[libcxx-commits] [libcxx] [libc++][strings] P2591R5: Concatenation of strings and string views (PR #88389)
Hristo Hristov via libcxx-commits
libcxx-commits at lists.llvm.org
Sun May 5 02:30:02 PDT 2024
================
@@ -4003,6 +4044,69 @@ operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs) {
#endif // _LIBCPP_CXX03_LANG
+#if _LIBCPP_STD_VER >= 26
+
+template <class _CharT, class _Traits, class _Allocator>
+_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
+operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
+ type_identity_t<basic_string_view<_CharT, _Traits>> __rhs) {
+ using _String = basic_string<_CharT, _Traits, _Allocator>;
+ typename _String::size_type __lhs_sz = __lhs.size();
+ typename _String::size_type __rhs_sz = __rhs.size();
+ _String __r(__uninitialized_size_tag(),
+ __lhs_sz + __rhs_sz,
+ _String::__alloc_traits::select_on_container_copy_construction(__lhs.get_allocator()));
+ auto __ptr = std::__to_address(__r.__get_pointer());
+ _Traits::copy(__ptr, __lhs.data(), __lhs_sz);
+ _Traits::copy(__ptr + __lhs_sz, __rhs.data(), __rhs_sz);
+ _Traits::assign(__ptr + __lhs_sz + __rhs_sz, 1, _CharT());
+ return __r;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
+operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs,
+ type_identity_t<basic_string_view<_CharT, _Traits>> __rhs) {
+ __lhs.append(__rhs);
+ return std::move(__lhs);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
+operator+(type_identity_t<basic_string_view<_CharT, _Traits>> __lhs,
+ const basic_string<_CharT, _Traits, _Allocator>& __rhs) {
+ using _String = basic_string<_CharT, _Traits, _Allocator>;
+ typename _String::size_type __lhs_sz = __lhs.size();
+ typename _String::size_type __rhs_sz = __rhs.size();
+ _String __r(__uninitialized_size_tag(),
+ __lhs_sz + __rhs_sz,
+ _String::__alloc_traits::select_on_container_copy_construction(__rhs.get_allocator()));
+ auto __ptr = std::__to_address(__r.__get_pointer());
+ _Traits::copy(__ptr, __lhs.data(), __lhs_sz);
+ _Traits::copy(__ptr + __lhs_sz, __rhs.data(), __rhs_sz);
+ _Traits::assign(__ptr + __lhs_sz + __rhs_sz, 1, _CharT());
+ return __r;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
+operator+(type_identity_t<basic_string_view<_CharT, _Traits>> __lhs,
+ basic_string<_CharT, _Traits, _Allocator>&& __rhs) {
+ using _String = basic_string<_CharT, _Traits, _Allocator>;
+ typename _String::size_type __lhs_sz = __lhs.size();
+ typename _String::size_type __rhs_sz = __rhs.size();
+ _String __r(__uninitialized_size_tag(),
+ __lhs_sz + __rhs_sz,
+ _String::__alloc_traits::select_on_container_copy_construction(__rhs.get_allocator()));
+ auto __ptr = std::__to_address(__r.__get_pointer());
+ _Traits::copy(__ptr, __lhs.data(), __lhs_sz);
+ _Traits::copy(__ptr + __lhs_sz, __rhs.data(), __rhs_sz);
+ _Traits::assign(__ptr + __lhs_sz + __rhs_sz, 1, _CharT());
+ return __r;
----------------
Zingam wrote:
@frederick-vs-ja Thanks. I'll address the comments once the `constexpr_char_traits` fix is merged. I'll revert to the papers implementation.
https://github.com/llvm/llvm-project/pull/88389
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