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Add raw array pointer types #496

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merged 10 commits into from Nov 29, 2018
Merged

Add raw array pointer types #496

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355b153
Make do_collapse_axis return offset instead of performing it
jturner314 Nov 19, 2018
ebf864f
Add DataRaw and DataRawMut traits
jturner314 Sep 28, 2018
2a98148
Add RawArrayView and RawArrayViewMut
jturner314 Sep 28, 2018
0a7fafd
Add conversions to/from RawArrayView(Mut)
jturner314 Sep 28, 2018
8baa1cc
Relax constraints on ArrayBase methods
jturner314 Sep 28, 2018
4b91c6b
Remove duplication in from_shape_ptr and split_at
jturner314 Nov 19, 2018
e2fcf22
Add DataRawClone and relax Clone implementation
jturner314 Sep 28, 2018
6ef3b48
Remove deref_view and deref_view_mut
jturner314 Nov 19, 2018
c81ccdd
Deprecate the DataClone trait
jturner314 Nov 19, 2018
218bb88
Rename DataRaw* traits to RawData*
jturner314 Nov 28, 2018
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257 changes: 198 additions & 59 deletions src/data_traits.rs
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Expand Up @@ -14,6 +14,7 @@ use std::sync::Arc;
use {
ArrayBase,
Dimension,
RawViewRepr,
ViewRepr,
OwnedRepr,
OwnedRcRepr,
Expand All @@ -22,92 +23,177 @@ use {

/// Array representation trait.
///
/// ***Note:*** `Data` is not an extension interface at this point.
/// For an array that meets the invariants of the `ArrayBase` type. This trait
/// does not imply any ownership or lifetime; pointers to elements in the array
/// may not be safe to dereference.
///
/// ***Note:*** `RawData` is not an extension interface at this point.
/// Traits in Rust can serve many different roles. This trait is public because
/// it is used as a bound on public methods.
pub unsafe trait Data : Sized {
pub unsafe trait RawData : Sized {
/// The array element type.
type Elem;

#[doc(hidden)]
// This method is only used for debugging
fn _data_slice(&self) -> &[Self::Elem];
fn _data_slice(&self) -> Option<&[Self::Elem]>;

private_decl!{}
}

/// Array representation trait.
///
/// For an array with writable elements.
///
/// ***Internal trait, see `RawData`.***
pub unsafe trait RawDataMut : RawData {
/// If possible, ensures that the array has unique access to its data.
///
/// If `Self` provides safe mutable access to array elements, then it
/// **must** panic or ensure that the data is unique.
#[doc(hidden)]
fn try_ensure_unique<D>(&mut ArrayBase<Self, D>)
where Self: Sized,
D: Dimension;

/// If possible, returns whether the array has unique access to its data.
///
/// If `Self` provides safe mutable access to array elements, then it
/// **must** return `Some(_)`.
#[doc(hidden)]
fn try_is_unique(&mut self) -> Option<bool>;
}

/// Array representation trait.
///
/// An array representation that can be cloned.
///
/// ***Internal trait, see `RawData`.***
pub unsafe trait RawDataClone : RawData {
#[doc(hidden)]
/// Unsafe because, `ptr` must point inside the current storage.
unsafe fn clone_with_ptr(&self, ptr: *mut Self::Elem) -> (Self, *mut Self::Elem);

#[doc(hidden)]
unsafe fn clone_from_with_ptr(&mut self, other: &Self, ptr: *mut Self::Elem) -> *mut Self::Elem {
let (data, ptr) = other.clone_with_ptr(ptr);
*self = data;
ptr
}
}

/// Array representation trait.
///
/// For an array with elements that can be accessed with safe code.
///
/// ***Internal trait, see `RawData`.***
pub unsafe trait Data : RawData {
/// Converts the array to a uniquely owned array, cloning elements if necessary.
#[doc(hidden)]
fn into_owned<D>(self_: ArrayBase<Self, D>) -> ArrayBase<OwnedRepr<Self::Elem>, D>
where
Self::Elem: Clone,
D: Dimension;

private_decl!{}
}

/// Array representation trait.
///
/// For an array with writable elements.
/// For an array with writable elements that can be accessed with safe code.
///
/// ***Internal trait, see `Data`.***
pub unsafe trait DataMut : Data {
//
// # For implementers
//
// If you implement the `DataMut` trait, you are guaranteeing that the
// `RawDataMut::try_ensure_unique` implementation always panics or ensures that
// the data is unique. You are also guaranteeing that `try_is_unique` always
// returns `Some(_)`.
pub unsafe trait DataMut : Data + RawDataMut {
/// Ensures that the array has unique access to its data.
#[doc(hidden)]
#[inline]
fn ensure_unique<D>(&mut ArrayBase<Self, D>)
where Self: Sized,
D: Dimension
{ }
fn ensure_unique<D>(self_: &mut ArrayBase<Self, D>)
where Self: Sized,
D: Dimension
{
Self::try_ensure_unique(self_)
}

/// Returns whether the array has unique access to its data.
#[doc(hidden)]
#[inline]
fn is_unique(&mut self) -> bool {
true
self.try_is_unique().unwrap()
}
}

/// Array representation trait.
///
/// An array representation that can be cloned.
/// An array representation that can be cloned and allows elements to be
/// accessed with safe code.
///
/// ***Internal trait, see `Data`.***
pub unsafe trait DataClone : Data {
#[doc(hidden)]
/// Unsafe because, `ptr` must point inside the current storage.
unsafe fn clone_with_ptr(&self, ptr: *mut Self::Elem) -> (Self, *mut Self::Elem);
#[deprecated(note="use `Data + RawDataClone` instead", since="0.13")]
pub trait DataClone : Data + RawDataClone {}

#[doc(hidden)]
unsafe fn clone_from_with_ptr(&mut self, other: &Self, ptr: *mut Self::Elem) -> *mut Self::Elem {
let (data, ptr) = other.clone_with_ptr(ptr);
*self = data;
ptr
#[allow(deprecated)]
impl<T> DataClone for T where T: Data + RawDataClone {}

unsafe impl<A> RawData for RawViewRepr<*const A> {
type Elem = A;
fn _data_slice(&self) -> Option<&[A]> {
None
}
private_impl!{}
}

unsafe impl<A> Data for OwnedArcRepr<A> {
unsafe impl<A> RawDataClone for RawViewRepr<*const A> {
unsafe fn clone_with_ptr(&self, ptr: *mut Self::Elem) -> (Self, *mut Self::Elem) {
(*self, ptr)
}
}
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I think we can be without this trait, and just use DataClone? Clone is the only consumer of the trait

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In current ndarray, DataClone has a Data bound. If we want to be able to clone ArrayPtr/ArrayPtrMut, this is too restrictive given only the current implementation of Clone for ArrayBase. Possible alternatives to the approach in this PR:

  1. Don't add a DataRawClone trait; instead, implement Clone individually for ArrayPtr and ArrayPtrMut. That would be inconsistent and would prevent code with just a DataClone bound from being able to clone ArrayPtr and ArrayPtrMut.

    With a breaking change, though, we could get rid of DataClone entirely and just implement Clone individually for ArcArray, Array, ArrayView, ArrayPtr, and ArrayPtrMut. This actually seems pretty nice, but it does make writing generic code more difficult. (In user code, the bound to allow array.clone() would have to be ArrayBase<S, D>: Clone instead of S: DataRawClone.)

  2. Add the DataRawClone trait and remove the DataClone trait. That would work but would be a breaking change.

Fwiw, DataClone does have a small amount of utility as the combination of Data and DataRawClone, but I agree it does seem like unnecessary complication.

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(2) I think a breaking change is ok. We have lots of them queued? We should get on to merging them as soon as 0.12.1 is released (and I can do the releasing if you want).

I'd hope it has very little impact on users, but maybe I underestimate how much these representation traits are used?

I'd use the name DataClone for the new trait.

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I'd use the name DataClone for the new trait.

The only thing that I don't like about this is consistency of naming with the other data traits, especially DataMut vs. DataRawMut. I was naming traits without a Data bound DataRaw* and traits with a Data bound Data*.

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Good point. We still should use only one trait if we don't need 2, we could use the name DataRawClone and let DataClone be a deprecated reexport of it.

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DataClone could be a trait alias of DataRawClone + Data? That's a new Rust feature we can transition to.

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Woah, I had no idea trait aliases were a thing. They look very convenient.

I've added a commit deprecating DataClone. We can switch DataClone to a trait alias once they're available on stable.


unsafe impl<A> RawData for RawViewRepr<*mut A> {
type Elem = A;
fn _data_slice(&self) -> &[A] {
&self.0
fn _data_slice(&self) -> Option<&[A]> {
None
}
fn into_owned<D>(mut self_: ArrayBase<Self, D>) -> ArrayBase<OwnedRepr<Self::Elem>, D>
where
A: Clone,
D: Dimension,
{
Self::ensure_unique(&mut self_);
let data = OwnedRepr(Arc::try_unwrap(self_.data.0).ok().unwrap());
ArrayBase {
data: data,
ptr: self_.ptr,
dim: self_.dim,
strides: self_.strides,
}
private_impl!{}
}

unsafe impl<A> RawDataMut for RawViewRepr<*mut A> {
#[inline]
fn try_ensure_unique<D>(_: &mut ArrayBase<Self, D>)
where Self: Sized,
D: Dimension
{}

#[inline]
fn try_is_unique(&mut self) -> Option<bool> {
None
}
}

unsafe impl<A> RawDataClone for RawViewRepr<*mut A> {
unsafe fn clone_with_ptr(&self, ptr: *mut Self::Elem) -> (Self, *mut Self::Elem) {
(*self, ptr)
}
}

unsafe impl<A> RawData for OwnedArcRepr<A> {
type Elem = A;
fn _data_slice(&self) -> Option<&[A]> {
Some(&self.0)
}
private_impl!{}
}

// NOTE: Copy on write
unsafe impl<A> DataMut for OwnedArcRepr<A>
where A: Clone
unsafe impl<A> RawDataMut for OwnedArcRepr<A>
where
A: Clone,
{
fn ensure_unique<D>(self_: &mut ArrayBase<Self, D>)
fn try_ensure_unique<D>(self_: &mut ArrayBase<Self, D>)
where Self: Sized,
D: Dimension
{
Expand Down Expand Up @@ -136,23 +222,59 @@ unsafe impl<A> DataMut for OwnedArcRepr<A>
}
}

fn is_unique(&mut self) -> bool {
Arc::get_mut(&mut self.0).is_some()
fn try_is_unique(&mut self) -> Option<bool> {
Some(Arc::get_mut(&mut self.0).is_some())
}
}

unsafe impl<A> DataClone for OwnedArcRepr<A> {
unsafe impl<A> Data for OwnedArcRepr<A> {
fn into_owned<D>(mut self_: ArrayBase<Self, D>) -> ArrayBase<OwnedRepr<Self::Elem>, D>
where
A: Clone,
D: Dimension,
{
Self::ensure_unique(&mut self_);
let data = OwnedRepr(Arc::try_unwrap(self_.data.0).ok().unwrap());
ArrayBase {
data: data,
ptr: self_.ptr,
dim: self_.dim,
strides: self_.strides,
}
}
}

unsafe impl<A> DataMut for OwnedArcRepr<A> where A: Clone {}

unsafe impl<A> RawDataClone for OwnedArcRepr<A> {
unsafe fn clone_with_ptr(&self, ptr: *mut Self::Elem) -> (Self, *mut Self::Elem) {
// pointer is preserved
(self.clone(), ptr)
}
}

unsafe impl<A> Data for OwnedRepr<A> {
unsafe impl<A> RawData for OwnedRepr<A> {
type Elem = A;
fn _data_slice(&self) -> &[A] {
&self.0
fn _data_slice(&self) -> Option<&[A]> {
Some(&self.0)
}
private_impl!{}
}

unsafe impl<A> RawDataMut for OwnedRepr<A> {
#[inline]
fn try_ensure_unique<D>(_: &mut ArrayBase<Self, D>)
where Self: Sized,
D: Dimension
{}

#[inline]
fn try_is_unique(&mut self) -> Option<bool> {
Some(true)
}
}

unsafe impl<A> Data for OwnedRepr<A> {
#[inline]
fn into_owned<D>(self_: ArrayBase<Self, D>) -> ArrayBase<OwnedRepr<Self::Elem>, D>
where
Expand All @@ -161,12 +283,11 @@ unsafe impl<A> Data for OwnedRepr<A> {
{
self_
}
private_impl!{}
}

unsafe impl<A> DataMut for OwnedRepr<A> { }

unsafe impl<A> DataClone for OwnedRepr<A>
unsafe impl<A> RawDataClone for OwnedRepr<A>
where A: Clone
{
unsafe fn clone_with_ptr(&self, ptr: *mut Self::Elem) -> (Self, *mut Self::Elem) {
Expand All @@ -192,40 +313,58 @@ unsafe impl<A> DataClone for OwnedRepr<A>
}
}

unsafe impl<'a, A> Data for ViewRepr<&'a A> {
unsafe impl<'a, A> RawData for ViewRepr<&'a A> {
type Elem = A;
fn _data_slice(&self) -> &[A] {
&[]
fn _data_slice(&self) -> Option<&[A]> {
None
}
private_impl!{}
}

unsafe impl<'a, A> Data for ViewRepr<&'a A> {
fn into_owned<D>(self_: ArrayBase<Self, D>) -> ArrayBase<OwnedRepr<Self::Elem>, D>
where
Self::Elem: Clone,
D: Dimension,
{
self_.to_owned()
}
private_impl!{}
}

unsafe impl<'a, A> DataClone for ViewRepr<&'a A> {
unsafe impl<'a, A> RawDataClone for ViewRepr<&'a A> {
unsafe fn clone_with_ptr(&self, ptr: *mut Self::Elem) -> (Self, *mut Self::Elem) {
(*self, ptr)
}
}

unsafe impl<'a, A> Data for ViewRepr<&'a mut A> {
unsafe impl<'a, A> RawData for ViewRepr<&'a mut A> {
type Elem = A;
fn _data_slice(&self) -> &[A] {
&[]
fn _data_slice(&self) -> Option<&[A]> {
None
}
private_impl!{}
}

unsafe impl<'a, A> RawDataMut for ViewRepr<&'a mut A> {
#[inline]
fn try_ensure_unique<D>(_: &mut ArrayBase<Self, D>)
where Self: Sized,
D: Dimension {}

#[inline]
fn try_is_unique(&mut self) -> Option<bool> {
Some(true)
}
}

unsafe impl<'a, A> Data for ViewRepr<&'a mut A> {
fn into_owned<D>(self_: ArrayBase<Self, D>) -> ArrayBase<OwnedRepr<Self::Elem>, D>
where
Self::Elem: Clone,
D: Dimension,
{
self_.to_owned()
}
private_impl!{}
}

unsafe impl<'a, A> DataMut for ViewRepr<&'a mut A> { }
Expand All @@ -250,7 +389,7 @@ pub unsafe trait DataOwned : Data {
/// A representation that is a lightweight view.
///
/// ***Internal trait, see `Data`.***
pub unsafe trait DataShared : Clone + DataClone { }
pub unsafe trait DataShared : Clone + Data + RawDataClone { }

unsafe impl<A> DataShared for OwnedRcRepr<A> {}
unsafe impl<'a, A> DataShared for ViewRepr<&'a A> {}
Expand Down