variadic/
lib.rs

1pub trait Variadic<T, A = T, B = A, C = B> {
2    type OneLess: Variadic<A, B, C>;
3    fn pop(self) -> (Option<T>, Self::OneLess);
4}
5
6pub struct VarArgs4<A, B, C, D>(A, B, C, D);
7pub struct VarArgs3<A, B, C>(A, B, C);
8pub struct VarArgs2<A, B>(A, B);
9pub struct VarArgs1<A>(A);
10pub struct VarArgs0<A> {
11    _m: std::marker::PhantomData<A>,
12}
13
14impl<T, A, B, C> Variadic<T, A, B, C> for VarArgs4<T, A, B, C> {
15    type OneLess = VarArgs3<A, B, C>;
16    fn pop(self) -> (Option<T>, Self::OneLess) {
17        let VarArgs4(t, a, b, c) = self;
18        (Some(t), VarArgs3(a, b, c))
19    }
20}
21
22impl<T, A, B> Variadic<T, A, B> for VarArgs3<T, A, B> {
23    type OneLess = VarArgs2<A, B>;
24    fn pop(self) -> (Option<T>, Self::OneLess) {
25        let VarArgs3(t, a, b) = self;
26        (Some(t), VarArgs2(a, b))
27    }
28}
29
30impl<T, A> Variadic<T, A> for VarArgs2<T, A> {
31    type OneLess = VarArgs1<A>;
32    fn pop(self) -> (Option<T>, Self::OneLess) {
33        let VarArgs2(t, a) = self;
34        (Some(t), VarArgs1(a))
35    }
36}
37
38impl<T> Variadic<T> for VarArgs1<T> {
39    type OneLess = VarArgs0<T>;
40    fn pop(self) -> (Option<T>, Self::OneLess) {
41        let VarArgs1(t) = self;
42        (Some(t), VarArgs0 { _m: std::marker::PhantomData })
43    }
44}
45
46impl<T> Variadic<T> for VarArgs0<T> {
47    type OneLess = VarArgs0<T>;
48    fn pop(self) -> (Option<T>, Self) {
49        (None, VarArgs0 { _m: std::marker::PhantomData })
50    }
51}
52
variadic/lib.rs

variadic/
lib.rs
