anodized 0.6.0

A common specification layer for Rust
Documentation 
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
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

use anodized::spec;

//////////////////////////
// Test runtime checks. //
//////////////////////////

#[spec]
trait MinFinder<T: PartialOrd> {
    #[spec(
        total,
        requires: [
            !input.is_empty(),
        ],
        ensures: |ref output| [
            input.iter().all(|item| output <= item),
            input.iter().any(|item| output == item) || input.is_empty(),
        ],
    )]
    fn find_min(input: &[T]) -> T;
}

pub struct ValidNarrowing;

#[spec]
impl MinFinder<f32> for ValidNarrowing {
    #[spec(
        // Stronger than trait qualifiers: is also `pure` (`deterministic` and `effectfree`).
        functional,
        // Weaker than trait precondition: allows `input` to be empty.
        requires: [],
        // Stronger than trait postcondition: clarifies what to output when `input` is empty.
        ensures: |ref output| [
            input.iter().all(|item| output <= item),
            input.iter().any(|item| output == item)
                || (input.is_empty() && *output == f32::INFINITY),
        ],
    )]
    #[warn(unused_comparisons)]
    fn find_min(input: &[f32]) -> f32 {
        let mut min = f32::INFINITY;
        for item in input.iter().copied() {
            if item < min {
                min = item;
            }
        }
        min
    }
}

pub struct StrongerImplPre;

#[spec]
impl MinFinder<i32> for StrongerImplPre {
    #[spec(
        total,
        // INVALID - Stronger than trait precondition: requires sorted `input`.
        requires: [
            !input.is_empty(),
            input.is_sorted(),
        ],
        ensures: |ref output| [
            input.iter().all(|item| output <= item),
            input.iter().any(|item| output == item) || input.is_empty(),
        ],
    )]
    fn find_min(input: &[i32]) -> i32 {
        input[0]
    }
}

pub struct WeakerImplPost;

#[spec]
impl MinFinder<u32> for WeakerImplPost {
    #[spec(
        total,
        requires: [
            !input.is_empty(),
        ],
        // INVALID - Weaker than trait postcondition: `input` may be ignored completely.
        ensures: |ref output| [
            input.iter().all(|item| output <= item),
        ],
    )]
    fn find_min(input: &[u32]) -> u32 {
        let _ = input;
        0
    }
}

#[test]
fn runtime_allows_valid_narrowing() {
    // NOTE: The trait's runtime checks are active even when the concrete type is statically known.
    let seq = [5.0, -42.0, std::f32::consts::PI];
    assert_eq!(ValidNarrowing::find_min(&seq), -42.0);
}

#[cfg(all(anodized_print, anodized_panic))]
#[test]
#[should_panic(expected = "precondition failed:\
\n    input.is_sorted()")]
fn runtime_rejects_stronger_impl_precondition() {
    // NOTE: The trait's runtime checks are active even when the concrete type is statically known.
    let seq = [5, -42, 3];
    assert_eq!(StrongerImplPre::find_min(&seq), -42);
}

#[cfg(all(anodized_print, anodized_panic))]
#[test]
#[should_panic(expected = "postcondition failed:\
\n    input.iter().any(| item | output == item) || input.is_empty()")]
fn runtime_rejects_weaker_impl_postcondition() {
    // NOTE: The trait's runtime checks are active even when the concrete type is statically known.
    let seq = [5, 42, 3];
    assert_eq!(WeakerImplPost::find_min(&seq), 3);
}

//////////////////////////////////////////////////////
// Smoke-test instrumentation on more complex code. //
//////////////////////////////////////////////////////

#[spec]
pub trait Matrix<T> {
    fn count_rows(&self) -> usize;
    fn count_cols(&self) -> usize;

    #[spec(
        requires: [
            input.count_rows() == self.count_cols(),
        ],
        ensures: |ref output| [
            output.count_rows() == self.count_rows(),
            output.count_cols() == input.count_cols(),
        ],
    )]
    fn mul<Input: Matrix<T>, Output: Matrix<T>>(&self, input: &Input) -> Output;
}

pub struct DiagonalMatrix<T>(Vec<T>);

#[spec]
impl<T> Matrix<T> for DiagonalMatrix<T> {
    #[spec(ensures: |output| output == self.count_cols())]
    fn count_rows(&self) -> usize {
        self.0.len()
    }

    #[spec(ensures: |output| output == self.count_rows())]
    fn count_cols(&self) -> usize {
        self.0.len()
    }

    #[spec(
        requires: [
            input.count_rows() == self.count_cols(),
        ],
        ensures: |ref output| [
            output.count_rows() == input.count_rows(),
            output.count_cols() == input.count_cols(),
        ],
    )]
    fn mul<Input: Matrix<T>, Output: Matrix<T>>(&self, input: &Input) -> Output {
        let _ = input;
        todo!()
    }
}