creusot_contracts/std/iter/
skip.rs

1#[cfg(creusot)]
2use crate::resolve::structural_resolve;
3use crate::{std::iter::Skip, *};
4
5pub trait SkipExt<I> {
6    #[logic]
7    fn iter(self) -> I;
8
9    #[logic]
10    fn n(self) -> Int;
11}
12
13impl<I> SkipExt<I> for Skip<I> {
14    #[trusted]
15    #[logic(opaque)]
16    #[ensures(inv(self) ==> inv(result))]
17    fn iter(self) -> I {
18        dead
19    }
20
21    #[trusted]
22    #[logic(opaque)]
23    #[ensures(result >= 0 && result <= usize::MAX@)]
24    fn n(self) -> Int {
25        dead
26    }
27}
28
29impl<I> Resolve for Skip<I> {
30    #[logic(open, prophetic, inline)]
31    fn resolve(self) -> bool {
32        resolve(self.iter())
33    }
34
35    #[trusted]
36    #[logic(prophetic)]
37    #[requires(structural_resolve(self))]
38    #[ensures(self.resolve())]
39    fn resolve_coherence(self) {}
40}
41
42impl<I: Iterator> Iterator for Skip<I> {
43    #[logic(open, prophetic)]
44    fn completed(&mut self) -> bool {
45        pearlite! {
46            (^self).n() == 0 &&
47            exists<s: Seq<Self::Item>, i: &mut I>
48                   s.len() <= (*self).n()
49                && self.iter().produces(s, *i)
50                && (forall<i> 0 <= i && i < s.len() ==> resolve(s[i]))
51                && i.completed()
52                && ^i == (^self).iter()
53        }
54    }
55
56    #[logic(open, prophetic)]
57    fn produces(self, visited: Seq<Self::Item>, o: Self) -> bool {
58        pearlite! {
59            visited == Seq::empty() && self == o ||
60            o.n() == 0 && visited.len() > 0 &&
61            exists<s: Seq<Self::Item>>
62                   s.len() == self.n()
63                && self.iter().produces(s.concat(visited), o.iter())
64                && forall<i> 0 <= i && i < s.len() ==> resolve(s[i])
65        }
66    }
67
68    #[logic(law)]
69    #[ensures(self.produces(Seq::empty(), self))]
70    fn produces_refl(self) {}
71
72    #[logic(law)]
73    #[requires(a.produces(ab, b))]
74    #[requires(b.produces(bc, c))]
75    #[ensures(a.produces(ab.concat(bc), c))]
76    fn produces_trans(a: Self, ab: Seq<Self::Item>, b: Self, bc: Seq<Self::Item>, c: Self) {}
77}
creusot_contracts/std/iter/skip.rs

creusot_contracts/std/iter/
skip.rs
