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libstdc++: Implement LWG 3523 changes to ranges::iota_view

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libstdc++-v3/ChangeLog:

	* include/std/ranges (iota_view::_Iterator): Befriend iota_view.
	(iota_view::_Sentinel): Likewise.
	(iota_view::iota_view): Add three overloads, each taking an
	iterator/sentinel pair as per LWG 3523.
	* testsuite/std/ranges/iota/iota_view.cc (test06): New test.
This commit is contained in:
Patrick Palka 2021-10-19 17:54:24 -04:00
parent 53b1c382d5
commit 861440a77b
2 changed files with 42 additions and 0 deletions
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21
libstdc++-v3/include/std/ranges
View File

@ -532,6 +532,7 @@ namespace ranges
private:
_Winc _M_value = _Winc();
friend iota_view;
friend _Sentinel;
};
@ -568,6 +569,8 @@ namespace ranges
operator-(const _Sentinel& __x, const _Iterator& __y)
requires sized_sentinel_for<_Bound, _Winc>
{ return __x._M_distance_from(__y); }
friend iota_view;
};
_Winc _M_value = _Winc();
@ -590,6 +593,24 @@ namespace ranges
__glibcxx_assert( bool(__value <= __bound) );
}
constexpr
iota_view(_Iterator __first, _Iterator __last)
requires same_as<_Winc, _Bound>
: iota_view(__first._M_value, __last._M_value)
{ }
constexpr
iota_view(_Iterator __first, unreachable_sentinel_t __last)
requires same_as<_Bound, unreachable_sentinel_t>
: iota_view(__first._M_value, __last)
{ }
constexpr
iota_view(_Iterator __first, _Sentinel __last)
requires (!same_as<_Winc, _Bound>) && (!same_as<_Bound, unreachable_sentinel_t>)
: iota_view(__first._M_value, __last._M_bound)
{ }
constexpr _Iterator
begin() const { return _Iterator{_M_value}; }

21
libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc
View File

@ -18,6 +18,7 @@
// { dg-options "-std=gnu++2a" }
// { dg-do run { target c++2a } }
#include <algorithm>
#include <ranges>
#include <testsuite_hooks.h>
@ -90,6 +91,25 @@ test05()
VERIFY( r.begin() - r.end() == -3 );
}
void
test06()
{
// Verify LWG 3523 changes.
auto v1 = std::views::iota(0, 5);
auto w1 = decltype(v1)(v1.begin(), v1.end());
VERIFY( std::ranges::equal(v1, w1) );
auto v2 = std::views::iota(0);
auto w2 = decltype(v2)(v2.begin(), v2.end());
static_assert(std::same_as<decltype(w2.end()), std::unreachable_sentinel_t>);
VERIFY( *w2.begin() == 0 );
auto v3 = std::views::iota(0, 5l);
auto w3 = decltype(v3)(v3.begin(), v3.end());
static_assert(!std::ranges::common_range<decltype(w3)>);
VERIFY( std::ranges::equal(v3, w3) );
}
int
main()
{
@ -98,4 +118,5 @@ main()
test03();
test04();
test05();
test06();
}