Add an NBT tree structure

[peterbell10]

This is the first step in fixing #3682 and adding support for storing arbitrary NBT in cItem.

[bibo38]

Just for the naming I would prefer NBTTree, because I thought first, that you would add NBT data to a tree 🤣 .

[peterbell10]

The name is meant to complement cFastNBT and cParsedNBT.

[12xx12]

@peterbell10 are you still working on this? May I help you?

I'd like to use the NBT tags with my banner pull request

[peterbell10]

As far as I remember this works as-is. It just never got reviewed.

[bearbin]

Time for a review then, I'll try rebasing and have a go this evening.

[12xx12]

So I rebased on master.

There were two words which required attention in MVSC.
The tests are not done with the new test "engine"

I fixed this but i'm not quite shure if I should commit.

In all I think the code should be merged

[12xx12]

Suggested change

	void swap(cList & a_Other) NOEXCEPT
	void swap(cList & a_Other) noexcept

MSVC doesn't like this. Didn't check other. Yeah GCC doesn't like this either

[12xx12]

Suggested change

	friend void swap(cList & a_Lhs, cList & a_Rhs) NOEXCEPT
	friend void swap(cList & a_Lhs, cList & a_Rhs) noexcept

same here

[12xx12]

Another thing: we should enable the Packet writer and the NBT write to write those tags into themselves for easy transimission and saving

[tigerw]

Bearbin and I took a look at this and we came to the conclusion that this was a reimplementation of std::variant.

Something like this may suffice.

#include <cassert>
#include <iostream>
#include <map>
#include <variant>
#include <vector>

class NBT
{
public:

	using List = std::vector<NBT>;
	using Compound = std::map<std::string, NBT>;

	using NubbyTree = std::variant<
		int,
		bool,
		List,
		Compound
	>;

	NBT(NubbyTree canopy)
	{
		top = canopy;
	}

	auto & Expose() const
	{
		return top;
	}

	void Poosh(NBT nubby)
	{
		assert(std::holds_alternative<List>(top));

		auto & lIsT = std::get<List>(top);
		assert(
			lIsT.empty() ||
			lIsT.back().top.index() == nubby.top.index()
		);

		lIsT.emplace_back(std::move(nubby));
	}

private:  // its privates

	NubbyTree top;
};

void MakeNubby()
{
	NBT Root{ NBT::List() };
	Root.Poosh({ 1 });
	Root.Poosh({ 2 });

	for (const auto & Item : std::get<NBT::List>(Root.Expose()))
	{
		std::cout << std::get<int>(Item.Expose()) << '\n';
	}
}

int main()
{
    MakeNubby();
}

[12xx12]

Yeah I just noticed that also that you use a variant and make a nice interface

[12xx12]

So what do we do now? I'd like to have the NBT for items added for other projects (Banner, Potions,...)

standart did provide better option

[PureTryOut]

Has there been any progress on this recently?

[12xx12]

Check the discussion in #5015