fn_traits/fns/
copy_fn.rs

1use crate::{Fn, FnMut, FnOnce};
2use core::marker::PhantomData;
3
4/// A function for copying an object.
5#[derive(Clone, Copy, Default)]
6pub struct CopyFn {
7    _phantom: PhantomData<()>,
8}
9
10impl<'a, T> FnOnce<(&'a T,)> for CopyFn
11where
12    T: Copy,
13{
14    type Output = T;
15
16    fn call_once(self, args: (&'a T,)) -> Self::Output {
17        *args.0
18    }
19}
20
21impl<'a, T> FnMut<(&'a T,)> for CopyFn
22where
23    T: Copy,
24{
25    type Output = T;
26
27    fn call_mut(&mut self, args: (&'a T,)) -> Self::Output {
28        self.call_once(args)
29    }
30}
31
32impl<'a, T> Fn<(&'a T,)> for CopyFn
33where
34    T: Copy,
35{
36    type Output = T;
37
38    fn call(&self, args: (&'a T,)) -> Self::Output {
39        self.call_once(args)
40    }
41}
42
43impl<'a, T> FnOnce<(&'a mut T,)> for CopyFn
44where
45    T: Copy,
46{
47    type Output = T;
48
49    fn call_once(self, args: (&'a mut T,)) -> Self::Output {
50        self.call_once((&*args.0,))
51    }
52}
53
54impl<'a, T> FnMut<(&'a mut T,)> for CopyFn
55where
56    T: Copy,
57{
58    type Output = T;
59
60    fn call_mut(&mut self, args: (&'a mut T,)) -> Self::Output {
61        self.call_once(args)
62    }
63}
64
65impl<'a, T> Fn<(&'a mut T,)> for CopyFn
66where
67    T: Copy,
68{
69    type Output = T;
70
71    fn call(&self, args: (&'a mut T,)) -> Self::Output {
72        self.call_once(args)
73    }
74}
75
76#[cfg(test)]
77mod tests {
78    use super::super::tests::{into_std_fn, into_std_fn_mut, into_std_fn_once};
79    use super::CopyFn;
80
81    #[test]
82    fn test_copy_fn() {
83        let f = CopyFn::default();
84        let mut x = 2;
85
86        assert_eq!(into_std_fn_once(Clone::clone(&f))(&x), 2);
87        assert_eq!(into_std_fn_mut(Clone::clone(&f))(&x), 2);
88        assert_eq!(into_std_fn(Clone::clone(&f))(&x), 2);
89
90        assert_eq!(into_std_fn_once(Clone::clone(&f))(&mut x), 2);
91        assert_eq!(into_std_fn_mut(Clone::clone(&f))(&mut x), 2);
92        assert_eq!(into_std_fn(Clone::clone(&f))(&mut x), 2);
93    }
94}
fn_traits/fns/copy_fn.rs

fn_traits/fns/
copy_fn.rs
