Avoid cloning in Array::filter_map_to (for map_each)#183
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marmeladema merged 4 commits intoJul 8, 2026
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| let mut write = 0; | ||
| for read in 0..vec.len() { | ||
| let elem = &mut vec[read]; | ||
| if let Some(elem) = func(std::mem::replace(elem, LhsValue::Bool(false))) { |
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At first glance, I am not convince by this change. Before/after seem equivalent? Before we would only allocate a vec for the borrowed case; which is done anyway in the new code further down.
The only thing that seems to be avoided in the new code is the mem::replace in the borrowed case. Is that really responsible for a substantial speedup?
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The change is in the deleted line 166: slice.to_vec(), which clones & allocates, only to throw away the cloned/allocated LhsValues (often bytes) & using the Vec to store bools. It is better to pass a borrowed LhsValue & let the called function be optimised for borrowed cases.
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