Replace syntax's SmallVector with AccumulateVec #37551
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Also cc #37371, which has some discussion on expanding/generalizing SmallVector. |
Mark-Simulacrum
commented
Nov 3, 2016
| _ => unreachable!() | ||
| } | ||
| } | ||
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This code would look better with @ticki's replace_with, but it's not altogether that bad without either.
This was referenced Nov 3, 2016
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LLVM gets confused by |
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There should probably be two types still, at least a |
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Alright, the implementation now consists of This currently doesn't compile, but I don't know why--from what I can tell, I didn't change the method signatures shown here. Edit: Also, as a sidenote, this error message could really be improved: I can't tell what is being moved out of borrowed content. cc @jonathandturner. |
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That's an odd error - are you sure you didn't change a signature by accident? |
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Mark-Simulacrum
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The current code segfaults with this backtrace. I don't know why this is, and would appreciate any suggestions. |
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Hmm, after removing the derives for |
eddyb
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Nov 6, 2016
| pub fn pop(&mut self) -> Option<A::Element> { | ||
| if self.count > 0 { | ||
| let arr = &mut self.values as &mut [ManuallyDrop<_>]; | ||
| let value = mem::replace(&mut arr[self.count - 1], ManuallyDrop::new()); |
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You don't need mem::replace, you can just do ptr::read(&arr[self.count - 1].value).
Also, you can decrement first, and use self.count then.
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| impl<A: Array> Iterator for ArrayVec<A> { |
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Why? You could make a forward by-value iterator if you wanted to (by having an ArrayVec and a start index), and then implement IntoIterator on ArrayVec.
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| fn next(&mut self) -> Option<A::Element> { | ||
| match self.repr { | ||
| IntoIterRepr::Array(ref mut arr) => arr.pop(), |
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This is not a good idea at all, it goes in the reverse order!
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| fn into_iter(self) -> Self::IntoIter { | ||
| match *self { | ||
| AccumulateVec::Array(ref arr) => arr.iter(), | ||
| AccumulateVec::Heap(ref vec) => vec.iter(), |
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You can just self.iter() - same for the mutable version below.
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| fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> { | ||
| s.emit_seq(self.len(), |s| { | ||
| for (i, e) in self.iter().enumerate() { | ||
| try!(s.emit_seq_elt(i, |s| e.encode(s))); |
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You can use ? instead of try! here and below.
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I was going to, but then we need to add ? to the feature list and I recalled needing to mess with cfg(stage0) or something like that in order for that to work properly.
I can change it if you'd like, though--let me know.
eddyb
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Nov 7, 2016
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f? @erickt |
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Eh, it looks fine enough for me. @bors r+ |
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📌 Commit 8380d32 has been approved by |
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☔ The latest upstream changes (presumably #37246) made this pull request unmergeable. Please resolve the merge conflicts. |
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Rebased. |
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@bors r+ |
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📌 Commit 7bbebb1 has been approved by |
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Nov 11, 2016
…ddyb Replace syntax's SmallVector with AccumulateVec This adds a new type to data_structures, `SmallVec`, which wraps `AccumulateVec` with support for re-allocating onto the heap (`SmallVec::reserve`). `SmallVec` is then used to replace the implementation of `SmallVector` in libsyntax. r? @eddyb Fixes rust-lang#37371. Using `SmallVec` instead of libsyntax's `SmallVector` will provide the `N = 2/4` case easily (just needs a few more `Array` impls). cc @nnethercote, probably interested in this area
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This is nice, thank you. I particularly like that you found a way to let N be choosable. E.g. I was looking at |
eddyb
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…ddyb Replace syntax's SmallVector with AccumulateVec This adds a new type to data_structures, `SmallVec`, which wraps `AccumulateVec` with support for re-allocating onto the heap (`SmallVec::reserve`). `SmallVec` is then used to replace the implementation of `SmallVector` in libsyntax. r? @eddyb Fixes rust-lang#37371. Using `SmallVec` instead of libsyntax's `SmallVector` will provide the `N = 2/4` case easily (just needs a few more `Array` impls). cc @nnethercote, probably interested in this area
bors
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Nov 12, 2016
Rollup of 30 pull requests - Successful merges: #37190, #37368, #37481, #37503, #37527, #37535, #37551, #37584, #37600, #37613, #37615, #37659, #37662, #37669, #37682, #37688, #37690, #37692, #37693, #37694, #37695, #37696, #37698, #37699, #37705, #37708, #37709, #37716, #37724, #37727 - Failed merges: #37640, #37689, #37717
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This adds a new type to data_structures,
SmallVec, which wrapsAccumulateVecwith support for re-allocating onto the heap (SmallVec::reserve).SmallVecis then used to replace the implementation ofSmallVectorin libsyntax.r? @eddyb
Fixes #37371. Using
SmallVecinstead of libsyntax'sSmallVectorwill provide theN = 2/4case easily (just needs a few moreArrayimpls).cc @nnethercote, probably interested in this area