Luna::VariantUtils::add_diff_prefix

void add_diff_prefix(Variant &delta, Span< const Variant > prefix_nodes)

Adds prefix nodes to the delta object.

This can be used if the delta object is computed from a child variant, but the user wants to patch the delta object to a parent variant. See remarks for details.

Parameters

• in delta

  The delta object to modify.

• in prefix_nodes

  The prefix nodes to add to the delta object.

Remark

For example, if we have the following variant:

{
    "rootRegion":
    {
        "members":
        [
            {
                "row":2
            }
        ]
    }
}

and we have the following delta:

{
    "row": [2,3]
}

after adding prefix nodes { "rootRegion", "members", (u64)0 } to the delta, the result delta object will be:

{
    "rootRegion": {
        "members": {
            "_t": "a",
            "0": {
                "row": [2,3]
            }
        }
    }
}

which can be used to change the value of ["rootRegion"]["members"][0]["rows"] from 2 to 3.