Make take_while short-circuit #2358
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This change makes `Iter.take_while` short-circuit the first time that the predicate `f` returns false or raises an error. Previously, this adapter would infinitely pull from an infinite iterator after the predicate had already returned false. resolves #2356
Theodus
added
the
changelog - fixed
mfelsche
reviewed
Nov 20, 2017
| .take_while({(n) => n < 2 }) | ||
| h.assert_eq[USize](0, infinite.next()?) | ||
| h.assert_eq[USize](1, infinite.next()?) | ||
| h.assert_false(infinite.has_next()) |
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Do you think it makes sense to verify that a call to infinite.next() is also properly erroring?
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This is a very good question and relates to a question that I was planning to ask in the next sync about what it means for an iterator to be "well behaved". I leave it out currently since some of the most common iterators will continue to give values after has_next returns false (such as Range).
mfelsche
approved these changes
Nov 22, 2017
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This change makes
Iter.take_whileshort-circuit the first time thatthe predicate
freturns false or raises an error. Previously, thisadapter would infinitely pull from an infinite iterator after the
predicate had already returned false.
resolves #2356