Implement fold
on hash::table::{Iter,IterMut}.
#37362
Closed
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Also forwards
fold
to the wrapped iterator forHashMap
andHashSet
iterators to actually gain something from the change.There are more places where this could be applied (eg.
Drain
,IntoIter
), but I wanted to first decide whether this is a good idea or not. This PR could also do with some additional tests. A simple benchmark which sums up 1000, 10000, 100000 elements in aHashSet
sees the following gains:Before:
After:
Note that these gains only work if you explicitly call
fold
. Callingsum
callscloned
which doesn't forward thefold
call to the inner iterator (but will after #37315).Benchmark code