New dice expressions to reroll exactly once, and either keep the new value or choose the higher

[selquest]

Is your feature request related to a problem? Please describe.
D&D 5th edition (and likely other systems) has a number of features that allow for dice below a certain threshold to be rerolled once, and either the new value must be kept or a choice is allowed to take the higher. The existing 2d6r3 syntax doesn't work here, as dice are rerolled repeatedly until all results are at least the threshold.

Describe the solution you'd like

• A new expression syntax like 2d6rk3 to reroll dice exactly once, and force the use of the new value.
• A new expression syntax like 2d6rc3 to reroll dice exactly once, and choose the higher result

Describe alternatives you've considered
This is currently achievable through macros checking the values in getNewRolls(), but would be much easier to manipulate in framework implementations as a dice expression.

[Phergus]

Appears to be a bug when more than one die is less than keep value.
[2d5rk3] returned 5 though [getNewRolls()] showed [1,2,1,3]. Result should be 4 as both of th second rolls should be used.

Also saw return of 7 with getNewRolls() of [2,2,1,5]. Result should be 6.

For [2d6rc3], it appears to be rerolling the rerolls
Result of 9 with getNewRolls() of [2,6,2,3]

Also saw result of 8 with getNewRolls() of [2,2,6]. Should have been two rerolls.

[selquest]

Ahh ok, actually in your examples here I think it's working as intended - since it's rolling each die at a time (and re-rolling if necessary), [1, 2, 1, 3] is showing that the 1 was re-rolled (and became a 2), and then the "second die" was originally a 1, re-rolled to become a 3. Total is 5.

I'll still take a look to confirm, but that's the sequence I'd expect.

[selquest]

@Phergus confirmed working as expected. The confusion here is that it re-rolls each die immediately in sequence - the same way the repeating reroll() function does.

[Phergus]

That's it. Didn't realize it was doing the rerolls immediately.

Tested. Rolls performing as expected.

[selquest]

Updated wiki page for Dice Expressions, added page for rerollOnce() function