Zig libraries need to manage their own memory

[mnemnion]

I was looking for a diffing library to use on a Zig project, and diffz looked like the best candidate. Even with just the diffing portion of diff-match-patch, and a lack of recent commits (it happens), I figured hey, community-supported library, it's got the part I actually need, and maybe I could take some time to continue the port.

I was disappointed to see that the library uses an arena as though it were a garbage collector. In a ziglib, functions are expected to take a generic Allocator, and behave accordingly, by freeing any memory they don't return. If the user wants to use an ArenaAllocator, that's fine, free is a no-op unless the allocation happens to be the last one performed, so one ends up with the performance benefits, while maintaining the flexibility which is a core competency of the language.

I assume this unfortunate state of affairs came to be because this version of diff-match-patch is a port from a garbage collected language, C♯ presumably. It's just a pity, because Zig provides such excellent tools for finding memory leaks, use after free, and double free, and the library has a robust test suite. Proper memory management could have been added during the port, and then this would be a real Zig library, not just a promising sketch of one.

Anyway, now there's an issue to track this, in case anyone wants to close it...

[Techatrix]

fixed by #23