Towards 1.13

[peterbell10]

And that's the main problem of your solution - for some blocks this number is really huge.

I don't see how this is problem, could you explain?

A bit of a problem with your solution is the conversion between BlockStateId and the block state represented as a map<AString, AString> that is serialized in the on-disk format and used in the network protocol. The part of old code you saved from refactoring is (imho more than) offset by the code that does the conversion.

I would expect you only need a single function per block type to perform the translation from the state index to (e.g.) a JSON value for the full block state itself.  Whatsmore, I expect most of these to be pretty simple functions e.g. for Bamboo

Json::Value ReadableBlockState(BlockStateMeta Meta)
{
    Json::Value State;
    State["age"] = Meta % 2;
    State["leaves"] = [&]{
        switch((Meta / 2) % 3)
        {
            case 0: return "large";
            case 1: return "none";
            case 2: return "small";
        }
    }();
    State["stage"] = Meta / (2 * 3);
    return State;
}

Also it look like  Mojang uses a global palette internally, or at least wiki.vg claims  so:
https://wiki.vg/Chunk_Format#Global_and_...n_palettes