Add conversions between typed arrays and Rust #1147
Conversation
For all typed arrays, this commit adds: * `TypedArray::view(src: &[Type])` * `TypedArray::copy_to(&self, dst: &mut [Type])` The `view` function is unsafe because it doesn't provide any guarantees about lifetimes or mutability. The `copy_to` function is, however, safe. Closes rustwasm#811
| /// Copy the contents of this JS typed array into the destination | ||
| /// Rust slice. | ||
| /// | ||
| /// This function will efficiently copy the memory from a typed |
There was a problem hiding this comment.
Curious, what does "efficiently" mean here? What is the less efficient alternative?
Thanks!
There was a problem hiding this comment.
Ah this just means that it uses the set API which eventually translates to something like a raw memcpy. That's the fastest way (even in Rust) to copy chunks of memory.
The slow way would be to copy bytes one-by-one in wasm which misses on on things like vectorization and eliding bounds checks
There was a problem hiding this comment.
Gains knowledge
Cool - thanks!!
| macro_rules! arrays { | ||
| ($($name:ident: $ty:ident,)*) => ($( | ||
| impl $name { | ||
| /// Creates a JS typed array which is a few into wasm's linear |
There was a problem hiding this comment.
Just a minor thing that I noticed -> few -> view
There was a problem hiding this comment.
Oops, I'll be sure to handle before landing!
|
This looks great, thanks! Is there a way to return a single element from the typed array as well? There doesn’t seem to be an indexing getter for typed arrays in js-sys, but this is supported in JavaScript. |
|
@grovesNL Currently you would use let value = js_sys::Reflect::get(typed_array.as_ref(), &JsValue::from_f64(0.0)).unwrap();
It's equivalent to the @alexcrichton @fitzgen Any thoughts on adding a convenience method which basically does the above? I think it'd be especially nice if the convenience method could avoid the If you're okay with it, I can try sending a PR. |
|
Oh right, using It feels slightly confusing now because of the availability of |
|
Adding a convenience or a method to just get one item sounds like a good idea to me! @Pauan I'd be down for such a PR |
|
PR made at #1225 |
For all typed arrays, this commit adds:
TypedArray::view(src: &[Type])TypedArray::copy_to(&self, dst: &mut [Type])The
viewfunction is unsafe because it doesn't provide any guaranteesabout lifetimes or mutability. The
copy_tofunction is, however, safe.Closes #811