Function rustc_expand::mbe::transcribe::count_repetitions

fn count_repetitions<'a>(
    cx: &ExtCtxt<'a>,
    depth_opt: Option<usize>,
    matched: &NamedMatch,
    repeats: &[(usize, usize)],
    sp: &DelimSpan
) -> PResult<'a, usize>

Used solely by the count meta-variable expression, counts the outer-most repetitions at a given optional nested depth.

For example, a macro parameter of $( { $( $foo:ident ),* } )* called with { a, b } { c }:

• [ $( ${count(foo)} ),* ] will return [2, 1] with a, b = 2 and c = 1
• [ $( ${count(foo, 0)} ),* ] will be the same as [ $( ${count(foo)} ),* ]
• [ $( ${count(foo, 1)} ),* ] will return an error because ${count(foo, 1)} is declared inside a single repetition and the index 1 implies two nested repetitions.