facet-reflect 0.43.2

Build and manipulate values of arbitrary Facet types at runtime while respecting invariants - safe runtime reflection
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

#![allow(clippy::needless_lifetimes)]
use facet::Facet;
use facet_reflect::{Partial, ReflectError};
use facet_testhelpers::test;

#[derive(Debug, Facet)]
struct CovariantLifetime<'a> {
    _pd: std::marker::PhantomData<fn() -> &'a ()>,
}

#[derive(Debug, Facet)]
struct ContravariantLifetime<'a> {
    _pd: std::marker::PhantomData<fn(&'a ())>,
}

#[derive(Debug, Facet)]
struct InvariantLifetime<'a> {
    _pd: std::marker::PhantomData<fn(&'a ()) -> &'a ()>,
}

#[test]
fn covariant_works() {
    #[derive(Debug, Facet)]
    struct Wrapper<'a> {
        token: CovariantLifetime<'a>,
    }

    fn scope<'a>(token: CovariantLifetime<'a>) -> Result<Wrapper<'a>, ReflectError> {
        // SAFETY: Wrapper::<'a>::SHAPE comes from the derived Facet implementation
        let partial: Partial<'a> = unsafe { Partial::alloc_shape(Wrapper::<'a>::SHAPE) }.unwrap();
        partial
            .begin_field("token")
            .unwrap()
            .set(token)
            .unwrap()
            .end()
            .unwrap()
            .build()
            .unwrap()
            .materialize::<Wrapper>()
    }
    scope(CovariantLifetime {
        _pd: std::marker::PhantomData,
    })
    .unwrap();
}

#[test]
fn contravariant_works() {
    #[derive(Debug, Facet)]
    struct Wrapper<'a> {
        token: ContravariantLifetime<'a>,
    }

    fn scope<'a>(token: ContravariantLifetime<'a>) -> Result<Wrapper<'a>, ReflectError> {
        // SAFETY: Wrapper::<'a>::SHAPE comes from the derived Facet implementation
        let partial: Partial<'a> = unsafe { Partial::alloc_shape(Wrapper::<'a>::SHAPE) }.unwrap();
        partial
            .begin_field("token")
            .unwrap()
            .set(token)
            .unwrap()
            .end()
            .unwrap()
            .build()
            .unwrap()
            .materialize::<Wrapper>()
    }
    scope(ContravariantLifetime {
        _pd: std::marker::PhantomData,
    })
    .unwrap();
}

#[test]
fn invariant_works() {
    #[derive(Debug, Facet)]
    struct Wrapper<'a> {
        token: InvariantLifetime<'a>,
    }

    fn scope<'a>(token: InvariantLifetime<'a>) -> Result<Wrapper<'a>, ReflectError> {
        // SAFETY: Wrapper::<'a>::SHAPE comes from the derived Facet implementation
        let partial: Partial<'a> = unsafe { Partial::alloc_shape(Wrapper::<'a>::SHAPE) }.unwrap();
        partial
            .begin_field("token")
            .unwrap()
            .set(token)
            .unwrap()
            .end()
            .unwrap()
            .build()
            .unwrap()
            .materialize::<Wrapper>()
    }
    scope(InvariantLifetime {
        _pd: std::marker::PhantomData,
    })
    .unwrap();
}