Is there any way of anchoring regex by beginning and ending of selections?

[TaylorRichberger]

If I have, for example, a json file:

{
  "alpha--beta": "gamma",
  "delta--": "epsilon",
  "zeta--eta--": "theta",
  "iota--kappa": "lambda"
}

And I have a selection encompassing each of the keys. I want to filter to just the keys that match the entire regex ^[a-z]+--[a-z]+$. Unfortunately, ^ and $ only match the beginning and ending of lines, not selections. If I do [a-z]+--[a-z]+, it keeps the zeta--eta-- line, which I don't want.

I know I can select the surrounding quotes too in this case, but I think in general, it would be useful to be able to use keep_selections and remove_selections with a regex that matches against the beginning, ending, or entire selection via some selection-specific anchor, if not ^ and $, or \A and \z. I realize this might not be possible, due to deferring the regex processing to the regex crate, but I was wondering if anybody had any specific workarounds for this kind of editing action?

[the-mikedavis]

Ideally this would be supported by \A / \z but it is not supported upstream yet, see rust-lang/regex#1161