clp-s: Delete clp_s::FileReader

[gibber9809]

Request

There are not many uses of clp_s::FileReader left in our codebase, and clp-s is increasingly using readers from clp, so it would be beneficial to remove clp_s::FileReader as a step towards consolidating the reader classes for clp and clp_s.

Possible implementation

• Remove remaining references to clp_s::FileReader or replace with clp::FileReader where required
• Delete clp_s::FileReader

[aestriplex]

@gibber9809 While I was familiarizing with the structure of the codebase, I came across this issue. I thought it was a good way to get an in-dept overview of the various modules. I made a commit with my changes, although it is probably too big to be put directly into a pull request. That is why I am starting to write comments here.

I followed this methodology:

1. I deleted the clp_s::FileReader class in the clp_s module;
2. I tried to compile the code progressively, fixing it whenever it did not compile;
   Quickly I realized that most of the changes involved error codes. The clip::FileReader class, in fact, returns the error codes defined in clp::ErrorCode, while the clp_s::FileReader, those defined in clp_s::ErrorCode. it seemed reasonable to me that by using clp::FileReader, it should also use clp::ErrorCode, because otherwise you would have to make clp::FileReader depend on clp_s::ErrorCode, which seems inconvenient to me;
3. I ran all the unit tests to make sure they all passed.

I would like to specify that I did not replace all occurrences of clp_s::ErrorCode with clp::ErrorCode, but only those that did not compile as they were directly affected by the removal of clp_s::FileReader.

[gibber9809]

Sorry @aestriplex, but changing instances of clp_s::ErrorCode to clp::ErrorCode is definitely not required to fix this issue. The current main users of clp::FileReader in clp_s already convert clp::ErrorCode to clp_s::ErrorCode when returning/handle clp::ErrorCode locally without propagating it in some way. Some of that translation between clp::ErrorCode and clp_s::ErrorCode could be better, but it's not an immediate concern.

The only real remaining user of clp_s::FileReader is the open(clp_s::FileReader&...) usage in clp_s::ZstdDecompressor + associated code, which can be safely deleted since it is unused. Besides that all you should have to do is delete includes for FileReader.hpp which were missed in previous commits, and add includes for "ErrorCode.hpp" where we had been depending on it being included indirectly via FileReader.hpp.

[aestriplex]

@gibber9809 Ok, thank you for your comment. I had misinterpreted the task. Tomorrow I'll focus on this

The only real remaining user of clp_s::FileReader is the open(clp_s::FileReader&...) usage in clp_s::ZstdDecompressor + associated code, which can be safely deleted since it is unused. Besides that all you should have to do is delete includes for FileReader.hpp which were missed in previous commits, and add includes for "ErrorCode.hpp" where we had been depending on it being included indirectly via FileReader.hpp.