[libcxx-commits] [libcxx] [libc++] Simplify the implementation of std::get for pairs (PR #114984)
Nikolas Klauser via libcxx-commits
libcxx-commits at lists.llvm.org
Thu Mar 27 06:56:51 PDT 2025
https://github.com/philnik777 updated https://github.com/llvm/llvm-project/pull/114984
>From 331ac8c12cd149175526aa9574507deda9318268 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Tue, 5 Nov 2024 14:13:03 +0100
Subject: [PATCH] [libc++] Simplify the implementation of std::get for pairs
---
libcxx/include/__utility/pair.h | 16 +--
.../pairs/pair.astuple/pairs.by.type.pass.cpp | 105 ++++++++++++------
2 files changed, 82 insertions(+), 39 deletions(-)
diff --git a/libcxx/include/__utility/pair.h b/libcxx/include/__utility/pair.h
index 1f596a87f7cc7..3cc22555d4224 100644
--- a/libcxx/include/__utility/pair.h
+++ b/libcxx/include/__utility/pair.h
@@ -629,42 +629,42 @@ get(const pair<_T1, _T2>&& __p) _NOEXCEPT {
#if _LIBCPP_STD_VER >= 14
template <class _T1, class _T2>
inline _LIBCPP_HIDE_FROM_ABI constexpr _T1& get(pair<_T1, _T2>& __p) _NOEXCEPT {
- return __get_pair<0>::get(__p);
+ return __p.first;
}
template <class _T1, class _T2>
inline _LIBCPP_HIDE_FROM_ABI constexpr _T1 const& get(pair<_T1, _T2> const& __p) _NOEXCEPT {
- return __get_pair<0>::get(__p);
+ return __p.first;
}
template <class _T1, class _T2>
inline _LIBCPP_HIDE_FROM_ABI constexpr _T1&& get(pair<_T1, _T2>&& __p) _NOEXCEPT {
- return __get_pair<0>::get(std::move(__p));
+ return std::forward<_T1&&>(__p.first);
}
template <class _T1, class _T2>
inline _LIBCPP_HIDE_FROM_ABI constexpr _T1 const&& get(pair<_T1, _T2> const&& __p) _NOEXCEPT {
- return __get_pair<0>::get(std::move(__p));
+ return std::forward<_T1 const&&>(__p.first);
}
template <class _T1, class _T2>
inline _LIBCPP_HIDE_FROM_ABI constexpr _T1& get(pair<_T2, _T1>& __p) _NOEXCEPT {
- return __get_pair<1>::get(__p);
+ return __p.second;
}
template <class _T1, class _T2>
inline _LIBCPP_HIDE_FROM_ABI constexpr _T1 const& get(pair<_T2, _T1> const& __p) _NOEXCEPT {
- return __get_pair<1>::get(__p);
+ return __p.second;
}
template <class _T1, class _T2>
inline _LIBCPP_HIDE_FROM_ABI constexpr _T1&& get(pair<_T2, _T1>&& __p) _NOEXCEPT {
- return __get_pair<1>::get(std::move(__p));
+ return std::forward<_T1&&>(__p.second);
}
template <class _T1, class _T2>
inline _LIBCPP_HIDE_FROM_ABI constexpr _T1 const&& get(pair<_T2, _T1> const&& __p) _NOEXCEPT {
- return __get_pair<1>::get(std::move(__p));
+ return std::forward<_T1 const&&>(__p.second);
}
#endif // _LIBCPP_STD_VER >= 14
diff --git a/libcxx/test/std/utilities/utility/pairs/pair.astuple/pairs.by.type.pass.cpp b/libcxx/test/std/utilities/utility/pairs/pair.astuple/pairs.by.type.pass.cpp
index f6940c468a81d..588bb7a033900 100644
--- a/libcxx/test/std/utilities/utility/pairs/pair.astuple/pairs.by.type.pass.cpp
+++ b/libcxx/test/std/utilities/utility/pairs/pair.astuple/pairs.by.type.pass.cpp
@@ -8,43 +8,77 @@
// UNSUPPORTED: c++03, c++11
-#include <utility>
-#include <string>
-#include <type_traits>
+#include <cassert>
#include <complex>
#include <memory>
-
-#include <cassert>
+#include <type_traits>
+#include <utility>
#include "test_macros.h"
-int main(int, char**)
-{
- typedef std::complex<float> cf;
+TEST_CONSTEXPR_CXX14 bool test() {
+ { // Make sure that references work as expected
+ int i = 1;
+ int j = 2;
+
{
- auto t1 = std::make_pair<int, cf> ( 42, { 1,2 } );
- assert ( std::get<int>(t1) == 42 );
- assert ( std::get<cf>(t1).real() == 1 );
- assert ( std::get<cf>(t1).imag() == 2 );
+ std::pair<int&, int&&> p(i, std::move(j));
+ assert(&std::get<int&>(p) == &i);
+ assert(&std::get<int&&>(p) == &j);
+
+ assert(&std::get<int&>(std::move(p)) == &i);
+ assert(std::get<int&&>(std::move(p)) == 2);
+
+ const std::pair<int&, int&&> cp(i, std::move(j));
+ assert(&std::get<int&>(cp) == &i);
+ assert(&std::get<int&&>(cp) == &j);
+
+ assert(&std::get<int&>(std::move(cp)) == &i);
+ assert(std::get<int&&>(std::move(cp)) == 2);
}
{
- const std::pair<int, const int> p1 { 1, 2 };
- const int &i1 = std::get<int>(p1);
- const int &i2 = std::get<const int>(p1);
- assert ( i1 == 1 );
- assert ( i2 == 2 );
+ std::pair<int&&, int&> p(std::move(i), j);
+ assert(&std::get<int&>(p) == &j);
+ assert(&std::get<int&&>(p) == &i);
+
+ assert(&std::get<int&>(std::move(p)) == &j);
+ assert(std::get<int&&>(std::move(p)) == 1);
+
+ const std::pair<int&&, int&> cp(std::move(i), j);
+ assert(&std::get<int&>(cp) == &j);
+ assert(&std::get<int&&>(cp) == &i);
+
+ assert(&std::get<int&>(std::move(cp)) == &j);
+ assert(std::get<int&&>(std::move(cp)) == 1);
}
+ }
- {
+ {
+ typedef std::complex<float> cf;
+ auto t1 = std::make_pair<int, cf>(42, {1, 2});
+ assert(std::get<int>(t1) == 42);
+ assert(std::get<cf>(t1).real() == 1);
+ assert(std::get<cf>(t1).imag() == 2);
+ }
+
+ {
+ const std::pair<int, const int> p1{1, 2};
+ const int& i1 = std::get<int>(p1);
+ const int& i2 = std::get<const int>(p1);
+ assert(i1 == 1);
+ assert(i2 == 2);
+ }
+
+ {
typedef std::unique_ptr<int> upint;
std::pair<upint, int> t(upint(new int(4)), 42);
upint p = std::get<upint>(std::move(t)); // get rvalue
assert(*p == 4);
assert(std::get<upint>(t) == nullptr); // has been moved from
- }
+ }
- {
+ {
typedef std::unique_ptr<int> upint;
const std::pair<upint, int> t(upint(new int(4)), 42);
static_assert(std::is_same<const upint&&, decltype(std::get<upint>(std::move(t)))>::value, "");
@@ -52,37 +86,46 @@ int main(int, char**)
static_assert(std::is_same<const int&&, decltype(std::get<int>(std::move(t)))>::value, "");
static_assert(noexcept(std::get<int>(std::move(t))), "");
auto&& p = std::get<upint>(std::move(t)); // get const rvalue
- auto&& i = std::get<int>(std::move(t)); // get const rvalue
+ auto&& i = std::get<int>(std::move(t)); // get const rvalue
assert(*p == 4);
assert(i == 42);
assert(std::get<upint>(t) != nullptr);
- }
+ }
- {
- int x = 42;
+ {
+ int x = 42;
int const y = 43;
std::pair<int&, int const&> const p(x, y);
static_assert(std::is_same<int&, decltype(std::get<int&>(std::move(p)))>::value, "");
static_assert(noexcept(std::get<int&>(std::move(p))), "");
static_assert(std::is_same<int const&, decltype(std::get<int const&>(std::move(p)))>::value, "");
static_assert(noexcept(std::get<int const&>(std::move(p))), "");
- }
+ }
- {
- int x = 42;
+ {
+ int x = 42;
int const y = 43;
std::pair<int&&, int const&&> const p(std::move(x), std::move(y));
static_assert(std::is_same<int&&, decltype(std::get<int&&>(std::move(p)))>::value, "");
static_assert(noexcept(std::get<int&&>(std::move(p))), "");
static_assert(std::is_same<int const&&, decltype(std::get<int const&&>(std::move(p)))>::value, "");
static_assert(noexcept(std::get<int const&&>(std::move(p))), "");
- }
+ }
- {
- constexpr const std::pair<int, const int> p { 1, 2 };
+ {
+ constexpr const std::pair<int, const int> p{1, 2};
static_assert(std::get<int>(std::move(p)) == 1, "");
static_assert(std::get<const int>(std::move(p)) == 2, "");
- }
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+#if TEST_STD_VER >= 14
+ static_assert(test(), "");
+#endif
return 0;
}
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