1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
crate::do_impl!("length", tuple_length, {
/// Return the length of a tuple.
///
/// ```
/// use tupleops::length;
///
/// assert_eq!(0, length(&()));
/// assert_eq!(1, length(&(1,)));
/// assert_eq!(2, length(&(1, 2)));
/// assert_eq!(3, length(&(1, 2, 3)));
/// ```
///
/// See also: [TupleLength].
#[cfg_attr(docsrs, doc(cfg(feature = "length")))]
#[cfg_attr(docsrs, doc(cfg(feature = "feature-const_fn_trait_bound")))]
#[cfg(feature = "feature-const_fn_trait_bound")]
pub const fn length<Tpl>(_: &Tpl) -> usize
where
Tpl: TupleLength,
{
<Tpl as TupleLength>::LENGTH
}
/// A tuple with a known length.
///
/// ```
/// use tupleops::TupleLength;
///
/// assert_eq!(0, <() as TupleLength>::LENGTH);
///
/// assert_eq!(1, <(u8,) as TupleLength>::LENGTH);
///
/// assert_eq!(2, <(u8, u16) as TupleLength>::LENGTH);
///
/// assert_eq!(3, <(u8, u16, u32) as TupleLength>::LENGTH);
/// ```
///
/// See also: [length()].
#[cfg_attr(docsrs, doc(cfg(feature = "length")))]
pub trait TupleLength {
/// The number of elements in this tuple
const LENGTH: usize;
}
impl TupleLength for () {
const LENGTH: usize = 0;
}
});