Copy Effect

[UnderscoreTud]

Description

This PR adds a new effect for copying objects over into variables. With this newly added effect, you can now copy a list into another and preserving its indices, plus copying over its sub-lists.

Example:

set {_foo::bar} to 1
set {_foo::sublist::foobar} to "hey"
copy {_foo::*} to {_copy::*}
broadcast indices of {_copy::*} # "bar", "sublist"
broadcast {_copy::bar} # 1
broadcast {_copy::sublist::foobar} # "hey!"

---

Target Minecraft Versions: any
Requirements: none
Related Issues: #3127, #4947

[moraedu]

If it isn't too much to ask, maybe add the ability to copy up to certain length of a variable, like:

copy %objects% into %objects% [from %integer% to %integer%]
copy %objects% into %objects% [up to %integer%]

maybe with a better syntax but you get the gist of it

[Fusezion]

If it isn't too much to ask, maybe add the ability to copy up to certain length of a variable, like:

Is there any practical use?

[Moderocky]

If it isn't too much to ask, maybe add the ability to copy up to certain length of a variable, like:

copy %objects% into %objects% [from %integer% to %integer%]
copy %objects% into %objects% [up to %integer%]

maybe with a better syntax but you get the gist of it

This isn't very practical because lists are actually string-keyed maps in practice, so even if the indices happen to be numerical there's no guarantee they will resemble a proper order (e.g. you could have a list of 5 items with the indices 1, 2, 14, 22, 23, having deleted the intermediate entries or having set the indices individually) which means this would probably be very unintuitive and impractical.

[APickledWalrus]

tests? :)

[sovdeeth]

Needs tests and name change (see ayham review)