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pub trait Arity {
fn arity() -> usize;
}
macro_rules! impl_tuple_arity {
($len:expr, $($tuple_arg:ident),*) => {
impl<$($tuple_arg,)*> Arity for ($($tuple_arg,)*) {
#[inline(always)]
fn arity() -> usize {
$len
}
}
}
}
#[inline(always)]
pub fn tuple_arity<T: Arity>(_: &T) -> usize {
T::arity()
}
impl_tuple_arity!(0,);
impl_tuple_arity!(1, T1);
impl_tuple_arity!(2, T1, T2);
impl_tuple_arity!(3, T1, T2, T3);
impl_tuple_arity!(4, T1, T2, T3, T4);
impl_tuple_arity!(5, T1, T2, T3, T4, T5);
impl_tuple_arity!(6, T1, T2, T3, T4, T5, T6);
impl_tuple_arity!(7, T1, T2, T3, T4, T5, T6, T7);
impl_tuple_arity!(8, T1, T2, T3, T4, T5, T6, T7, T8);
impl_tuple_arity!(9, T1, T2, T3, T4, T5, T6, T7, T8, T9);
impl_tuple_arity!(10, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10);
impl_tuple_arity!(11, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11);
impl_tuple_arity!(12, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12);