Remove the unnecessary copy in Blob::new
#152
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hamza1311
requested changes
Jul 31, 2021
crates/file/src/blob.rs
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| name, | ||
| // SAFETY: `Self::new_` doesn't modify the `Uint8Array`, | ||
| // or hold on to the reference past the end of the function call. | ||
| unsafe { contents.into_jsvalue() }, |
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I think we should pass contents to Self::new_. Currently, someone could change Self::new_ without realizing it this safety requirements. Also, that would reduce the number of places unsafe block is required.
First, I made `new_` take a `BlobContents`, to move the unsafety inside the function to make it easier to check. Then I got rid of it in favour of `new_with_options` since the signature was the same. That broke `File::slice`, though, since it passed a `Blob` for `contents`, which didn't implement `BlobContents`. Since having `Blob` implement `BlobContents` is useful anyway, I decided to do that and simplify things. I then also implemented `BlobContents` for `JsString`, so that if you already have one you don't have to go via `&str`. I then noticed that `Blob` encoded JS strings as UTF-8, which meant that passing `&str` to `new Blob()` by converting it to a JS string meant converting it into UTF-16 and then back to UTF-8. So, I made it instead pass it as bytes, since it's already correctly encoded.
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Use
Uint8Array::viewinstead ofUint8Array::fromto avoid making two copies of slices passed toBlob::new.Fixes #150