creusot_std/std/iter/
enumerate.rs

1#[cfg(creusot)]
2use crate::resolve::structural_resolve;
3use crate::{
4    invariant::*,
5    prelude::*,
6    std::iter::{Enumerate, ExactSizeIteratorSpec},
7};
8
9pub trait EnumerateExt<I> {
10    #[logic]
11    fn iter(self) -> I;
12
13    #[logic]
14    fn n(self) -> usize;
15}
16
17impl<I> EnumerateExt<I> for Enumerate<I> {
18    #[logic(opaque)]
19    fn iter(self) -> I {
20        dead
21    }
22
23    #[logic(opaque)]
24    fn n(self) -> usize {
25        dead
26    }
27}
28
29impl<I> Resolve for Enumerate<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: IteratorSpec> Invariant for Enumerate<I> {
43    #[logic(prophetic)]
44    #[ensures(result ==> inv(self.iter()))]
45    fn invariant(self) -> bool {
46        pearlite! {
47            inv(self.iter())
48            && (forall<s: Seq<I::Item>, i: I>
49                #[trigger(self.iter().produces(s, i))]
50                self.iter().produces(s, i) ==>
51                self.n()@ + s.len() < core::usize::MAX@)
52            && (forall<i: &mut I> i.completed() ==> (*i).produces(Seq::empty(), ^i))
53        }
54    }
55}
56
57impl<I: IteratorSpec> IteratorSpec for Enumerate<I> {
58    #[logic(open, prophetic)]
59    fn completed(&mut self) -> bool {
60        pearlite! {
61            exists<inner: &mut _> *inner == self.iter() && ^inner == (^self).iter()
62                && inner.completed()
63                && self.n()@ == (^self).n()@
64        }
65    }
66
67    #[logic(open, prophetic)]
68    fn produces(self, visited: Seq<Self::Item>, o: Self) -> bool {
69        pearlite! {
70            visited.len() == o.n()@ - self.n()@
71            && exists<s: Seq<I::Item>>
72                   self.iter().produces(s, o.iter())
73                && visited.len() == s.len()
74                && forall<i> 0 <= i && i < s.len() ==> visited[i].0@ == self.n()@ + i && visited[i].1 == s[i]
75        }
76    }
77
78    #[logic(law)]
79    #[ensures(self.produces(Seq::empty(), self))]
80    fn produces_refl(self) {}
81
82    #[logic(law)]
83    #[requires(a.produces(ab, b))]
84    #[requires(b.produces(bc, c))]
85    #[ensures(a.produces(ab.concat(bc), c))]
86    fn produces_trans(a: Self, ab: Seq<Self::Item>, b: Self, bc: Seq<Self::Item>, c: Self) {}
87}
88
89extern_spec! {
90    impl<I: Iterator> Iterator for Enumerate<I> {
91        #[ensures(I::size_hint.postcondition((&self.iter(),), result))]
92        fn size_hint(&self) -> (usize, Option<usize>);
93    }
94}
95
96impl<'a, I: ExactSizeIteratorSpec> ExactSizeIteratorSpec for Enumerate<I> {
97    #[logic(law)]
98    #[requires(Self::size_hint.postcondition((self,), r))]
99    #[ensures(r.1 == Some(r.0))]
100    fn size_hint_exact(&self, r: (usize, Option<usize>)) {
101        self.iter().size_hint_exact(r)
102    }
103}
creusot_std/std/iter/enumerate.rs

creusot_std/std/iter/
enumerate.rs
