From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1888) id E7BAB3858D3C; Wed, 19 Oct 2022 19:43:39 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E7BAB3858D3C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1666208619; bh=GdLGEK/Hnp8d1Klc2bbsYpz7QW4MaLOtv/FS/xeDZQU=; h=From:To:Subject:Date:From; b=DMHqmTrNThcTka/Nweuz0ceucra+AxJcLfLaSwu1pX/X+sO2OXh+xQQlCKuGXtR1x B7UE4gaJD3cRetVWwq1Ix4EJeTidpe6FlO5vzj/MJVN4eU4EdB7CQ8i4nnZExX4haJ nQYbtx84DV780O6/XnxhMnafNBeNRIWEP9xdWpYo= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Patrick Palka To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r13-3389] libstdc++: Implement remaining P2474R2 changes to views::take/drop X-Act-Checkin: gcc X-Git-Author: Patrick Palka X-Git-Refname: refs/heads/master X-Git-Oldrev: b3c98d6a59a6dcd5b0b52bd5676b586ef4fe785f X-Git-Newrev: fb4db9bc1c567eaf850e997853d084d0832dd4c1 Message-Id: <20221019194339.E7BAB3858D3C@sourceware.org> Date: Wed, 19 Oct 2022 19:43:39 +0000 (GMT) List-Id: https://gcc.gnu.org/g:fb4db9bc1c567eaf850e997853d084d0832dd4c1 commit r13-3389-gfb4db9bc1c567eaf850e997853d084d0832dd4c1 Author: Patrick Palka Date: Wed Oct 19 15:43:13 2022 -0400 libstdc++: Implement remaining P2474R2 changes to views::take/drop libstdc++-v3/ChangeLog: * include/std/ranges (views::__detail::__is_repeat_view): Define and later define a partial specialization. (views::__detail::__take_of_repeat_view): Declare and later define. (views::__detail::__drop_of_repeat_view): Likewise. (views::_Take::operator()): Return a repeat_view if the argument is a repeat_view as per P2474R2. (views::_Drop::operator()): Likewise. (repeat_view): Befriend __take/drop_of_repeat_view. * testsuite/std/ranges/repeat/1.cc (test04): New test. Diff: --- libstdc++-v3/include/std/ranges | 56 +++++++++++++++++++++++++++ libstdc++-v3/testsuite/std/ranges/repeat/1.cc | 33 ++++++++++++++++ 2 files changed, 89 insertions(+) diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index b29264931cc..a55e9e7f760 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -2257,6 +2257,13 @@ namespace views::__adaptor template inline constexpr bool __is_iota_view> = true; + template + inline constexpr bool __is_repeat_view = false; + + template + constexpr auto + __take_of_repeat_view(_Range&&, range_difference_t<_Range>); // defined later + template concept __can_take_view = requires { take_view(std::declval<_Range>(), std::declval<_Dp>()); }; @@ -2291,6 +2298,8 @@ namespace views::__adaptor else return iota_view(*__begin, *__end); } + else if constexpr (__detail::__is_repeat_view<_Tp>) + return __detail::__take_of_repeat_view(std::forward<_Range>(__r), __n); else return take_view(std::forward<_Range>(__r), __n); } @@ -2527,6 +2536,10 @@ namespace views::__adaptor { namespace __detail { + template + constexpr auto + __drop_of_repeat_view(_Range&&, range_difference_t<_Range>); // defined later + template concept __can_drop_view = requires { drop_view(std::declval<_Range>(), std::declval<_Dp>()); }; @@ -2568,6 +2581,8 @@ namespace views::__adaptor else return _Tp(__begin, __end); } + else if constexpr (__detail::__is_repeat_view<_Tp>) + return __detail::__drop_of_repeat_view(std::forward<_Range>(__r), __n); else return drop_view(std::forward<_Range>(__r), __n); } @@ -7367,6 +7382,14 @@ namespace views::__adaptor struct _Iterator; + template + friend constexpr auto + views::__detail::__take_of_repeat_view(_Range&&, range_difference_t<_Range>); + + template + friend constexpr auto + views::__detail::__drop_of_repeat_view(_Range&&, range_difference_t<_Range>); + public: repeat_view() requires default_initializable<_Tp> = default; @@ -7540,6 +7563,9 @@ namespace views::__adaptor { namespace __detail { + template + inline constexpr bool __is_repeat_view> = true; + template concept __can_repeat_view = requires { repeat_view(std::declval<_Tp>()); }; @@ -7565,6 +7591,36 @@ namespace views::__adaptor }; inline constexpr _Repeat repeat; + + namespace __detail + { + template + constexpr auto + __take_of_repeat_view(_Range&& __r, range_difference_t<_Range> __n) + { + using _Tp = remove_cvref_t<_Range>; + static_assert(__is_repeat_view<_Tp>); + if constexpr (sized_range<_Tp>) + return views::repeat(*__r._M_value, std::min(ranges::distance(__r), __n)); + else + return views::repeat(*__r._M_value, __n); + } + + template + constexpr auto + __drop_of_repeat_view(_Range&& __r, range_difference_t<_Range> __n) + { + using _Tp = remove_cvref_t<_Range>; + static_assert(__is_repeat_view<_Tp>); + if constexpr (sized_range<_Tp>) + { + auto __sz = ranges::distance(__r); + return views::repeat(*__r._M_value, __sz - std::min(__sz, __n)); + } + else + return __r; + } + } } template diff --git a/libstdc++-v3/testsuite/std/ranges/repeat/1.cc b/libstdc++-v3/testsuite/std/ranges/repeat/1.cc index 3698ed12c14..f9817c99600 100644 --- a/libstdc++-v3/testsuite/std/ranges/repeat/1.cc +++ b/libstdc++-v3/testsuite/std/ranges/repeat/1.cc @@ -84,10 +84,43 @@ test03() return true; } +constexpr bool +test04() +{ + // Verify P2474R2 changes to views::take/drop. + auto r = views::repeat(42); + + auto rt = r | views::take(10); + static_assert(views::__detail::__is_repeat_view); + VERIFY( ranges::equal(rt, views::repeat(42, 10)) ); + + auto rd = r | views::drop(10); + static_assert(std::same_as); + + auto br = views::repeat(42, 37); + + auto brt = br | views::take(10); + static_assert(std::same_as); + VERIFY( ranges::equal(brt, views::repeat(42, 10)) ); + + auto brt100 = br | views::take(100); + VERIFY( ranges::equal(brt100, br) ); + + auto brd = br | views::drop(10); + static_assert(std::same_as); + VERIFY( ranges::equal(brd, views::repeat(42, 27)) ); + + auto brd100 = br | views::drop(100); + VERIFY( ranges::empty(brd100) ); + + return true; +} + int main() { static_assert(test01()); static_assert(test02()); static_assert(test03()); + static_assert(test04()); }