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
use std::cell::UnsafeCell;
use std::marker::PhantomData;
use std::ptr;
use objc::Message;
use objc::runtime::Object;
use {Id, ShareId};
#[link(name = "objc", kind = "dylib")]
extern {
fn objc_storeWeak(location: *mut *mut Object, obj: *mut Object) -> *mut Object;
fn objc_loadWeakRetained(location: *mut *mut Object) -> *mut Object;
fn objc_destroyWeak(addr: *mut *mut Object);
}
struct WeakPtr(Box<UnsafeCell<*mut Object>>);
impl WeakPtr {
fn new(obj: *mut Object) -> WeakPtr {
let ptr = Box::new(UnsafeCell::new(ptr::null_mut()));
unsafe {
objc_storeWeak(ptr.get(), obj);
}
WeakPtr(ptr)
}
fn load(&self) -> *mut Object {
unsafe {
objc_loadWeakRetained(self.0.get())
}
}
}
impl Drop for WeakPtr {
fn drop(&mut self) {
unsafe {
objc_destroyWeak(self.0.get());
}
}
}
pub struct WeakId<T> {
ptr: WeakPtr,
item: PhantomData<T>,
}
impl<T> WeakId<T> where T: Message {
pub fn new(obj: &ShareId<T>) -> WeakId<T> {
let obj_ptr: *const T = &**obj;
WeakId {
ptr: WeakPtr::new(obj_ptr as *mut Object),
item: PhantomData,
}
}
pub fn load(&self) -> Option<ShareId<T>> {
let obj = self.ptr.load();
if obj.is_null() {
None
} else {
unsafe { Some(Id::from_retained_ptr(obj as *mut T)) }
}
}
}
unsafe impl<T> Sync for WeakId<T> where T: Sync { }
unsafe impl<T> Send for WeakId<T> where T: Sync { }
#[cfg(test)]
mod tests {
use objc::runtime::{Class, Object};
use {Id, ShareId};
use super::WeakId;
#[test]
fn test_weak() {
let cls = Class::get("NSObject").unwrap();
let obj: ShareId<Object> = unsafe {
let obj: *mut Object = msg_send![cls, alloc];
let obj: *mut Object = msg_send![obj, init];
Id::from_retained_ptr(obj)
};
let weak = WeakId::new(&obj);
let strong = weak.load().unwrap();
let strong_ptr: *const Object = &*strong;
let obj_ptr: *const Object = &*obj;
assert!(strong_ptr == obj_ptr);
drop(strong);
drop(obj);
assert!(weak.load().is_none());
}
}