	75.00% <0.00%> (-25.00%)	⬇️
examples/templating/askama/src/main.rs	66.66% <0.00%> (-7.41%)	⬇️
gotham/src/helpers/http/request/path.rs	78.57% <0.00%> (-7.15%)	⬇️
gotham/src/handler/mod.rs	77.27% <0.00%> (-4.55%)	⬇️
... and 16 more

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[nyarly]

This looks fantastic. I've created a couple issues around respecting q parameters, and updating the examples, but I'd rather come closer to the conneg spec than block on perfection.

[msrd0]

Well, as I understand the task of the accept header matcher is to see whether there is a match, but has no way to inform the handler as to what quality that match is. Even worse, when a handler has several types it can produce, there is currently no way the matcher can inform the handler which of the types actually produces that match. This is most certainly an issue but sounds like it can't (currently) be solved through a route matcher.

Also, I have kept your documentation on both matcher, although the code contained in them reads more as a test than as a usage example. Let me know if you'd like to see this changed.

[msrd0]

I just caught a case I hadn't considered yet and pushed a fix for it.

[pksunkara]

@msrd0 I have a small question. This is just for matching, right? So, the router looks for matches and if the route doesn't match because of this, it would check other routes and at the end returns 404. But not 406 or 415. Or am I mistaken?

[msrd0]

@pksunkara Well, I guess the idea is for gotham to return the NonMatch status code if this route didn't match and no other matching route was found. However, I found this behaviour to be inconsistent. For example, when I tried to return a NonMatch with status code 404, I got a 405 from the router instead (#434).