Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
-- >8 --
This avoids redundant moves when composing and partially applying range
adaptor objects.
Note that the new constraints on _Partial's constructor templates are
needed so that it's not inadvertently chosen over the copy constructor
when constructing a _Partial object from a non-const _Partial lvalue.
libstdc++-v3/ChangeLog:
* include/std/ranges (views::__adaptor::operator|): Perform
perfect forwarding of arguments.
(views::__adaptor::_Partial::_Partial): Likewise.
(views::__adaptor::_Pipe::__Pipe): Likewise.
---
libstdc++-v3/include/std/ranges | 65 ++++++++++++++++++++-------------
1 file changed, 39 insertions(+), 26 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 81a857502e3..0734daa42bf 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -957,8 +957,11 @@ 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.
//
@@ -1004,10 +1007,12 @@ namespace views::__adaptor
{
tuple<_Args...> _M_args;
- constexpr
- _Partial(_Args... __args)
- : _M_args(std::move(__args)...)
- { }
+ template<typename... _Ts>
+ requires (sizeof...(_Ts) == sizeof...(_Args))
+ constexpr
+ _Partial(_Ts&&... __args)
+ : _M_args(std::forward<_Ts>(__args)...)
+ { }
// Invoke _Adaptor with arguments __r, _M_args... according to the
// value category of this _Partial object.
@@ -1046,10 +1051,12 @@ namespace views::__adaptor
{
_Arg _M_arg;
- constexpr
- _Partial(_Arg __arg)
- : _M_arg(std::move(__arg))
- { }
+ template<typename _Tp>
+ requires (!same_as<remove_cvref_t<_Tp>, _Partial>)
+ constexpr
+ _Partial(_Tp&& __arg)
+ : _M_arg(std::forward<_Tp>(__arg))
+ { }
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
@@ -1079,10 +1086,12 @@ namespace views::__adaptor
{
tuple<_Args...> _M_args;
- constexpr
- _Partial(_Args... __args)
- : _M_args(std::move(__args)...)
- { }
+ template<typename... _Ts>
+ requires (sizeof...(_Ts) == sizeof...(_Args))
+ constexpr
+ _Partial(_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.
@@ -1109,10 +1118,12 @@ namespace views::__adaptor
{
_Arg _M_arg;
- constexpr
- _Partial(_Arg __arg)
- : _M_arg(std::move(__arg))
- { }
+ template<typename _Tp>
+ requires (!same_as<remove_cvref_t<_Tp>, _Partial>)
+ constexpr
+ _Partial(_Tp&& __arg)
+ : _M_arg(std::forward<_Tp>(__arg))
+ { }
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
@@ -1135,10 +1146,11 @@ 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.
@@ -1172,10 +1184,11 @@ 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>
--
2.43.0.283.ga54a84b333
