Avi Kivity d3d7698502 interval: support C++20 three-way comparisons ...

Allow the tri-comparator input to range functions to return
std::strong_ordering, e.g. the result of operator<=>. An int
input is still allowed, and coerced to std::strong_ordering by
tri-comparing it against zero. Once all users are converted, this
will be disallowed.

The clever code that performs boundary comparisons unfortunately
has to be dumbed down to conditionals. A helper
require_ordering_and_on_equal_return() is introduced that accepts
a comparison result between bound values, an expected comparison
result, and what to return if the bound value matches (this depends
on whether individual bounds are exclusive or inclusive, on
whether the bounds are start bounds or end bounds, and on the
sense of the comparison).

Unfortunately, the code is somewhat pessimized, and there is no
way to pessimize it as the enum underlying std::strong_ordering
is hidden.

2021-02-28 21:03:25 +02:00

32 KiB

Raw Blame History

View Raw