Implement the Iterator trait for JS iterators
#797
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crates/js-sys/src/lib.rs
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| let val = Iterator::next(&*self) | ||
| .expect("JS object didn't obey iterator protocol"); | ||
| if val.done() { | ||
| None |
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I thought this was wrong, and that if both done and value are present (happens when returning from a generator), that we should add the value to the iterator, but it seems that it doesn't get into the iterable in JS:
Carry on!
crates/js-sys/src/lib.rs
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| fn next(&mut self) -> Option<JsValue> { | ||
| let val = Iterator::next(&*self) | ||
| .expect("JS object didn't obey iterator protocol"); |
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Iterables (such as generators) can totally throw, and it isn't really violating the protocol :-/
I think we should have Iterator<Item = Result<JsValue, JsValue>> and then fuse the iterator such that calling next after the first Err always returns None and doesn't call back into JS again.
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Interesting!
I don't think we could auto-fuse though unless we start setting a JS property on the iterator (which seems icky) or have a wrapper in Rust. I'd be ok returning a Result<JsValue, JsValue> but that would make fusing difficult for sure
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I think the fusing is important for combinators and .collect() to work correctly.
Perhaps we should implement IntoIterator for &'a js_sys::Iterator witha custom type that has a bool for fusing?
This commit implements the standard library's `Iterator` trait for the `js_sys::Iterator` type, using the iterator protocol described on [MDN] Closes rustwasm#777 [MDN]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
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This commit implements the standard library's
Iteratortrait for thejs_sys::Iteratortype, using the iterator protocol described on MDNCloses #777