[go: up one dir, main page]

pin-project 0.3.3

An attribute that creates a projection struct covering all the fields.
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

#![recursion_limit = "128"]
#![no_std]
#![warn(unsafe_code)]
#![warn(rust_2018_idioms)]
#![allow(dead_code)]

use core::pin::Pin;
use pin_project::unsafe_project;

#[test]
fn test_unsafe_project() {
    // struct

    #[unsafe_project(Unpin)]
    struct Foo<T, U> {
        #[pin]
        field1: T,
        field2: U,
    }

    let mut foo = Foo { field1: 1, field2: 2 };

    let foo = Pin::new(&mut foo).project();

    let x: Pin<&mut i32> = foo.field1;
    assert_eq!(*x, 1);

    let y: &mut i32 = foo.field2;
    assert_eq!(*y, 2);

    // tuple struct

    #[unsafe_project(Unpin)]
    struct Bar<T, U>(#[pin] T, U);

    let mut bar = Bar(1, 2);

    let bar = Pin::new(&mut bar).project();

    let x: Pin<&mut i32> = bar.0;
    assert_eq!(*x, 1);

    let y: &mut i32 = bar.1;
    assert_eq!(*y, 2);

    // enum

    #[unsafe_project(Unpin)]
    enum Baz<A, B, C, D> {
        Variant1(#[pin] A, B),
        Variant2 {
            #[pin]
            field1: C,
            field2: D,
        },
        None,
    }

    let mut baz = Baz::Variant1(1, 2);

    let baz = Pin::new(&mut baz).project();

    match baz {
        __BazProjection::Variant1(x, y) => {
            let x: Pin<&mut i32> = x;
            assert_eq!(*x, 1);

            let y: &mut i32 = y;
            assert_eq!(*y, 2);
        }
        __BazProjection::Variant2 { field1, field2 } => {
            let _x: Pin<&mut i32> = field1;
            let _y: &mut i32 = field2;
        }
        __BazProjection::None => {}
    }

    let mut baz = Baz::Variant2 { field1: 3, field2: 4 };

    let mut baz = Pin::new(&mut baz).project();

    match &mut baz {
        __BazProjection::Variant1(x, y) => {
            let _x: &mut Pin<&mut i32> = x;
            let _y: &mut &mut i32 = y;
        }
        __BazProjection::Variant2 { field1, field2 } => {
            let x: &mut Pin<&mut i32> = field1;
            assert_eq!(**x, 3);

            let y: &mut &mut i32 = field2;
            assert_eq!(**y, 4);
        }
        __BazProjection::None => {}
    }

    if let __BazProjection::Variant2 { field1, field2 } = baz {
        let x: Pin<&mut i32> = field1;
        assert_eq!(*x, 3);

        let y: &mut i32 = field2;
        assert_eq!(*y, 4);
    }
}

#[test]
fn where_clause_and_associated_type_fields() {
    // struct

    #[unsafe_project(Unpin)]
    struct Foo<I>
    where
        I: Iterator,
    {
        #[pin]
        field1: I,
        field2: I::Item,
    }

    // enum

    #[unsafe_project(Unpin)]
    enum Baz<I>
    where
        I: Iterator,
    {
        Variant1(#[pin] I),
        Variant2(I::Item),
    }
}

#[test]
fn trait_bounds_on_type_generics() {
    // struct

    #[unsafe_project(Unpin)]
    pub struct Foo<'a, T: ?Sized> {
        field: &'a mut T,
    }

    // tuple struct
    #[unsafe_project(Unpin)]
    pub struct Bar<'a, T: ?Sized>(&'a mut T);

    // enum

    #[unsafe_project(Unpin)]
    enum Baz<'a, T: ?Sized> {
        Variant(&'a mut T),
    }
}