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
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67

#[inline]
pub fn fst<T: Fst>(t: T) -> T::Ret {
    t.fst()
}

pub trait Fst {
    type Ret;
    fn fst(self) -> Self::Ret;
}

pub trait FstTest {
    type Ret;
    fn fst(self) -> Self::Ret;
}

macro_rules! impl_fst {
    (
        $( $t:tt ),+ ;$r:ty
    ) => {
        impl < $($t),+ > Fst for ($($t),+) {
            type Ret = $r;
            fn fst(self) -> Self::Ret {
                self.0
            }
        }

        impl <'a, $($t),+ > Fst for &'a ($($t),+) {
            type Ret = &'a $r;
            fn fst(self) -> Self::Ret {
                &self.0
            }
        }
    };
}

impl<T> Fst for (T,) {
    type Ret = T;

    fn fst(self) -> Self::Ret {
        self.0
    }
}

impl<'a, T> Fst for &'a (T,) {
    type Ret = &'a T;

    fn fst(self) -> Self::Ret {
        &self.0
    }
}

impl_fst!(T0,T1;T0);
impl_fst!(T0,T1, T2;T0);
impl_fst!(T0,T1, T2 , T3;T0);
impl_fst!(T0,T1, T2, T3, T4;T0);
impl_fst!(T0,T1, T2, T3, T4, T5;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8, T9;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8, T9, T10;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15;T0);
impl_fst!(T0,T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16;T0);