Hash implementation

[timothee-haudebourg]

I need to organize JsonValues into a HashSet however I just noticed that JsonValue does not implement the Hash trait. Is there a reason for that?

[timothee-haudebourg]

Going deeper, I see that Object is implemented as a Binary tree, so there is a defined order between the keys of an object. Then I see no reason why it would not be possible to define an order between every JSON value? And a Hash?

[maciejhirsz]

The keys are sorted into a tree, but the tree will be balanced differently depending on insertion order, so hashes would differ. If you are fine with matching objects with keys at insertion order then adding Hash impl should be pretty straight forward (at least in the new implementation, which is much cleaner, though still quite a bit in flux).

[timothee-haudebourg]

When can we expect this new implementation to be released? Can we follow its development somewhere?

[A248]

Even if Object does not have a defined order, it is still possible to create a Hash implementation for it.

See rust-lang/rust#48366 for an implementation of Hash on an unordered data structure.