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1 | #![warn(missing_docs)] |
2 | ||
3 | /*! | |
4 | # An owning reference. | |
5 | ||
6 | This crate provides the _owning reference_ types `OwningRef` and `OwningRefMut` | |
7 | that enables it to bundle a reference together with the owner of the data it points to. | |
8 | This allows moving and dropping of a `OwningRef` without needing to recreate the reference. | |
9 | ||
10 | This can sometimes be useful because Rust borrowing rules normally prevent | |
11 | moving a type that has been moved from. For example, this kind of code gets rejected: | |
12 | ||
13 | ```rust,ignore | |
14 | fn return_owned_and_referenced<'a>() -> (Vec<u8>, &'a [u8]) { | |
15 | let v = vec![1, 2, 3, 4]; | |
16 | let s = &v[1..3]; | |
17 | (v, s) | |
18 | } | |
19 | ``` | |
20 | ||
21 | Even though, from a memory-layout point of view, this can be entirely safe | |
22 | if the new location of the vector still lives longer than the lifetime `'a` | |
23 | of the reference because the backing allocation of the vector does not change. | |
24 | ||
25 | This library enables this safe usage by keeping the owner and the reference | |
26 | bundled together in a wrapper type that ensure that lifetime constraint: | |
27 | ||
28 | ```rust | |
29 | # extern crate owning_ref; | |
30 | # use owning_ref::OwningRef; | |
31 | # fn main() { | |
32 | fn return_owned_and_referenced() -> OwningRef<Vec<u8>, [u8]> { | |
33 | let v = vec![1, 2, 3, 4]; | |
34 | let or = OwningRef::new(v); | |
35 | let or = or.map(|v| &v[1..3]); | |
36 | or | |
37 | } | |
38 | # } | |
39 | ``` | |
40 | ||
41 | It works by requiring owner types to dereference to stable memory locations | |
42 | and preventing mutable access to root containers, which in practice requires heap allocation | |
43 | as provided by `Box<T>`, `Rc<T>`, etc. | |
44 | ||
45 | Also provided are typedefs for common owner type combinations, | |
46 | which allow for less verbose type signatures. For example, `BoxRef<T>` instead of `OwningRef<Box<T>, T>`. | |
47 | ||
48 | The crate also provides the more advanced `OwningHandle` type, | |
49 | which allows more freedom in bundling a dependent handle object | |
50 | along with the data it depends on, at the cost of some unsafe needed in the API. | |
51 | See the documentation around `OwningHandle` for more details. | |
52 | ||
53 | # Examples | |
54 | ||
55 | ## Basics | |
56 | ||
57 | ``` | |
58 | extern crate owning_ref; | |
59 | use owning_ref::BoxRef; | |
60 | ||
61 | fn main() { | |
62 | // Create an array owned by a Box. | |
63 | let arr = Box::new([1, 2, 3, 4]) as Box<[i32]>; | |
64 | ||
65 | // Transfer into a BoxRef. | |
66 | let arr: BoxRef<[i32]> = BoxRef::new(arr); | |
67 | assert_eq!(&*arr, &[1, 2, 3, 4]); | |
68 | ||
69 | // We can slice the array without losing ownership or changing type. | |
70 | let arr: BoxRef<[i32]> = arr.map(|arr| &arr[1..3]); | |
71 | assert_eq!(&*arr, &[2, 3]); | |
72 | ||
73 | // Also works for Arc, Rc, String and Vec! | |
74 | } | |
75 | ``` | |
76 | ||
77 | ## Caching a reference to a struct field | |
78 | ||
79 | ``` | |
80 | extern crate owning_ref; | |
81 | use owning_ref::BoxRef; | |
82 | ||
83 | fn main() { | |
84 | struct Foo { | |
85 | tag: u32, | |
86 | x: u16, | |
87 | y: u16, | |
88 | z: u16, | |
89 | } | |
90 | let foo = Foo { tag: 1, x: 100, y: 200, z: 300 }; | |
91 | ||
92 | let or = BoxRef::new(Box::new(foo)).map(|foo| { | |
93 | match foo.tag { | |
94 | 0 => &foo.x, | |
95 | 1 => &foo.y, | |
96 | 2 => &foo.z, | |
97 | _ => panic!(), | |
98 | } | |
99 | }); | |
100 | ||
101 | assert_eq!(*or, 200); | |
102 | } | |
103 | ``` | |
104 | ||
105 | ## Caching a reference to an entry in a vector | |
106 | ||
107 | ``` | |
108 | extern crate owning_ref; | |
109 | use owning_ref::VecRef; | |
110 | ||
111 | fn main() { | |
112 | let v = VecRef::new(vec![1, 2, 3, 4, 5]).map(|v| &v[3]); | |
113 | assert_eq!(*v, 4); | |
114 | } | |
115 | ``` | |
116 | ||
117 | ## Caching a subslice of a String | |
118 | ||
119 | ``` | |
120 | extern crate owning_ref; | |
121 | use owning_ref::StringRef; | |
122 | ||
123 | fn main() { | |
124 | let s = StringRef::new("hello world".to_owned()) | |
125 | .map(|s| s.split(' ').nth(1).unwrap()); | |
126 | ||
127 | assert_eq!(&*s, "world"); | |
128 | } | |
129 | ``` | |
130 | ||
131 | ## Reference counted slices that share ownership of the backing storage | |
132 | ||
133 | ``` | |
134 | extern crate owning_ref; | |
135 | use owning_ref::RcRef; | |
136 | use std::rc::Rc; | |
137 | ||
138 | fn main() { | |
139 | let rc: RcRef<[i32]> = RcRef::new(Rc::new([1, 2, 3, 4]) as Rc<[i32]>); | |
140 | assert_eq!(&*rc, &[1, 2, 3, 4]); | |
141 | ||
142 | let rc_a: RcRef<[i32]> = rc.clone().map(|s| &s[0..2]); | |
143 | let rc_b = rc.clone().map(|s| &s[1..3]); | |
144 | let rc_c = rc.clone().map(|s| &s[2..4]); | |
145 | assert_eq!(&*rc_a, &[1, 2]); | |
146 | assert_eq!(&*rc_b, &[2, 3]); | |
147 | assert_eq!(&*rc_c, &[3, 4]); | |
148 | ||
149 | let rc_c_a = rc_c.clone().map(|s| &s[1]); | |
150 | assert_eq!(&*rc_c_a, &4); | |
151 | } | |
152 | ``` | |
153 | ||
154 | ## Atomic reference counted slices that share ownership of the backing storage | |
155 | ||
156 | ``` | |
157 | extern crate owning_ref; | |
158 | use owning_ref::ArcRef; | |
159 | use std::sync::Arc; | |
160 | ||
161 | fn main() { | |
162 | use std::thread; | |
163 | ||
164 | fn par_sum(rc: ArcRef<[i32]>) -> i32 { | |
165 | if rc.len() == 0 { | |
166 | return 0; | |
167 | } else if rc.len() == 1 { | |
168 | return rc[0]; | |
169 | } | |
170 | let mid = rc.len() / 2; | |
171 | let left = rc.clone().map(|s| &s[..mid]); | |
172 | let right = rc.map(|s| &s[mid..]); | |
173 | ||
174 | let left = thread::spawn(move || par_sum(left)); | |
175 | let right = thread::spawn(move || par_sum(right)); | |
176 | ||
177 | left.join().unwrap() + right.join().unwrap() | |
178 | } | |
179 | ||
180 | let rc: Arc<[i32]> = Arc::new([1, 2, 3, 4]); | |
181 | let rc: ArcRef<[i32]> = rc.into(); | |
182 | ||
183 | assert_eq!(par_sum(rc), 10); | |
184 | } | |
185 | ``` | |
186 | ||
187 | ## References into RAII locks | |
188 | ||
189 | ``` | |
190 | extern crate owning_ref; | |
191 | use owning_ref::RefRef; | |
192 | use std::cell::{RefCell, Ref}; | |
193 | ||
194 | fn main() { | |
195 | let refcell = RefCell::new((1, 2, 3, 4)); | |
196 | // Also works with Mutex and RwLock | |
197 | ||
198 | let refref = { | |
199 | let refref = RefRef::new(refcell.borrow()).map(|x| &x.3); | |
200 | assert_eq!(*refref, 4); | |
201 | ||
202 | // We move the RAII lock and the reference to one of | |
203 | // the subfields in the data it guards here: | |
204 | refref | |
205 | }; | |
206 | ||
207 | assert_eq!(*refref, 4); | |
208 | ||
209 | drop(refref); | |
210 | ||
211 | assert_eq!(*refcell.borrow(), (1, 2, 3, 4)); | |
212 | } | |
213 | ``` | |
214 | ||
215 | ## Mutable reference | |
216 | ||
217 | When the owned container implements `DerefMut`, it is also possible to make | |
0731742a | 218 | a _mutable owning reference_. (e.g., with `Box`, `RefMut`, `MutexGuard`) |
ff7c6d11 XL |
219 | |
220 | ``` | |
221 | extern crate owning_ref; | |
222 | use owning_ref::RefMutRefMut; | |
223 | use std::cell::{RefCell, RefMut}; | |
224 | ||
225 | fn main() { | |
226 | let refcell = RefCell::new((1, 2, 3, 4)); | |
227 | ||
228 | let mut refmut_refmut = { | |
229 | let mut refmut_refmut = RefMutRefMut::new(refcell.borrow_mut()).map_mut(|x| &mut x.3); | |
230 | assert_eq!(*refmut_refmut, 4); | |
231 | *refmut_refmut *= 2; | |
232 | ||
233 | refmut_refmut | |
234 | }; | |
235 | ||
236 | assert_eq!(*refmut_refmut, 8); | |
237 | *refmut_refmut *= 2; | |
238 | ||
239 | drop(refmut_refmut); | |
240 | ||
241 | assert_eq!(*refcell.borrow(), (1, 2, 3, 16)); | |
242 | } | |
243 | ``` | |
244 | */ | |
245 | ||
0531ce1d | 246 | use std::mem; |
ff7c6d11 XL |
247 | pub use stable_deref_trait::{StableDeref as StableAddress, CloneStableDeref as CloneStableAddress}; |
248 | ||
249 | /// An owning reference. | |
250 | /// | |
251 | /// This wraps an owner `O` and a reference `&T` pointing | |
252 | /// at something reachable from `O::Target` while keeping | |
253 | /// the ability to move `self` around. | |
254 | /// | |
255 | /// The owner is usually a pointer that points at some base type. | |
256 | /// | |
257 | /// For more details and examples, see the module and method docs. | |
258 | pub struct OwningRef<O, T: ?Sized> { | |
259 | owner: O, | |
260 | reference: *const T, | |
261 | } | |
262 | ||
263 | /// An mutable owning reference. | |
264 | /// | |
265 | /// This wraps an owner `O` and a reference `&mut T` pointing | |
266 | /// at something reachable from `O::Target` while keeping | |
267 | /// the ability to move `self` around. | |
268 | /// | |
269 | /// The owner is usually a pointer that points at some base type. | |
270 | /// | |
271 | /// For more details and examples, see the module and method docs. | |
272 | pub struct OwningRefMut<O, T: ?Sized> { | |
273 | owner: O, | |
274 | reference: *mut T, | |
275 | } | |
276 | ||
277 | /// Helper trait for an erased concrete type an owner dereferences to. | |
278 | /// This is used in form of a trait object for keeping | |
279 | /// something around to (virtually) call the destructor. | |
280 | pub trait Erased {} | |
281 | impl<T> Erased for T {} | |
282 | ||
0531ce1d | 283 | /// Helper trait for erasing the concrete type of what an owner dereferences to, |
ff7c6d11 XL |
284 | /// for example `Box<T> -> Box<Erased>`. This would be unneeded with |
285 | /// higher kinded types support in the language. | |
286 | pub unsafe trait IntoErased<'a> { | |
287 | /// Owner with the dereference type substituted to `Erased`. | |
288 | type Erased; | |
9fa01778 | 289 | /// Performs the type erasure. |
ff7c6d11 XL |
290 | fn into_erased(self) -> Self::Erased; |
291 | } | |
292 | ||
0531ce1d XL |
293 | /// Helper trait for erasing the concrete type of what an owner dereferences to, |
294 | /// for example `Box<T> -> Box<Erased + Send>`. This would be unneeded with | |
295 | /// higher kinded types support in the language. | |
296 | pub unsafe trait IntoErasedSend<'a> { | |
297 | /// Owner with the dereference type substituted to `Erased + Send`. | |
298 | type Erased: Send; | |
9fa01778 | 299 | /// Performs the type erasure. |
0531ce1d XL |
300 | fn into_erased_send(self) -> Self::Erased; |
301 | } | |
302 | ||
303 | /// Helper trait for erasing the concrete type of what an owner dereferences to, | |
ff7c6d11 XL |
304 | /// for example `Box<T> -> Box<Erased + Send + Sync>`. This would be unneeded with |
305 | /// higher kinded types support in the language. | |
0531ce1d | 306 | pub unsafe trait IntoErasedSendSync<'a> { |
ff7c6d11 XL |
307 | /// Owner with the dereference type substituted to `Erased + Send + Sync`. |
308 | type Erased: Send + Sync; | |
9fa01778 | 309 | /// Performs the type erasure. |
ff7c6d11 XL |
310 | fn into_erased_send_sync(self) -> Self::Erased; |
311 | } | |
312 | ||
313 | ///////////////////////////////////////////////////////////////////////////// | |
314 | // OwningRef | |
315 | ///////////////////////////////////////////////////////////////////////////// | |
316 | ||
317 | impl<O, T: ?Sized> OwningRef<O, T> { | |
318 | /// Creates a new owning reference from a owner | |
319 | /// initialized to the direct dereference of it. | |
320 | /// | |
321 | /// # Example | |
322 | /// ``` | |
323 | /// extern crate owning_ref; | |
324 | /// use owning_ref::OwningRef; | |
325 | /// | |
326 | /// fn main() { | |
327 | /// let owning_ref = OwningRef::new(Box::new(42)); | |
328 | /// assert_eq!(*owning_ref, 42); | |
329 | /// } | |
330 | /// ``` | |
331 | pub fn new(o: O) -> Self | |
332 | where O: StableAddress, | |
333 | O: Deref<Target = T>, | |
334 | { | |
335 | OwningRef { | |
336 | reference: &*o, | |
337 | owner: o, | |
338 | } | |
339 | } | |
340 | ||
341 | /// Like `new`, but doesn’t require `O` to implement the `StableAddress` trait. | |
342 | /// Instead, the caller is responsible to make the same promises as implementing the trait. | |
343 | /// | |
344 | /// This is useful for cases where coherence rules prevents implementing the trait | |
345 | /// without adding a dependency to this crate in a third-party library. | |
346 | pub unsafe fn new_assert_stable_address(o: O) -> Self | |
347 | where O: Deref<Target = T>, | |
348 | { | |
349 | OwningRef { | |
350 | reference: &*o, | |
351 | owner: o, | |
352 | } | |
353 | } | |
354 | ||
355 | /// Converts `self` into a new owning reference that points at something reachable | |
356 | /// from the previous one. | |
357 | /// | |
358 | /// This can be a reference to a field of `U`, something reachable from a field of | |
359 | /// `U`, or even something unrelated with a `'static` lifetime. | |
360 | /// | |
361 | /// # Example | |
362 | /// ``` | |
363 | /// extern crate owning_ref; | |
364 | /// use owning_ref::OwningRef; | |
365 | /// | |
366 | /// fn main() { | |
367 | /// let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4])); | |
368 | /// | |
369 | /// // create a owning reference that points at the | |
370 | /// // third element of the array. | |
371 | /// let owning_ref = owning_ref.map(|array| &array[2]); | |
372 | /// assert_eq!(*owning_ref, 3); | |
373 | /// } | |
374 | /// ``` | |
375 | pub fn map<F, U: ?Sized>(self, f: F) -> OwningRef<O, U> | |
376 | where O: StableAddress, | |
377 | F: FnOnce(&T) -> &U | |
378 | { | |
379 | OwningRef { | |
380 | reference: f(&self), | |
381 | owner: self.owner, | |
382 | } | |
383 | } | |
384 | ||
385 | /// Tries to convert `self` into a new owning reference that points | |
386 | /// at something reachable from the previous one. | |
387 | /// | |
388 | /// This can be a reference to a field of `U`, something reachable from a field of | |
389 | /// `U`, or even something unrelated with a `'static` lifetime. | |
390 | /// | |
391 | /// # Example | |
392 | /// ``` | |
393 | /// extern crate owning_ref; | |
394 | /// use owning_ref::OwningRef; | |
395 | /// | |
396 | /// fn main() { | |
397 | /// let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4])); | |
398 | /// | |
399 | /// // create a owning reference that points at the | |
400 | /// // third element of the array. | |
401 | /// let owning_ref = owning_ref.try_map(|array| { | |
402 | /// if array[2] == 3 { Ok(&array[2]) } else { Err(()) } | |
403 | /// }); | |
404 | /// assert_eq!(*owning_ref.unwrap(), 3); | |
405 | /// } | |
406 | /// ``` | |
407 | pub fn try_map<F, U: ?Sized, E>(self, f: F) -> Result<OwningRef<O, U>, E> | |
408 | where O: StableAddress, | |
409 | F: FnOnce(&T) -> Result<&U, E> | |
410 | { | |
411 | Ok(OwningRef { | |
412 | reference: f(&self)?, | |
413 | owner: self.owner, | |
414 | }) | |
415 | } | |
416 | ||
417 | /// Converts `self` into a new owning reference with a different owner type. | |
418 | /// | |
419 | /// The new owner type needs to still contain the original owner in some way | |
420 | /// so that the reference into it remains valid. This function is marked unsafe | |
421 | /// because the user needs to manually uphold this guarantee. | |
422 | pub unsafe fn map_owner<F, P>(self, f: F) -> OwningRef<P, T> | |
423 | where O: StableAddress, | |
424 | P: StableAddress, | |
425 | F: FnOnce(O) -> P | |
426 | { | |
427 | OwningRef { | |
428 | reference: self.reference, | |
429 | owner: f(self.owner), | |
430 | } | |
431 | } | |
432 | ||
433 | /// Converts `self` into a new owning reference where the owner is wrapped | |
434 | /// in an additional `Box<O>`. | |
435 | /// | |
436 | /// This can be used to safely erase the owner of any `OwningRef<O, T>` | |
437 | /// to a `OwningRef<Box<Erased>, T>`. | |
438 | pub fn map_owner_box(self) -> OwningRef<Box<O>, T> { | |
439 | OwningRef { | |
440 | reference: self.reference, | |
441 | owner: Box::new(self.owner), | |
442 | } | |
443 | } | |
444 | ||
445 | /// Erases the concrete base type of the owner with a trait object. | |
446 | /// | |
447 | /// This allows mixing of owned references with different owner base types. | |
448 | /// | |
449 | /// # Example | |
450 | /// ``` | |
451 | /// extern crate owning_ref; | |
452 | /// use owning_ref::{OwningRef, Erased}; | |
453 | /// | |
454 | /// fn main() { | |
0731742a | 455 | /// // N.B., using the concrete types here for explicitness. |
ff7c6d11 XL |
456 | /// // For less verbose code type aliases like `BoxRef` are provided. |
457 | /// | |
458 | /// let owning_ref_a: OwningRef<Box<[i32; 4]>, [i32; 4]> | |
459 | /// = OwningRef::new(Box::new([1, 2, 3, 4])); | |
460 | /// | |
461 | /// let owning_ref_b: OwningRef<Box<Vec<(i32, bool)>>, Vec<(i32, bool)>> | |
462 | /// = OwningRef::new(Box::new(vec![(0, false), (1, true)])); | |
463 | /// | |
464 | /// let owning_ref_a: OwningRef<Box<[i32; 4]>, i32> | |
465 | /// = owning_ref_a.map(|a| &a[0]); | |
466 | /// | |
467 | /// let owning_ref_b: OwningRef<Box<Vec<(i32, bool)>>, i32> | |
468 | /// = owning_ref_b.map(|a| &a[1].0); | |
469 | /// | |
470 | /// let owning_refs: [OwningRef<Box<Erased>, i32>; 2] | |
471 | /// = [owning_ref_a.erase_owner(), owning_ref_b.erase_owner()]; | |
472 | /// | |
473 | /// assert_eq!(*owning_refs[0], 1); | |
474 | /// assert_eq!(*owning_refs[1], 1); | |
475 | /// } | |
476 | /// ``` | |
477 | pub fn erase_owner<'a>(self) -> OwningRef<O::Erased, T> | |
478 | where O: IntoErased<'a>, | |
479 | { | |
480 | OwningRef { | |
481 | reference: self.reference, | |
482 | owner: self.owner.into_erased(), | |
483 | } | |
484 | } | |
485 | ||
0531ce1d XL |
486 | /// Erases the concrete base type of the owner with a trait object which implements `Send`. |
487 | /// | |
488 | /// This allows mixing of owned references with different owner base types. | |
489 | pub fn erase_send_owner<'a>(self) -> OwningRef<O::Erased, T> | |
490 | where O: IntoErasedSend<'a>, | |
491 | { | |
492 | OwningRef { | |
493 | reference: self.reference, | |
494 | owner: self.owner.into_erased_send(), | |
495 | } | |
496 | } | |
497 | ||
ff7c6d11 XL |
498 | /// Erases the concrete base type of the owner with a trait object which implements `Send` and `Sync`. |
499 | /// | |
500 | /// This allows mixing of owned references with different owner base types. | |
501 | pub fn erase_send_sync_owner<'a>(self) -> OwningRef<O::Erased, T> | |
502 | where O: IntoErasedSendSync<'a>, | |
503 | { | |
504 | OwningRef { | |
505 | reference: self.reference, | |
506 | owner: self.owner.into_erased_send_sync(), | |
507 | } | |
508 | } | |
509 | ||
510 | // TODO: wrap_owner | |
511 | ||
512 | // FIXME: Naming convention? | |
513 | /// A getter for the underlying owner. | |
514 | pub fn owner(&self) -> &O { | |
515 | &self.owner | |
516 | } | |
517 | ||
518 | // FIXME: Naming convention? | |
519 | /// Discards the reference and retrieves the owner. | |
520 | pub fn into_inner(self) -> O { | |
521 | self.owner | |
522 | } | |
523 | } | |
524 | ||
525 | impl<O, T: ?Sized> OwningRefMut<O, T> { | |
526 | /// Creates a new owning reference from a owner | |
527 | /// initialized to the direct dereference of it. | |
528 | /// | |
529 | /// # Example | |
530 | /// ``` | |
531 | /// extern crate owning_ref; | |
532 | /// use owning_ref::OwningRefMut; | |
533 | /// | |
534 | /// fn main() { | |
535 | /// let owning_ref_mut = OwningRefMut::new(Box::new(42)); | |
536 | /// assert_eq!(*owning_ref_mut, 42); | |
537 | /// } | |
538 | /// ``` | |
539 | pub fn new(mut o: O) -> Self | |
540 | where O: StableAddress, | |
541 | O: DerefMut<Target = T>, | |
542 | { | |
543 | OwningRefMut { | |
544 | reference: &mut *o, | |
545 | owner: o, | |
546 | } | |
547 | } | |
548 | ||
549 | /// Like `new`, but doesn’t require `O` to implement the `StableAddress` trait. | |
550 | /// Instead, the caller is responsible to make the same promises as implementing the trait. | |
551 | /// | |
552 | /// This is useful for cases where coherence rules prevents implementing the trait | |
553 | /// without adding a dependency to this crate in a third-party library. | |
554 | pub unsafe fn new_assert_stable_address(mut o: O) -> Self | |
555 | where O: DerefMut<Target = T>, | |
556 | { | |
557 | OwningRefMut { | |
558 | reference: &mut *o, | |
559 | owner: o, | |
560 | } | |
561 | } | |
562 | ||
563 | /// Converts `self` into a new _shared_ owning reference that points at | |
564 | /// something reachable from the previous one. | |
565 | /// | |
566 | /// This can be a reference to a field of `U`, something reachable from a field of | |
567 | /// `U`, or even something unrelated with a `'static` lifetime. | |
568 | /// | |
569 | /// # Example | |
570 | /// ``` | |
571 | /// extern crate owning_ref; | |
572 | /// use owning_ref::OwningRefMut; | |
573 | /// | |
574 | /// fn main() { | |
575 | /// let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4])); | |
576 | /// | |
577 | /// // create a owning reference that points at the | |
578 | /// // third element of the array. | |
579 | /// let owning_ref = owning_ref_mut.map(|array| &array[2]); | |
580 | /// assert_eq!(*owning_ref, 3); | |
581 | /// } | |
582 | /// ``` | |
583 | pub fn map<F, U: ?Sized>(mut self, f: F) -> OwningRef<O, U> | |
584 | where O: StableAddress, | |
585 | F: FnOnce(&mut T) -> &U | |
586 | { | |
587 | OwningRef { | |
588 | reference: f(&mut self), | |
589 | owner: self.owner, | |
590 | } | |
591 | } | |
592 | ||
593 | /// Converts `self` into a new _mutable_ owning reference that points at | |
594 | /// something reachable from the previous one. | |
595 | /// | |
596 | /// This can be a reference to a field of `U`, something reachable from a field of | |
597 | /// `U`, or even something unrelated with a `'static` lifetime. | |
598 | /// | |
599 | /// # Example | |
600 | /// ``` | |
601 | /// extern crate owning_ref; | |
602 | /// use owning_ref::OwningRefMut; | |
603 | /// | |
604 | /// fn main() { | |
605 | /// let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4])); | |
606 | /// | |
607 | /// // create a owning reference that points at the | |
608 | /// // third element of the array. | |
609 | /// let owning_ref_mut = owning_ref_mut.map_mut(|array| &mut array[2]); | |
610 | /// assert_eq!(*owning_ref_mut, 3); | |
611 | /// } | |
612 | /// ``` | |
613 | pub fn map_mut<F, U: ?Sized>(mut self, f: F) -> OwningRefMut<O, U> | |
614 | where O: StableAddress, | |
615 | F: FnOnce(&mut T) -> &mut U | |
616 | { | |
617 | OwningRefMut { | |
618 | reference: f(&mut self), | |
619 | owner: self.owner, | |
620 | } | |
621 | } | |
622 | ||
623 | /// Tries to convert `self` into a new _shared_ owning reference that points | |
624 | /// at something reachable from the previous one. | |
625 | /// | |
626 | /// This can be a reference to a field of `U`, something reachable from a field of | |
627 | /// `U`, or even something unrelated with a `'static` lifetime. | |
628 | /// | |
629 | /// # Example | |
630 | /// ``` | |
631 | /// extern crate owning_ref; | |
632 | /// use owning_ref::OwningRefMut; | |
633 | /// | |
634 | /// fn main() { | |
635 | /// let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4])); | |
636 | /// | |
637 | /// // create a owning reference that points at the | |
638 | /// // third element of the array. | |
639 | /// let owning_ref = owning_ref_mut.try_map(|array| { | |
640 | /// if array[2] == 3 { Ok(&array[2]) } else { Err(()) } | |
641 | /// }); | |
642 | /// assert_eq!(*owning_ref.unwrap(), 3); | |
643 | /// } | |
644 | /// ``` | |
645 | pub fn try_map<F, U: ?Sized, E>(mut self, f: F) -> Result<OwningRef<O, U>, E> | |
646 | where O: StableAddress, | |
647 | F: FnOnce(&mut T) -> Result<&U, E> | |
648 | { | |
649 | Ok(OwningRef { | |
650 | reference: f(&mut self)?, | |
651 | owner: self.owner, | |
652 | }) | |
653 | } | |
654 | ||
655 | /// Tries to convert `self` into a new _mutable_ owning reference that points | |
656 | /// at something reachable from the previous one. | |
657 | /// | |
658 | /// This can be a reference to a field of `U`, something reachable from a field of | |
659 | /// `U`, or even something unrelated with a `'static` lifetime. | |
660 | /// | |
661 | /// # Example | |
662 | /// ``` | |
663 | /// extern crate owning_ref; | |
664 | /// use owning_ref::OwningRefMut; | |
665 | /// | |
666 | /// fn main() { | |
667 | /// let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4])); | |
668 | /// | |
669 | /// // create a owning reference that points at the | |
670 | /// // third element of the array. | |
671 | /// let owning_ref_mut = owning_ref_mut.try_map_mut(|array| { | |
672 | /// if array[2] == 3 { Ok(&mut array[2]) } else { Err(()) } | |
673 | /// }); | |
674 | /// assert_eq!(*owning_ref_mut.unwrap(), 3); | |
675 | /// } | |
676 | /// ``` | |
677 | pub fn try_map_mut<F, U: ?Sized, E>(mut self, f: F) -> Result<OwningRefMut<O, U>, E> | |
678 | where O: StableAddress, | |
679 | F: FnOnce(&mut T) -> Result<&mut U, E> | |
680 | { | |
681 | Ok(OwningRefMut { | |
682 | reference: f(&mut self)?, | |
683 | owner: self.owner, | |
684 | }) | |
685 | } | |
686 | ||
687 | /// Converts `self` into a new owning reference with a different owner type. | |
688 | /// | |
689 | /// The new owner type needs to still contain the original owner in some way | |
690 | /// so that the reference into it remains valid. This function is marked unsafe | |
691 | /// because the user needs to manually uphold this guarantee. | |
692 | pub unsafe fn map_owner<F, P>(self, f: F) -> OwningRefMut<P, T> | |
693 | where O: StableAddress, | |
694 | P: StableAddress, | |
695 | F: FnOnce(O) -> P | |
696 | { | |
697 | OwningRefMut { | |
698 | reference: self.reference, | |
699 | owner: f(self.owner), | |
700 | } | |
701 | } | |
702 | ||
703 | /// Converts `self` into a new owning reference where the owner is wrapped | |
704 | /// in an additional `Box<O>`. | |
705 | /// | |
706 | /// This can be used to safely erase the owner of any `OwningRefMut<O, T>` | |
707 | /// to a `OwningRefMut<Box<Erased>, T>`. | |
708 | pub fn map_owner_box(self) -> OwningRefMut<Box<O>, T> { | |
709 | OwningRefMut { | |
710 | reference: self.reference, | |
711 | owner: Box::new(self.owner), | |
712 | } | |
713 | } | |
714 | ||
715 | /// Erases the concrete base type of the owner with a trait object. | |
716 | /// | |
717 | /// This allows mixing of owned references with different owner base types. | |
718 | /// | |
719 | /// # Example | |
720 | /// ``` | |
721 | /// extern crate owning_ref; | |
722 | /// use owning_ref::{OwningRefMut, Erased}; | |
723 | /// | |
724 | /// fn main() { | |
0731742a | 725 | /// // N.B., using the concrete types here for explicitness. |
ff7c6d11 XL |
726 | /// // For less verbose code type aliases like `BoxRef` are provided. |
727 | /// | |
728 | /// let owning_ref_mut_a: OwningRefMut<Box<[i32; 4]>, [i32; 4]> | |
729 | /// = OwningRefMut::new(Box::new([1, 2, 3, 4])); | |
730 | /// | |
731 | /// let owning_ref_mut_b: OwningRefMut<Box<Vec<(i32, bool)>>, Vec<(i32, bool)>> | |
732 | /// = OwningRefMut::new(Box::new(vec![(0, false), (1, true)])); | |
733 | /// | |
734 | /// let owning_ref_mut_a: OwningRefMut<Box<[i32; 4]>, i32> | |
735 | /// = owning_ref_mut_a.map_mut(|a| &mut a[0]); | |
736 | /// | |
737 | /// let owning_ref_mut_b: OwningRefMut<Box<Vec<(i32, bool)>>, i32> | |
738 | /// = owning_ref_mut_b.map_mut(|a| &mut a[1].0); | |
739 | /// | |
740 | /// let owning_refs_mut: [OwningRefMut<Box<Erased>, i32>; 2] | |
741 | /// = [owning_ref_mut_a.erase_owner(), owning_ref_mut_b.erase_owner()]; | |
742 | /// | |
743 | /// assert_eq!(*owning_refs_mut[0], 1); | |
744 | /// assert_eq!(*owning_refs_mut[1], 1); | |
745 | /// } | |
746 | /// ``` | |
747 | pub fn erase_owner<'a>(self) -> OwningRefMut<O::Erased, T> | |
748 | where O: IntoErased<'a>, | |
749 | { | |
750 | OwningRefMut { | |
751 | reference: self.reference, | |
752 | owner: self.owner.into_erased(), | |
753 | } | |
754 | } | |
755 | ||
756 | // TODO: wrap_owner | |
757 | ||
758 | // FIXME: Naming convention? | |
759 | /// A getter for the underlying owner. | |
760 | pub fn owner(&self) -> &O { | |
761 | &self.owner | |
762 | } | |
763 | ||
764 | // FIXME: Naming convention? | |
765 | /// Discards the reference and retrieves the owner. | |
766 | pub fn into_inner(self) -> O { | |
767 | self.owner | |
768 | } | |
769 | } | |
770 | ||
771 | ///////////////////////////////////////////////////////////////////////////// | |
772 | // OwningHandle | |
773 | ///////////////////////////////////////////////////////////////////////////// | |
774 | ||
775 | use std::ops::{Deref, DerefMut}; | |
776 | ||
777 | /// `OwningHandle` is a complement to `OwningRef`. Where `OwningRef` allows | |
778 | /// consumers to pass around an owned object and a dependent reference, | |
779 | /// `OwningHandle` contains an owned object and a dependent _object_. | |
780 | /// | |
781 | /// `OwningHandle` can encapsulate a `RefMut` along with its associated | |
782 | /// `RefCell`, or an `RwLockReadGuard` along with its associated `RwLock`. | |
783 | /// However, the API is completely generic and there are no restrictions on | |
784 | /// what types of owning and dependent objects may be used. | |
785 | /// | |
786 | /// `OwningHandle` is created by passing an owner object (which dereferences | |
787 | /// to a stable address) along with a callback which receives a pointer to | |
788 | /// that stable location. The callback may then dereference the pointer and | |
789 | /// mint a dependent object, with the guarantee that the returned object will | |
790 | /// not outlive the referent of the pointer. | |
791 | /// | |
792 | /// Since the callback needs to dereference a raw pointer, it requires `unsafe` | |
793 | /// code. To avoid forcing this unsafety on most callers, the `ToHandle` trait is | |
794 | /// implemented for common data structures. Types that implement `ToHandle` can | |
795 | /// be wrapped into an `OwningHandle` without passing a callback. | |
796 | pub struct OwningHandle<O, H> | |
797 | where O: StableAddress, H: Deref, | |
798 | { | |
799 | handle: H, | |
800 | _owner: O, | |
801 | } | |
802 | ||
803 | impl<O, H> Deref for OwningHandle<O, H> | |
804 | where O: StableAddress, H: Deref, | |
805 | { | |
806 | type Target = H::Target; | |
807 | fn deref(&self) -> &H::Target { | |
808 | self.handle.deref() | |
809 | } | |
810 | } | |
811 | ||
812 | unsafe impl<O, H> StableAddress for OwningHandle<O, H> | |
813 | where O: StableAddress, H: StableAddress, | |
814 | {} | |
815 | ||
816 | impl<O, H> DerefMut for OwningHandle<O, H> | |
817 | where O: StableAddress, H: DerefMut, | |
818 | { | |
819 | fn deref_mut(&mut self) -> &mut H::Target { | |
820 | self.handle.deref_mut() | |
821 | } | |
822 | } | |
823 | ||
824 | /// Trait to implement the conversion of owner to handle for common types. | |
825 | pub trait ToHandle { | |
826 | /// The type of handle to be encapsulated by the OwningHandle. | |
827 | type Handle: Deref; | |
828 | ||
829 | /// Given an appropriately-long-lived pointer to ourselves, create a | |
830 | /// handle to be encapsulated by the `OwningHandle`. | |
831 | unsafe fn to_handle(x: *const Self) -> Self::Handle; | |
832 | } | |
833 | ||
834 | /// Trait to implement the conversion of owner to mutable handle for common types. | |
835 | pub trait ToHandleMut { | |
836 | /// The type of handle to be encapsulated by the OwningHandle. | |
837 | type HandleMut: DerefMut; | |
838 | ||
839 | /// Given an appropriately-long-lived pointer to ourselves, create a | |
840 | /// mutable handle to be encapsulated by the `OwningHandle`. | |
841 | unsafe fn to_handle_mut(x: *const Self) -> Self::HandleMut; | |
842 | } | |
843 | ||
844 | impl<O, H> OwningHandle<O, H> | |
845 | where O: StableAddress, O::Target: ToHandle<Handle = H>, H: Deref, | |
846 | { | |
9fa01778 | 847 | /// Creates a new `OwningHandle` for a type that implements `ToHandle`. For types |
ff7c6d11 XL |
848 | /// that don't implement `ToHandle`, callers may invoke `new_with_fn`, which accepts |
849 | /// a callback to perform the conversion. | |
850 | pub fn new(o: O) -> Self { | |
851 | OwningHandle::new_with_fn(o, |x| unsafe { O::Target::to_handle(x) }) | |
852 | } | |
853 | } | |
854 | ||
855 | impl<O, H> OwningHandle<O, H> | |
856 | where O: StableAddress, O::Target: ToHandleMut<HandleMut = H>, H: DerefMut, | |
857 | { | |
9fa01778 | 858 | /// Creates a new mutable `OwningHandle` for a type that implements `ToHandleMut`. |
ff7c6d11 XL |
859 | pub fn new_mut(o: O) -> Self { |
860 | OwningHandle::new_with_fn(o, |x| unsafe { O::Target::to_handle_mut(x) }) | |
861 | } | |
862 | } | |
863 | ||
864 | impl<O, H> OwningHandle<O, H> | |
865 | where O: StableAddress, H: Deref, | |
866 | { | |
9fa01778 | 867 | /// Creates a new OwningHandle. The provided callback will be invoked with |
ff7c6d11 XL |
868 | /// a pointer to the object owned by `o`, and the returned value is stored |
869 | /// as the object to which this `OwningHandle` will forward `Deref` and | |
870 | /// `DerefMut`. | |
871 | pub fn new_with_fn<F>(o: O, f: F) -> Self | |
872 | where F: FnOnce(*const O::Target) -> H | |
873 | { | |
874 | let h: H; | |
875 | { | |
876 | h = f(o.deref() as *const O::Target); | |
877 | } | |
878 | ||
879 | OwningHandle { | |
880 | handle: h, | |
881 | _owner: o, | |
882 | } | |
883 | } | |
884 | ||
9fa01778 | 885 | /// Creates a new OwningHandle. The provided callback will be invoked with |
ff7c6d11 XL |
886 | /// a pointer to the object owned by `o`, and the returned value is stored |
887 | /// as the object to which this `OwningHandle` will forward `Deref` and | |
888 | /// `DerefMut`. | |
889 | pub fn try_new<F, E>(o: O, f: F) -> Result<Self, E> | |
890 | where F: FnOnce(*const O::Target) -> Result<H, E> | |
891 | { | |
892 | let h: H; | |
893 | { | |
894 | h = f(o.deref() as *const O::Target)?; | |
895 | } | |
896 | ||
897 | Ok(OwningHandle { | |
898 | handle: h, | |
899 | _owner: o, | |
900 | }) | |
901 | } | |
902 | } | |
903 | ||
904 | ///////////////////////////////////////////////////////////////////////////// | |
905 | // std traits | |
906 | ///////////////////////////////////////////////////////////////////////////// | |
907 | ||
908 | use std::convert::From; | |
909 | use std::fmt::{self, Debug}; | |
910 | use std::marker::{Send, Sync}; | |
911 | use std::cmp::{Eq, PartialEq, Ord, PartialOrd, Ordering}; | |
912 | use std::hash::{Hash, Hasher}; | |
913 | use std::borrow::Borrow; | |
914 | ||
915 | impl<O, T: ?Sized> Deref for OwningRef<O, T> { | |
916 | type Target = T; | |
917 | ||
918 | fn deref(&self) -> &T { | |
919 | unsafe { | |
920 | &*self.reference | |
921 | } | |
922 | } | |
923 | } | |
924 | ||
925 | impl<O, T: ?Sized> Deref for OwningRefMut<O, T> { | |
926 | type Target = T; | |
927 | ||
928 | fn deref(&self) -> &T { | |
929 | unsafe { | |
930 | &*self.reference | |
931 | } | |
932 | } | |
933 | } | |
934 | ||
935 | impl<O, T: ?Sized> DerefMut for OwningRefMut<O, T> { | |
936 | fn deref_mut(&mut self) -> &mut T { | |
937 | unsafe { | |
938 | &mut *self.reference | |
939 | } | |
940 | } | |
941 | } | |
942 | ||
943 | unsafe impl<O, T: ?Sized> StableAddress for OwningRef<O, T> {} | |
944 | ||
945 | impl<O, T: ?Sized> AsRef<T> for OwningRef<O, T> { | |
946 | fn as_ref(&self) -> &T { | |
947 | &*self | |
948 | } | |
949 | } | |
950 | ||
951 | impl<O, T: ?Sized> AsRef<T> for OwningRefMut<O, T> { | |
952 | fn as_ref(&self) -> &T { | |
953 | &*self | |
954 | } | |
955 | } | |
956 | ||
957 | impl<O, T: ?Sized> AsMut<T> for OwningRefMut<O, T> { | |
958 | fn as_mut(&mut self) -> &mut T { | |
959 | &mut *self | |
960 | } | |
961 | } | |
962 | ||
963 | impl<O, T: ?Sized> Borrow<T> for OwningRef<O, T> { | |
964 | fn borrow(&self) -> &T { | |
965 | &*self | |
966 | } | |
967 | } | |
968 | ||
969 | impl<O, T: ?Sized> From<O> for OwningRef<O, T> | |
970 | where O: StableAddress, | |
971 | O: Deref<Target = T>, | |
972 | { | |
973 | fn from(owner: O) -> Self { | |
974 | OwningRef::new(owner) | |
975 | } | |
976 | } | |
977 | ||
978 | impl<O, T: ?Sized> From<O> for OwningRefMut<O, T> | |
979 | where O: StableAddress, | |
980 | O: DerefMut<Target = T> | |
981 | { | |
982 | fn from(owner: O) -> Self { | |
983 | OwningRefMut::new(owner) | |
984 | } | |
985 | } | |
986 | ||
987 | impl<O, T: ?Sized> From<OwningRefMut<O, T>> for OwningRef<O, T> | |
988 | where O: StableAddress, | |
989 | O: DerefMut<Target = T> | |
990 | { | |
991 | fn from(other: OwningRefMut<O, T>) -> Self { | |
992 | OwningRef { | |
993 | owner: other.owner, | |
994 | reference: other.reference, | |
995 | } | |
996 | } | |
997 | } | |
998 | ||
999 | // ^ FIXME: Is a Into impl for calling into_inner() possible as well? | |
1000 | ||
1001 | impl<O, T: ?Sized> Debug for OwningRef<O, T> | |
1002 | where O: Debug, | |
1003 | T: Debug, | |
1004 | { | |
9fa01778 | 1005 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
ff7c6d11 XL |
1006 | write!(f, |
1007 | "OwningRef {{ owner: {:?}, reference: {:?} }}", | |
1008 | self.owner(), | |
1009 | &**self) | |
1010 | } | |
1011 | } | |
1012 | ||
1013 | impl<O, T: ?Sized> Debug for OwningRefMut<O, T> | |
1014 | where O: Debug, | |
1015 | T: Debug, | |
1016 | { | |
9fa01778 | 1017 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
ff7c6d11 XL |
1018 | write!(f, |
1019 | "OwningRefMut {{ owner: {:?}, reference: {:?} }}", | |
1020 | self.owner(), | |
1021 | &**self) | |
1022 | } | |
1023 | } | |
1024 | ||
1025 | impl<O, T: ?Sized> Clone for OwningRef<O, T> | |
1026 | where O: CloneStableAddress, | |
1027 | { | |
1028 | fn clone(&self) -> Self { | |
1029 | OwningRef { | |
1030 | owner: self.owner.clone(), | |
1031 | reference: self.reference, | |
1032 | } | |
1033 | } | |
1034 | } | |
1035 | ||
1036 | unsafe impl<O, T: ?Sized> CloneStableAddress for OwningRef<O, T> | |
1037 | where O: CloneStableAddress {} | |
1038 | ||
1039 | unsafe impl<O, T: ?Sized> Send for OwningRef<O, T> | |
1040 | where O: Send, for<'a> (&'a T): Send {} | |
1041 | unsafe impl<O, T: ?Sized> Sync for OwningRef<O, T> | |
1042 | where O: Sync, for<'a> (&'a T): Sync {} | |
1043 | ||
1044 | unsafe impl<O, T: ?Sized> Send for OwningRefMut<O, T> | |
1045 | where O: Send, for<'a> (&'a mut T): Send {} | |
1046 | unsafe impl<O, T: ?Sized> Sync for OwningRefMut<O, T> | |
1047 | where O: Sync, for<'a> (&'a mut T): Sync {} | |
1048 | ||
8faf50e0 | 1049 | impl Debug for dyn Erased { |
9fa01778 | 1050 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
ff7c6d11 XL |
1051 | write!(f, "<Erased>",) |
1052 | } | |
1053 | } | |
1054 | ||
1055 | impl<O, T: ?Sized> PartialEq for OwningRef<O, T> where T: PartialEq { | |
1056 | fn eq(&self, other: &Self) -> bool { | |
1057 | (&*self as &T).eq(&*other as &T) | |
1058 | } | |
1059 | } | |
1060 | ||
1061 | impl<O, T: ?Sized> Eq for OwningRef<O, T> where T: Eq {} | |
1062 | ||
1063 | impl<O, T: ?Sized> PartialOrd for OwningRef<O, T> where T: PartialOrd { | |
1064 | fn partial_cmp(&self, other: &Self) -> Option<Ordering> { | |
1065 | (&*self as &T).partial_cmp(&*other as &T) | |
1066 | } | |
1067 | } | |
1068 | ||
1069 | impl<O, T: ?Sized> Ord for OwningRef<O, T> where T: Ord { | |
1070 | fn cmp(&self, other: &Self) -> Ordering { | |
1071 | (&*self as &T).cmp(&*other as &T) | |
1072 | } | |
1073 | } | |
1074 | ||
1075 | impl<O, T: ?Sized> Hash for OwningRef<O, T> where T: Hash { | |
1076 | fn hash<H: Hasher>(&self, state: &mut H) { | |
1077 | (&*self as &T).hash(state); | |
1078 | } | |
1079 | } | |
1080 | ||
1081 | impl<O, T: ?Sized> PartialEq for OwningRefMut<O, T> where T: PartialEq { | |
1082 | fn eq(&self, other: &Self) -> bool { | |
1083 | (&*self as &T).eq(&*other as &T) | |
1084 | } | |
1085 | } | |
1086 | ||
1087 | impl<O, T: ?Sized> Eq for OwningRefMut<O, T> where T: Eq {} | |
1088 | ||
1089 | impl<O, T: ?Sized> PartialOrd for OwningRefMut<O, T> where T: PartialOrd { | |
1090 | fn partial_cmp(&self, other: &Self) -> Option<Ordering> { | |
1091 | (&*self as &T).partial_cmp(&*other as &T) | |
1092 | } | |
1093 | } | |
1094 | ||
1095 | impl<O, T: ?Sized> Ord for OwningRefMut<O, T> where T: Ord { | |
1096 | fn cmp(&self, other: &Self) -> Ordering { | |
1097 | (&*self as &T).cmp(&*other as &T) | |
1098 | } | |
1099 | } | |
1100 | ||
1101 | impl<O, T: ?Sized> Hash for OwningRefMut<O, T> where T: Hash { | |
1102 | fn hash<H: Hasher>(&self, state: &mut H) { | |
1103 | (&*self as &T).hash(state); | |
1104 | } | |
1105 | } | |
1106 | ||
1107 | ///////////////////////////////////////////////////////////////////////////// | |
1108 | // std types integration and convenience type defs | |
1109 | ///////////////////////////////////////////////////////////////////////////// | |
1110 | ||
1111 | use std::boxed::Box; | |
1112 | use std::rc::Rc; | |
1113 | use std::sync::Arc; | |
1114 | use std::sync::{MutexGuard, RwLockReadGuard, RwLockWriteGuard}; | |
1115 | use std::cell::{Ref, RefCell, RefMut}; | |
1116 | ||
1117 | impl<T: 'static> ToHandle for RefCell<T> { | |
1118 | type Handle = Ref<'static, T>; | |
1119 | unsafe fn to_handle(x: *const Self) -> Self::Handle { (*x).borrow() } | |
1120 | } | |
1121 | ||
1122 | impl<T: 'static> ToHandleMut for RefCell<T> { | |
1123 | type HandleMut = RefMut<'static, T>; | |
1124 | unsafe fn to_handle_mut(x: *const Self) -> Self::HandleMut { (*x).borrow_mut() } | |
1125 | } | |
1126 | ||
0731742a XL |
1127 | // N.B., implementing ToHandle{,Mut} for Mutex and RwLock requires a decision |
1128 | // about which handle creation to use (i.e., read() vs try_read()) as well as | |
ff7c6d11 XL |
1129 | // what to do with error results. |
1130 | ||
1131 | /// Typedef of a owning reference that uses a `Box` as the owner. | |
1132 | pub type BoxRef<T, U = T> = OwningRef<Box<T>, U>; | |
1133 | /// Typedef of a owning reference that uses a `Vec` as the owner. | |
1134 | pub type VecRef<T, U = T> = OwningRef<Vec<T>, U>; | |
1135 | /// Typedef of a owning reference that uses a `String` as the owner. | |
1136 | pub type StringRef = OwningRef<String, str>; | |
1137 | ||
1138 | /// Typedef of a owning reference that uses a `Rc` as the owner. | |
1139 | pub type RcRef<T, U = T> = OwningRef<Rc<T>, U>; | |
1140 | /// Typedef of a owning reference that uses a `Arc` as the owner. | |
1141 | pub type ArcRef<T, U = T> = OwningRef<Arc<T>, U>; | |
1142 | ||
1143 | /// Typedef of a owning reference that uses a `Ref` as the owner. | |
1144 | pub type RefRef<'a, T, U = T> = OwningRef<Ref<'a, T>, U>; | |
1145 | /// Typedef of a owning reference that uses a `RefMut` as the owner. | |
1146 | pub type RefMutRef<'a, T, U = T> = OwningRef<RefMut<'a, T>, U>; | |
1147 | /// Typedef of a owning reference that uses a `MutexGuard` as the owner. | |
1148 | pub type MutexGuardRef<'a, T, U = T> = OwningRef<MutexGuard<'a, T>, U>; | |
1149 | /// Typedef of a owning reference that uses a `RwLockReadGuard` as the owner. | |
1150 | pub type RwLockReadGuardRef<'a, T, U = T> = OwningRef<RwLockReadGuard<'a, T>, U>; | |
1151 | /// Typedef of a owning reference that uses a `RwLockWriteGuard` as the owner. | |
1152 | pub type RwLockWriteGuardRef<'a, T, U = T> = OwningRef<RwLockWriteGuard<'a, T>, U>; | |
1153 | ||
1154 | /// Typedef of a mutable owning reference that uses a `Box` as the owner. | |
1155 | pub type BoxRefMut<T, U = T> = OwningRefMut<Box<T>, U>; | |
1156 | /// Typedef of a mutable owning reference that uses a `Vec` as the owner. | |
1157 | pub type VecRefMut<T, U = T> = OwningRefMut<Vec<T>, U>; | |
1158 | /// Typedef of a mutable owning reference that uses a `String` as the owner. | |
1159 | pub type StringRefMut = OwningRefMut<String, str>; | |
1160 | ||
1161 | /// Typedef of a mutable owning reference that uses a `RefMut` as the owner. | |
1162 | pub type RefMutRefMut<'a, T, U = T> = OwningRefMut<RefMut<'a, T>, U>; | |
1163 | /// Typedef of a mutable owning reference that uses a `MutexGuard` as the owner. | |
1164 | pub type MutexGuardRefMut<'a, T, U = T> = OwningRefMut<MutexGuard<'a, T>, U>; | |
1165 | /// Typedef of a mutable owning reference that uses a `RwLockWriteGuard` as the owner. | |
1166 | pub type RwLockWriteGuardRefMut<'a, T, U = T> = OwningRef<RwLockWriteGuard<'a, T>, U>; | |
1167 | ||
1168 | unsafe impl<'a, T: 'a> IntoErased<'a> for Box<T> { | |
8faf50e0 | 1169 | type Erased = Box<dyn Erased + 'a>; |
ff7c6d11 XL |
1170 | fn into_erased(self) -> Self::Erased { |
1171 | self | |
1172 | } | |
1173 | } | |
1174 | unsafe impl<'a, T: 'a> IntoErased<'a> for Rc<T> { | |
8faf50e0 | 1175 | type Erased = Rc<dyn Erased + 'a>; |
ff7c6d11 XL |
1176 | fn into_erased(self) -> Self::Erased { |
1177 | self | |
1178 | } | |
1179 | } | |
1180 | unsafe impl<'a, T: 'a> IntoErased<'a> for Arc<T> { | |
8faf50e0 | 1181 | type Erased = Arc<dyn Erased + 'a>; |
ff7c6d11 XL |
1182 | fn into_erased(self) -> Self::Erased { |
1183 | self | |
1184 | } | |
1185 | } | |
1186 | ||
0531ce1d | 1187 | unsafe impl<'a, T: Send + 'a> IntoErasedSend<'a> for Box<T> { |
8faf50e0 | 1188 | type Erased = Box<dyn Erased + Send + 'a>; |
0531ce1d | 1189 | fn into_erased_send(self) -> Self::Erased { |
ff7c6d11 XL |
1190 | self |
1191 | } | |
1192 | } | |
1193 | ||
0531ce1d | 1194 | unsafe impl<'a, T: Send + 'a> IntoErasedSendSync<'a> for Box<T> { |
8faf50e0 | 1195 | type Erased = Box<dyn Erased + Sync + Send + 'a>; |
0531ce1d | 1196 | fn into_erased_send_sync(self) -> Self::Erased { |
8faf50e0 | 1197 | let result: Box<dyn Erased + Send + 'a> = self; |
0531ce1d XL |
1198 | // This is safe since Erased can always implement Sync |
1199 | // Only the destructor is available and it takes &mut self | |
1200 | unsafe { | |
1201 | mem::transmute(result) | |
1202 | } | |
1203 | } | |
1204 | } | |
1205 | ||
ff7c6d11 | 1206 | unsafe impl<'a, T: Send + Sync + 'a> IntoErasedSendSync<'a> for Arc<T> { |
8faf50e0 | 1207 | type Erased = Arc<dyn Erased + Send + Sync + 'a>; |
ff7c6d11 XL |
1208 | fn into_erased_send_sync(self) -> Self::Erased { |
1209 | self | |
1210 | } | |
1211 | } | |
1212 | ||
1213 | /// Typedef of a owning reference that uses an erased `Box` as the owner. | |
8faf50e0 | 1214 | pub type ErasedBoxRef<U> = OwningRef<Box<dyn Erased>, U>; |
ff7c6d11 | 1215 | /// Typedef of a owning reference that uses an erased `Rc` as the owner. |
8faf50e0 | 1216 | pub type ErasedRcRef<U> = OwningRef<Rc<dyn Erased>, U>; |
ff7c6d11 | 1217 | /// Typedef of a owning reference that uses an erased `Arc` as the owner. |
8faf50e0 | 1218 | pub type ErasedArcRef<U> = OwningRef<Arc<dyn Erased>, U>; |
ff7c6d11 XL |
1219 | |
1220 | /// Typedef of a mutable owning reference that uses an erased `Box` as the owner. | |
8faf50e0 | 1221 | pub type ErasedBoxRefMut<U> = OwningRefMut<Box<dyn Erased>, U>; |
ff7c6d11 XL |
1222 | |
1223 | #[cfg(test)] | |
dc9dc135 | 1224 | mod tests; |