31 replace underlying option value datastructure #33

rsore · 2024-10-14T15:53:32Z

Description

In this development branch I have implemented the proposed changes in #31, replacing the underlying datastructure of ValueContainer with a much more memory-efficient solution, without sacrificing safety or run-time performance.

Essentially the change moves the type of the underlying datastructure from std::array<std::variant<std::optional<typename Option::ValueType>...>> to std::tuple<std::optional<typename Option::ValueType>...>.
The previous solution of using std::variant did work fine, but the issue was that it forces all elements of the array to be the same size, meaning if most value types of the parser takes up a small amount of bytes, but you have a single larger value type, the size of all of them will be forced to the largest size.

Using std::tuple, we can store the values as their exact parsed type, leading to no memory overhead at all. Since the indices of all options are known at compile-time, setting and retrieving values from the container essentially becomes a direct variable lookup, insanely fast!

An additional improvement, though irrelevant to the real scope of this branch, is that I have refactored part of the array_from_delimited_string function. Specifically, I have updated the part of the code that segments the string and appends the views to the resulting array. Previously this was done through manual logic, and the code was a bit hard to follow. Now I utilize a combination of std::views::split and std::ranges::transform to do both the segmentation and appending in a concise manner.

Finally, due to the usage of modern C++20 features, I have had to update the gcc compiler for the test workflow to use gcc14. gcc13 would likely do, but why not just be more modern, it might potentially catch more errors.

Related Issues

Closes #31.

How Has This Been Tested?

The datastructure itself has been closely observed using the debugger to ensure that the data is layed out as expected before, during and after parsing. Functionally there is no change, so no new tests have been introduced, but all existing tests still pass.

…ple rather than std::array. Removes need for std::variant, much more memory efficient

…ality. Reduced mutability and increased readability.

github-actions · 2024-10-14T15:55:08Z