Refactor fields_base

[ashtum]

No description provided.

[cppalliance-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 96.65428% with 9 lines in your changes missing coverage. Please review.

Project coverage is 91.82%. Comparing base (7b48277) to head (17f5bb3).
Report is 7 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/rfc/transfer_coding_rule.cpp	88.33%	7 Missing ⚠️
src/detail/header.cpp	97.95%	1 Missing ⚠️
src/field.cpp	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #149      +/-   ##
===========================================
+ Coverage    91.56%   91.82%   +0.26%     
===========================================
  Files           76       76              
  Lines         5001     5005       +4     
===========================================
+ Hits          4579     4596      +17     
+ Misses         422      409      -13     

Files with missing lines	Coverage Δ
include/boost/http_proto/detail/header.hpp	100.00% <ø> (ø)
include/boost/http_proto/fields.hpp	100.00% <100.00%> (ø)
include/boost/http_proto/fields_base.hpp	100.00% <100.00%> (ø)
include/boost/http_proto/fields_view_base.hpp	100.00% <ø> (ø)
include/boost/http_proto/metadata.hpp	100.00% <ø> (ø)
include/boost/http_proto/request.hpp	100.00% <100.00%> (ø)
include/boost/http_proto/response.hpp	100.00% <100.00%> (ø)
src/fields_base.cpp	94.87% <100.00%> (+1.26%)	⬆️
src/fields_view_base.cpp	96.20% <100.00%> (+0.31%)	⬆️
src/parser.cpp	87.61% <100.00%> (ø)
... and 5 more

... and 2 files with indirect coverage changes

---

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[vinniefalco]

why are we changing this?

[ashtum]

we store unknown fields using the id field::unknown. calling erase(id) or set(id, value) with id == field::unknown would affect all these fields, which is not what users expect.
I made it an exception because it's a precondition violation that's likely to occur in user code.
for example, this can happen when generating a response based on the field id of a received request. if the field is not well-known the parser assigns it the field::unknown id.

[cppalliance-bot]

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[cppalliance-bot]

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[cppalliance-bot]

An automated preview of the documentation is available at https://149.http-proto.prtest.cppalliance.org/index.html

[cppalliance-bot]

An automated preview of the documentation is available at https://149.http-proto.prtest.cppalliance.org/index.html

[cppalliance-bot]

An automated preview of the documentation is available at https://149.http-proto.prtest.cppalliance.org/index.html

[cppalliance-bot]

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An automated preview of the documentation is available at https://149.http-proto.prtest.cppalliance.org/index.html