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* [gcc r14-7218] libstdc++/ranges: Use perfect forwarding in _Pipe and _Partial ctors
@ 2024-01-13 4:02 Patrick Palka
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From: Patrick Palka @ 2024-01-13 4:02 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:c48bedd180672276cc58f379a6346309366b7ea7
commit r14-7218-gc48bedd180672276cc58f379a6346309366b7ea7
Author: Patrick Palka <ppalka@redhat.com>
Date: Fri Jan 12 22:54:59 2024 -0500
libstdc++/ranges: Use perfect forwarding in _Pipe and _Partial ctors
This avoids redundant moves when composing and partially applying range
adaptor objects.
libstdc++-v3/ChangeLog:
* include/std/ranges (views::__adaptor::operator|): Perform
perfect forwarding of arguments.
(views::__adaptor::_RangeAdaptor::operator()): Pass dummy
first argument to _Partial.
(views::__adaptor::_Partial::_Partial): Likewise. Add dummy
first parameter.
(views::__adaptor::_Pipe::_Pipe): Perform perfect forwarding
of arguments.
(to): Pass dummy first argument to _Partial.
Diff:
---
libstdc++-v3/include/std/ranges | 69 ++++++++++++++++++++++++-----------------
1 file changed, 40 insertions(+), 29 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 5ef4443fc64..3135e6f0c08 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -956,8 +956,11 @@ namespace views::__adaptor
requires __is_range_adaptor_closure<_Lhs>
&& __is_range_adaptor_closure<_Rhs>
constexpr auto
- operator|(_Lhs __lhs, _Rhs __rhs)
- { return _Pipe<_Lhs, _Rhs>{std::move(__lhs), std::move(__rhs)}; }
+ operator|(_Lhs&& __lhs, _Rhs&& __rhs)
+ {
+ return _Pipe<decay_t<_Lhs>, decay_t<_Rhs>>{std::forward<_Lhs>(__lhs),
+ std::forward<_Rhs>(__rhs)};
+ }
// The base class of every range adaptor non-closure.
//
@@ -980,7 +983,7 @@ namespace views::__adaptor
constexpr auto
operator()(_Args&&... __args) const
{
- return _Partial<_Derived, decay_t<_Args>...>{std::forward<_Args>(__args)...};
+ return _Partial<_Derived, decay_t<_Args>...>{0, std::forward<_Args>(__args)...};
}
};
@@ -1003,10 +1006,13 @@ namespace views::__adaptor
{
tuple<_Args...> _M_args;
- constexpr
- _Partial(_Args... __args)
- : _M_args(std::move(__args)...)
- { }
+ // First parameter is to ensure this constructor is never used
+ // instead of the copy/move constructor.
+ template<typename... _Ts>
+ constexpr
+ _Partial(int, _Ts&&... __args)
+ : _M_args(std::forward<_Ts>(__args)...)
+ { }
// Invoke _Adaptor with arguments __r, _M_args... according to the
// value category of this _Partial object.
@@ -1058,10 +1064,11 @@ namespace views::__adaptor
{
_Arg _M_arg;
- constexpr
- _Partial(_Arg __arg)
- : _M_arg(std::move(__arg))
- { }
+ template<typename _Tp>
+ constexpr
+ _Partial(int, _Tp&& __arg)
+ : _M_arg(std::forward<_Tp>(__arg))
+ { }
#if __cpp_explicit_this_parameter
template<typename _Self, typename _Range>
@@ -1099,10 +1106,11 @@ namespace views::__adaptor
{
tuple<_Args...> _M_args;
- constexpr
- _Partial(_Args... __args)
- : _M_args(std::move(__args)...)
- { }
+ template<typename... _Ts>
+ constexpr
+ _Partial(int, _Ts&&... __args)
+ : _M_args(std::forward<_Ts>(__args)...)
+ { }
// Invoke _Adaptor with arguments __r, const _M_args&... regardless
// of the value category of this _Partial object.
@@ -1129,10 +1137,11 @@ namespace views::__adaptor
{
_Arg _M_arg;
- constexpr
- _Partial(_Arg __arg)
- : _M_arg(std::move(__arg))
- { }
+ template<typename _Tp>
+ constexpr
+ _Partial(int, _Tp&& __arg)
+ : _M_arg(std::forward<_Tp>(__arg))
+ { }
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
@@ -1155,10 +1164,11 @@ namespace views::__adaptor
[[no_unique_address]] _Lhs _M_lhs;
[[no_unique_address]] _Rhs _M_rhs;
- constexpr
- _Pipe(_Lhs __lhs, _Rhs __rhs)
- : _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
- { }
+ template<typename _Tp, typename _Up>
+ constexpr
+ _Pipe(_Tp&& __lhs, _Up&& __rhs)
+ : _M_lhs(std::forward<_Tp>(__lhs)), _M_rhs(std::forward<_Up>(__rhs))
+ { }
// Invoke _M_rhs(_M_lhs(__r)) according to the value category of this
// range adaptor closure object.
@@ -1203,10 +1213,11 @@ namespace views::__adaptor
[[no_unique_address]] _Lhs _M_lhs;
[[no_unique_address]] _Rhs _M_rhs;
- constexpr
- _Pipe(_Lhs __lhs, _Rhs __rhs)
- : _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
- { }
+ template<typename _Tp, typename _Up>
+ constexpr
+ _Pipe(_Tp&& __lhs, _Up&& __rhs)
+ : _M_lhs(std::forward<_Tp>(__lhs)), _M_rhs(std::forward<_Up>(__rhs))
+ { }
template<typename _Range>
requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
@@ -9458,7 +9469,7 @@ namespace __detail
{
using __detail::_To;
using views::__adaptor::_Partial;
- return _Partial<_To<_Cont>, decay_t<_Args>...>{std::forward<_Args>(__args)...};
+ return _Partial<_To<_Cont>, decay_t<_Args>...>{0, std::forward<_Args>(__args)...};
}
/// @cond undocumented
@@ -9503,7 +9514,7 @@ namespace __detail
{
using __detail::_To2;
using views::__adaptor::_Partial;
- return _Partial<_To2<_Cont>, decay_t<_Args>...>{std::forward<_Args>(__args)...};
+ return _Partial<_To2<_Cont>, decay_t<_Args>...>{0, std::forward<_Args>(__args)...};
}
} // namespace ranges
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