/
pin.rs
160 lines (138 loc) · 5.35 KB
/
pin.rs
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
//! Types which pin data to its location in memory
//!
//! See the [standard library module] for more information.
//!
//! [standard library module]: ../../std/pin/index.html
#![unstable(feature = "pin", issue = "49150")]
use fmt;
use future::{Future, UnsafeFutureObj};
use marker::{Sized, Unpin, Unsize};
use task::{Context, Poll};
use ops::{Deref, DerefMut, CoerceUnsized};
/// A pinned reference.
///
/// This type is similar to a mutable reference, except that it pins its value,
/// which prevents it from moving out of the reference, unless it implements [`Unpin`].
///
/// See the [`pin` module] documentation for furthur explanation on pinning.
///
/// [`Unpin`]: ../../std/marker/trait.Unpin.html
/// [`pin` module]: ../../std/pin/index.html
#[unstable(feature = "pin", issue = "49150")]
#[fundamental]
pub struct PinMut<'a, T: ?Sized + 'a> {
inner: &'a mut T,
}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: ?Sized + Unpin> PinMut<'a, T> {
/// Construct a new `PinMut` around a reference to some data of a type that
/// implements `Unpin`.
#[unstable(feature = "pin", issue = "49150")]
pub fn new(reference: &'a mut T) -> PinMut<'a, T> {
PinMut { inner: reference }
}
/// Get a mutable reference to the data inside of this `PinMut`.
#[unstable(feature = "pin", issue = "49150")]
pub fn get_mut(this: PinMut<'a, T>) -> &'a mut T {
this.inner
}
}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: ?Sized> PinMut<'a, T> {
/// Construct a new `PinMut` around a reference to some data of a type that
/// may or may not implement `Unpin`.
///
/// This constructor is unsafe because we do not know what will happen with
/// that data after the lifetime of the reference ends. If you cannot guarantee that the
/// data will never move again, calling this constructor is invalid.
#[unstable(feature = "pin", issue = "49150")]
pub unsafe fn new_unchecked(reference: &'a mut T) -> PinMut<'a, T> {
PinMut { inner: reference }
}
/// Reborrow a `PinMut` for a shorter lifetime.
///
/// For example, `PinMut::get_mut(x.reborrow())` (unsafely) returns a
/// short-lived mutable reference reborrowing from `x`.
#[unstable(feature = "pin", issue = "49150")]
pub fn reborrow<'b>(&'b mut self) -> PinMut<'b, T> {
PinMut { inner: self.inner }
}
/// Get a mutable reference to the data inside of this `PinMut`.
///
/// This function is unsafe. You must guarantee that you will never move
/// the data out of the mutable reference you receive when you call this
/// function.
#[unstable(feature = "pin", issue = "49150")]
pub unsafe fn get_mut_unchecked(this: PinMut<'a, T>) -> &'a mut T {
this.inner
}
/// Construct a new pin by mapping the interior value.
///
/// For example, if you wanted to get a `PinMut` of a field of something,
/// you could use this to get access to that field in one line of code.
///
/// This function is unsafe. You must guarantee that the data you return
/// will not move so long as the argument value does not move (for example,
/// because it is one of the fields of that value), and also that you do
/// not move out of the argument you receive to the interior function.
#[unstable(feature = "pin", issue = "49150")]
pub unsafe fn map_unchecked<U, F>(this: PinMut<'a, T>, f: F) -> PinMut<'a, U> where
F: FnOnce(&mut T) -> &mut U
{
PinMut { inner: f(this.inner) }
}
/// Assign a new value to the memory behind the pinned reference.
#[unstable(feature = "pin", issue = "49150")]
pub fn set(this: PinMut<'a, T>, value: T)
where T: Sized,
{
*this.inner = value;
}
}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: ?Sized> Deref for PinMut<'a, T> {
type Target = T;
fn deref(&self) -> &T {
&*self.inner
}
}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: ?Sized + Unpin> DerefMut for PinMut<'a, T> {
fn deref_mut(&mut self) -> &mut T {
self.inner
}
}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: fmt::Debug + ?Sized> fmt::Debug for PinMut<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(&**self, f)
}
}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: fmt::Display + ?Sized> fmt::Display for PinMut<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Display::fmt(&**self, f)
}
}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: ?Sized> fmt::Pointer for PinMut<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Pointer::fmt(&(&*self.inner as *const T), f)
}
}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<PinMut<'a, U>> for PinMut<'a, T> {}
#[unstable(feature = "pin", issue = "49150")]
impl<'a, T: ?Sized> Unpin for PinMut<'a, T> {}
#[unstable(feature = "futures_api", issue = "50547")]
unsafe impl<'a, T, F> UnsafeFutureObj<'a, T> for PinMut<'a, F>
where F: Future<Output = T> + 'a
{
fn into_raw(self) -> *mut () {
unsafe { PinMut::get_mut_unchecked(self) as *mut F as *mut () }
}
unsafe fn poll(ptr: *mut (), cx: &mut Context) -> Poll<T> {
PinMut::new_unchecked(&mut *(ptr as *mut F)).poll(cx)
}
unsafe fn drop(_ptr: *mut ()) {}
}