Function canonical_repeat 

pub fn canonical_repeat(
    expr: GrammarExpr,
    min: u64,
    max: Option<u64>,
) -> Result<GrammarExpr, RepetitionBoundsError>

Lowers counted repetition to its most specific expression variant.

As the JavaScript canonicalRepeat builder does, 0.. is zero-or-more, 1.. is one-or-more, 0..1 is optional, and every other range is a counted repeat.

Errors

Returns RepetitionBoundsError when max is below min or either bound exceeds the JavaScript safe-integer range.