* [PATCH 1/2] libstdc++: Implement LWG 3523 changes to ranges::iota_view
@ 2021-10-19 12:17 Patrick Palka
2021-10-19 12:17 ` [PATCH 2/2] libstdc++: Implement P1739R4 changes to views::take/drop/counted Patrick Palka
2021-10-19 12:37 ` [PATCH 1/2] libstdc++: Implement LWG 3523 changes to ranges::iota_view Jonathan Wakely
0 siblings, 2 replies; 4+ messages in thread
From: Patrick Palka @ 2021-10-19 12:17 UTC (permalink / raw)
To: gcc-patches; +Cc: libstdc++, Patrick Palka
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.
---
libstdc++-v3/include/std/ranges | 21 +++++++++++++++++++
.../testsuite/std/ranges/iota/iota_view.cc | 21 +++++++++++++++++++
2 files changed, 42 insertions(+)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index b8de400dfbb..85f232d8fb9 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -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}; }
diff --git a/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc b/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc
index 362ef1f7f78..5bebe4be693 100644
--- a/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc
+++ b/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc
@@ -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();
}
--
2.33.1.637.gf443b226ca
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 2/2] libstdc++: Implement P1739R4 changes to views::take/drop/counted
2021-10-19 12:17 [PATCH 1/2] libstdc++: Implement LWG 3523 changes to ranges::iota_view Patrick Palka
@ 2021-10-19 12:17 ` Patrick Palka
2021-10-21 15:22 ` Jonathan Wakely
2021-10-19 12:37 ` [PATCH 1/2] libstdc++: Implement LWG 3523 changes to ranges::iota_view Jonathan Wakely
1 sibling, 1 reply; 4+ messages in thread
From: Patrick Palka @ 2021-10-19 12:17 UTC (permalink / raw)
To: gcc-patches; +Cc: libstdc++, Patrick Palka
This implements P1739R4 along with the resolution for LWG 3407 which
corrects the paper's wording.
Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
libstdc++-v3/ChangeLog:
* include/bits/ranges_util.h (views::_Drop): Forward declare.
(subrange): Befriend views::_Drop.
(subrange::_S_store_size): Declare constexpr instead of just
const, remove obsolete comment.
* include/std/ranges (views::__detail::__is_empty_view): Define.
(views::__detail::__is_basic_string_view): Likewise.
(views::__detail::__is_subrange): Likewise.
(views::__detail::__is_iota_view): Likewise.
(views::__detail::__can_take_view): Rename template parm _Tp to _Dp.
(views::_Take): Rename template parm _Tp to _Dp, make it non-deducible
and fix its type to range_difference_t<_Range>. Implement P1739R4 and
LWG 3407 changes.
(views::__detail::__can_drop_view): Rename template parm _Tp to _Dp.
(views::_Drop): As with views::_Take.
(views::_Counted): Implement P1739R4 changes.
* include/std/span (__detail::__is_std_span): Rename to ...
(__detail::__is_span): ... this and turn it into a variable
template.
(__detail::__is_std_array): Turn it into a variable template.
(span::span): Adjust uses of __is_std_span and __is_std_array
accordingly.
* testsuite/std/ranges/adaptors/p1739.cc: New test.
---
libstdc++-v3/include/bits/ranges_util.h | 7 +-
libstdc++-v3/include/std/ranges | 106 +++++++++++++++---
libstdc++-v3/include/std/span | 12 +-
.../testsuite/std/ranges/adaptors/p1739.cc | 88 +++++++++++++++
4 files changed, 192 insertions(+), 21 deletions(-)
create mode 100644 libstdc++-v3/testsuite/std/ranges/adaptors/p1739.cc
diff --git a/libstdc++-v3/include/bits/ranges_util.h b/libstdc++-v3/include/bits/ranges_util.h
index 7e7b958d274..1afa66d298c 100644
--- a/libstdc++-v3/include/bits/ranges_util.h
+++ b/libstdc++-v3/include/bits/ranges_util.h
@@ -211,6 +211,8 @@ namespace ranges
} // namespace __detail
+ namespace views { struct _Drop; }
+
enum class subrange_kind : bool { unsized, sized };
/// The ranges::subrange class template
@@ -221,8 +223,9 @@ namespace ranges
class subrange : public view_interface<subrange<_It, _Sent, _Kind>>
{
private:
- // XXX: gcc complains when using constexpr here
- static const bool _S_store_size
+ friend struct views::_Drop; // Needs to inspect _S_store_size.
+
+ static constexpr bool _S_store_size
= _Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _It>;
_It _M_begin = _It();
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 85f232d8fb9..64396027c1b 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -42,6 +42,7 @@
#include <initializer_list>
#include <iterator>
#include <optional>
+#include <span>
#include <tuple>
#include <bits/ranges_util.h>
#include <bits/refwrap.h>
@@ -2147,19 +2148,66 @@ namespace views::__adaptor
{
namespace __detail
{
- template<typename _Range, typename _Tp>
+ template<typename _Range>
+ constexpr bool __is_empty_view = false;
+
+ template<typename _Tp>
+ constexpr bool __is_empty_view<empty_view<_Tp>> = true;
+
+ template<typename _Range>
+ constexpr bool __is_basic_string_view = false;
+
+ template<typename _CharT, typename _Traits>
+ constexpr bool __is_basic_string_view<basic_string_view<_CharT, _Traits>> = true;
+
+ template<typename _Range>
+ constexpr bool __is_subrange = false;
+
+ template<typename _Iter, typename _Sent, subrange_kind _Kind>
+ constexpr bool __is_subrange<subrange<_Iter, _Sent, _Kind>> = true;
+
+ template<typename _Range>
+ constexpr bool __is_iota_view = false;
+
+ template<typename _Winc, typename _Bound>
+ constexpr bool __is_iota_view<iota_view<_Winc, _Bound>> = true;
+
+ template<typename _Range, typename _Dp>
concept __can_take_view
- = requires { take_view(std::declval<_Range>(), std::declval<_Tp>()); };
+ = requires { take_view(std::declval<_Range>(), std::declval<_Dp>()); };
} // namespace __detail
struct _Take : __adaptor::_RangeAdaptor<_Take>
{
- template<viewable_range _Range, typename _Tp>
- requires __detail::__can_take_view<_Range, _Tp>
+ template<viewable_range _Range, typename _Dp = range_difference_t<_Range>>
+ requires __detail::__can_take_view<_Range, _Dp>
constexpr auto
- operator() [[nodiscard]] (_Range&& __r, _Tp&& __n) const
+ operator() [[nodiscard]] (_Range&& __r, type_identity_t<_Dp> __n) const
{
- return take_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
+ using _Tp = remove_cvref_t<_Range>;
+ if constexpr (__detail::__is_empty_view<_Tp>)
+ return _Tp();
+ else if constexpr (random_access_range<_Tp>
+ && sized_range<_Tp>
+ && (std::__detail::__is_span<_Tp>
+ || __detail::__is_basic_string_view<_Tp>
+ || __detail::__is_subrange<_Tp>
+ || __detail::__is_iota_view<_Tp>))
+ {
+ __n = std::min<_Dp>(ranges::distance(__r), __n);
+ auto __begin = ranges::begin(__r);
+ auto __end = __begin + __n;
+ if constexpr (std::__detail::__is_span<_Tp>)
+ return span<typename _Tp::element_type>(__begin, __end);
+ else if constexpr (__detail::__is_basic_string_view<_Tp>)
+ return _Tp(__begin, __end);
+ else if constexpr (__detail::__is_subrange<_Tp>)
+ return subrange<iterator_t<_Tp>>(__begin, __end);
+ else
+ return iota_view(*__begin, *__end);
+ }
+ else
+ return take_view(std::forward<_Range>(__r), __n);
}
using _RangeAdaptor<_Take>::operator();
@@ -2394,19 +2442,49 @@ namespace views::__adaptor
{
namespace __detail
{
- template<typename _Range, typename _Tp>
+ template<typename _Range, typename _Dp>
concept __can_drop_view
- = requires { drop_view(std::declval<_Range>(), std::declval<_Tp>()); };
+ = requires { drop_view(std::declval<_Range>(), std::declval<_Dp>()); };
} // namespace __detail
struct _Drop : __adaptor::_RangeAdaptor<_Drop>
{
- template<viewable_range _Range, typename _Tp>
- requires __detail::__can_drop_view<_Range, _Tp>
+ template<viewable_range _Range, typename _Dp = range_difference_t<_Range>>
+ requires __detail::__can_drop_view<_Range, _Dp>
constexpr auto
- operator() [[nodiscard]] (_Range&& __r, _Tp&& __n) const
+ operator() [[nodiscard]] (_Range&& __r, type_identity_t<_Dp> __n) const
{
- return drop_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
+ using _Tp = remove_cvref_t<_Range>;
+ if constexpr (__detail::__is_empty_view<_Tp>)
+ return _Tp();
+ else if constexpr (random_access_range<_Tp>
+ && sized_range<_Tp>
+ && (std::__detail::__is_span<_Tp>
+ || __detail::__is_basic_string_view<_Tp>
+ || __detail::__is_iota_view<_Tp>
+ || __detail::__is_subrange<_Tp>))
+ {
+ __n = std::min<_Dp>(ranges::distance(__r), __n);
+ auto __begin = ranges::begin(__r) + __n;
+ auto __end = ranges::end(__r);
+ if constexpr (std::__detail::__is_span<_Tp>)
+ return span<typename _Tp::element_type>(__begin, __end);
+ else if constexpr (__detail::__is_subrange<_Tp>)
+ {
+ if constexpr (_Tp::_S_store_size)
+ {
+ using ranges::__detail::__to_unsigned_like;
+ auto __m = ranges::distance(__r) - __n;
+ return _Tp(__begin, __end, __to_unsigned_like(__m));
+ }
+ else
+ return _Tp(__begin, __end);
+ }
+ else
+ return _Tp(__begin, __end);
+ }
+ else
+ return drop_view(std::forward<_Range>(__r), __n);
}
using _RangeAdaptor<_Drop>::operator();
@@ -3536,7 +3614,9 @@ namespace views::__adaptor
constexpr auto
operator() [[nodiscard]] (_Iter __i, iter_difference_t<_Iter> __n) const
{
- if constexpr (random_access_iterator<_Iter>)
+ if constexpr (contiguous_iterator<_Iter>)
+ return span(std::__to_address(__i), __n);
+ else if constexpr (random_access_iterator<_Iter>)
return subrange(__i, __i + __n);
else
return subrange(counted_iterator(std::move(__i), __n),
diff --git a/libstdc++-v3/include/std/span b/libstdc++-v3/include/std/span
index af0d24b29f2..ba75a497310 100644
--- a/libstdc++-v3/include/std/span
+++ b/libstdc++-v3/include/std/span
@@ -58,16 +58,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace __detail
{
template<typename _Tp>
- struct __is_std_span : false_type { };
+ constexpr bool __is_span = false;
template<typename _Tp, size_t _Num>
- struct __is_std_span<span<_Tp, _Num>> : true_type { };
+ constexpr bool __is_span<span<_Tp, _Num>> = true;
template<typename _Tp>
- struct __is_std_array : false_type { };
+ constexpr bool __is_std_array = false;
template<typename _Tp, size_t _Num>
- struct __is_std_array<std::array<_Tp, _Num>> : true_type { };
+ constexpr bool __is_std_array<std::array<_Tp, _Num>> = true;
template<size_t _Extent>
class __extent_storage
@@ -203,8 +203,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Range>
requires ranges::contiguous_range<_Range> && ranges::sized_range<_Range>
&& (ranges::borrowed_range<_Range> || is_const_v<element_type>)
- && (!__detail::__is_std_span<remove_cvref_t<_Range>>::value)
- && (!__detail::__is_std_array<remove_cvref_t<_Range>>::value)
+ && (!__detail::__is_span<remove_cvref_t<_Range>>)
+ && (!__detail::__is_std_array<remove_cvref_t<_Range>>)
&& (!is_array_v<remove_cvref_t<_Range>>)
&& __is_compatible_ref<ranges::range_reference_t<_Range>>::value
constexpr explicit(extent != dynamic_extent)
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/p1739.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/p1739.cc
new file mode 100644
index 00000000000..243b8a03583
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/p1739.cc
@@ -0,0 +1,88 @@
+// { dg-options "-std=gnu++20" }
+// { dg-do run { target c++20 } }
+
+#include <algorithm>
+#include <ranges>
+#include <testsuite_hooks.h>
+
+// Verify P1739R4 (and LWG 3407) changes views::take/drop/counted.
+
+namespace ranges = std::ranges;
+namespace views = ranges::views;
+
+void
+test01()
+{
+ ranges::empty_view<int> v;
+ using ty = decltype(v);
+ using ty = decltype(views::take(v, 42));
+ using ty = decltype(views::drop(v, 42));
+}
+
+void
+test02()
+{
+ int x[] = {1,2,3,4,5};
+ std::span r(x, x+5);
+ using ty = decltype(r);
+
+ std::same_as<ty> auto v1 = views::take(r, 2);
+ VERIFY( ranges::equal(v1, (int[]){1,2}) );
+
+ std::same_as<ty> auto v2 = views::drop(r, 3);
+ VERIFY( ranges::equal(v2, (int[]){4,5}) );
+
+ std::same_as<ty> auto v3 = views::counted(r.begin(), 4);
+ VERIFY( ranges::equal(v3, (int[]){1,2,3,4}) );
+}
+
+void
+test03()
+{
+ using namespace std::literals;
+ std::string_view r = "hello world"sv;
+ using ty = decltype(r);
+
+ std::same_as<ty> auto v1 = views::take(r, 5);
+ VERIFY( ranges::equal(v1, "hello"sv) );
+
+ std::same_as<ty> auto v2 = views::drop(r, 6);
+ VERIFY( ranges::equal(v2, "world"sv) );
+}
+
+void
+test04()
+{
+ int x[] = {1,2,3,4,5};
+ ranges::subrange r(x, x+5);
+ using ty = decltype(r);
+
+ std::same_as<ty> auto v1 = views::take(r, 2);
+ VERIFY( ranges::equal(v1, (int[]){1,2}) );
+
+ std::same_as<ty> auto v2 = views::drop(r, 1);
+ VERIFY( ranges::equal(v2, (int[]){2,3,4,5}) );
+}
+
+void
+test05()
+{
+ auto r1 = views::iota(1, 6);
+ using ty1 = decltype(r1);
+
+ std::same_as<ty1> auto v1 = views::take(r1, 2);
+ VERIFY( ranges::equal(v1, (int[]){1,2}) );
+
+ std::same_as<ty1> auto v2 = views::drop(r1, 3);
+ VERIFY( ranges::equal(v2, (int[]){4,5}) );
+}
+
+int
+main()
+{
+ test01();
+ test02();
+ test03();
+ test04();
+ test05();
+}
--
2.33.1.637.gf443b226ca
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 1/2] libstdc++: Implement LWG 3523 changes to ranges::iota_view
2021-10-19 12:17 [PATCH 1/2] libstdc++: Implement LWG 3523 changes to ranges::iota_view Patrick Palka
2021-10-19 12:17 ` [PATCH 2/2] libstdc++: Implement P1739R4 changes to views::take/drop/counted Patrick Palka
@ 2021-10-19 12:37 ` Jonathan Wakely
1 sibling, 0 replies; 4+ messages in thread
From: Jonathan Wakely @ 2021-10-19 12:37 UTC (permalink / raw)
To: Patrick Palka; +Cc: gcc Patches, libstdc++
On Tue, 19 Oct 2021 at 13:18, Patrick Palka via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> 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.
OK for trunk and gcc-11 (after some soak time), thanks.
> ---
> libstdc++-v3/include/std/ranges | 21 +++++++++++++++++++
> .../testsuite/std/ranges/iota/iota_view.cc | 21 +++++++++++++++++++
> 2 files changed, 42 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
> index b8de400dfbb..85f232d8fb9 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -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}; }
>
> diff --git a/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc b/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc
> index 362ef1f7f78..5bebe4be693 100644
> --- a/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc
> @@ -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();
> }
> --
> 2.33.1.637.gf443b226ca
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 2/2] libstdc++: Implement P1739R4 changes to views::take/drop/counted
2021-10-19 12:17 ` [PATCH 2/2] libstdc++: Implement P1739R4 changes to views::take/drop/counted Patrick Palka
@ 2021-10-21 15:22 ` Jonathan Wakely
0 siblings, 0 replies; 4+ messages in thread
From: Jonathan Wakely @ 2021-10-21 15:22 UTC (permalink / raw)
To: Patrick Palka; +Cc: gcc Patches, libstdc++
On Tue, 19 Oct 2021 at 13:20, Patrick Palka via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:
> This implements P1739R4 along with the resolution for LWG 3407 which
> corrects the paper's wording.
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
>
Yes, thanks.
> libstdc++-v3/ChangeLog:
>
> * include/bits/ranges_util.h (views::_Drop): Forward declare.
> (subrange): Befriend views::_Drop.
> (subrange::_S_store_size): Declare constexpr instead of just
> const, remove obsolete comment.
> * include/std/ranges (views::__detail::__is_empty_view): Define.
> (views::__detail::__is_basic_string_view): Likewise.
> (views::__detail::__is_subrange): Likewise.
> (views::__detail::__is_iota_view): Likewise.
> (views::__detail::__can_take_view): Rename template parm _Tp to
> _Dp.
> (views::_Take): Rename template parm _Tp to _Dp, make it
> non-deducible
> and fix its type to range_difference_t<_Range>. Implement P1739R4
> and
> LWG 3407 changes.
> (views::__detail::__can_drop_view): Rename template parm _Tp to
> _Dp.
> (views::_Drop): As with views::_Take.
> (views::_Counted): Implement P1739R4 changes.
> * include/std/span (__detail::__is_std_span): Rename to ...
> (__detail::__is_span): ... this and turn it into a variable
> template.
> (__detail::__is_std_array): Turn it into a variable template.
> (span::span): Adjust uses of __is_std_span and __is_std_array
> accordingly.
> * testsuite/std/ranges/adaptors/p1739.cc: New test.
> ---
> libstdc++-v3/include/bits/ranges_util.h | 7 +-
> libstdc++-v3/include/std/ranges | 106 +++++++++++++++---
> libstdc++-v3/include/std/span | 12 +-
> .../testsuite/std/ranges/adaptors/p1739.cc | 88 +++++++++++++++
> 4 files changed, 192 insertions(+), 21 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/std/ranges/adaptors/p1739.cc
>
> diff --git a/libstdc++-v3/include/bits/ranges_util.h
> b/libstdc++-v3/include/bits/ranges_util.h
> index 7e7b958d274..1afa66d298c 100644
> --- a/libstdc++-v3/include/bits/ranges_util.h
> +++ b/libstdc++-v3/include/bits/ranges_util.h
> @@ -211,6 +211,8 @@ namespace ranges
>
> } // namespace __detail
>
> + namespace views { struct _Drop; }
> +
> enum class subrange_kind : bool { unsized, sized };
>
> /// The ranges::subrange class template
> @@ -221,8 +223,9 @@ namespace ranges
> class subrange : public view_interface<subrange<_It, _Sent, _Kind>>
> {
> private:
> - // XXX: gcc complains when using constexpr here
> - static const bool _S_store_size
> + friend struct views::_Drop; // Needs to inspect _S_store_size.
> +
> + static constexpr bool _S_store_size
> = _Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _It>;
>
> _It _M_begin = _It();
> diff --git a/libstdc++-v3/include/std/ranges
> b/libstdc++-v3/include/std/ranges
> index 85f232d8fb9..64396027c1b 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -42,6 +42,7 @@
> #include <initializer_list>
> #include <iterator>
> #include <optional>
> +#include <span>
> #include <tuple>
> #include <bits/ranges_util.h>
> #include <bits/refwrap.h>
> @@ -2147,19 +2148,66 @@ namespace views::__adaptor
> {
> namespace __detail
> {
> - template<typename _Range, typename _Tp>
> + template<typename _Range>
> + constexpr bool __is_empty_view = false;
> +
> + template<typename _Tp>
> + constexpr bool __is_empty_view<empty_view<_Tp>> = true;
> +
> + template<typename _Range>
> + constexpr bool __is_basic_string_view = false;
> +
> + template<typename _CharT, typename _Traits>
> + constexpr bool __is_basic_string_view<basic_string_view<_CharT,
> _Traits>> = true;
> +
> + template<typename _Range>
> + constexpr bool __is_subrange = false;
> +
> + template<typename _Iter, typename _Sent, subrange_kind _Kind>
> + constexpr bool __is_subrange<subrange<_Iter, _Sent, _Kind>> = true;
> +
> + template<typename _Range>
> + constexpr bool __is_iota_view = false;
> +
> + template<typename _Winc, typename _Bound>
> + constexpr bool __is_iota_view<iota_view<_Winc, _Bound>> = true;
> +
> + template<typename _Range, typename _Dp>
> concept __can_take_view
> - = requires { take_view(std::declval<_Range>(),
> std::declval<_Tp>()); };
> + = requires { take_view(std::declval<_Range>(),
> std::declval<_Dp>()); };
> } // namespace __detail
>
> struct _Take : __adaptor::_RangeAdaptor<_Take>
> {
> - template<viewable_range _Range, typename _Tp>
> - requires __detail::__can_take_view<_Range, _Tp>
> + template<viewable_range _Range, typename _Dp =
> range_difference_t<_Range>>
> + requires __detail::__can_take_view<_Range, _Dp>
> constexpr auto
> - operator() [[nodiscard]] (_Range&& __r, _Tp&& __n) const
> + operator() [[nodiscard]] (_Range&& __r, type_identity_t<_Dp> __n)
> const
> {
> - return take_view(std::forward<_Range>(__r),
> std::forward<_Tp>(__n));
> + using _Tp = remove_cvref_t<_Range>;
> + if constexpr (__detail::__is_empty_view<_Tp>)
> + return _Tp();
> + else if constexpr (random_access_range<_Tp>
> + && sized_range<_Tp>
> + && (std::__detail::__is_span<_Tp>
> + || __detail::__is_basic_string_view<_Tp>
> + || __detail::__is_subrange<_Tp>
> + || __detail::__is_iota_view<_Tp>))
> + {
> + __n = std::min<_Dp>(ranges::distance(__r), __n);
> + auto __begin = ranges::begin(__r);
> + auto __end = __begin + __n;
> + if constexpr (std::__detail::__is_span<_Tp>)
> + return span<typename _Tp::element_type>(__begin, __end);
> + else if constexpr (__detail::__is_basic_string_view<_Tp>)
> + return _Tp(__begin, __end);
> + else if constexpr (__detail::__is_subrange<_Tp>)
> + return subrange<iterator_t<_Tp>>(__begin, __end);
> + else
> + return iota_view(*__begin, *__end);
> + }
> + else
> + return take_view(std::forward<_Range>(__r), __n);
> }
>
> using _RangeAdaptor<_Take>::operator();
> @@ -2394,19 +2442,49 @@ namespace views::__adaptor
> {
> namespace __detail
> {
> - template<typename _Range, typename _Tp>
> + template<typename _Range, typename _Dp>
> concept __can_drop_view
> - = requires { drop_view(std::declval<_Range>(),
> std::declval<_Tp>()); };
> + = requires { drop_view(std::declval<_Range>(),
> std::declval<_Dp>()); };
> } // namespace __detail
>
> struct _Drop : __adaptor::_RangeAdaptor<_Drop>
> {
> - template<viewable_range _Range, typename _Tp>
> - requires __detail::__can_drop_view<_Range, _Tp>
> + template<viewable_range _Range, typename _Dp =
> range_difference_t<_Range>>
> + requires __detail::__can_drop_view<_Range, _Dp>
> constexpr auto
> - operator() [[nodiscard]] (_Range&& __r, _Tp&& __n) const
> + operator() [[nodiscard]] (_Range&& __r, type_identity_t<_Dp> __n)
> const
> {
> - return drop_view(std::forward<_Range>(__r),
> std::forward<_Tp>(__n));
> + using _Tp = remove_cvref_t<_Range>;
> + if constexpr (__detail::__is_empty_view<_Tp>)
> + return _Tp();
> + else if constexpr (random_access_range<_Tp>
> + && sized_range<_Tp>
> + && (std::__detail::__is_span<_Tp>
> + || __detail::__is_basic_string_view<_Tp>
> + || __detail::__is_iota_view<_Tp>
> + || __detail::__is_subrange<_Tp>))
> + {
> + __n = std::min<_Dp>(ranges::distance(__r), __n);
> + auto __begin = ranges::begin(__r) + __n;
> + auto __end = ranges::end(__r);
> + if constexpr (std::__detail::__is_span<_Tp>)
> + return span<typename _Tp::element_type>(__begin, __end);
> + else if constexpr (__detail::__is_subrange<_Tp>)
> + {
> + if constexpr (_Tp::_S_store_size)
> + {
> + using ranges::__detail::__to_unsigned_like;
> + auto __m = ranges::distance(__r) - __n;
> + return _Tp(__begin, __end, __to_unsigned_like(__m));
> + }
> + else
> + return _Tp(__begin, __end);
> + }
> + else
> + return _Tp(__begin, __end);
> + }
> + else
> + return drop_view(std::forward<_Range>(__r), __n);
> }
>
> using _RangeAdaptor<_Drop>::operator();
> @@ -3536,7 +3614,9 @@ namespace views::__adaptor
> constexpr auto
> operator() [[nodiscard]] (_Iter __i, iter_difference_t<_Iter> __n)
> const
> {
> - if constexpr (random_access_iterator<_Iter>)
> + if constexpr (contiguous_iterator<_Iter>)
> + return span(std::__to_address(__i), __n);
> + else if constexpr (random_access_iterator<_Iter>)
> return subrange(__i, __i + __n);
> else
> return subrange(counted_iterator(std::move(__i), __n),
> diff --git a/libstdc++-v3/include/std/span b/libstdc++-v3/include/std/span
> index af0d24b29f2..ba75a497310 100644
> --- a/libstdc++-v3/include/std/span
> +++ b/libstdc++-v3/include/std/span
> @@ -58,16 +58,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> namespace __detail
> {
> template<typename _Tp>
> - struct __is_std_span : false_type { };
> + constexpr bool __is_span = false;
>
> template<typename _Tp, size_t _Num>
> - struct __is_std_span<span<_Tp, _Num>> : true_type { };
> + constexpr bool __is_span<span<_Tp, _Num>> = true;
>
> template<typename _Tp>
> - struct __is_std_array : false_type { };
> + constexpr bool __is_std_array = false;
>
> template<typename _Tp, size_t _Num>
> - struct __is_std_array<std::array<_Tp, _Num>> : true_type { };
> + constexpr bool __is_std_array<std::array<_Tp, _Num>> = true;
>
> template<size_t _Extent>
> class __extent_storage
> @@ -203,8 +203,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> template<typename _Range>
> requires ranges::contiguous_range<_Range> &&
> ranges::sized_range<_Range>
> && (ranges::borrowed_range<_Range> || is_const_v<element_type>)
> - && (!__detail::__is_std_span<remove_cvref_t<_Range>>::value)
> - && (!__detail::__is_std_array<remove_cvref_t<_Range>>::value)
> + && (!__detail::__is_span<remove_cvref_t<_Range>>)
> + && (!__detail::__is_std_array<remove_cvref_t<_Range>>)
> && (!is_array_v<remove_cvref_t<_Range>>)
> && __is_compatible_ref<ranges::range_reference_t<_Range>>::value
> constexpr explicit(extent != dynamic_extent)
> diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/p1739.cc
> b/libstdc++-v3/testsuite/std/ranges/adaptors/p1739.cc
> new file mode 100644
> index 00000000000..243b8a03583
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/p1739.cc
> @@ -0,0 +1,88 @@
> +// { dg-options "-std=gnu++20" }
> +// { dg-do run { target c++20 } }
> +
> +#include <algorithm>
> +#include <ranges>
> +#include <testsuite_hooks.h>
> +
> +// Verify P1739R4 (and LWG 3407) changes views::take/drop/counted.
> +
> +namespace ranges = std::ranges;
> +namespace views = ranges::views;
> +
> +void
> +test01()
> +{
> + ranges::empty_view<int> v;
> + using ty = decltype(v);
> + using ty = decltype(views::take(v, 42));
> + using ty = decltype(views::drop(v, 42));
> +}
> +
> +void
> +test02()
> +{
> + int x[] = {1,2,3,4,5};
> + std::span r(x, x+5);
> + using ty = decltype(r);
> +
> + std::same_as<ty> auto v1 = views::take(r, 2);
> + VERIFY( ranges::equal(v1, (int[]){1,2}) );
> +
> + std::same_as<ty> auto v2 = views::drop(r, 3);
> + VERIFY( ranges::equal(v2, (int[]){4,5}) );
> +
> + std::same_as<ty> auto v3 = views::counted(r.begin(), 4);
> + VERIFY( ranges::equal(v3, (int[]){1,2,3,4}) );
> +}
> +
> +void
> +test03()
> +{
> + using namespace std::literals;
> + std::string_view r = "hello world"sv;
> + using ty = decltype(r);
> +
> + std::same_as<ty> auto v1 = views::take(r, 5);
> + VERIFY( ranges::equal(v1, "hello"sv) );
> +
> + std::same_as<ty> auto v2 = views::drop(r, 6);
> + VERIFY( ranges::equal(v2, "world"sv) );
> +}
> +
> +void
> +test04()
> +{
> + int x[] = {1,2,3,4,5};
> + ranges::subrange r(x, x+5);
> + using ty = decltype(r);
> +
> + std::same_as<ty> auto v1 = views::take(r, 2);
> + VERIFY( ranges::equal(v1, (int[]){1,2}) );
> +
> + std::same_as<ty> auto v2 = views::drop(r, 1);
> + VERIFY( ranges::equal(v2, (int[]){2,3,4,5}) );
> +}
> +
> +void
> +test05()
> +{
> + auto r1 = views::iota(1, 6);
> + using ty1 = decltype(r1);
> +
> + std::same_as<ty1> auto v1 = views::take(r1, 2);
> + VERIFY( ranges::equal(v1, (int[]){1,2}) );
> +
> + std::same_as<ty1> auto v2 = views::drop(r1, 3);
> + VERIFY( ranges::equal(v2, (int[]){4,5}) );
> +}
> +
> +int
> +main()
> +{
> + test01();
> + test02();
> + test03();
> + test04();
> + test05();
> +}
> --
> 2.33.1.637.gf443b226ca
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-10-21 15:23 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-10-19 12:17 [PATCH 1/2] libstdc++: Implement LWG 3523 changes to ranges::iota_view Patrick Palka
2021-10-19 12:17 ` [PATCH 2/2] libstdc++: Implement P1739R4 changes to views::take/drop/counted Patrick Palka
2021-10-21 15:22 ` Jonathan Wakely
2021-10-19 12:37 ` [PATCH 1/2] libstdc++: Implement LWG 3523 changes to ranges::iota_view Jonathan Wakely
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