refactor quality and use TryFrom instead of custom trait

[robjtede]

PR Type

Refactor

PR Checklist

• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.
• A changelog entry has been made for the appropriate packages.
• Format code with the latest stable rustfmt

Overview

Refactor Quality struct and associated methods. Now uses TryFrom for u16 and f32 conversions instead of the old custom sealed trait IntoQuality. Since it was sealed this change is fully compatible (the q function still panics on out-of-range numbers) but now Quality can be created by lib consumer using these standard traits as well.

[codecov]

Codecov Report

Merging #1797 (304a962) into master (70f4747) will decrease coverage by 0.06%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1797      +/-   ##
==========================================
- Coverage   53.82%   53.75%   -0.07%     
==========================================
  Files         128      131       +3     
  Lines       12262    12277      +15     
==========================================
  Hits         6600     6600              
- Misses       5662     5677      +15     

Impacted Files	Coverage Δ
actix-http/src/header/mod.rs	26.85% <ø> (ø)
actix-http/src/header/shared/charset.rs	0.00% <ø> (ø)
actix-http/src/header/shared/quality_item.rs	0.00% <0.00%> (ø)
actix-http/src/header/common/mod.rs	7.69% <0.00%> (-2.31%)	⬇️
actix-http/src/header/common/last_modified.rs
actix-http/src/header/common/content_language.rs	0.00% <0.00%> (ø)
actix-http/src/header/common/allow.rs	0.00% <0.00%> (ø)
actix-http/src/header/common/if_match.rs	0.00% <0.00%> (ø)
actix-http/src/header/common/if_modified_since.rs	0.00% <0.00%> (ø)

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[jplatte]

I guess you could also provide an infallible From<u8> conversion, but not sure whether that would be useful.

[robjtede]

I guess you could also provide an infallible From conversion, but not sure whether that would be useful.

Hmm, yeah... an infallible u8 constructor wouldn't be able to use what is arguably the most useful value of 1000.