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#![warn(missing_docs)]
/*!
# An owning reference.
This crate provides the _owning reference_ types `OwningRef` and `OwningRefMut`
that enables it to bundle a reference together with the owner of the data it points to.
This allows moving and dropping of a `OwningRef` without needing to recreate the reference.
This can sometimes be useful because Rust borrowing rules normally prevent
moving a type that has been moved from. For example, this kind of code gets rejected:
```rust,ignore
fn return_owned_and_referenced<'a>() -> (Vec<u8>, &'a [u8]) {
let v = vec![1, 2, 3, 4];
let s = &v[1..3];
(v, s)
}
```
Even though, from a memory-layout point of view, this can be entirely safe
if the new location of the vector still lives longer than the lifetime `'a`
of the reference because the backing allocation of the vector does not change.
This library enables this safe usage by keeping the owner and the reference
bundled together in a wrapper type that ensure that lifetime constraint:
```rust
# extern crate owning_ref;
# use owning_ref::OwningRef;
# fn main() {
fn return_owned_and_referenced() -> OwningRef<Vec<u8>, [u8]> {
let v = vec![1, 2, 3, 4];
let or = OwningRef::new(v);
let or = or.map(|v| &v[1..3]);
or
}
# }
```
It works by requiring owner types to dereference to stable memory locations
and preventing mutable access to root containers, which in practice requires heap allocation
as provided by `Box<T>`, `Rc<T>`, etc.
Also provided are typedefs for common owner type combinations,
which allow for less verbose type signatures. For example, `BoxRef<T>` instead of `OwningRef<Box<T>, T>`.
The crate also provides the more advanced `OwningHandle` type,
which allows more freedom in bundling a dependent handle object
along with the data it depends on, at the cost of some unsafe needed in the API.
See the documentation around `OwningHandle` for more details.
# Examples
## Basics
```
extern crate owning_ref;
use owning_ref::BoxRef;
fn main() {
// Create an array owned by a Box.
let arr = Box::new([1, 2, 3, 4]) as Box<[i32]>;
// Transfer into a BoxRef.
let arr: BoxRef<[i32]> = BoxRef::new(arr);
assert_eq!(&*arr, &[1, 2, 3, 4]);
// We can slice the array without losing ownership or changing type.
let arr: BoxRef<[i32]> = arr.map(|arr| &arr[1..3]);
assert_eq!(&*arr, &[2, 3]);
// Also works for Arc, Rc, String and Vec!
}
```
## Caching a reference to a struct field
```
extern crate owning_ref;
use owning_ref::BoxRef;
fn main() {
struct Foo {
tag: u32,
x: u16,
y: u16,
z: u16,
}
let foo = Foo { tag: 1, x: 100, y: 200, z: 300 };
let or = BoxRef::new(Box::new(foo)).map(|foo| {
match foo.tag {
0 => &foo.x,
1 => &foo.y,
2 => &foo.z,
_ => panic!(),
}
});
assert_eq!(*or, 200);
}
```
## Caching a reference to an entry in a vector
```
extern crate owning_ref;
use owning_ref::VecRef;
fn main() {
let v = VecRef::new(vec![1, 2, 3, 4, 5]).map(|v| &v[3]);
assert_eq!(*v, 4);
}
```
## Caching a subslice of a String
```
extern crate owning_ref;
use owning_ref::StringRef;
fn main() {
let s = StringRef::new("hello world".to_owned())
.map(|s| s.split(' ').nth(1).unwrap());
assert_eq!(&*s, "world");
}
```
## Reference counted slices that share ownership of the backing storage
```
extern crate owning_ref;
use owning_ref::RcRef;
use std::rc::Rc;
fn main() {
let rc: RcRef<[i32]> = RcRef::new(Rc::new([1, 2, 3, 4]) as Rc<[i32]>);
assert_eq!(&*rc, &[1, 2, 3, 4]);
let rc_a: RcRef<[i32]> = rc.clone().map(|s| &s[0..2]);
let rc_b = rc.clone().map(|s| &s[1..3]);
let rc_c = rc.clone().map(|s| &s[2..4]);
assert_eq!(&*rc_a, &[1, 2]);
assert_eq!(&*rc_b, &[2, 3]);
assert_eq!(&*rc_c, &[3, 4]);
let rc_c_a = rc_c.clone().map(|s| &s[1]);
assert_eq!(&*rc_c_a, &4);
}
```
## Atomic reference counted slices that share ownership of the backing storage
```
extern crate owning_ref;
use owning_ref::ArcRef;
use std::sync::Arc;
fn main() {
use std::thread;
fn par_sum(rc: ArcRef<[i32]>) -> i32 {
if rc.len() == 0 {
return 0;
} else if rc.len() == 1 {
return rc[0];
}
let mid = rc.len() / 2;
let left = rc.clone().map(|s| &s[..mid]);
let right = rc.map(|s| &s[mid..]);
let left = thread::spawn(move || par_sum(left));
let right = thread::spawn(move || par_sum(right));
left.join().unwrap() + right.join().unwrap()
}
let rc: Arc<[i32]> = Arc::new([1, 2, 3, 4]);
let rc: ArcRef<[i32]> = rc.into();
assert_eq!(par_sum(rc), 10);
}
```
## References into RAII locks
```
extern crate owning_ref;
use owning_ref::RefRef;
use std::cell::{RefCell, Ref};
fn main() {
let refcell = RefCell::new((1, 2, 3, 4));
// Also works with Mutex and RwLock
let refref = {
let refref = RefRef::new(refcell.borrow()).map(|x| &x.3);
assert_eq!(*refref, 4);
// We move the RAII lock and the reference to one of
// the subfields in the data it guards here:
refref
};
assert_eq!(*refref, 4);
drop(refref);
assert_eq!(*refcell.borrow(), (1, 2, 3, 4));
}
```
## Mutable reference
When the owned container implements `DerefMut`, it is also possible to make
a _mutable owning reference_. (E.g. with `Box`, `RefMut`, `MutexGuard`)
```
extern crate owning_ref;
use owning_ref::RefMutRefMut;
use std::cell::{RefCell, RefMut};
fn main() {
let refcell = RefCell::new((1, 2, 3, 4));
let mut refmut_refmut = {
let mut refmut_refmut = RefMutRefMut::new(refcell.borrow_mut()).map_mut(|x| &mut x.3);
assert_eq!(*refmut_refmut, 4);
*refmut_refmut *= 2;
refmut_refmut
};
assert_eq!(*refmut_refmut, 8);
*refmut_refmut *= 2;
drop(refmut_refmut);
assert_eq!(*refcell.borrow(), (1, 2, 3, 16));
}
```
*/
extern crate stable_deref_trait;
pub use stable_deref_trait::{StableDeref as StableAddress, CloneStableDeref as CloneStableAddress};
/// An owning reference.
///
/// This wraps an owner `O` and a reference `&T` pointing
/// at something reachable from `O::Target` while keeping
/// the ability to move `self` around.
///
/// The owner is usually a pointer that points at some base type.
///
/// For more details and examples, see the module and method docs.
pub struct OwningRef<O, T: ?Sized> {
owner: O,
reference: *const T,
}
/// An mutable owning reference.
///
/// This wraps an owner `O` and a reference `&mut T` pointing
/// at something reachable from `O::Target` while keeping
/// the ability to move `self` around.
///
/// The owner is usually a pointer that points at some base type.
///
/// For more details and examples, see the module and method docs.
pub struct OwningRefMut<O, T: ?Sized> {
owner: O,
reference: *mut T,
}
/// Helper trait for an erased concrete type an owner dereferences to.
/// This is used in form of a trait object for keeping
/// something around to (virtually) call the destructor.
pub trait Erased {}
impl<T> Erased for T {}
/// Helper trait for erasing the concrete type of what an owner derferences to,
/// for example `Box<T> -> Box<dyn Erased>`. This would be unneeded with
/// higher kinded types support in the language.
pub unsafe trait IntoErased<'a> {
/// Owner with the dereference type substituted to `Erased`.
type Erased;
/// Perform the type erasure.
fn into_erased(self) -> Self::Erased;
}
/////////////////////////////////////////////////////////////////////////////
// OwningRef
/////////////////////////////////////////////////////////////////////////////
impl<O, T: ?Sized> OwningRef<O, T> {
/// Creates a new owning reference from a owner
/// initialized to the direct dereference of it.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRef;
///
/// fn main() {
/// let owning_ref = OwningRef::new(Box::new(42));
/// assert_eq!(*owning_ref, 42);
/// }
/// ```
pub fn new(o: O) -> Self
where O: StableAddress,
O: Deref<Target = T>,
{
OwningRef {
reference: &*o,
owner: o,
}
}
/// Like `new`, but doesn’t require `O` to implement the `StableAddress` trait.
/// Instead, the caller is responsible to make the same promises as implementing the trait.
///
/// This is useful for cases where coherence rules prevents implementing the trait
/// without adding a dependency to this crate in a third-party library.
pub unsafe fn new_assert_stable_address(o: O) -> Self
where O: Deref<Target = T>,
{
OwningRef {
reference: &*o,
owner: o,
}
}
/// Converts `self` into a new owning reference that points at something reachable
/// from the previous one.
///
/// This can be a reference to a field of `U`, something reachable from a field of
/// `U`, or even something unrelated with a `'static` lifetime.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRef;
///
/// fn main() {
/// let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4]));
///
/// // create a owning reference that points at the
/// // third element of the array.
/// let owning_ref = owning_ref.map(|array| &array[2]);
/// assert_eq!(*owning_ref, 3);
/// }
/// ```
pub fn map<F, U: ?Sized>(self, f: F) -> OwningRef<O, U>
where O: StableAddress,
F: FnOnce(&T) -> &U
{
OwningRef {
reference: f(&self),
owner: self.owner,
}
}
/// Converts `self` into a new owning reference that points at something reachable
/// from the previous one or from the owner itself.
///
/// This can be a reference to a field of `U`, something reachable from a field of
/// `U` or from the owner `O`, or even something unrelated with a `'static` lifetime.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRef;
///
/// fn main() {
/// let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4]));
/// let owning_ref = owning_ref.map(|array| &array[2]);
/// assert_eq!(*owning_ref, 3);
///
/// // create a owning reference that points at the
/// // second element of the array from the owning ref that was pointing to the third
/// let owning_ref = owning_ref.map_with_owner(|array, _prev| &array[1]);
/// assert_eq!(*owning_ref, 2);
/// }
/// ```
pub fn map_with_owner<F, U: ?Sized>(self, f: F) -> OwningRef<O, U>
where O: StableAddress,
F: for<'a> FnOnce(&'a O, &'a T) -> &'a U
{
OwningRef {
reference: f(&self.owner, &self),
owner: self.owner,
}
}
/// Tries to convert `self` into a new owning reference that points
/// at something reachable from the previous one.
///
/// This can be a reference to a field of `U`, something reachable from a field of
/// `U`, or even something unrelated with a `'static` lifetime.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRef;
///
/// fn main() {
/// let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4]));
///
/// // create a owning reference that points at the
/// // third element of the array.
/// let owning_ref = owning_ref.try_map(|array| {
/// if array[2] == 3 { Ok(&array[2]) } else { Err(()) }
/// });
/// assert_eq!(*owning_ref.unwrap(), 3);
/// }
/// ```
pub fn try_map<F, U: ?Sized, E>(self, f: F) -> Result<OwningRef<O, U>, E>
where O: StableAddress,
F: FnOnce(&T) -> Result<&U, E>
{
Ok(OwningRef {
reference: f(&self)?,
owner: self.owner,
})
}
/// Tries to convert `self` into a new owning reference that points
/// at something reachable from the previous one.
///
/// This can be a reference to a field of `U`, something reachable from a field of
/// `U`, or even something unrelated with a `'static` lifetime.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRef;
///
/// fn main() {
/// let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4]));
/// let owning_ref = owning_ref.map(|array| &array[2]);
///
/// // create a owning reference that points at the
/// // second element of the array from the owning ref that was pointing to the third
/// let owning_ref = owning_ref.try_map_with_owner(|array, _prev| {
/// if array[1] == 2 { Ok(&array[1]) } else { Err(()) }
/// });
/// assert_eq!(*owning_ref.unwrap(), 2);
/// }
/// ```
pub fn try_map_with_owner<F, U: ?Sized, E>(self, f: F) -> Result<OwningRef<O, U>, E>
where O: StableAddress,
F: for<'a> FnOnce(&'a O, &'a T) -> Result<&'a U, E>
{
Ok(OwningRef {
reference: f(&self.owner, &self)?,
owner: self.owner,
})
}
/// Converts `self` into a new owning reference with a different owner type.
///
/// The new owner type needs to still contain the original owner in some way
/// so that the reference into it remains valid. This function is marked unsafe
/// because the user needs to manually uphold this guarantee.
pub unsafe fn map_owner<F, P>(self, f: F) -> OwningRef<P, T>
where O: StableAddress,
P: StableAddress,
F: FnOnce(O) -> P
{
OwningRef {
reference: self.reference,
owner: f(self.owner),
}
}
/// Converts `self` into a new owning reference where the owner is wrapped
/// in an additional `Box<O>`.
///
/// This can be used to safely erase the owner of any `OwningRef<O, T>`
/// to a `OwningRef<Box<dyn Erased>, T>`.
pub fn map_owner_box(self) -> OwningRef<Box<O>, T> {
OwningRef {
reference: self.reference,
owner: Box::new(self.owner),
}
}
/// Erases the concrete base type of the owner with a trait object.
///
/// This allows mixing of owned references with different owner base types.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::{OwningRef, Erased};
///
/// fn main() {
/// // NB: Using the concrete types here for explicitnes.
/// // For less verbose code type aliases like `BoxRef` are provided.
///
/// let owning_ref_a: OwningRef<Box<[i32; 4]>, [i32; 4]>
/// = OwningRef::new(Box::new([1, 2, 3, 4]));
///
/// let owning_ref_b: OwningRef<Box<Vec<(i32, bool)>>, Vec<(i32, bool)>>
/// = OwningRef::new(Box::new(vec![(0, false), (1, true)]));
///
/// let owning_ref_a: OwningRef<Box<[i32; 4]>, i32>
/// = owning_ref_a.map(|a| &a[0]);
///
/// let owning_ref_b: OwningRef<Box<Vec<(i32, bool)>>, i32>
/// = owning_ref_b.map(|a| &a[1].0);
///
/// let owning_refs: [OwningRef<Box<dyn Erased>, i32>; 2]
/// = [owning_ref_a.erase_owner(), owning_ref_b.erase_owner()];
///
/// assert_eq!(*owning_refs[0], 1);
/// assert_eq!(*owning_refs[1], 1);
/// }
/// ```
pub fn erase_owner<'a>(self) -> OwningRef<O::Erased, T>
where O: IntoErased<'a>,
{
OwningRef {
reference: self.reference,
owner: self.owner.into_erased(),
}
}
// TODO: wrap_owner
/// A reference to the underlying owner.
pub fn as_owner(&self) -> &O {
&self.owner
}
/// Discards the reference and retrieves the owner.
pub fn into_owner(self) -> O {
self.owner
}
}
impl<O, T: ?Sized> OwningRefMut<O, T> {
/// Creates a new owning reference from a owner
/// initialized to the direct dereference of it.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRefMut;
///
/// fn main() {
/// let owning_ref_mut = OwningRefMut::new(Box::new(42));
/// assert_eq!(*owning_ref_mut, 42);
/// }
/// ```
pub fn new(mut o: O) -> Self
where O: StableAddress,
O: DerefMut<Target = T>,
{
OwningRefMut {
reference: &mut *o,
owner: o,
}
}
/// Like `new`, but doesn’t require `O` to implement the `StableAddress` trait.
/// Instead, the caller is responsible to make the same promises as implementing the trait.
///
/// This is useful for cases where coherence rules prevents implementing the trait
/// without adding a dependency to this crate in a third-party library.
pub unsafe fn new_assert_stable_address(mut o: O) -> Self
where O: DerefMut<Target = T>,
{
OwningRefMut {
reference: &mut *o,
owner: o,
}
}
/// Converts `self` into a new _shared_ owning reference that points at
/// something reachable from the previous one.
///
/// This can be a reference to a field of `U`, something reachable from a field of
/// `U`, or even something unrelated with a `'static` lifetime.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRefMut;
///
/// fn main() {
/// let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4]));
///
/// // create a owning reference that points at the
/// // third element of the array.
/// let owning_ref = owning_ref_mut.map(|array| &array[2]);
/// assert_eq!(*owning_ref, 3);
/// }
/// ```
pub fn map<F, U: ?Sized>(mut self, f: F) -> OwningRef<O, U>
where O: StableAddress,
F: FnOnce(&mut T) -> &U
{
OwningRef {
reference: f(&mut self),
owner: self.owner,
}
}
/// Converts `self` into a new _mutable_ owning reference that points at
/// something reachable from the previous one.
///
/// This can be a reference to a field of `U`, something reachable from a field of
/// `U`, or even something unrelated with a `'static` lifetime.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRefMut;
///
/// fn main() {
/// let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4]));
///
/// // create a owning reference that points at the
/// // third element of the array.
/// let owning_ref_mut = owning_ref_mut.map_mut(|array| &mut array[2]);
/// assert_eq!(*owning_ref_mut, 3);
/// }
/// ```
pub fn map_mut<F, U: ?Sized>(mut self, f: F) -> OwningRefMut<O, U>
where O: StableAddress,
F: FnOnce(&mut T) -> &mut U
{
OwningRefMut {
reference: f(&mut self),
owner: self.owner,
}
}
/// Tries to convert `self` into a new _shared_ owning reference that points
/// at something reachable from the previous one.
///
/// This can be a reference to a field of `U`, something reachable from a field of
/// `U`, or even something unrelated with a `'static` lifetime.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRefMut;
///
/// fn main() {
/// let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4]));
///
/// // create a owning reference that points at the
/// // third element of the array.
/// let owning_ref = owning_ref_mut.try_map(|array| {
/// if array[2] == 3 { Ok(&array[2]) } else { Err(()) }
/// });
/// assert_eq!(*owning_ref.unwrap(), 3);
/// }
/// ```
pub fn try_map<F, U: ?Sized, E>(mut self, f: F) -> Result<OwningRef<O, U>, E>
where O: StableAddress,
F: FnOnce(&mut T) -> Result<&U, E>
{
Ok(OwningRef {
reference: f(&mut self)?,
owner: self.owner,
})
}
/// Tries to convert `self` into a new _mutable_ owning reference that points
/// at something reachable from the previous one.
///
/// This can be a reference to a field of `U`, something reachable from a field of
/// `U`, or even something unrelated with a `'static` lifetime.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::OwningRefMut;
///
/// fn main() {
/// let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4]));
///
/// // create a owning reference that points at the
/// // third element of the array.
/// let owning_ref_mut = owning_ref_mut.try_map_mut(|array| {
/// if array[2] == 3 { Ok(&mut array[2]) } else { Err(()) }
/// });
/// assert_eq!(*owning_ref_mut.unwrap(), 3);
/// }
/// ```
pub fn try_map_mut<F, U: ?Sized, E>(mut self, f: F) -> Result<OwningRefMut<O, U>, E>
where O: StableAddress,
F: FnOnce(&mut T) -> Result<&mut U, E>
{
Ok(OwningRefMut {
reference: f(&mut self)?,
owner: self.owner,
})
}
/// Converts `self` into a new owning reference with a different owner type.
///
/// The new owner type needs to still contain the original owner in some way
/// so that the reference into it remains valid. This function is marked unsafe
/// because the user needs to manually uphold this guarantee.
pub unsafe fn map_owner<F, P>(self, f: F) -> OwningRefMut<P, T>
where O: StableAddress,
P: StableAddress,
F: FnOnce(O) -> P
{
OwningRefMut {
reference: self.reference,
owner: f(self.owner),
}
}
/// Converts `self` into a new owning reference where the owner is wrapped
/// in an additional `Box<O>`.
///
/// This can be used to safely erase the owner of any `OwningRefMut<O, T>`
/// to a `OwningRefMut<Box<dyn Erased>, T>`.
pub fn map_owner_box(self) -> OwningRefMut<Box<O>, T> {
OwningRefMut {
reference: self.reference,
owner: Box::new(self.owner),
}
}
/// Erases the concrete base type of the owner with a trait object.
///
/// This allows mixing of owned references with different owner base types.
///
/// # Example
/// ```
/// extern crate owning_ref;
/// use owning_ref::{OwningRefMut, Erased};
///
/// fn main() {
/// // NB: Using the concrete types here for explicitnes.
/// // For less verbose code type aliases like `BoxRef` are provided.
///
/// let owning_ref_mut_a: OwningRefMut<Box<[i32; 4]>, [i32; 4]>
/// = OwningRefMut::new(Box::new([1, 2, 3, 4]));
///
/// let owning_ref_mut_b: OwningRefMut<Box<Vec<(i32, bool)>>, Vec<(i32, bool)>>
/// = OwningRefMut::new(Box::new(vec![(0, false), (1, true)]));
///
/// let owning_ref_mut_a: OwningRefMut<Box<[i32; 4]>, i32>
/// = owning_ref_mut_a.map_mut(|a| &mut a[0]);
///
/// let owning_ref_mut_b: OwningRefMut<Box<Vec<(i32, bool)>>, i32>
/// = owning_ref_mut_b.map_mut(|a| &mut a[1].0);
///
/// let owning_refs_mut: [OwningRefMut<Box<dyn Erased>, i32>; 2]
/// = [owning_ref_mut_a.erase_owner(), owning_ref_mut_b.erase_owner()];
///
/// assert_eq!(*owning_refs_mut[0], 1);
/// assert_eq!(*owning_refs_mut[1], 1);
/// }
/// ```
pub fn erase_owner<'a>(self) -> OwningRefMut<O::Erased, T>
where O: IntoErased<'a>,
{
OwningRefMut {
reference: self.reference,
owner: self.owner.into_erased(),
}
}
// TODO: wrap_owner
/// A reference to the underlying owner.
pub fn as_owner(&self) -> &O {
&self.owner
}
/// A mutable reference to the underlying owner.
pub fn as_owner_mut(&mut self) -> &mut O {
&mut self.owner
}
/// Discards the reference and retrieves the owner.
pub fn into_owner(self) -> O {
self.owner
}
}
/////////////////////////////////////////////////////////////////////////////
// OwningHandle
/////////////////////////////////////////////////////////////////////////////
use std::ops::{Deref, DerefMut};
/// `OwningHandle` is a complement to `OwningRef`. Where `OwningRef` allows
/// consumers to pass around an owned object and a dependent reference,
/// `OwningHandle` contains an owned object and a dependent _object_.
///
/// `OwningHandle` can encapsulate a `RefMut` along with its associated
/// `RefCell`, or an `RwLockReadGuard` along with its associated `RwLock`.
/// However, the API is completely generic and there are no restrictions on
/// what types of owning and dependent objects may be used.
///
/// `OwningHandle` is created by passing an owner object (which dereferences
/// to a stable address) along with a callback which receives a pointer to
/// that stable location. The callback may then dereference the pointer and
/// mint a dependent object, with the guarantee that the returned object will
/// not outlive the referent of the pointer.
///
/// Since the callback needs to dereference a raw pointer, it requires `unsafe`
/// code. To avoid forcing this unsafety on most callers, the `ToHandle` trait is
/// implemented for common data structures. Types that implement `ToHandle` can
/// be wrapped into an `OwningHandle` without passing a callback.
pub struct OwningHandle<O, H>
where O: StableAddress, H: Deref,
{
handle: H,
_owner: O,
}
impl<O, H> Deref for OwningHandle<O, H>
where O: StableAddress, H: Deref,
{
type Target = H::Target;
fn deref(&self) -> &H::Target {
self.handle.deref()
}
}
unsafe impl<O, H> StableAddress for OwningHandle<O, H>
where O: StableAddress, H: StableAddress,
{}
impl<O, H> DerefMut for OwningHandle<O, H>
where O: StableAddress, H: DerefMut,
{
fn deref_mut(&mut self) -> &mut H::Target {
self.handle.deref_mut()
}
}
/// Trait to implement the conversion of owner to handle for common types.
pub trait ToHandle {
/// The type of handle to be encapsulated by the OwningHandle.
type Handle: Deref;
/// Given an appropriately-long-lived pointer to ourselves, create a
/// handle to be encapsulated by the `OwningHandle`.
unsafe fn to_handle(x: *const Self) -> Self::Handle;
}
/// Trait to implement the conversion of owner to mutable handle for common types.
pub trait ToHandleMut {
/// The type of handle to be encapsulated by the OwningHandle.
type HandleMut: DerefMut;
/// Given an appropriately-long-lived pointer to ourselves, create a
/// mutable handle to be encapsulated by the `OwningHandle`.
unsafe fn to_handle_mut(x: *const Self) -> Self::HandleMut;
}
impl<O, H> OwningHandle<O, H>
where O: StableAddress, O::Target: ToHandle<Handle = H>, H: Deref,
{
/// Create a new `OwningHandle` for a type that implements `ToHandle`. For types
/// that don't implement `ToHandle`, callers may invoke `new_with_fn`, which accepts
/// a callback to perform the conversion.
pub fn new(o: O) -> Self {
OwningHandle::new_with_fn(o, |x| unsafe { O::Target::to_handle(x) })
}
}
impl<O, H> OwningHandle<O, H>
where O: StableAddress, O::Target: ToHandleMut<HandleMut = H>, H: DerefMut,
{
/// Create a new mutable `OwningHandle` for a type that implements `ToHandleMut`.
pub fn new_mut(o: O) -> Self {
OwningHandle::new_with_fn(o, |x| unsafe { O::Target::to_handle_mut(x) })
}
}
impl<O, H> OwningHandle<O, H>
where O: StableAddress, H: Deref,
{
/// Create a new OwningHandle. The provided callback will be invoked with
/// a pointer to the object owned by `o`, and the returned value is stored
/// as the object to which this `OwningHandle` will forward `Deref` and
/// `DerefMut`.
pub fn new_with_fn<F>(o: O, f: F) -> Self
where F: FnOnce(*const O::Target) -> H
{
let h: H;
{
h = f(o.deref() as *const O::Target);
}
OwningHandle {
handle: h,
_owner: o,
}
}
/// Create a new OwningHandle. The provided callback will be invoked with
/// a pointer to the object owned by `o`, and the returned value is stored
/// as the object to which this `OwningHandle` will forward `Deref` and
/// `DerefMut`.
pub fn try_new<F, E>(o: O, f: F) -> Result<Self, E>
where F: FnOnce(*const O::Target) -> Result<H, E>
{
let h: H;
{
h = f(o.deref() as *const O::Target)?;
}
Ok(OwningHandle {
handle: h,
_owner: o,
})
}
/// A getter for the underlying owner.
pub fn as_owner(&self) -> &O {
&self._owner
}
/// Discards the dependent object and returns the owner.
pub fn into_owner(self) -> O {
self._owner
}
}
/////////////////////////////////////////////////////////////////////////////
// std traits
/////////////////////////////////////////////////////////////////////////////
use std::convert::From;
use std::fmt::{self, Debug};
use std::marker::{Send, Sync};
use std::cmp::{Eq, PartialEq, Ord, PartialOrd, Ordering};
use std::hash::{Hash, Hasher};
use std::borrow::Borrow;
impl<O, T: ?Sized> Deref for OwningRef<O, T> {
type Target = T;
fn deref(&self) -> &T {
unsafe {
&*self.reference
}
}
}
impl<O, T: ?Sized> Deref for OwningRefMut<O, T> {
type Target = T;
fn deref(&self) -> &T {
unsafe {
&*self.reference
}
}
}
impl<O, T: ?Sized> DerefMut for OwningRefMut<O, T> {
fn deref_mut(&mut self) -> &mut T {
unsafe {
&mut *self.reference
}
}
}
unsafe impl<O, T: ?Sized> StableAddress for OwningRef<O, T> {}
unsafe impl<O, T: ?Sized> StableAddress for OwningRefMut<O, T> {}
impl<O, T: ?Sized> AsRef<T> for OwningRef<O, T> {
fn as_ref(&self) -> &T {
&*self
}
}
impl<O, T: ?Sized> AsRef<T> for OwningRefMut<O, T> {
fn as_ref(&self) -> &T {
&*self
}
}
impl<O, T: ?Sized> AsMut<T> for OwningRefMut<O, T> {
fn as_mut(&mut self) -> &mut T {
&mut *self
}
}
impl<O, T: ?Sized> Borrow<T> for OwningRef<O, T> {
fn borrow(&self) -> &T {
&*self
}
}
impl<O, T: ?Sized> From<O> for OwningRef<O, T>
where O: StableAddress,
O: Deref<Target = T>,
{
fn from(owner: O) -> Self {
OwningRef::new(owner)
}
}
impl<O, T: ?Sized> From<O> for OwningRefMut<O, T>
where O: StableAddress,
O: DerefMut<Target = T>
{
fn from(owner: O) -> Self {
OwningRefMut::new(owner)
}
}
impl<O, T: ?Sized> From<OwningRefMut<O, T>> for OwningRef<O, T>
where O: StableAddress,
O: DerefMut<Target = T>
{
fn from(other: OwningRefMut<O, T>) -> Self {
OwningRef {
owner: other.owner,
reference: other.reference,
}
}
}
// ^ FIXME: Is a Into impl for calling into_owner() possible as well?
impl<O, T: ?Sized> Debug for OwningRef<O, T>
where O: Debug,
T: Debug,
{
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
write!(f,
"OwningRef {{ owner: {:?}, reference: {:?} }}",
self.as_owner(),
&**self)
}
}
impl<O, T: ?Sized> Debug for OwningRefMut<O, T>
where O: Debug,
T: Debug,
{
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
write!(f,
"OwningRefMut {{ owner: {:?}, reference: {:?} }}",
self.as_owner(),
&**self)
}
}
impl<O, T: ?Sized> Clone for OwningRef<O, T>
where O: CloneStableAddress,
{
fn clone(&self) -> Self {
OwningRef {
owner: self.owner.clone(),
reference: self.reference,
}
}
}
unsafe impl<O, T: ?Sized> CloneStableAddress for OwningRef<O, T>
where O: CloneStableAddress {}
unsafe impl<O, T: ?Sized> Send for OwningRef<O, T>
where O: Send, for<'a> (&'a T): Send {}
unsafe impl<O, T: ?Sized> Sync for OwningRef<O, T>
where O: Sync, for<'a> (&'a T): Sync {}
unsafe impl<O, T: ?Sized> Send for OwningRefMut<O, T>
where O: Send, for<'a> (&'a mut T): Send {}
unsafe impl<O, T: ?Sized> Sync for OwningRefMut<O, T>
where O: Sync, for<'a> (&'a mut T): Sync {}
impl Debug for dyn Erased {
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
write!(f, "<dyn Erased>",)
}
}
impl<O, T: ?Sized> PartialEq for OwningRef<O, T> where T: PartialEq {
fn eq(&self, other: &Self) -> bool {
(&*self as &T).eq(&*other as &T)
}
}
impl<O, T: ?Sized> Eq for OwningRef<O, T> where T: Eq {}
impl<O, T: ?Sized> PartialOrd for OwningRef<O, T> where T: PartialOrd {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
(&*self as &T).partial_cmp(&*other as &T)
}
}
impl<O, T: ?Sized> Ord for OwningRef<O, T> where T: Ord {
fn cmp(&self, other: &Self) -> Ordering {
(&*self as &T).cmp(&*other as &T)
}
}
impl<O, T: ?Sized> Hash for OwningRef<O, T> where T: Hash {
fn hash<H: Hasher>(&self, state: &mut H) {
(&*self as &T).hash(state);
}
}
impl<O, T: ?Sized> PartialEq for OwningRefMut<O, T> where T: PartialEq {
fn eq(&self, other: &Self) -> bool {
(&*self as &T).eq(&*other as &T)
}
}
impl<O, T: ?Sized> Eq for OwningRefMut<O, T> where T: Eq {}
impl<O, T: ?Sized> PartialOrd for OwningRefMut<O, T> where T: PartialOrd {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
(&*self as &T).partial_cmp(&*other as &T)
}
}
impl<O, T: ?Sized> Ord for OwningRefMut<O, T> where T: Ord {
fn cmp(&self, other: &Self) -> Ordering {
(&*self as &T).cmp(&*other as &T)
}
}
impl<O, T: ?Sized> Hash for OwningRefMut<O, T> where T: Hash {
fn hash<H: Hasher>(&self, state: &mut H) {
(&*self as &T).hash(state);
}
}
/////////////////////////////////////////////////////////////////////////////
// std types integration and convenience type defs
/////////////////////////////////////////////////////////////////////////////
use std::boxed::Box;
use std::rc::Rc;
use std::sync::Arc;
use std::sync::{MutexGuard, RwLockReadGuard, RwLockWriteGuard};
use std::cell::{Ref, RefCell, RefMut};
impl<T: 'static> ToHandle for RefCell<T> {
type Handle = Ref<'static, T>;
unsafe fn to_handle(x: *const Self) -> Self::Handle { (*x).borrow() }
}
impl<T: 'static> ToHandleMut for RefCell<T> {
type HandleMut = RefMut<'static, T>;
unsafe fn to_handle_mut(x: *const Self) -> Self::HandleMut { (*x).borrow_mut() }
}
// NB: Implementing ToHandle{,Mut} for Mutex and RwLock requires a decision
// about which handle creation to use (i.e. read() vs try_read()) as well as
// what to do with error results.
/// Typedef of a owning reference that uses a `Box` as the owner.
pub type BoxRef<T, U = T> = OwningRef<Box<T>, U>;
/// Typedef of a owning reference that uses a `Vec` as the owner.
pub type VecRef<T, U = T> = OwningRef<Vec<T>, U>;
/// Typedef of a owning reference that uses a `String` as the owner.
pub type StringRef = OwningRef<String, str>;
/// Typedef of a owning reference that uses a `Rc` as the owner.
pub type RcRef<T, U = T> = OwningRef<Rc<T>, U>;
/// Typedef of a owning reference that uses a `Arc` as the owner.
pub type ArcRef<T, U = T> = OwningRef<Arc<T>, U>;
/// Typedef of a owning reference that uses a `Ref` as the owner.
pub type RefRef<'a, T, U = T> = OwningRef<Ref<'a, T>, U>;
/// Typedef of a owning reference that uses a `RefMut` as the owner.
pub type RefMutRef<'a, T, U = T> = OwningRef<RefMut<'a, T>, U>;
/// Typedef of a owning reference that uses a `MutexGuard` as the owner.
pub type MutexGuardRef<'a, T, U = T> = OwningRef<MutexGuard<'a, T>, U>;
/// Typedef of a owning reference that uses a `RwLockReadGuard` as the owner.
pub type RwLockReadGuardRef<'a, T, U = T> = OwningRef<RwLockReadGuard<'a, T>, U>;
/// Typedef of a owning reference that uses a `RwLockWriteGuard` as the owner.
pub type RwLockWriteGuardRef<'a, T, U = T> = OwningRef<RwLockWriteGuard<'a, T>, U>;
/// Typedef of a mutable owning reference that uses a `Box` as the owner.
pub type BoxRefMut<T, U = T> = OwningRefMut<Box<T>, U>;
/// Typedef of a mutable owning reference that uses a `Vec` as the owner.
pub type VecRefMut<T, U = T> = OwningRefMut<Vec<T>, U>;
/// Typedef of a mutable owning reference that uses a `String` as the owner.
pub type StringRefMut = OwningRefMut<String, str>;
/// Typedef of a mutable owning reference that uses a `RefMut` as the owner.
pub type RefMutRefMut<'a, T, U = T> = OwningRefMut<RefMut<'a, T>, U>;
/// Typedef of a mutable owning reference that uses a `MutexGuard` as the owner.
pub type MutexGuardRefMut<'a, T, U = T> = OwningRefMut<MutexGuard<'a, T>, U>;
/// Typedef of a mutable owning reference that uses a `RwLockWriteGuard` as the owner.
pub type RwLockWriteGuardRefMut<'a, T, U = T> = OwningRefMut<RwLockWriteGuard<'a, T>, U>;
unsafe impl<'a, T: 'a> IntoErased<'a> for Box<T> {
type Erased = Box<dyn Erased + 'a>;
fn into_erased(self) -> Self::Erased {
self
}
}
unsafe impl<'a, T: 'a> IntoErased<'a> for Rc<T> {
type Erased = Rc<dyn Erased + 'a>;
fn into_erased(self) -> Self::Erased {
self
}
}
unsafe impl<'a, T: 'a> IntoErased<'a> for Arc<T> {
type Erased = Arc<dyn Erased + 'a>;
fn into_erased(self) -> Self::Erased {
self
}
}
/// Typedef of a owning reference that uses an erased `Box` as the owner.
pub type ErasedBoxRef<U> = OwningRef<Box<dyn Erased>, U>;
/// Typedef of a owning reference that uses an erased `Rc` as the owner.
pub type ErasedRcRef<U> = OwningRef<Rc<dyn Erased>, U>;
/// Typedef of a owning reference that uses an erased `Arc` as the owner.
pub type ErasedArcRef<U> = OwningRef<Arc<dyn Erased>, U>;
/// Typedef of a mutable owning reference that uses an erased `Box` as the owner.
pub type ErasedBoxRefMut<U> = OwningRefMut<Box<dyn Erased>, U>;
#[cfg(test)]
mod tests {
mod owning_ref {
use super::super::OwningRef;
use super::super::{RcRef, BoxRef, Erased, ErasedBoxRef};
use std::cmp::{PartialEq, Ord, PartialOrd, Ordering};
use std::hash::{Hash, Hasher};
use std::collections::hash_map::DefaultHasher;
use std::collections::HashMap;
use std::rc::Rc;
#[derive(Debug, PartialEq)]
struct Example(u32, String, [u8; 3]);
fn example() -> Example {
Example(42, "hello world".to_string(), [1, 2, 3])
}
#[test]
fn new_deref() {
let or: OwningRef<Box<()>, ()> = OwningRef::new(Box::new(()));
assert_eq!(&*or, &());
}
#[test]
fn into() {
let or: OwningRef<Box<()>, ()> = Box::new(()).into();
assert_eq!(&*or, &());
}
#[test]
fn map_offset_ref() {
let or: BoxRef<Example> = Box::new(example()).into();
let or: BoxRef<_, u32> = or.map(|x| &x.0);
assert_eq!(&*or, &42);
let or: BoxRef<Example> = Box::new(example()).into();
let or: BoxRef<_, u8> = or.map(|x| &x.2[1]);
assert_eq!(&*or, &2);
}
#[test]
fn map_heap_ref() {
let or: BoxRef<Example> = Box::new(example()).into();
let or: BoxRef<_, str> = or.map(|x| &x.1[..5]);
assert_eq!(&*or, "hello");
}
#[test]
fn map_static_ref() {
let or: BoxRef<()> = Box::new(()).into();
let or: BoxRef<_, str> = or.map(|_| "hello");
assert_eq!(&*or, "hello");
}
#[test]
fn map_chained() {
let or: BoxRef<String> = Box::new(example().1).into();
let or: BoxRef<_, str> = or.map(|x| &x[1..5]);
let or: BoxRef<_, str> = or.map(|x| &x[..2]);
assert_eq!(&*or, "el");
}
#[test]
fn map_chained_inference() {
let or = BoxRef::new(Box::new(example().1))
.map(|x| &x[..5])
.map(|x| &x[1..3]);
assert_eq!(&*or, "el");
}
#[test]
fn as_owner() {
let or: BoxRef<String> = Box::new(example().1).into();
let or = or.map(|x| &x[..5]);
assert_eq!(&*or, "hello");
assert_eq!(&**or.as_owner(), "hello world");
}
#[test]
fn into_owner() {
let or: BoxRef<String> = Box::new(example().1).into();
let or = or.map(|x| &x[..5]);
assert_eq!(&*or, "hello");
let s = *or.into_owner();
assert_eq!(&s, "hello world");
}
#[test]
fn fmt_debug() {
let or: BoxRef<String> = Box::new(example().1).into();
let or = or.map(|x| &x[..5]);
let s = format!("{:?}", or);
assert_eq!(&s, "OwningRef { owner: \"hello world\", reference: \"hello\" }");
}
#[test]
fn erased_owner() {
let o1: BoxRef<Example, str> = BoxRef::new(Box::new(example()))
.map(|x| &x.1[..]);
let o2: BoxRef<String, str> = BoxRef::new(Box::new(example().1))
.map(|x| &x[..]);
let os: Vec<ErasedBoxRef<str>> = vec![o1.erase_owner(), o2.erase_owner()];
assert!(os.iter().all(|e| &e[..] == "hello world"));
}
#[test]
fn non_static_erased_owner() {
let foo = [413, 612];
let bar = &foo;
// FIXME: lifetime inference fails us, and we can't easily define a lifetime for a closure
// So we use a function to identify the lifetimes instead.
fn borrow<'a>(a: &'a &[i32; 2]) -> &'a i32 {
&a[0]
}
let o: BoxRef<&[i32; 2]> = Box::new(bar).into();
let o: BoxRef<&[i32; 2], i32> = o.map(borrow);
let o: BoxRef<dyn Erased, i32> = o.erase_owner();
assert_eq!(*o, 413);
}
#[test]
fn raii_locks() {
use super::super::{RefRef, RefMutRef};
use std::cell::RefCell;
use super::super::{MutexGuardRef, RwLockReadGuardRef, RwLockWriteGuardRef};
use std::sync::{Mutex, RwLock};
{
let a = RefCell::new(1);
let a = {
let a = RefRef::new(a.borrow());
assert_eq!(*a, 1);
a
};
assert_eq!(*a, 1);
drop(a);
}
{
let a = RefCell::new(1);
let a = {
let a = RefMutRef::new(a.borrow_mut());
assert_eq!(*a, 1);
a
};
assert_eq!(*a, 1);
drop(a);
}
{
let a = Mutex::new(1);
let a = {
let a = MutexGuardRef::new(a.lock().unwrap());
assert_eq!(*a, 1);
a
};
assert_eq!(*a, 1);
drop(a);
}
{
let a = RwLock::new(1);
let a = {
let a = RwLockReadGuardRef::new(a.read().unwrap());
assert_eq!(*a, 1);
a
};
assert_eq!(*a, 1);
drop(a);
}
{
let a = RwLock::new(1);
let a = {
let a = RwLockWriteGuardRef::new(a.write().unwrap());
assert_eq!(*a, 1);
a
};
assert_eq!(*a, 1);
drop(a);
}
}
#[test]
fn eq() {
let or1: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
let or2: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
assert_eq!(or1.eq(&or2), true);
}
#[test]
fn cmp() {
let or1: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
let or2: BoxRef<[u8]> = BoxRef::new(vec![4, 5, 6].into_boxed_slice());
assert_eq!(or1.cmp(&or2), Ordering::Less);
}
#[test]
fn partial_cmp() {
let or1: BoxRef<[u8]> = BoxRef::new(vec![4, 5, 6].into_boxed_slice());
let or2: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
assert_eq!(or1.partial_cmp(&or2), Some(Ordering::Greater));
}
#[test]
fn hash() {
let mut h1 = DefaultHasher::new();
let mut h2 = DefaultHasher::new();
let or1: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
let or2: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
or1.hash(&mut h1);
or2.hash(&mut h2);
assert_eq!(h1.finish(), h2.finish());
}
#[test]
fn borrow() {
let mut hash = HashMap::new();
let key = RcRef::<String>::new(Rc::new("foo-bar".to_string())).map(|s| &s[..]);
hash.insert(key.clone().map(|s| &s[..3]), 42);
hash.insert(key.clone().map(|s| &s[4..]), 23);
assert_eq!(hash.get("foo"), Some(&42));
assert_eq!(hash.get("bar"), Some(&23));
}
#[test]
fn total_erase() {
let a: OwningRef<Vec<u8>, [u8]>
= OwningRef::new(vec![]).map(|x| &x[..]);
let b: OwningRef<Box<[u8]>, [u8]>
= OwningRef::new(vec![].into_boxed_slice()).map(|x| &x[..]);
let c: OwningRef<Rc<Vec<u8>>, [u8]> = unsafe {a.map_owner(Rc::new)};
let d: OwningRef<Rc<Box<[u8]>>, [u8]> = unsafe {b.map_owner(Rc::new)};
let e: OwningRef<Rc<dyn Erased>, [u8]> = c.erase_owner();
let f: OwningRef<Rc<dyn Erased>, [u8]> = d.erase_owner();
let _g = e.clone();
let _h = f.clone();
}
#[test]
fn total_erase_box() {
let a: OwningRef<Vec<u8>, [u8]>
= OwningRef::new(vec![]).map(|x| &x[..]);
let b: OwningRef<Box<[u8]>, [u8]>
= OwningRef::new(vec![].into_boxed_slice()).map(|x| &x[..]);
let c: OwningRef<Box<Vec<u8>>, [u8]> = a.map_owner_box();
let d: OwningRef<Box<Box<[u8]>>, [u8]> = b.map_owner_box();
let _e: OwningRef<Box<dyn Erased>, [u8]> = c.erase_owner();
let _f: OwningRef<Box<dyn Erased>, [u8]> = d.erase_owner();
}
#[test]
fn try_map1() {
use std::any::Any;
let x = Box::new(123_i32);
let y: Box<dyn Any> = x;
OwningRef::new(y).try_map(|x| x.downcast_ref::<i32>().ok_or(())).unwrap();
}
#[test]
fn try_map2() {
use std::any::Any;
let x = Box::new(123_u32);
let y: Box<dyn Any> = x;
OwningRef::new(y).try_map(|x| x.downcast_ref::<i32>().ok_or(())).unwrap_err();
}
#[test]
fn map_with_owner() {
let owning_ref: BoxRef<Example> = Box::new(example()).into();
let owning_ref = owning_ref.map(|owner| &owner.1);
owning_ref.map_with_owner(|owner, ref_field| {
assert_eq!(owner.1, *ref_field);
ref_field
});
}
#[test]
fn try_map_with_owner_ok() {
let owning_ref: BoxRef<Example> = Box::new(example()).into();
let owning_ref = owning_ref.map(|owner| &owner.1);
owning_ref.try_map_with_owner(|owner, ref_field| {
assert_eq!(owner.1, *ref_field);
Ok(ref_field) as Result<_, ()>
}).unwrap();
}
#[test]
fn try_map_with_owner_err() {
let owning_ref: BoxRef<Example> = Box::new(example()).into();
let owning_ref = owning_ref.map(|owner| &owner.1);
owning_ref.try_map_with_owner(|owner, ref_field| {
assert_eq!(owner.1, *ref_field);
Err(()) as Result<&(), _>
}).unwrap_err();
}
}
mod owning_handle {
use super::super::OwningHandle;
use super::super::RcRef;
use std::rc::Rc;
use std::cell::RefCell;
use std::sync::Arc;
use std::sync::RwLock;
#[test]
fn owning_handle() {
use std::cell::RefCell;
let cell = Rc::new(RefCell::new(2));
let cell_ref = RcRef::new(cell);
let mut handle = OwningHandle::new_with_fn(cell_ref, |x| unsafe { x.as_ref() }.unwrap().borrow_mut());
assert_eq!(*handle, 2);
*handle = 3;
assert_eq!(*handle, 3);
}
#[test]
fn try_owning_handle_ok() {
use std::cell::RefCell;
let cell = Rc::new(RefCell::new(2));
let cell_ref = RcRef::new(cell);
let mut handle = OwningHandle::try_new::<_, ()>(cell_ref, |x| {
Ok(unsafe {
x.as_ref()
}.unwrap().borrow_mut())
}).unwrap();
assert_eq!(*handle, 2);
*handle = 3;
assert_eq!(*handle, 3);
}
#[test]
fn try_owning_handle_err() {
use std::cell::RefCell;
let cell = Rc::new(RefCell::new(2));
let cell_ref = RcRef::new(cell);
let handle = OwningHandle::try_new::<_, ()>(cell_ref, |x| {
if false {
return Ok(unsafe {
x.as_ref()
}.unwrap().borrow_mut())
}
Err(())
});
assert!(handle.is_err());
}
#[test]
fn nested() {
use std::cell::RefCell;
use std::sync::{Arc, RwLock};
let result = {
let complex = Rc::new(RefCell::new(Arc::new(RwLock::new("someString"))));
let curr = RcRef::new(complex);
let curr = OwningHandle::new_with_fn(curr, |x| unsafe { x.as_ref() }.unwrap().borrow_mut());
let mut curr = OwningHandle::new_with_fn(curr, |x| unsafe { x.as_ref() }.unwrap().try_write().unwrap());
assert_eq!(*curr, "someString");
*curr = "someOtherString";
curr
};
assert_eq!(*result, "someOtherString");
}
#[test]
fn owning_handle_safe() {
use std::cell::RefCell;
let cell = Rc::new(RefCell::new(2));
let cell_ref = RcRef::new(cell);
let handle = OwningHandle::new(cell_ref);
assert_eq!(*handle, 2);
}
#[test]
fn owning_handle_mut_safe() {
use std::cell::RefCell;
let cell = Rc::new(RefCell::new(2));
let cell_ref = RcRef::new(cell);
let mut handle = OwningHandle::new_mut(cell_ref);
assert_eq!(*handle, 2);
*handle = 3;
assert_eq!(*handle, 3);
}
#[test]
fn owning_handle_safe_2() {
let result = {
let complex = Rc::new(RefCell::new(Arc::new(RwLock::new("someString"))));
let curr = RcRef::new(complex);
let curr = OwningHandle::new_with_fn(curr, |x| unsafe { x.as_ref() }.unwrap().borrow_mut());
let mut curr = OwningHandle::new_with_fn(curr, |x| unsafe { x.as_ref() }.unwrap().try_write().unwrap());
assert_eq!(*curr, "someString");
*curr = "someOtherString";
curr
};
assert_eq!(*result, "someOtherString");
}
}
mod owning_ref_mut {
use super::super::{OwningRefMut, BoxRefMut, Erased, ErasedBoxRefMut};
use super::super::BoxRef;
use std::cmp::{PartialEq, Ord, PartialOrd, Ordering};
use std::hash::{Hash, Hasher};
use std::collections::hash_map::DefaultHasher;
use std::collections::HashMap;
#[derive(Debug, PartialEq)]
struct Example(u32, String, [u8; 3]);
fn example() -> Example {
Example(42, "hello world".to_string(), [1, 2, 3])
}
#[test]
fn new_deref() {
let or: OwningRefMut<Box<()>, ()> = OwningRefMut::new(Box::new(()));
assert_eq!(&*or, &());
}
#[test]
fn new_deref_mut() {
let mut or: OwningRefMut<Box<()>, ()> = OwningRefMut::new(Box::new(()));
assert_eq!(&mut *or, &mut ());
}
#[test]
fn mutate() {
let mut or: OwningRefMut<Box<usize>, usize> = OwningRefMut::new(Box::new(0));
assert_eq!(&*or, &0);
*or = 1;
assert_eq!(&*or, &1);
}
#[test]
fn into() {
let or: OwningRefMut<Box<()>, ()> = Box::new(()).into();
assert_eq!(&*or, &());
}
#[test]
fn map_offset_ref() {
let or: BoxRefMut<Example> = Box::new(example()).into();
let or: BoxRef<_, u32> = or.map(|x| &mut x.0);
assert_eq!(&*or, &42);
let or: BoxRefMut<Example> = Box::new(example()).into();
let or: BoxRef<_, u8> = or.map(|x| &mut x.2[1]);
assert_eq!(&*or, &2);
}
#[test]
fn map_heap_ref() {
let or: BoxRefMut<Example> = Box::new(example()).into();
let or: BoxRef<_, str> = or.map(|x| &mut x.1[..5]);
assert_eq!(&*or, "hello");
}
#[test]
fn map_static_ref() {
let or: BoxRefMut<()> = Box::new(()).into();
let or: BoxRef<_, str> = or.map(|_| "hello");
assert_eq!(&*or, "hello");
}
#[test]
fn map_mut_offset_ref() {
let or: BoxRefMut<Example> = Box::new(example()).into();
let or: BoxRefMut<_, u32> = or.map_mut(|x| &mut x.0);
assert_eq!(&*or, &42);
let or: BoxRefMut<Example> = Box::new(example()).into();
let or: BoxRefMut<_, u8> = or.map_mut(|x| &mut x.2[1]);
assert_eq!(&*or, &2);
}
#[test]
fn map_mut_heap_ref() {
let or: BoxRefMut<Example> = Box::new(example()).into();
let or: BoxRefMut<_, str> = or.map_mut(|x| &mut x.1[..5]);
assert_eq!(&*or, "hello");
}
#[test]
fn map_mut_static_ref() {
static mut MUT_S: [u8; 5] = *b"hello";
let mut_s: &'static mut [u8] = unsafe { &mut MUT_S };
let or: BoxRefMut<()> = Box::new(()).into();
let or: BoxRefMut<_, [u8]> = or.map_mut(move |_| mut_s);
assert_eq!(&*or, b"hello");
}
#[test]
fn map_mut_chained() {
let or: BoxRefMut<String> = Box::new(example().1).into();
let or: BoxRefMut<_, str> = or.map_mut(|x| &mut x[1..5]);
let or: BoxRefMut<_, str> = or.map_mut(|x| &mut x[..2]);
assert_eq!(&*or, "el");
}
#[test]
fn map_chained_inference() {
let or = BoxRefMut::new(Box::new(example().1))
.map_mut(|x| &mut x[..5])
.map_mut(|x| &mut x[1..3]);
assert_eq!(&*or, "el");
}
#[test]
fn try_map_mut() {
let or: BoxRefMut<String> = Box::new(example().1).into();
let or: Result<BoxRefMut<_, str>, ()> = or.try_map_mut(|x| Ok(&mut x[1..5]));
assert_eq!(&*or.unwrap(), "ello");
let or: BoxRefMut<String> = Box::new(example().1).into();
let or: Result<BoxRefMut<_, str>, ()> = or.try_map_mut(|_| Err(()));
assert!(or.is_err());
}
#[test]
fn as_owner() {
let or: BoxRefMut<String> = Box::new(example().1).into();
let or = or.map_mut(|x| &mut x[..5]);
assert_eq!(&*or, "hello");
assert_eq!(&**or.as_owner(), "hello world");
}
#[test]
fn into_owner() {
let or: BoxRefMut<String> = Box::new(example().1).into();
let or = or.map_mut(|x| &mut x[..5]);
assert_eq!(&*or, "hello");
let s = *or.into_owner();
assert_eq!(&s, "hello world");
}
#[test]
fn fmt_debug() {
let or: BoxRefMut<String> = Box::new(example().1).into();
let or = or.map_mut(|x| &mut x[..5]);
let s = format!("{:?}", or);
assert_eq!(&s,
"OwningRefMut { owner: \"hello world\", reference: \"hello\" }");
}
#[test]
fn erased_owner() {
let o1: BoxRefMut<Example, str> = BoxRefMut::new(Box::new(example()))
.map_mut(|x| &mut x.1[..]);
let o2: BoxRefMut<String, str> = BoxRefMut::new(Box::new(example().1))
.map_mut(|x| &mut x[..]);
let os: Vec<ErasedBoxRefMut<str>> = vec![o1.erase_owner(), o2.erase_owner()];
assert!(os.iter().all(|e| &e[..] == "hello world"));
}
#[test]
fn non_static_erased_owner() {
let mut foo = [413, 612];
let bar = &mut foo;
// FIXME: lifetime inference fails us, and we can't easily define a lifetime for a closure
// So we use a function to identify the lifetimes instead.
fn borrow<'a>(a: &'a mut &mut [i32; 2]) -> &'a mut i32 {
&mut a[0]
}
let o: BoxRefMut<&mut [i32; 2]> = Box::new(bar).into();
let o: BoxRefMut<&mut [i32; 2], i32> = o.map_mut(borrow);
let o: BoxRefMut<dyn Erased, i32> = o.erase_owner();
assert_eq!(*o, 413);
}
#[test]
fn raii_locks() {
use super::super::RefMutRefMut;
use std::cell::RefCell;
use super::super::{MutexGuardRefMut, RwLockWriteGuardRefMut};
use std::sync::{Mutex, RwLock};
{
let a = RefCell::new(1);
let a = {
let a = RefMutRefMut::new(a.borrow_mut());
assert_eq!(*a, 1);
a
};
assert_eq!(*a, 1);
drop(a);
}
{
let a = Mutex::new(1);
let a = {
let a = MutexGuardRefMut::new(a.lock().unwrap());
assert_eq!(*a, 1);
a
};
assert_eq!(*a, 1);
drop(a);
}
{
let a = RwLock::new(1);
let a = {
let a = RwLockWriteGuardRefMut::new(a.write().unwrap());
assert_eq!(*a, 1);
a
};
assert_eq!(*a, 1);
drop(a);
}
}
#[test]
fn eq() {
let or1: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
let or2: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
assert_eq!(or1.eq(&or2), true);
}
#[test]
fn cmp() {
let or1: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
let or2: BoxRefMut<[u8]> = BoxRefMut::new(vec![4, 5, 6].into_boxed_slice());
assert_eq!(or1.cmp(&or2), Ordering::Less);
}
#[test]
fn partial_cmp() {
let or1: BoxRefMut<[u8]> = BoxRefMut::new(vec![4, 5, 6].into_boxed_slice());
let or2: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
assert_eq!(or1.partial_cmp(&or2), Some(Ordering::Greater));
}
#[test]
fn hash() {
let mut h1 = DefaultHasher::new();
let mut h2 = DefaultHasher::new();
let or1: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
let or2: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
or1.hash(&mut h1);
or2.hash(&mut h2);
assert_eq!(h1.finish(), h2.finish());
}
#[test]
fn borrow() {
let mut hash = HashMap::new();
let key1 = BoxRefMut::<String>::new(Box::new("foo".to_string())).map(|s| &s[..]);
let key2 = BoxRefMut::<String>::new(Box::new("bar".to_string())).map(|s| &s[..]);
hash.insert(key1, 42);
hash.insert(key2, 23);
assert_eq!(hash.get("foo"), Some(&42));
assert_eq!(hash.get("bar"), Some(&23));
}
#[test]
fn total_erase() {
let a: OwningRefMut<Vec<u8>, [u8]>
= OwningRefMut::new(vec![]).map_mut(|x| &mut x[..]);
let b: OwningRefMut<Box<[u8]>, [u8]>
= OwningRefMut::new(vec![].into_boxed_slice()).map_mut(|x| &mut x[..]);
let c: OwningRefMut<Box<Vec<u8>>, [u8]> = unsafe {a.map_owner(Box::new)};
let d: OwningRefMut<Box<Box<[u8]>>, [u8]> = unsafe {b.map_owner(Box::new)};
let _e: OwningRefMut<Box<dyn Erased>, [u8]> = c.erase_owner();
let _f: OwningRefMut<Box<dyn Erased>, [u8]> = d.erase_owner();
}
#[test]
fn total_erase_box() {
let a: OwningRefMut<Vec<u8>, [u8]>
= OwningRefMut::new(vec![]).map_mut(|x| &mut x[..]);
let b: OwningRefMut<Box<[u8]>, [u8]>
= OwningRefMut::new(vec![].into_boxed_slice()).map_mut(|x| &mut x[..]);
let c: OwningRefMut<Box<Vec<u8>>, [u8]> = a.map_owner_box();
let d: OwningRefMut<Box<Box<[u8]>>, [u8]> = b.map_owner_box();
let _e: OwningRefMut<Box<dyn Erased>, [u8]> = c.erase_owner();
let _f: OwningRefMut<Box<dyn Erased>, [u8]> = d.erase_owner();
}
#[test]
fn try_map1() {
use std::any::Any;
let x = Box::new(123_i32);
let y: Box<dyn Any> = x;
OwningRefMut::new(y).try_map_mut(|x| x.downcast_mut::<i32>().ok_or(())).unwrap();
}
#[test]
fn try_map2() {
use std::any::Any;
let x = Box::new(123_u32);
let y: Box<dyn Any> = x;
OwningRefMut::new(y).try_map_mut(|x| x.downcast_mut::<i32>().ok_or(())).unwrap_err();
}
#[test]
fn try_map3() {
use std::any::Any;
let x = Box::new(123_i32);
let y: Box<dyn Any> = x;
OwningRefMut::new(y).try_map(|x| x.downcast_ref::<i32>().ok_or(())).unwrap();
}
#[test]
fn try_map4() {
use std::any::Any;
let x = Box::new(123_u32);
let y: Box<dyn Any> = x;
OwningRefMut::new(y).try_map(|x| x.downcast_ref::<i32>().ok_or(())).unwrap_err();
}
#[test]
fn into_owning_ref() {
use super::super::BoxRef;
let or: BoxRefMut<()> = Box::new(()).into();
let or: BoxRef<()> = or.into();
assert_eq!(&*or, &());
}
struct Foo {
u: u32,
}
struct Bar {
f: Foo,
}
#[test]
fn ref_mut() {
use std::cell::RefCell;
let a = RefCell::new(Bar { f: Foo { u: 42 } });
let mut b = OwningRefMut::new(a.borrow_mut());
assert_eq!(b.f.u, 42);
b.f.u = 43;
let mut c = b.map_mut(|x| &mut x.f);
assert_eq!(c.u, 43);
c.u = 44;
let mut d = c.map_mut(|x| &mut x.u);
assert_eq!(*d, 44);
*d = 45;
assert_eq!(*d, 45);
}
}
}