creusot_std/std/iter/
empty.rs

1use crate::{
2    prelude::*,
3    std::iter::{Empty, ExactSizeIteratorSpec},
4};
5
6impl<T> IteratorSpec for Empty<T> {
7    #[logic(open, prophetic)]
8    fn completed(&mut self) -> bool {
9        resolve(self)
10    }
11
12    #[logic(open)]
13    fn produces(self, visited: Seq<T>, o: Self) -> bool {
14        pearlite! { visited == Seq::empty() && self == o }
15    }
16
17    #[logic(law)]
18    #[ensures(self.produces(Seq::empty(), self))]
19    fn produces_refl(self) {}
20
21    #[logic(law)]
22    #[requires(a.produces(ab, b))]
23    #[requires(b.produces(bc, c))]
24    #[ensures(a.produces(ab.concat(bc), c))]
25    fn produces_trans(a: Self, ab: Seq<T>, b: Self, bc: Seq<T>, c: Self) {
26        proof_assert!(Seq::<T>::empty().concat(Seq::empty()) == Seq::empty())
27    }
28}
29
30extern_spec! {
31    impl<T> Iterator for Empty<T> {
32        #[check(ghost)]
33        #[ensures(result == None && self.completed())]
34        fn next(&mut self) -> Option<T>;
35
36        #[check(ghost)]
37        #[ensures(result == (0usize, Some(0usize)))]
38        fn size_hint(&self) -> (usize, Option<usize>);
39    }
40}
41
42impl<T> ExactSizeIteratorSpec for Empty<T> {
43    #[logic(law)]
44    #[requires(Self::size_hint.postcondition((self,), r))]
45    #[ensures(r.1 == Some(r.0))]
46    #[allow(unused_variables)]
47    fn size_hint_exact(&self, r: (usize, Option<usize>)) {}
48}
creusot_std/std/iter/empty.rs

creusot_std/std/iter/
empty.rs
