On Wednesday, 8 August 2018 at 01:33:26 UTC, Steven Schveighoffer
wrote:
On 8/7/18 9:20 PM, Nicholas Wilson wrote:
the first overload is
ptrdiff_t countUntil(alias pred = "a == b", R, Rs...)(R
haystack, Rs needles)
if (isForwardRange!R
&& Rs.length > 0
&& isForwardRange!(Rs[0]) == isInputRange!(Rs[0])
&& is(typeof(startsWith!pred(haystack, needles[0])))
&& (Rs.length == 1
|| is(typeof(countUntil!pred(haystack, needles[1 .. $])))))
What does `isForwardRange!(Rs[0]) == isInputRange!(Rs[0]` mean
here?
Is it just the same as `isForwardRange!(Rs[0])`? Why is it
written like that?
No, not exactly the same.
Superficially, this rejects elements that are input ranges but
NOT forward ranges. Other than that, I can't tell you the
reason why it's that way.
-Steve
But forward ranges are a superset of input ranges so
`isForwardRange!(Rs[0]) == isInputRange!(Rs[0]` <=>
`isForwardRange!(Rs[0])`, right?
