Libconfig support

[friedkeenan]

"libconfig" is a C library that parses its own syntax for configuration files. Its repository can be found here and a description of its syntax can be found here.

My primary usecase for libconfig support would be for backwards compatibility essentially, to read configuration files from another program which uses libconfig. I wouldn't need the ability to write libconfig files.

I think it'd be nice for this to be in Glaze, but if it's not wanted then I don't think I would mind making my own separate project to add support for it using Glaze's facilities for user-defined formats. But I'm making this issue mainly to see whether you would be willing for libconfig support to be upstreamed, and if so then I'd be willing to work on that. Or if you wanted to do the work to add it yourself, I wouldn't complain about that either, but I'd be willing to put effort towards it myself.

[stephenberry]

So, the architecture of Glaze allows you to define your own to/from specialization for custom formats. Because it's low level it would take a deep dive into the architecture to implement this format yourself, but it would be possible to build on top of what Glaze provides and you could even use the glz namespace.

However, I don't think I'm going to add this format into this main repository right now, because I want to focus on the most popular or highest performance formats.

As the codebase improves and we get reflection in C++, it should become easier to develop "extensions" to Glaze that support various formats like libconfig.

I'm going to move this to discussions because it isn't in the current plan.